From 54f4ca647b1e6a9fcb86b7decbc06c1bab1cf1e9 Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Mon, 10 Nov 2025 22:42:01 +0300
Subject: [PATCH 01/10] task 0 implement

---
 app/build.gradle                              |  3 +++
 app/src/main/AndroidManifest.xml              |  6 ++++++
 .../otus/gpb/homework/fragments/ActivityA.kt  | 11 ++++++++++
 .../otus/gpb/homework/fragments/ActivityB.kt  | 11 ++++++++++
 .../gpb/homework/fragments/MainActivity.kt    | 15 +++++++++++++-
 app/src/main/res/layout/activity_a.xml        | 13 ++++++++++++
 app/src/main/res/layout/activity_b.xml        | 15 ++++++++++++++
 app/src/main/res/layout/activity_main.xml     | 20 ++++++++++++++-----
 app/src/main/res/values/strings.xml           |  2 ++
 9 files changed, 90 insertions(+), 6 deletions(-)
 create mode 100644 app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
 create mode 100644 app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
 create mode 100644 app/src/main/res/layout/activity_a.xml
 create mode 100644 app/src/main/res/layout/activity_b.xml

diff --git a/app/build.gradle b/app/build.gradle
index c5cf1b8..d1802cb 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -34,6 +34,9 @@ android {
     kotlinOptions {
         jvmTarget = '17'
     }
+    buildFeatures {
+        viewBinding = true
+    }
 }
 
 dependencies {
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 9604b34..46bc072 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -12,6 +12,12 @@
         android:supportsRtl="true"
         android:theme="@style/Theme.Fragments"
         tools:targetApi="31">
+        <activity
+            android:name=".ActivityB"
+            android:exported="false" />
+        <activity
+            android:name=".ActivityA"
+            android:exported="false" />
         <activity
             android:name=".MainActivity"
             android:exported="true">
diff --git a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
new file mode 100644
index 0000000..bba9667
--- /dev/null
+++ b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
@@ -0,0 +1,11 @@
+package otus.gpb.homework.fragments
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+
+class ActivityA : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_a)
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt b/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
new file mode 100644
index 0000000..96b7bcb
--- /dev/null
+++ b/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
@@ -0,0 +1,11 @@
+package otus.gpb.homework.fragments
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+
+class ActivityB : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_b)
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/MainActivity.kt b/app/src/main/java/otus/gpb/homework/fragments/MainActivity.kt
index 5e89c44..0f6dab0 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/MainActivity.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/MainActivity.kt
@@ -1,12 +1,25 @@
 package otus.gpb.homework.fragments
 
+import android.content.Intent
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
+import otus.gpb.homework.fragments.databinding.ActivityMainBinding
 
 class MainActivity : AppCompatActivity() {
 
+    lateinit var binding: ActivityMainBinding
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_main)
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        binding.activityAButton.setOnClickListener {
+            startActivity(Intent(this, ActivityA::class.java))
+        }
+        binding.activityBButton.setOnClickListener {
+            startActivity(Intent(this, ActivityB::class.java))
+        }
+
+
     }
 }
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_a.xml b/app/src/main/res/layout/activity_a.xml
new file mode 100644
index 0000000..743824e
--- /dev/null
+++ b/app/src/main/res/layout/activity_a.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/main"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".ActivityA">
+
+<androidx.fragment.app.FragmentContainerView
+    android:id="@+id/fragment_container_a"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent" />
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_b.xml b/app/src/main/res/layout/activity_b.xml
new file mode 100644
index 0000000..4f04c7d
--- /dev/null
+++ b/app/src/main/res/layout/activity_b.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/main"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".ActivityB">
+
+    <androidx.fragment.app.FragmentContainerView
+        android:id="@+id/fragment_container_b"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 17eab17..a654977 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -6,13 +6,23 @@
     android:layout_height="match_parent"
     tools:context=".MainActivity">
 
-    <TextView
-        android:layout_width="wrap_content"
+    <Button
+        android:id="@+id/activity_a_button"
+        android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:text="Hello World!"
+        android:text="@string/activity_a_button_text"
+        app:layout_constraintBottom_toTopOf="@+id/activity_b_button"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintVertical_chainStyle="packed" />
+
+    <Button
+        android:id="@+id/activity_b_button"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/activity_b_button_text"
         app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintTop_toBottomOf="@+id/activity_a_button" />
 
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 34277aa..15240c1 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1,3 +1,5 @@
 <resources>
     <string name="app_name">Fragments</string>
+    <string name="activity_a_button_text">ActivityA</string>
+    <string name="activity_b_button_text">ActivityB</string>
 </resources>
\ No newline at end of file

From 1f4b855097ade292e06c59df0c880829e164c68b Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Mon, 10 Nov 2025 22:54:28 +0300
Subject: [PATCH 02/10] task 1.1 implement

---
 .../otus/gpb/homework/fragments/ActivityA.kt  | 10 ++++
 .../otus/gpb/homework/fragments/FragmentA.kt  | 59 +++++++++++++++++++
 .../gpb/homework/fragments/MainActivity.kt    |  3 +-
 app/src/main/res/layout/fragment_a.xml        | 14 +++++
 app/src/main/res/values/strings.xml           |  2 +
 5 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
 create mode 100644 app/src/main/res/layout/fragment_a.xml

diff --git a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
index bba9667..70441b9 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
@@ -4,8 +4,18 @@ import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
 
 class ActivityA : AppCompatActivity() {
+
+    private lateinit var activityA: FragmentA
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_a)
+        if (savedInstanceState == null) {
+            activityA = FragmentA()
+            supportFragmentManager.beginTransaction()
+                .replace(R.id.fragment_container_a, activityA, "fragmentA")
+                .commit()
+        }
+
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
new file mode 100644
index 0000000..9d2c4b9
--- /dev/null
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
@@ -0,0 +1,59 @@
+package otus.gpb.homework.fragments
+
+import android.os.Bundle
+import androidx.fragment.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+
+// TODO: Rename parameter arguments, choose names that match
+// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
+private const val ARG_PARAM1 = "param1"
+private const val ARG_PARAM2 = "param2"
+
+/**
+ * A simple [Fragment] subclass.
+ * Use the [FragmentA.newInstance] factory method to
+ * create an instance of this fragment.
+ */
+class FragmentA : Fragment() {
+    // TODO: Rename and change types of parameters
+    private var param1: String? = null
+    private var param2: String? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        arguments?.let {
+            param1 = it.getString(ARG_PARAM1)
+            param2 = it.getString(ARG_PARAM2)
+        }
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        // Inflate the layout for this fragment
+        return inflater.inflate(R.layout.fragment_a, container, false)
+    }
+
+    companion object {
+        /**
+         * Use this factory method to create a new instance of
+         * this fragment using the provided parameters.
+         *
+         * @param param1 Parameter 1.
+         * @param param2 Parameter 2.
+         * @return A new instance of fragment BlankFragment.
+         */
+        // TODO: Rename and change types and number of parameters
+        @JvmStatic
+        fun newInstance(param1: String, param2: String) =
+            FragmentA().apply {
+                arguments = Bundle().apply {
+                    putString(ARG_PARAM1, param1)
+                    putString(ARG_PARAM2, param2)
+                }
+            }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/MainActivity.kt b/app/src/main/java/otus/gpb/homework/fragments/MainActivity.kt
index 0f6dab0..44c284d 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/MainActivity.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/MainActivity.kt
@@ -7,7 +7,8 @@ import otus.gpb.homework.fragments.databinding.ActivityMainBinding
 
 class MainActivity : AppCompatActivity() {
 
-    lateinit var binding: ActivityMainBinding
+    private lateinit var binding: ActivityMainBinding
+
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
diff --git a/app/src/main/res/layout/fragment_a.xml b/app/src/main/res/layout/fragment_a.xml
new file mode 100644
index 0000000..aa3ae43
--- /dev/null
+++ b/app/src/main/res/layout/fragment_a.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".FragmentA">
+
+    <!-- TODO: Update blank fragment layout -->
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:text="@string/hello_blank_fragment" />
+
+</FrameLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 15240c1..85d7559 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -2,4 +2,6 @@
     <string name="app_name">Fragments</string>
     <string name="activity_a_button_text">ActivityA</string>
     <string name="activity_b_button_text">ActivityB</string>
+    <!-- TODO: Remove or change this placeholder text -->
+    <string name="hello_blank_fragment">Hello blank fragment</string>
 </resources>
\ No newline at end of file

From e8681c8930ca9ddcf57bee1694af85fe102aeb90 Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Tue, 11 Nov 2025 19:48:24 +0300
Subject: [PATCH 03/10] task 1.2 implement

