My homework is done

app/build.gradle

@@ -8,7 +8,7 @@ kotlin {
 }
 
 android {
-    compileSdk 34
+    compileSdk 35
     namespace "otus.gpb.homework.fragments"
 
     defaultConfig {
@@ -34,6 +34,10 @@ android {
     kotlinOptions {
         jvmTarget = '17'
     }
+
+    buildFeatures {
+        viewBinding = true
+    }
 }
 
 dependencies {
@@ -42,6 +46,7 @@ dependencies {
     implementation 'androidx.appcompat:appcompat:1.5.1'
     implementation 'com.google.android.material:material:1.6.1'
     implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
+    implementation 'androidx.activity:activity:1.10.1'
     testImplementation 'junit:junit:4.13.2'
     androidTestImplementation 'androidx.test.ext:junit:1.1.3'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'

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">

app/src/main/java/otus/gpb/homework/fragments/ActivityA.kt

@@ -0,0 +1,34 @@
+package otus.gpb.homework.fragments
+
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import androidx.activity.enableEdgeToEdge
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.view.ViewCompat
+import androidx.core.view.WindowInsetsCompat
+import androidx.fragment.app.Fragment
+
+class ActivityA : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        enableEdgeToEdge()
+        setContentView(R.layout.activity_a)
+        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.container_a)) { v, insets ->
+            val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
+            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
+            insets
+        }
+        if (savedInstanceState == null) {
+            supportFragmentManager.beginTransaction()
+                .replace(R.id.container_a, FragmentA.newInstance())
+                .commit()
+        }
+    }
+
+    companion object {
+        fun newIntent(context: Context): Intent{
+            return Intent(context, ActivityA::class.java)
+        }
+    }
+}

app/src/main/java/otus/gpb/homework/fragments/ActivityB.kt

@@ -0,0 +1,33 @@
+package otus.gpb.homework.fragments
+
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import androidx.activity.enableEdgeToEdge
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.view.ViewCompat
+import androidx.core.view.WindowInsetsCompat
+
+class ActivityB : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        enableEdgeToEdge()
+        setContentView(R.layout.activity_b)
+        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.container_b)) { v, insets ->
+            val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
+            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
+            insets
+        }
+        if (savedInstanceState == null){
+            supportFragmentManager.beginTransaction()
+                .replace(R.id.container_b, FragmentB.newInstance())
+                .commit()
+        }
+    }
+
+    companion object {
+        fun newIntent(context: Context): Intent {
+            return Intent(context, ActivityB::class.java)
+        }
+    }
+}

app/src/main/java/otus/gpb/homework/fragments/FragmentA.kt

@@ -0,0 +1,55 @@
+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.activity.OnBackPressedCallback
+import otus.gpb.homework.fragments.databinding.FragmentABinding
+
+class FragmentA : Fragment() {
+
+    private var _binding: FragmentABinding? = null
+    private val binding: FragmentABinding
+        get() = _binding ?: throw RuntimeException("FragmentABinding == null")
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentABinding.inflate(inflater, container, false)
+        return binding.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner, object : OnBackPressedCallback(true){
+            override fun handleOnBackPressed() {
+                if (childFragmentManager.backStackEntryCount <= 0){
+                    requireActivity().finish()
+                } else {
+                    childFragmentManager.popBackStack()
+                }
+            }
+        })
+        binding.buttonFragmentAA.setOnClickListener(){
+            childFragmentManager.popBackStack()
+            childFragmentManager.beginTransaction()
+                .replace(R.id.containerFragmentA, FragmentAA.newInstance(ColorGenerator.generateColor()))
+                .addToBackStack(null)
+                .commit()
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+
+    companion object {
+        fun newInstance(): FragmentA{
+            return FragmentA()
+        }
+    }
+}

app/src/main/java/otus/gpb/homework/fragments/FragmentAA.kt

@@ -0,0 +1,63 @@
+package otus.gpb.homework.fragments
+
+import android.os.Bundle
+import android.util.Log
+import androidx.fragment.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import otus.gpb.homework.fragments.databinding.FragmentAABinding
+
+class FragmentAA : Fragment() {
+
+    private var _binding: FragmentAABinding? = null
+    private val binding: FragmentAABinding
+        get() = _binding ?: throw RuntimeException("FragmentAABinding == null")
+    private var colorInt: Int? = 0
+
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        colorInt = arguments?.getInt(COLOR)
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentAABinding.inflate(inflater, container, false)
+        return binding.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        binding.buttonFragmentAB.setOnClickListener(){
+            parentFragmentManager.beginTransaction()
+                .replace(R.id.containerFragmentA, FragmentAB.newInstance(ColorGenerator.generateColor()))
+                .addToBackStack(null)
+                .commit()
+        }
+        colorInt?.let {
+            binding.layoutFragmentAA.setBackgroundColor(it)
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+
+    companion object {
+
+        private const val COLOR = "color"
+
+        fun newInstance(color: Int): FragmentAA {
+            return FragmentAA().apply {
+                arguments = Bundle().apply {
+                    putInt(COLOR, color)
+                }
+            }
+        }
+    }
+
+}

app/src/main/java/otus/gpb/homework/fragments/FragmentAB.kt

@@ -0,0 +1,56 @@
+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 otus.gpb.homework.fragments.FragmentAA.Companion
+import otus.gpb.homework.fragments.databinding.FragmentAABinding
+import otus.gpb.homework.fragments.databinding.FragmentABBinding
+
+class FragmentAB : Fragment() {
+
+    private var _binding: FragmentABBinding? = null
+    private val binding: FragmentABBinding
+        get() = _binding ?: throw RuntimeException("FragmentAABinding == null")
+    private var colorInt: Int? = 0
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        colorInt = arguments?.getInt(COLOR)
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentABBinding.inflate(inflater, container, false)
+        return binding.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        colorInt?.let {
+            binding.layoutFragmentAB.setBackgroundColor(it)
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+
+    companion object {
+
+        private const val COLOR = "color"
+
+        fun newInstance(color: Int): FragmentAB {
+            return FragmentAB().apply {
+                arguments = Bundle().apply {
+                    putInt(COLOR, color)
+                }
+            }
+        }
+    }
+}

app/src/main/java/otus/gpb/homework/fragments/FragmentB.kt

@@ -0,0 +1,54 @@
+package otus.gpb.homework.fragments
+
+import android.os.Bundle
+import android.util.Log
+import androidx.fragment.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.FragmentContainerView
+import otus.gpb.homework.fragments.databinding.FragmentBBinding
+
+class FragmentB : Fragment() {
+
+    private var _binding: FragmentBBinding? = null
+    private val binding: FragmentBBinding
+        get() = _binding ?: throw RuntimeException("FragmentAABinding == null")
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentBBinding.inflate(inflater, container, false)
+        return binding.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        if (binding.containerFragmentB == null) {
+            childFragmentManager.beginTransaction()
+                .replace(R.id.containerFragmentB1, FragmentBA.newInstance())
+                .commit()
+            childFragmentManager.beginTransaction()
+                .replace(R.id.containerFragmentB2, FragmentBB.newInstance())
+                .commit()
+        } else {
+            childFragmentManager.beginTransaction()
+                .replace(R.id.containerFragmentB, FragmentBA.newInstance())
+                .addToBackStack(null)
+                .commit()
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+
+    companion object {
+
+        fun newInstance(): FragmentB{
+            return FragmentB()
+        }
+    }
+}