---
 .../otus/gpb/homework/fragments/ActivityA.kt  | 13 ++--
 .../otus/gpb/homework/fragments/FragmentA.kt  | 74 ++++++++++---------
 .../otus/gpb/homework/fragments/FragmentAA.kt | 60 +++++++++++++++
 app/src/main/res/layout/activity_a.xml        |  2 +-
 app/src/main/res/layout/fragment_a.xml        | 26 +++++--
 app/src/main/res/layout/fragment_a_a.xml      | 15 ++++
 app/src/main/res/values/strings.xml           |  4 +-
 7 files changed, 144 insertions(+), 50 deletions(-)
 create mode 100644 app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
 create mode 100644 app/src/main/res/layout/fragment_a_a.xml

diff --git a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
index 70441b9..b5f3092 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
@@ -5,17 +5,20 @@ import androidx.appcompat.app.AppCompatActivity
 
 class ActivityA : AppCompatActivity() {
 
-    private lateinit var activityA: FragmentA
+    private lateinit var fragmentA: FragmentA
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_a)
         if (savedInstanceState == null) {
-            activityA = FragmentA()
-            supportFragmentManager.beginTransaction()
-                .replace(R.id.fragment_container_a, activityA, "fragmentA")
-                .commit()
+            fragmentA = FragmentA.newInstance()
+        } else {
+            fragmentA = supportFragmentManager.findFragmentByTag("fragmentA") as FragmentA
         }
+        supportFragmentManager.beginTransaction()
+            .replace(R.id.fragment_activity_a, fragmentA, "fragmentA")
+            .addToBackStack("fragmentA")
+            .commit()
 
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
index 9d2c4b9..bfdefd1 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
@@ -1,15 +1,12 @@
 package otus.gpb.homework.fragments
 
 import android.os.Bundle
-import androidx.fragment.app.Fragment
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import otus.gpb.homework.fragments.databinding.FragmentABinding
 
-// TODO: Rename parameter arguments, choose names that match
-// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
-private const val ARG_PARAM1 = "param1"
-private const val ARG_PARAM2 = "param2"
 
 /**
  * A simple [Fragment] subclass.
@@ -17,43 +14,48 @@ private const val ARG_PARAM2 = "param2"
  * create an instance of this fragment.
  */
 class FragmentA : Fragment() {
-    // TODO: Rename and change types of parameters
-    private var param1: String? = null
-    private var param2: String? = null
-
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-        arguments?.let {
-            param1 = it.getString(ARG_PARAM1)
-            param2 = it.getString(ARG_PARAM2)
-        }
-    }
+    private var _binding: FragmentABinding? = null
+
+    // This property is only valid between onCreateView and
+    // onDestroyView.
+    private val binding get() = _binding!!
+
+    private lateinit var fragmentAA: FragmentAA
 
     override fun onCreateView(
-        inflater: LayoutInflater, container: ViewGroup?,
+        inflater: LayoutInflater,
+        container: ViewGroup?,
         savedInstanceState: Bundle?
-    ): View? {
-        // Inflate the layout for this fragment
-        return inflater.inflate(R.layout.fragment_a, container, false)
+    ): View {
+        _binding = FragmentABinding.inflate(inflater, container, false)
+        val root: View = binding.root
+        return root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        fragmentAA = if (savedInstanceState == null) {
+            FragmentAA.newInstance(ColorGenerator.generateColor())
+        } else {
+            childFragmentManager.findFragmentByTag("fragmentA") as FragmentAA
+        }
+        with(binding) {
+            fragmentAAButton.setOnClickListener {
+                childFragmentManager.beginTransaction()
+                    .replace(R.id.fragment_a_container, fragmentAA)
+                    .addToBackStack("fragmentA")
+                    .commit()
+            }
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
     }
 
     companion object {
-        /**
-         * Use this factory method to create a new instance of
-         * this fragment using the provided parameters.
-         *
-         * @param param1 Parameter 1.
-         * @param param2 Parameter 2.
-         * @return A new instance of fragment BlankFragment.
-         */
-        // TODO: Rename and change types and number of parameters
         @JvmStatic
-        fun newInstance(param1: String, param2: String) =
-            FragmentA().apply {
-                arguments = Bundle().apply {
-                    putString(ARG_PARAM1, param1)
-                    putString(ARG_PARAM2, param2)
-                }
-            }
+        fun newInstance() = FragmentA()
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
new file mode 100644
index 0000000..3be1778
--- /dev/null
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
@@ -0,0 +1,60 @@
+package otus.gpb.homework.fragments
+
+import android.graphics.Color
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import otus.gpb.homework.fragments.databinding.FragmentAABinding
+
+private const val COLOR_ARG_PARAM = "color"
+
+/**
+ * A simple [Fragment] subclass.
+ * Use the [FragmentAA.newInstance] factory method to
+ * create an instance of this fragment.
+ */
+class FragmentAA : Fragment() {
+
+    private var _binding: FragmentAABinding? = null
+
+    // This property is only valid between onCreateView and
+    // onDestroyView.
+    private val binding get() = _binding!!
+
+
+    private var color: Int = Color.CYAN
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        arguments?.let {
+            color = it.getInt(COLOR_ARG_PARAM)
+        }
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentAABinding.inflate(inflater, container, false)
+        val root: View = binding.root
+        binding.root.setBackgroundColor(color)
+        return root
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+
+    companion object {
+        @JvmStatic
+        fun newInstance(param1: Int) =
+            FragmentAA().apply {
+                arguments = Bundle().apply {
+                    putInt(COLOR_ARG_PARAM, param1)
+                }
+            }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_a.xml b/app/src/main/res/layout/activity_a.xml
index 743824e..f455fc1 100644
--- a/app/src/main/res/layout/activity_a.xml
+++ b/app/src/main/res/layout/activity_a.xml
@@ -7,7 +7,7 @@
     tools:context=".ActivityA">
 
 <androidx.fragment.app.FragmentContainerView
-    android:id="@+id/fragment_container_a"
+    android:id="@+id/fragment_activity_a"
     android:layout_width="match_parent"
     android:layout_height="match_parent" />
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_a.xml b/app/src/main/res/layout/fragment_a.xml
index aa3ae43..3080e2b 100644
--- a/app/src/main/res/layout/fragment_a.xml
+++ b/app/src/main/res/layout/fragment_a.xml
@@ -1,14 +1,28 @@
 <?xml version="1.0" encoding="utf-8"?>
-<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context=".FragmentA">
 
-    <!-- TODO: Update blank fragment layout -->
-    <TextView
+    <Button
+        android:id="@+id/fragment_a_a_button"
         android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        android:text="@string/hello_blank_fragment" />
+        android:layout_height="wrap_content"
+        android:text="@string/fragment_aa_button_text"
+        app:layout_constraintBottom_toTopOf="@+id/fragment_a_container"
+        app:layout_constraintTop_toTopOf="parent" />
 
-</FrameLayout>
\ No newline at end of file
+    <FrameLayout
+        android:id="@+id/fragment_a_container"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/fragment_a_a_button"
+        tools:layout_editor_absoluteX="0dp">
+
+
+    </FrameLayout>
+
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_a_a.xml b/app/src/main/res/layout/fragment_a_a.xml
new file mode 100644
index 0000000..f3b529b
--- /dev/null
+++ b/app/src/main/res/layout/fragment_a_a.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    tools:context=".FragmentAA">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:textAlignment="center"
+        android:text="@string/hello_blank_fragment" />
+
+</FrameLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 85d7559..33f64fa 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -2,6 +2,6 @@
     <string name="app_name">Fragments</string>
     <string name="activity_a_button_text">ActivityA</string>
     <string name="activity_b_button_text">ActivityB</string>
-    <!-- TODO: Remove or change this placeholder text -->
-    <string name="hello_blank_fragment">Hello blank fragment</string>
+    <string name="fragment_aa_button_text">FragmentAA</string>
+    <string name="hello_blank_fragment">Hello FragmentAA</string>
 </resources>
\ No newline at end of file

From ce401635aa1d75b2b833caf4650efde35175b0ae Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Tue, 11 Nov 2025 20:20:24 +0300
Subject: [PATCH 04/10] task 1.3 implement

---
 .../otus/gpb/homework/fragments/FragmentAA.kt | 20 ++++++-
 .../otus/gpb/homework/fragments/FragmentAB.kt | 59 +++++++++++++++++++
 app/src/main/res/layout/fragment_a.xml        |  2 -
 app/src/main/res/layout/fragment_a_a.xml      | 28 +++++++--
 app/src/main/res/layout/fragment_a_b.xml      | 14 +++++
 app/src/main/res/values/strings.xml           | 10 ++--
 6 files changed, 121 insertions(+), 12 deletions(-)
 create mode 100644 app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
 create mode 100644 app/src/main/res/layout/fragment_a_b.xml

diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
index 3be1778..7358220 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
@@ -8,7 +8,7 @@ import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import otus.gpb.homework.fragments.databinding.FragmentAABinding
 
-private const val COLOR_ARG_PARAM = "color"
+const val COLOR_ARG_PARAM = "color"
 
 /**
  * A simple [Fragment] subclass.
@@ -23,6 +23,7 @@ class FragmentAA : Fragment() {
     // onDestroyView.
     private val binding get() = _binding!!
 
+    private lateinit var fragmentAB: FragmentAB
 
     private var color: Int = Color.CYAN
 
@@ -43,6 +44,23 @@ class FragmentAA : Fragment() {
         return root
     }
 
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        fragmentAB = if (savedInstanceState == null) {
+            FragmentAB.newInstance(ColorGenerator.generateColor())
+        } else {
+            childFragmentManager.findFragmentByTag("fragmentA") as FragmentAB
+        }
+        with(binding) {
+            fragmentAAButton.setOnClickListener {
+                childFragmentManager.beginTransaction()
+                    .replace(R.id.fragment_a_container, fragmentAB)
+                    .addToBackStack("fragmentA")
+                    .commit()
+            }
+        }
+    }
+
     override fun onDestroyView() {
         super.onDestroyView()
         _binding = null
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
new file mode 100644
index 0000000..f3e450f
--- /dev/null
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
@@ -0,0 +1,59 @@
+package otus.gpb.homework.fragments
+
+import android.graphics.Color
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import otus.gpb.homework.fragments.databinding.FragmentABBinding
+
+
+/**
+ * A simple [Fragment] subclass.
+ * Use the [FragmentAB.newInstance] factory method to
+ * create an instance of this fragment.
+ */
+class FragmentAB : Fragment() {
+
+
+    private var _binding: FragmentABBinding? = null
+
+    // This property is only valid between onCreateView and
+    // onDestroyView.
+    private val binding get() = _binding!!
+
+    private var color: Int = Color.CYAN
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        arguments?.let {
+            color = it.getInt(COLOR_ARG_PARAM)
+        }
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentABBinding.inflate(inflater, container, false)
+        val root: View = binding.root
+        binding.root.setBackgroundColor(color)
+        return root
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+
+    companion object {
+        @JvmStatic
+        fun newInstance(param1: Int) =
+            FragmentAB().apply {
+                arguments = Bundle().apply {
+                    putInt(COLOR_ARG_PARAM, param1)
+                }
+            }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_a.xml b/app/src/main/res/layout/fragment_a.xml
index 3080e2b..bd04756 100644
--- a/app/src/main/res/layout/fragment_a.xml
+++ b/app/src/main/res/layout/fragment_a.xml
@@ -21,8 +21,6 @@
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/fragment_a_a_button"
         tools:layout_editor_absoluteX="0dp">
-
-
     </FrameLayout>
 
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_a_a.xml b/app/src/main/res/layout/fragment_a_a.xml
index f3b529b..f5ac899 100644
--- a/app/src/main/res/layout/fragment_a_a.xml
+++ b/app/src/main/res/layout/fragment_a_a.xml
@@ -1,15 +1,33 @@
 <?xml version="1.0" encoding="utf-8"?>
-<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
     tools:context=".FragmentAA">
 
     <TextView
+        android:id="@id/fragment_a_a_text"
         android:layout_width="match_parent"
-        android:layout_height="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/hello_blank_fragment_a_a"
         android:textAlignment="center"
-        android:text="@string/hello_blank_fragment" />
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <Button
+        android:id="@+id/fragment_a_a_button"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/fragment_ab_button_text"
+        app:layout_constraintBottom_toTopOf="@+id/fragment_a_container"
+        app:layout_constraintTop_toBottomOf="@+id/fragment_a_a_text" />
+
+    <FrameLayout
+        android:id="@+id/fragment_a_container"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/fragment_a_a_button"/>
+
 
-</FrameLayout>
\ No newline at end of file
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_a_b.xml b/app/src/main/res/layout/fragment_a_b.xml
new file mode 100644
index 0000000..6382af1
--- /dev/null
+++ b/app/src/main/res/layout/fragment_a_b.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".FragmentAB">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:text="@string/hello_blank_fragment_a_b"
+        android:textAlignment="center" />
+
+</FrameLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 33f64fa..3a9dde6 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1,7 +1,9 @@
 <resources>
     <string name="app_name">Fragments</string>
-    <string name="activity_a_button_text">ActivityA</string>
-    <string name="activity_b_button_text">ActivityB</string>
-    <string name="fragment_aa_button_text">FragmentAA</string>
-    <string name="hello_blank_fragment">Hello FragmentAA</string>
+    <string name="activity_a_button_text">Activity A</string>
+    <string name="activity_b_button_text">Activity B</string>
+    <string name="fragment_aa_button_text">Fragment AA</string>
+    <string name="fragment_ab_button_text">Fragment AB</string>
+    <string name="hello_blank_fragment_a_a">Hello Fragment AA</string>
+    <string name="hello_blank_fragment_a_b">Hello Fragment AB</string>
 </resources>
\ No newline at end of file

From 1af4c283fa14b9676fbb5055b9212e3a6304735d Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Tue, 11 Nov 2025 21:11:21 +0300
Subject: [PATCH 05/10] task 1.4 implement (need help)

---
 .../otus/gpb/homework/fragments/ActivityA.kt  | 13 +++++---
 .../otus/gpb/homework/fragments/FragmentA.kt  | 30 +++++++++++++++--
 .../otus/gpb/homework/fragments/FragmentAA.kt | 32 +++++++++++++++++--
 .../otus/gpb/homework/fragments/FragmentAB.kt | 26 +++++++++++++++
 app/src/main/res/layout/fragment_a.xml        | 14 +++++---
 app/src/main/res/layout/fragment_a_a.xml      |  4 +--
 app/src/main/res/values/strings.xml           |  1 +
 7 files changed, 105 insertions(+), 15 deletions(-)

diff --git a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
index b5f3092..dc843ae 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
@@ -2,18 +2,23 @@ package otus.gpb.homework.fragments
 
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
+import otus.gpb.homework.fragments.databinding.ActivityABinding
 
 class ActivityA : AppCompatActivity() {
 
+
+    private lateinit var binding: ActivityABinding
+
     private lateinit var fragmentA: FragmentA
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_a)
-        if (savedInstanceState == null) {
-            fragmentA = FragmentA.newInstance()
+        binding = ActivityABinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        fragmentA = if (savedInstanceState == null) {
+            FragmentA.newInstance()
         } else {
-            fragmentA = supportFragmentManager.findFragmentByTag("fragmentA") as FragmentA
+            supportFragmentManager.findFragmentByTag("fragmentA") as FragmentA
         }
         supportFragmentManager.beginTransaction()
             .replace(R.id.fragment_activity_a, fragmentA, "fragmentA")
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
index bfdefd1..0692001 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
@@ -1,9 +1,12 @@
 package otus.gpb.homework.fragments
 
+import android.content.Context
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.Toast
+import androidx.activity.OnBackPressedCallback
 import androidx.fragment.app.Fragment
 import otus.gpb.homework.fragments.databinding.FragmentABinding
 
@@ -22,6 +25,29 @@ class FragmentA : Fragment() {
 
     private lateinit var fragmentAA: FragmentAA
 
+    override fun onAttach(context: Context) {
+        super.onAttach(context)
+
+        val onBackPressedCallback = object : OnBackPressedCallback(true) {
+            override fun handleOnBackPressed() {
+                val backStackEntryCount = childFragmentManager.backStackEntryCount
+                Toast.makeText(
+                    context,
+                    "FragmentA back stack entry count: $backStackEntryCount",
+                    Toast.LENGTH_SHORT
+                ).show()
+                if (backStackEntryCount > 0) {
+                    childFragmentManager.popBackStack()
+                } else {
+                    isEnabled = false
+                    requireActivity().onBackPressedDispatcher.onBackPressed()
+                }
+            }
+        }
+
+        requireActivity().onBackPressedDispatcher.addCallback(onBackPressedCallback)
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -37,12 +63,12 @@ class FragmentA : Fragment() {
         fragmentAA = if (savedInstanceState == null) {
             FragmentAA.newInstance(ColorGenerator.generateColor())
         } else {
-            childFragmentManager.findFragmentByTag("fragmentA") as FragmentAA
+            childFragmentManager.findFragmentByTag("fragmentAA") as FragmentAA
         }
         with(binding) {
             fragmentAAButton.setOnClickListener {
                 childFragmentManager.beginTransaction()
-                    .replace(R.id.fragment_a_container, fragmentAA)
+                    .replace(R.id.fragment_a_container, fragmentAA, "fragmentAA")
                     .addToBackStack("fragmentA")
                     .commit()
             }
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
index 7358220..08bb26d 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
@@ -1,10 +1,13 @@
 package otus.gpb.homework.fragments
 
+import android.content.Context
 import android.graphics.Color
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.Toast
+import androidx.activity.OnBackPressedCallback
 import androidx.fragment.app.Fragment
 import otus.gpb.homework.fragments.databinding.FragmentAABinding
 
@@ -27,6 +30,29 @@ class FragmentAA : Fragment() {
 
     private var color: Int = Color.CYAN
 
+    override fun onAttach(context: Context) {
+        super.onAttach(context)
+
+        val callback = object : OnBackPressedCallback(true) {
+            override fun handleOnBackPressed() {
+                val backStackEntryCount = childFragmentManager.backStackEntryCount
+                Toast.makeText(
+                    context,
+                    "FragmentAA back stack entry count: $backStackEntryCount",
+                    Toast.LENGTH_SHORT
+                ).show()
+                if (backStackEntryCount > 0) {
+                    childFragmentManager.popBackStack()
+                } else {
+                    isEnabled = false
+                    requireActivity().onBackPressedDispatcher.onBackPressed()
+                }
+            }
+        }
+
+        requireActivity().onBackPressedDispatcher.addCallback(callback)
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         arguments?.let {
@@ -49,12 +75,12 @@ class FragmentAA : Fragment() {
         fragmentAB = if (savedInstanceState == null) {
             FragmentAB.newInstance(ColorGenerator.generateColor())
         } else {
-            childFragmentManager.findFragmentByTag("fragmentA") as FragmentAB
+            childFragmentManager.findFragmentByTag("fragmentAB") as FragmentAB
         }
         with(binding) {
-            fragmentAAButton.setOnClickListener {
+            fragmentABButton.setOnClickListener {
                 childFragmentManager.beginTransaction()
-                    .replace(R.id.fragment_a_container, fragmentAB)
+                    .replace(R.id.fragment_a_container, fragmentAB, "fragmentAB")
                     .addToBackStack("fragmentA")
                     .commit()
             }
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
index f3e450f..5a680f6 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
@@ -1,10 +1,13 @@
 package otus.gpb.homework.fragments
 
+import android.content.Context
 import android.graphics.Color
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.Toast
+import androidx.activity.OnBackPressedCallback
 import androidx.fragment.app.Fragment
 import otus.gpb.homework.fragments.databinding.FragmentABBinding
 
@@ -25,6 +28,29 @@ class FragmentAB : Fragment() {
 
     private var color: Int = Color.CYAN
 
+    override fun onAttach(context: Context) {
+        super.onAttach(context)
+
+        val callback = object : OnBackPressedCallback(true) {
+            override fun handleOnBackPressed() {
+                val backStackEntryCount = childFragmentManager.backStackEntryCount
+                Toast.makeText(
+                    context,
+                    "FragmentAB back stack entry count: $backStackEntryCount",
+                    Toast.LENGTH_SHORT
+                ).show()
+                if (backStackEntryCount > 0) {
+                    childFragmentManager.popBackStack()
+                } else {
+                    isEnabled = false
+                    requireActivity().onBackPressedDispatcher.onBackPressed()
+                }
+            }
+        }
+
+        requireActivity().onBackPressedDispatcher.addCallback(callback)
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         arguments?.let {
diff --git a/app/src/main/res/layout/fragment_a.xml b/app/src/main/res/layout/fragment_a.xml
index bd04756..a7144be 100644
--- a/app/src/main/res/layout/fragment_a.xml
+++ b/app/src/main/res/layout/fragment_a.xml
@@ -6,21 +6,27 @@
     android:layout_height="match_parent"
     tools:context=".FragmentA">
 
+    <TextView
+        android:id="@id/fragment_a_text"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/hello_blank_fragment_a"
+        android:textAlignment="center"
+        app:layout_constraintTop_toTopOf="parent" />
+
     <Button
         android:id="@+id/fragment_a_a_button"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="@string/fragment_aa_button_text"
         app:layout_constraintBottom_toTopOf="@+id/fragment_a_container"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintTop_toBottomOf="@+id/fragment_a_text" />
 
     <FrameLayout
         android:id="@+id/fragment_a_container"
         android:layout_width="match_parent"
         android:layout_height="0dp"
         app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/fragment_a_a_button"
-        tools:layout_editor_absoluteX="0dp">
-    </FrameLayout>
+        app:layout_constraintTop_toBottomOf="@+id/fragment_a_a_button" />
 
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_a_a.xml b/app/src/main/res/layout/fragment_a_a.xml
index f5ac899..86eb74e 100644
--- a/app/src/main/res/layout/fragment_a_a.xml
+++ b/app/src/main/res/layout/fragment_a_a.xml
@@ -15,7 +15,7 @@
         app:layout_constraintTop_toTopOf="parent" />
 
     <Button
-        android:id="@+id/fragment_a_a_button"
+        android:id="@+id/fragment_a_b_button"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="@string/fragment_ab_button_text"
@@ -27,7 +27,7 @@
         android:layout_width="match_parent"
         android:layout_height="0dp"
         app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/fragment_a_a_button"/>
+        app:layout_constraintTop_toBottomOf="@+id/fragment_a_b_button" />
 
 
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 3a9dde6..2e356c9 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -4,6 +4,7 @@
     <string name="activity_b_button_text">Activity B</string>
     <string name="fragment_aa_button_text">Fragment AA</string>
     <string name="fragment_ab_button_text">Fragment AB</string>
+    <string name="hello_blank_fragment_a">Hello Fragment A</string>
     <string name="hello_blank_fragment_a_a">Hello Fragment AA</string>
     <string name="hello_blank_fragment_a_b">Hello Fragment AB</string>
 </resources>
\ No newline at end of file

From bdcaadf0ff43d06b4702b550fafdadc5e45b07ba Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Wed, 12 Nov 2025 10:02:54 +0300
Subject: [PATCH 06/10] task 2.1 implement

---
 app/build.gradle                              |  1 +
 .../otus/gpb/homework/fragments/ActivityB.kt  | 39 ++++++++++++++++-
 .../otus/gpb/homework/fragments/FragmentBA.kt | 42 ++++++++++++++++++
 .../otus/gpb/homework/fragments/FragmentBB.kt | 43 +++++++++++++++++++
 .../gpb/homework/fragments/utils/Consts.kt    |  5 +++
 .../main/res/layout-sw600dp/activity_b.xml    | 21 +++++++++
 .../main/res/layout-sw600dp/fragment_b_b.xml  | 26 +++++++++++
 app/src/main/res/layout/activity_b.xml        |  9 ++--
 app/src/main/res/layout/fragment_b_a.xml      | 17 ++++++++
 app/src/main/res/layout/fragment_b_b.xml      | 18 ++++++++
 app/src/main/res/values-sw600dp/bool.xml      |  4 ++
 app/src/main/res/values/bool.xml              |  4 ++
 app/src/main/res/values/strings.xml           |  3 ++
 13 files changed, 227 insertions(+), 5 deletions(-)
 create mode 100644 app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
 create mode 100644 app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
 create mode 100644 app/src/main/java/otus/gpb/homework/fragments/utils/Consts.kt
 create mode 100644 app/src/main/res/layout-sw600dp/activity_b.xml
 create mode 100644 app/src/main/res/layout-sw600dp/fragment_b_b.xml
 create mode 100644 app/src/main/res/layout/fragment_b_a.xml
 create mode 100644 app/src/main/res/layout/fragment_b_b.xml
 create mode 100644 app/src/main/res/values-sw600dp/bool.xml
 create mode 100644 app/src/main/res/values/bool.xml

diff --git a/app/build.gradle b/app/build.gradle
index d1802cb..fc2be4a 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -42,6 +42,7 @@ android {
 dependencies {
 
     implementation 'androidx.core:core-ktx:1.7.0'
+    implementation("androidx.fragment:fragment-ktx:1.7.0")
     implementation 'androidx.appcompat:appcompat:1.5.1'
     implementation 'com.google.android.material:material:1.6.1'
     implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
diff --git a/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt b/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
index 96b7bcb..53aaba5 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
@@ -2,10 +2,47 @@ package otus.gpb.homework.fragments
 
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
+import otus.gpb.homework.fragments.databinding.ActivityBBinding
 
 class ActivityB : AppCompatActivity() {
+
+    private lateinit var binding: ActivityBBinding
+
+    private lateinit var fragmentBA: FragmentBA
+    private lateinit var fragmentBB: FragmentBB
+
+    private val isTablet by lazy { resources.getBoolean(R.bool.is_tablet) }
+
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_b)
+        binding = ActivityBBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        if (isTablet) {
+            fragmentBA = savedInstanceState
+                ?.let { supportFragmentManager.findFragmentByTag(FragmentBA::class.simpleName) as? FragmentBA }
+                ?: FragmentBA()
+
+            fragmentBB = savedInstanceState
+                ?.let { supportFragmentManager.findFragmentByTag(FragmentBB::class.simpleName) as? FragmentBB }
+                ?: FragmentBB()
+
+            supportFragmentManager.beginTransaction()
+                .replace(R.id.fragment_b_a_container, fragmentBA, FragmentBA::class.simpleName)
+                .replace(R.id.fragment_b_b_container, fragmentBB, FragmentBB::class.simpleName)
+                .commit()
+        } else {
+            fragmentBA = savedInstanceState
+                ?.let { supportFragmentManager.findFragmentByTag(FragmentBA::class.simpleName) as? FragmentBA }
+                ?: FragmentBA()
+            supportFragmentManager.beginTransaction()
+                .replace(R.id.fragment_b_a_container, fragmentBA, FragmentBA::class.simpleName)
+                .commit()
+        }
+
+
     }
+
+
 }
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
new file mode 100644
index 0000000..64871ae
--- /dev/null
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
@@ -0,0 +1,42 @@
+package otus.gpb.homework.fragments
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.setFragmentResultListener
+import otus.gpb.homework.fragments.databinding.FragmentBABinding
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY
+
+
+class FragmentBA : Fragment() {
+    private var _binding: FragmentBABinding? = null
+    private val binding get() = _binding!!
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentBABinding.inflate(inflater, container, false)
+        val root: View = binding.root
+        return root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        setFragmentResultListener(COLOR_RESULT_KEY) { _, bundle ->
+            val color: Int = bundle.getInt(COLOR_RESULT_BUNDLE_KEY)
+            binding.root.setBackgroundColor(color)
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+
+
+}
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
new file mode 100644
index 0000000..bba2ca2
--- /dev/null
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
@@ -0,0 +1,43 @@
+package otus.gpb.homework.fragments
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.core.os.bundleOf
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.setFragmentResult
+import otus.gpb.homework.fragments.databinding.FragmentBBBinding
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY
+
+class FragmentBB : Fragment() {
+    private var _binding: FragmentBBBinding? = null
+
+    private val binding get() = _binding!!
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentBBBinding.inflate(inflater, container, false)
+        val root: View = binding.root
+        return root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        binding.fragmentBBButton?.setOnClickListener {
+            setFragmentResult(
+                COLOR_RESULT_KEY,
+                bundleOf(COLOR_RESULT_BUNDLE_KEY to ColorGenerator.generateColor())
+            )
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/utils/Consts.kt b/app/src/main/java/otus/gpb/homework/fragments/utils/Consts.kt
new file mode 100644
index 0000000..fe45822
--- /dev/null
+++ b/app/src/main/java/otus/gpb/homework/fragments/utils/Consts.kt
@@ -0,0 +1,5 @@
+package otus.gpb.homework.fragments.utils
+
+
+const val COLOR_RESULT_KEY = "color_result"
+const val COLOR_RESULT_BUNDLE_KEY = "color_result_bundle"
\ No newline at end of file
diff --git a/app/src/main/res/layout-sw600dp/activity_b.xml b/app/src/main/res/layout-sw600dp/activity_b.xml
new file mode 100644
index 0000000..e2356e9
--- /dev/null
+++ b/app/src/main/res/layout-sw600dp/activity_b.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/main"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    tools:context=".ActivityB">
+
+    <FrameLayout
+        android:id="@+id/fragment_b_a_container"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_weight="1" />
+
+    <FrameLayout
+        android:id="@+id/fragment_b_b_container"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_weight="1" />
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout-sw600dp/fragment_b_b.xml b/app/src/main/res/layout-sw600dp/fragment_b_b.xml
new file mode 100644
index 0000000..67e85e2
--- /dev/null
+++ b/app/src/main/res/layout-sw600dp/fragment_b_b.xml
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".FragmentBB">
+
+    <TextView
+        android:id="@+id/fragment_b_b_text"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/hello_blank_fragment_b_b"
+        android:textAlignment="center"
+        app:layout_constraintBottom_toBottomOf="@id/fragment_b_b_button"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <Button
+        android:id="@+id/fragment_b_b_button"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/fragment_b_b_button_text"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/fragment_b_b_text" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_b.xml b/app/src/main/res/layout/activity_b.xml
index 4f04c7d..6f519fd 100644
--- a/app/src/main/res/layout/activity_b.xml
+++ b/app/src/main/res/layout/activity_b.xml
@@ -7,9 +7,10 @@
     android:layout_height="match_parent"
     tools:context=".ActivityB">
 
-    <androidx.fragment.app.FragmentContainerView
-        android:id="@+id/fragment_container_b"
+    <FrameLayout
+        android:id="@+id/fragment_b_a_container"
         android:layout_width="match_parent"
-        android:layout_height="match_parent" />
-
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_b_a.xml b/app/src/main/res/layout/fragment_b_a.xml
new file mode 100644
index 0000000..787c55e
--- /dev/null
+++ b/app/src/main/res/layout/fragment_b_a.xml
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    tools:context=".FragmentBA">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:textAlignment="center"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        android:text="@string/hello_blank_fragment_b_a" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_b_b.xml b/app/src/main/res/layout/fragment_b_b.xml
new file mode 100644
index 0000000..8e06850
--- /dev/null
+++ b/app/src/main/res/layout/fragment_b_b.xml
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".FragmentBB">
+
+    <TextView
+        android:id="@+id/fragment_b_b_text"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/hello_blank_fragment_b_b"
+        android:textAlignment="center"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values-sw600dp/bool.xml b/app/src/main/res/values-sw600dp/bool.xml
new file mode 100644
index 0000000..5fc3a0d
--- /dev/null
+++ b/app/src/main/res/values-sw600dp/bool.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <bool name="is_tablet">true</bool>
+</resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/bool.xml b/app/src/main/res/values/bool.xml
new file mode 100644
index 0000000..84d7d2f
--- /dev/null
+++ b/app/src/main/res/values/bool.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <bool name="is_tablet">false</bool>
+</resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 2e356c9..0ad422c 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -7,4 +7,7 @@
     <string name="hello_blank_fragment_a">Hello Fragment A</string>
     <string name="hello_blank_fragment_a_a">Hello Fragment AA</string>
     <string name="hello_blank_fragment_a_b">Hello Fragment AB</string>
+    <string name="hello_blank_fragment_b_a">Hello Fragment BA</string>
+    <string name="hello_blank_fragment_b_b">Hello Fragment BB</string>
+    <string name="fragment_b_b_button_text">Change BA color</string>
 </resources>
\ No newline at end of file

From 818fac3158d432255b421ffc928892709de12dcd Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Wed, 12 Nov 2025 14:34:33 +0300
Subject: [PATCH 07/10] task 2.2 implement

---
 .../otus/gpb/homework/fragments/FragmentBA.kt | 31 ++++++++++++++++---
 .../otus/gpb/homework/fragments/FragmentBB.kt | 17 +++++++---
 .../gpb/homework/fragments/utils/Consts.kt    |  9 ++++--
 .../main/res/layout-sw600dp/fragment_b_a.xml  | 17 ++++++++++
 app/src/main/res/layout/fragment_b_a.xml      | 20 +++++++-----
 app/src/main/res/layout/fragment_b_b.xml      |  2 +-
 app/src/main/res/values/strings.xml           |  1 +
 7 files changed, 79 insertions(+), 18 deletions(-)
 create mode 100644 app/src/main/res/layout-sw600dp/fragment_b_a.xml

diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
index 64871ae..1ff0266 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
@@ -4,17 +4,23 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import androidx.core.os.bundleOf
 import androidx.fragment.app.Fragment
+import androidx.fragment.app.setFragmentResult
 import androidx.fragment.app.setFragmentResultListener
 import otus.gpb.homework.fragments.databinding.FragmentBABinding
-import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY
-import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY_BA_TO_BB
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY_BB_TO_BA
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY_BA_TO_BB
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY_BB_TO_BA
 
 
 class FragmentBA : Fragment() {
     private var _binding: FragmentBABinding? = null
     private val binding get() = _binding!!
 
+    private lateinit var fragmentBB: FragmentBB
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -27,10 +33,27 @@ class FragmentBA : Fragment() {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        setFragmentResultListener(COLOR_RESULT_KEY) { _, bundle ->
-            val color: Int = bundle.getInt(COLOR_RESULT_BUNDLE_KEY)
+        fragmentBB = if (savedInstanceState == null) {
+            FragmentBB()
+        } else {
+            childFragmentManager.getFragment(savedInstanceState, "fragmentBB") as FragmentBB
+        }
+        setFragmentResultListener(COLOR_RESULT_KEY_BB_TO_BA) { _, bundle ->
+            val color: Int = bundle.getInt(COLOR_RESULT_BUNDLE_KEY_BB_TO_BA)
             binding.root.setBackgroundColor(color)
         }
+
+        binding.fragmentBBButton?.setOnClickListener {
+            setFragmentResult(
+                COLOR_RESULT_KEY_BA_TO_BB,
+                bundleOf(COLOR_RESULT_BUNDLE_KEY_BA_TO_BB to ColorGenerator.generateColor())
+            )
+
+            parentFragmentManager.beginTransaction()
+                .replace(R.id.fragment_b_a_container, fragmentBB)
+                .commit()
+        }
+
     }
 
     override fun onDestroyView() {
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
index bba2ca2..84e9896 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
@@ -7,9 +7,12 @@ import android.view.ViewGroup
 import androidx.core.os.bundleOf
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.setFragmentResult
+import androidx.fragment.app.setFragmentResultListener
 import otus.gpb.homework.fragments.databinding.FragmentBBBinding
-import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY
-import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY_BA_TO_BB
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY_BB_TO_BA
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY_BA_TO_BB
+import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY_BB_TO_BA
 
 class FragmentBB : Fragment() {
     private var _binding: FragmentBBBinding? = null
@@ -28,10 +31,16 @@ class FragmentBB : Fragment() {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
+
+        setFragmentResultListener(COLOR_RESULT_KEY_BA_TO_BB) { _, bundle ->
+            val color = bundle.getInt(COLOR_RESULT_BUNDLE_KEY_BA_TO_BB)
+            binding.root.setBackgroundColor(color)
+        }
+
         binding.fragmentBBButton?.setOnClickListener {
             setFragmentResult(
-                COLOR_RESULT_KEY,
-                bundleOf(COLOR_RESULT_BUNDLE_KEY to ColorGenerator.generateColor())
+                COLOR_RESULT_KEY_BB_TO_BA,
+                bundleOf(COLOR_RESULT_BUNDLE_KEY_BB_TO_BA to ColorGenerator.generateColor())
             )
         }
     }
diff --git a/app/src/main/java/otus/gpb/homework/fragments/utils/Consts.kt b/app/src/main/java/otus/gpb/homework/fragments/utils/Consts.kt
index fe45822..fd5e4e0 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/utils/Consts.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/utils/Consts.kt
@@ -1,5 +1,10 @@
 package otus.gpb.homework.fragments.utils
 
 
-const val COLOR_RESULT_KEY = "color_result"
-const val COLOR_RESULT_BUNDLE_KEY = "color_result_bundle"
\ No newline at end of file
+const val COLOR_RESULT_KEY_BB_TO_BA = "color_result_bb_to_ba"
+const val COLOR_RESULT_BUNDLE_KEY_BB_TO_BA = "color_result_bundle_bb_to_ba"
+
+
+
+const val COLOR_RESULT_KEY_BA_TO_BB = "color_result_ba_to_bb"
+const val COLOR_RESULT_BUNDLE_KEY_BA_TO_BB = "color_result_bundle_ba_to_bb"
\ No newline at end of file
diff --git a/app/src/main/res/layout-sw600dp/fragment_b_a.xml b/app/src/main/res/layout-sw600dp/fragment_b_a.xml
new file mode 100644
index 0000000..787c55e
--- /dev/null
+++ b/app/src/main/res/layout-sw600dp/fragment_b_a.xml
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    tools:context=".FragmentBA">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:textAlignment="center"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        android:text="@string/hello_blank_fragment_b_a" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_b_a.xml b/app/src/main/res/layout/fragment_b_a.xml
index 787c55e..b9cf0ff 100644
--- a/app/src/main/res/layout/fragment_b_a.xml
+++ b/app/src/main/res/layout/fragment_b_a.xml
@@ -1,17 +1,23 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:orientation="vertical"
     tools:context=".FragmentBA">
 
     <TextView
         android:layout_width="match_parent"
-        android:layout_height="wrap_content"
+        android:layout_height="match_parent"
         android:textAlignment="center"
-        app:layout_constraintTop_toTopOf="parent"
-        app:layout_constraintBottom_toBottomOf="parent"
-        android:text="@string/hello_blank_fragment_b_a" />
+        android:text="@string/hello_blank_fragment_b_a"
+        android:layout_weight="1"/>
+
+    <Button
+        android:id="@+id/fragment_b_b_button"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/fragment_b_a_button_text"
+        android:layout_weight="1"/>
 
-</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_b_b.xml b/app/src/main/res/layout/fragment_b_b.xml
index 8e06850..271dfdc 100644
--- a/app/src/main/res/layout/fragment_b_b.xml
+++ b/app/src/main/res/layout/fragment_b_b.xml
@@ -10,8 +10,8 @@
         android:id="@+id/fragment_b_b_text"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:text="@string/hello_blank_fragment_b_b"
         android:textAlignment="center"
+        android:text="@string/hello_blank_fragment_b_b"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 0ad422c..2bafb2c 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -10,4 +10,5 @@
     <string name="hello_blank_fragment_b_a">Hello Fragment BA</string>
     <string name="hello_blank_fragment_b_b">Hello Fragment BB</string>
     <string name="fragment_b_b_button_text">Change BA color</string>
+    <string name="fragment_b_a_button_text">Change BB color</string>
 </resources>
\ No newline at end of file

From 8c593b6aeec9003eaccbfe3ec4f170d0b01dfd31 Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Wed, 12 Nov 2025 14:52:16 +0300
Subject: [PATCH 08/10] task 1.4 fix

---
 .../main/java/otus/gpb/homework/fragments/FragmentA.kt    | 8 ++++----
 .../main/java/otus/gpb/homework/fragments/FragmentAA.kt   | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
index 0692001..3afc427 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
@@ -30,14 +30,14 @@ class FragmentA : Fragment() {
 
         val onBackPressedCallback = object : OnBackPressedCallback(true) {
             override fun handleOnBackPressed() {
-                val backStackEntryCount = childFragmentManager.backStackEntryCount
+                val backStackEntryCount = parentFragmentManager.backStackEntryCount
                 Toast.makeText(
                     context,
                     "FragmentA back stack entry count: $backStackEntryCount",
                     Toast.LENGTH_SHORT
                 ).show()
                 if (backStackEntryCount > 0) {
-                    childFragmentManager.popBackStack()
+                    parentFragmentManager.popBackStack()
                 } else {
                     isEnabled = false
                     requireActivity().onBackPressedDispatcher.onBackPressed()
@@ -63,11 +63,11 @@ class FragmentA : Fragment() {
         fragmentAA = if (savedInstanceState == null) {
             FragmentAA.newInstance(ColorGenerator.generateColor())
         } else {
-            childFragmentManager.findFragmentByTag("fragmentAA") as FragmentAA
+            parentFragmentManager.findFragmentByTag("fragmentAA") as FragmentAA
         }
         with(binding) {
             fragmentAAButton.setOnClickListener {
-                childFragmentManager.beginTransaction()
+                parentFragmentManager.beginTransaction()
                     .replace(R.id.fragment_a_container, fragmentAA, "fragmentAA")
                     .addToBackStack("fragmentA")
                     .commit()
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
index 08bb26d..67332e6 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
@@ -35,14 +35,14 @@ class FragmentAA : Fragment() {
 
         val callback = object : OnBackPressedCallback(true) {
             override fun handleOnBackPressed() {
-                val backStackEntryCount = childFragmentManager.backStackEntryCount
+                val backStackEntryCount = parentFragmentManager.backStackEntryCount
                 Toast.makeText(
                     context,
                     "FragmentAA back stack entry count: $backStackEntryCount",
                     Toast.LENGTH_SHORT
                 ).show()
                 if (backStackEntryCount > 0) {
-                    childFragmentManager.popBackStack()
+                    parentFragmentManager.popBackStack()
                 } else {
                     isEnabled = false
                     requireActivity().onBackPressedDispatcher.onBackPressed()
@@ -75,11 +75,11 @@ class FragmentAA : Fragment() {
         fragmentAB = if (savedInstanceState == null) {
             FragmentAB.newInstance(ColorGenerator.generateColor())
         } else {
-            childFragmentManager.findFragmentByTag("fragmentAB") as FragmentAB
+            parentFragmentManager.findFragmentByTag("fragmentAB") as FragmentAB
         }
         with(binding) {
             fragmentABButton.setOnClickListener {
-                childFragmentManager.beginTransaction()
+                parentFragmentManager.beginTransaction()
                     .replace(R.id.fragment_a_container, fragmentAB, "fragmentAB")
                     .addToBackStack("fragmentA")
                     .commit()

From b12663fa873f72b8c2426610c3a674ffbca0f865 Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Sun, 16 Nov 2025 11:41:29 +0300
Subject: [PATCH 09/10] task 1 fix after review

---
 .../otus/gpb/homework/fragments/ActivityA.kt  |  2 -
 .../otus/gpb/homework/fragments/FragmentA.kt  | 29 +++--------
 .../otus/gpb/homework/fragments/FragmentAA.kt | 50 +++----------------
 .../otus/gpb/homework/fragments/FragmentAB.kt | 35 -------------
 app/src/main/res/layout/fragment_a_a.xml      |  4 +-
 app/src/main/res/values/strings.xml           |  4 +-
 6 files changed, 18 insertions(+), 106 deletions(-)

diff --git a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
index dc843ae..b36a990 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt
@@ -6,7 +6,6 @@ import otus.gpb.homework.fragments.databinding.ActivityABinding
 
 class ActivityA : AppCompatActivity() {
 
-
     private lateinit var binding: ActivityABinding
 
     private lateinit var fragmentA: FragmentA
@@ -22,7 +21,6 @@ class ActivityA : AppCompatActivity() {
         }
         supportFragmentManager.beginTransaction()
             .replace(R.id.fragment_activity_a, fragmentA, "fragmentA")
-            .addToBackStack("fragmentA")
             .commit()
 
     }
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
index 3afc427..d053692 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt
@@ -5,22 +5,14 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
-import android.widget.Toast
 import androidx.activity.OnBackPressedCallback
 import androidx.fragment.app.Fragment
 import otus.gpb.homework.fragments.databinding.FragmentABinding
 
 
-/**
- * A simple [Fragment] subclass.
- * Use the [FragmentA.newInstance] factory method to
- * create an instance of this fragment.
- */
 class FragmentA : Fragment() {
     private var _binding: FragmentABinding? = null
 
-    // This property is only valid between onCreateView and
-    // onDestroyView.
     private val binding get() = _binding!!
 
     private lateinit var fragmentAA: FragmentAA
@@ -28,24 +20,17 @@ class FragmentA : Fragment() {
     override fun onAttach(context: Context) {
         super.onAttach(context)
 
-        val onBackPressedCallback = object : OnBackPressedCallback(true) {
+        val callback = object : OnBackPressedCallback(true) {
             override fun handleOnBackPressed() {
-                val backStackEntryCount = parentFragmentManager.backStackEntryCount
-                Toast.makeText(
-                    context,
-                    "FragmentA back stack entry count: $backStackEntryCount",
-                    Toast.LENGTH_SHORT
-                ).show()
-                if (backStackEntryCount > 0) {
-                    parentFragmentManager.popBackStack()
+                if (childFragmentManager.backStackEntryCount > 0) {
+                    childFragmentManager.popBackStack()
                 } else {
                     isEnabled = false
                     requireActivity().onBackPressedDispatcher.onBackPressed()
                 }
             }
         }
-
-        requireActivity().onBackPressedDispatcher.addCallback(onBackPressedCallback)
+        requireActivity().onBackPressedDispatcher.addCallback(callback)
     }
 
     override fun onCreateView(
@@ -63,12 +48,12 @@ class FragmentA : Fragment() {
         fragmentAA = if (savedInstanceState == null) {
             FragmentAA.newInstance(ColorGenerator.generateColor())
         } else {
-            parentFragmentManager.findFragmentByTag("fragmentAA") as FragmentAA
+            childFragmentManager.findFragmentByTag("fragmentAA") as FragmentAA
         }
         with(binding) {
             fragmentAAButton.setOnClickListener {
-                parentFragmentManager.beginTransaction()
-                    .replace(R.id.fragment_a_container, fragmentAA, "fragmentAA")
+                childFragmentManager.beginTransaction()
+                    .replace(fragmentAContainer.id, fragmentAA, "fragmentAA")
                     .addToBackStack("fragmentA")
                     .commit()
             }
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
index 67332e6..a77e2f2 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt
@@ -1,58 +1,25 @@
 package otus.gpb.homework.fragments
 
-import android.content.Context
 import android.graphics.Color
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
-import android.widget.Toast
-import androidx.activity.OnBackPressedCallback
 import androidx.fragment.app.Fragment
 import otus.gpb.homework.fragments.databinding.FragmentAABinding
 
 const val COLOR_ARG_PARAM = "color"
 
-/**
- * A simple [Fragment] subclass.
- * Use the [FragmentAA.newInstance] factory method to
- * create an instance of this fragment.
- */
 class FragmentAA : Fragment() {
 
     private var _binding: FragmentAABinding? = null
 
-    // This property is only valid between onCreateView and
-    // onDestroyView.
     private val binding get() = _binding!!
 
     private lateinit var fragmentAB: FragmentAB
 
     private var color: Int = Color.CYAN
 
-    override fun onAttach(context: Context) {
-        super.onAttach(context)
-
-        val callback = object : OnBackPressedCallback(true) {
-            override fun handleOnBackPressed() {
-                val backStackEntryCount = parentFragmentManager.backStackEntryCount
-                Toast.makeText(
-                    context,
-                    "FragmentAA back stack entry count: $backStackEntryCount",
-                    Toast.LENGTH_SHORT
-                ).show()
-                if (backStackEntryCount > 0) {
-                    parentFragmentManager.popBackStack()
-                } else {
-                    isEnabled = false
-                    requireActivity().onBackPressedDispatcher.onBackPressed()
-                }
-            }
-        }
-
-        requireActivity().onBackPressedDispatcher.addCallback(callback)
-    }
-
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         arguments?.let {
@@ -61,8 +28,7 @@ class FragmentAA : Fragment() {
     }
 
     override fun onCreateView(
-        inflater: LayoutInflater, container: ViewGroup?,
-        savedInstanceState: Bundle?
+        inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?
     ): View {
         _binding = FragmentAABinding.inflate(inflater, container, false)
         val root: View = binding.root
@@ -80,9 +46,8 @@ class FragmentAA : Fragment() {
         with(binding) {
             fragmentABButton.setOnClickListener {
                 parentFragmentManager.beginTransaction()
-                    .replace(R.id.fragment_a_container, fragmentAB, "fragmentAB")
-                    .addToBackStack("fragmentA")
-                    .commit()
+                    .replace(fragmentAAContainer.id, fragmentAB, "fragmentAB")
+                    .addToBackStack("fragmentA").commit()
             }
         }
     }
@@ -94,11 +59,10 @@ class FragmentAA : Fragment() {
 
     companion object {
         @JvmStatic
-        fun newInstance(param1: Int) =
-            FragmentAA().apply {
-                arguments = Bundle().apply {
-                    putInt(COLOR_ARG_PARAM, param1)
-                }
+        fun newInstance(param1: Int) = FragmentAA().apply {
+            arguments = Bundle().apply {
+                putInt(COLOR_ARG_PARAM, param1)
             }
+        }
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
index 5a680f6..43592be 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt
@@ -1,56 +1,21 @@
 package otus.gpb.homework.fragments
 
-import android.content.Context
 import android.graphics.Color
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
-import android.widget.Toast
-import androidx.activity.OnBackPressedCallback
 import androidx.fragment.app.Fragment
 import otus.gpb.homework.fragments.databinding.FragmentABBinding
 
-
-/**
- * A simple [Fragment] subclass.
- * Use the [FragmentAB.newInstance] factory method to
- * create an instance of this fragment.
- */
 class FragmentAB : Fragment() {
 
 
     private var _binding: FragmentABBinding? = null
-
-    // This property is only valid between onCreateView and
-    // onDestroyView.
     private val binding get() = _binding!!
 
     private var color: Int = Color.CYAN
 
-    override fun onAttach(context: Context) {
-        super.onAttach(context)
-
-        val callback = object : OnBackPressedCallback(true) {
-            override fun handleOnBackPressed() {
-                val backStackEntryCount = childFragmentManager.backStackEntryCount
-                Toast.makeText(
-                    context,
-                    "FragmentAB back stack entry count: $backStackEntryCount",
-                    Toast.LENGTH_SHORT
-                ).show()
-                if (backStackEntryCount > 0) {
-                    childFragmentManager.popBackStack()
-                } else {
-                    isEnabled = false
-                    requireActivity().onBackPressedDispatcher.onBackPressed()
-                }
-            }
-        }
-
-        requireActivity().onBackPressedDispatcher.addCallback(callback)
-    }
-
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         arguments?.let {
diff --git a/app/src/main/res/layout/fragment_a_a.xml b/app/src/main/res/layout/fragment_a_a.xml
index 86eb74e..36fad2d 100644
--- a/app/src/main/res/layout/fragment_a_a.xml
+++ b/app/src/main/res/layout/fragment_a_a.xml
@@ -19,11 +19,11 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="@string/fragment_ab_button_text"
-        app:layout_constraintBottom_toTopOf="@+id/fragment_a_container"
+        app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/fragment_a_a_text" />
 
     <FrameLayout
-        android:id="@+id/fragment_a_container"
+        android:id="@+id/fragment_a_a_container"
         android:layout_width="match_parent"
         android:layout_height="0dp"
         app:layout_constraintBottom_toBottomOf="parent"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 2bafb2c..558ef39 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -2,8 +2,8 @@
     <string name="app_name">Fragments</string>
     <string name="activity_a_button_text">Activity A</string>
     <string name="activity_b_button_text">Activity B</string>
-    <string name="fragment_aa_button_text">Fragment AA</string>
-    <string name="fragment_ab_button_text">Fragment AB</string>
+    <string name="fragment_aa_button_text">To Fragment AA</string>
+    <string name="fragment_ab_button_text">To Fragment AB</string>
     <string name="hello_blank_fragment_a">Hello Fragment A</string>
     <string name="hello_blank_fragment_a_a">Hello Fragment AA</string>
     <string name="hello_blank_fragment_a_b">Hello Fragment AB</string>

From 65861ef961474b0ef4404a8b6e11efa22c5b83fd Mon Sep 17 00:00:00 2001
From: YURY TILMAN <uatilman@gmail.com>
Date: Sun, 16 Nov 2025 21:28:45 +0300
Subject: [PATCH 10/10] tasks 2 fix after review

---
 .../otus/gpb/homework/fragments/ActivityB.kt  |  8 +++---
 .../otus/gpb/homework/fragments/FragmentBA.kt | 23 ++++++----------
 .../otus/gpb/homework/fragments/FragmentBB.kt | 24 ++++++++++-------
 .../activity_b.xml                            | 10 ++++---
 .../fragment_b_a.xml                          |  0
 .../main/res/layout-sw600dp/fragment_b_b.xml  | 26 -------------------
 app/src/main/res/layout/activity_b.xml        |  2 +-
 app/src/main/res/layout/fragment_b_a.xml      | 18 ++++++++-----
 app/src/main/res/layout/fragment_b_b.xml      |  9 +++++++
 app/src/main/res/values-sw600dp/bool.xml      |  4 ---
 app/src/main/res/values/bool.xml              |  4 ---
 app/src/main/res/values/strings.xml           |  8 +++---
 12 files changed, 61 insertions(+), 75 deletions(-)
 rename app/src/main/res/{layout-sw600dp => layout-land}/activity_b.xml (69%)
 rename app/src/main/res/{layout-sw600dp => layout-land}/fragment_b_a.xml (100%)
 delete mode 100644 app/src/main/res/layout-sw600dp/fragment_b_b.xml
 delete mode 100644 app/src/main/res/values-sw600dp/bool.xml
 delete mode 100644 app/src/main/res/values/bool.xml

diff --git a/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt b/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
index 53aaba5..c96abde 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt
@@ -1,5 +1,7 @@
 package otus.gpb.homework.fragments
 
+import android.R.attr.orientation
+import android.content.res.Configuration
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
 import otus.gpb.homework.fragments.databinding.ActivityBBinding
@@ -11,15 +13,13 @@ class ActivityB : AppCompatActivity() {
     private lateinit var fragmentBA: FragmentBA
     private lateinit var fragmentBB: FragmentBB
 
-    private val isTablet by lazy { resources.getBoolean(R.bool.is_tablet) }
-
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         binding = ActivityBBinding.inflate(layoutInflater)
         setContentView(binding.root)
 
-        if (isTablet) {
+        if (resources.configuration.orientation == Configuration.ORIENTATION_LANDSCAPE) {
             fragmentBA = savedInstanceState
                 ?.let { supportFragmentManager.findFragmentByTag(FragmentBA::class.simpleName) as? FragmentBA }
                 ?: FragmentBA()
@@ -31,6 +31,7 @@ class ActivityB : AppCompatActivity() {
             supportFragmentManager.beginTransaction()
                 .replace(R.id.fragment_b_a_container, fragmentBA, FragmentBA::class.simpleName)
                 .replace(R.id.fragment_b_b_container, fragmentBB, FragmentBB::class.simpleName)
+                .addToBackStack(null)
                 .commit()
         } else {
             fragmentBA = savedInstanceState
@@ -38,6 +39,7 @@ class ActivityB : AppCompatActivity() {
                 ?: FragmentBA()
             supportFragmentManager.beginTransaction()
                 .replace(R.id.fragment_b_a_container, fragmentBA, FragmentBA::class.simpleName)
+                .addToBackStack(null)
                 .commit()
         }
 
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
index 1ff0266..ee1734a 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentBA.kt
@@ -4,14 +4,10 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
-import androidx.core.os.bundleOf
 import androidx.fragment.app.Fragment
-import androidx.fragment.app.setFragmentResult
 import androidx.fragment.app.setFragmentResultListener
 import otus.gpb.homework.fragments.databinding.FragmentBABinding
-import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY_BA_TO_BB
 import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY_BB_TO_BA
-import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY_BA_TO_BB
 import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY_BB_TO_BA
 
 
@@ -33,24 +29,21 @@ class FragmentBA : Fragment() {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        fragmentBB = if (savedInstanceState == null) {
-            FragmentBB()
-        } else {
-            childFragmentManager.getFragment(savedInstanceState, "fragmentBB") as FragmentBB
-        }
+        fragmentBB = savedInstanceState
+            ?.let {
+                parentFragmentManager.getFragment(savedInstanceState, "fragmentBB") as? FragmentBB
+            }
+            ?: FragmentBB()
+
         setFragmentResultListener(COLOR_RESULT_KEY_BB_TO_BA) { _, bundle ->
             val color: Int = bundle.getInt(COLOR_RESULT_BUNDLE_KEY_BB_TO_BA)
             binding.root.setBackgroundColor(color)
         }
 
         binding.fragmentBBButton?.setOnClickListener {
-            setFragmentResult(
-                COLOR_RESULT_KEY_BA_TO_BB,
-                bundleOf(COLOR_RESULT_BUNDLE_KEY_BA_TO_BB to ColorGenerator.generateColor())
-            )
-
             parentFragmentManager.beginTransaction()
-                .replace(R.id.fragment_b_a_container, fragmentBB)
+                .replace(R.id.fragment_b_a_container, fragmentBB, FragmentBB::class.simpleName)
+                .addToBackStack(null)
                 .commit()
         }
 
diff --git a/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt b/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
index 84e9896..4ba9792 100644
--- a/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
+++ b/app/src/main/java/otus/gpb/homework/fragments/FragmentBB.kt
@@ -1,5 +1,6 @@
 package otus.gpb.homework.fragments
 
+import android.content.res.Configuration
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
@@ -7,11 +8,8 @@ import android.view.ViewGroup
 import androidx.core.os.bundleOf
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.setFragmentResult
-import androidx.fragment.app.setFragmentResultListener
 import otus.gpb.homework.fragments.databinding.FragmentBBBinding
-import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY_BA_TO_BB
 import otus.gpb.homework.fragments.utils.COLOR_RESULT_BUNDLE_KEY_BB_TO_BA
-import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY_BA_TO_BB
 import otus.gpb.homework.fragments.utils.COLOR_RESULT_KEY_BB_TO_BA
 
 class FragmentBB : Fragment() {
@@ -19,6 +17,8 @@ class FragmentBB : Fragment() {
 
     private val binding get() = _binding!!
 
+    private lateinit var fragmentBA: FragmentBA
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -31,17 +31,23 @@ class FragmentBB : Fragment() {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
+        fragmentBA = savedInstanceState
+            ?.let {
+                parentFragmentManager.getFragment(savedInstanceState, "fragmentBA") as? FragmentBA
+            }
+            ?: FragmentBA()
 
-        setFragmentResultListener(COLOR_RESULT_KEY_BA_TO_BB) { _, bundle ->
-            val color = bundle.getInt(COLOR_RESULT_BUNDLE_KEY_BA_TO_BB)
-            binding.root.setBackgroundColor(color)
-        }
-
-        binding.fragmentBBButton?.setOnClickListener {
+        binding.fragmentBBButton.setOnClickListener {
             setFragmentResult(
                 COLOR_RESULT_KEY_BB_TO_BA,
                 bundleOf(COLOR_RESULT_BUNDLE_KEY_BB_TO_BA to ColorGenerator.generateColor())
             )
+            if (resources.configuration.orientation == Configuration.ORIENTATION_PORTRAIT) {
+                parentFragmentManager.beginTransaction()
+                    .replace(R.id.fragment_b_a_container, fragmentBA, FragmentBA::class.simpleName)
+                    .addToBackStack(null)
+                    .commit()
+            }
         }
     }
 
diff --git a/app/src/main/res/layout-sw600dp/activity_b.xml b/app/src/main/res/layout-land/activity_b.xml
similarity index 69%
rename from app/src/main/res/layout-sw600dp/activity_b.xml
rename to app/src/main/res/layout-land/activity_b.xml
index e2356e9..e905cdd 100644
--- a/app/src/main/res/layout-sw600dp/activity_b.xml
+++ b/app/src/main/res/layout-land/activity_b.xml
@@ -4,17 +4,21 @@
     android:id="@+id/main"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:orientation="vertical"
+    android:baselineAligned="false"
+    android:orientation="horizontal"
     tools:context=".ActivityB">
 
-    <FrameLayout
+
+    <androidx.fragment.app.FragmentContainerView
         android:id="@+id/fragment_b_a_container"
+        android:name="otus.gpb.homework.fragments.FragmentBA"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:layout_weight="1" />
 
-    <FrameLayout
+    <androidx.fragment.app.FragmentContainerView
         android:id="@+id/fragment_b_b_container"
+        android:name="otus.gpb.homework.fragments.FragmentBB"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:layout_weight="1" />
diff --git a/app/src/main/res/layout-sw600dp/fragment_b_a.xml b/app/src/main/res/layout-land/fragment_b_a.xml
similarity index 100%
rename from app/src/main/res/layout-sw600dp/fragment_b_a.xml
rename to app/src/main/res/layout-land/fragment_b_a.xml
diff --git a/app/src/main/res/layout-sw600dp/fragment_b_b.xml b/app/src/main/res/layout-sw600dp/fragment_b_b.xml
deleted file mode 100644
index 67e85e2..0000000
--- a/app/src/main/res/layout-sw600dp/fragment_b_b.xml
+++ /dev/null
@@ -1,26 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    tools:context=".FragmentBB">
-
-    <TextView
-        android:id="@+id/fragment_b_b_text"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:text="@string/hello_blank_fragment_b_b"
-        android:textAlignment="center"
-        app:layout_constraintBottom_toBottomOf="@id/fragment_b_b_button"
-        app:layout_constraintTop_toTopOf="parent" />
-
-    <Button
-        android:id="@+id/fragment_b_b_button"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:text="@string/fragment_b_b_button_text"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/fragment_b_b_text" />
-
-</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_b.xml b/app/src/main/res/layout/activity_b.xml
index 6f519fd..d77664f 100644
--- a/app/src/main/res/layout/activity_b.xml
+++ b/app/src/main/res/layout/activity_b.xml
@@ -10,7 +10,7 @@
     <FrameLayout
         android:id="@+id/fragment_b_a_container"
         android:layout_width="match_parent"
-        android:layout_height="wrap_content"
+        android:layout_height="match_parent"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_b_a.xml b/app/src/main/res/layout/fragment_b_a.xml
index b9cf0ff..e422fb6 100644
--- a/app/src/main/res/layout/fragment_b_a.xml
+++ b/app/src/main/res/layout/fragment_b_a.xml
@@ -1,23 +1,29 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:orientation="vertical"
     tools:context=".FragmentBA">
 
     <TextView
+        android:id="@+id/fragment_b_a_text"
         android:layout_width="match_parent"
-        android:layout_height="match_parent"
+        android:layout_height="wrap_content"
         android:textAlignment="center"
         android:text="@string/hello_blank_fragment_b_a"
-        android:layout_weight="1"/>
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent"/>
 
     <Button
         android:id="@+id/fragment_b_b_button"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
+        android:textAllCaps="false"
         android:text="@string/fragment_b_a_button_text"
-        android:layout_weight="1"/>
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/fragment_b_a_text"
+
+        />
 
-</LinearLayout>
\ No newline at end of file
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_b_b.xml b/app/src/main/res/layout/fragment_b_b.xml
index 271dfdc..3452902 100644
--- a/app/src/main/res/layout/fragment_b_b.xml
+++ b/app/src/main/res/layout/fragment_b_b.xml
@@ -15,4 +15,13 @@
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
+    <Button
+        android:id="@+id/fragment_b_b_button"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/fragment_b_b_button_text"
+        android:textAllCaps="false"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/fragment_b_b_text" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values-sw600dp/bool.xml b/app/src/main/res/values-sw600dp/bool.xml
deleted file mode 100644
index 5fc3a0d..0000000
--- a/app/src/main/res/values-sw600dp/bool.xml
+++ /dev/null
@@ -1,4 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <bool name="is_tablet">true</bool>
-</resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/bool.xml b/app/src/main/res/values/bool.xml
deleted file mode 100644
index 84d7d2f..0000000
--- a/app/src/main/res/values/bool.xml
+++ /dev/null
@@ -1,4 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <bool name="is_tablet">false</bool>
-</resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 558ef39..9cdbbf4 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -7,8 +7,8 @@
     <string name="hello_blank_fragment_a">Hello Fragment A</string>
     <string name="hello_blank_fragment_a_a">Hello Fragment AA</string>
     <string name="hello_blank_fragment_a_b">Hello Fragment AB</string>
-    <string name="hello_blank_fragment_b_a">Hello Fragment BA</string>
-    <string name="hello_blank_fragment_b_b">Hello Fragment BB</string>
-    <string name="fragment_b_b_button_text">Change BA color</string>
-    <string name="fragment_b_a_button_text">Change BB color</string>
+    <string name="hello_blank_fragment_b_a">Fragment BA</string>
+    <string name="hello_blank_fragment_b_b">Fragment BB</string>
+    <string name="fragment_b_b_button_text">SendColor</string>
+    <string name="fragment_b_a_button_text">Open Fragment BB</string>
 </resources>
\ No newline at end of file