From 178fb7be4b19eb2d44620a1d8c09c7ac515f9f9b Mon Sep 17 00:00:00 2001 From: Mykhailo Date: Wed, 8 Oct 2025 23:14:02 +0300 Subject: [PATCH 1/2] =?UTF-8?q?=D0=92=D0=B8=D0=BA=D0=BE=D0=BD=D0=B0=D0=BD?= =?UTF-8?q?=D1=96=20=D0=B7=D0=B0=D0=B2=D0=B4=D0=B0=D0=BD=D0=BD=D1=8F=20?= =?UTF-8?q?=D0=B7=20java-fundamentals-exercises?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../java/com/bobocode/intro/ExerciseIntroduction.java | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/0-0-intro/src/main/java/com/bobocode/intro/ExerciseIntroduction.java b/0-0-intro/src/main/java/com/bobocode/intro/ExerciseIntroduction.java index 35d925636..a3f320f45 100644 --- a/0-0-intro/src/main/java/com/bobocode/intro/ExerciseIntroduction.java +++ b/0-0-intro/src/main/java/com/bobocode/intro/ExerciseIntroduction.java @@ -2,6 +2,8 @@ import com.bobocode.util.ExerciseNotCompletedException; +import java.util.Base64; + /** * Welcome! This is an introduction exercise that will show you a simple example of Bobocode exercises. *

@@ -24,7 +26,8 @@ public class ExerciseIntroduction { */ public String getWelcomeMessage() { // todo: implement a method and return a message according to javadoc - throw new ExerciseNotCompletedException(); + // throw new ExerciseNotCompletedException(); + return "The key to efficient learning is practice!"; } /** @@ -40,6 +43,7 @@ public String getWelcomeMessage() { */ public String encodeMessage(String message) { // todo: switch to branch "completed" in order to see how it should be implemented - throw new ExerciseNotCompletedException(); + // throw new ExerciseNotCompletedException(); + return Base64.getEncoder().encodeToString(message.getBytes()); } } From 3a295ebc164341e7cfb09b5d7d9fd995f3449662 Mon Sep 17 00:00:00 2001 From: Mykhailo Date: Thu, 9 Oct 2025 13:33:21 +0300 Subject: [PATCH 2/2] =?UTF-8?q?=D0=92=D0=B8=D0=BA=D0=BE=D0=BD=D0=B0=D0=BD?= =?UTF-8?q?=D0=BD=D1=96=20=D0=B7=D0=B0=D0=B2=D0=B4=D0=B0=D0=BD=D0=BD=D1=8F?= =?UTF-8?q?=201-3-0,=201-3-1?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../main/java/com/bobocode/basics/Box.java | 10 +- .../com/bobocode/basics/CrazyGenerics.java | 103 ++++++++++++------ 2 files changed, 75 insertions(+), 38 deletions(-) diff --git a/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/Box.java b/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/Box.java index 5a2d860ee..180603a28 100644 --- a/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/Box.java +++ b/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/Box.java @@ -7,18 +7,18 @@ *

* todo: refactor this class so it uses generic type "T" and run {@link com.bobocode.basics.BoxTest} to verify it */ -public class Box { - private Object value; +public class Box { + private T value; - public Box(Object value) { + public Box(T value) { this.value = value; } - public Object getValue() { + public T getValue() { return value; } - public void setValue(Object value) { + public void setValue(T value) { this.value = value; } } diff --git a/1-0-java-basics/1-3-1-crazy-generics/src/main/java/com/bobocode/basics/CrazyGenerics.java b/1-0-java-basics/1-3-1-crazy-generics/src/main/java/com/bobocode/basics/CrazyGenerics.java index 751d5899f..79b693960 100644 --- a/1-0-java-basics/1-3-1-crazy-generics/src/main/java/com/bobocode/basics/CrazyGenerics.java +++ b/1-0-java-basics/1-3-1-crazy-generics/src/main/java/com/bobocode/basics/CrazyGenerics.java @@ -5,10 +5,8 @@ import lombok.Data; import java.io.Serializable; -import java.util.Collection; -import java.util.Comparator; -import java.util.List; -import java.util.Objects; +import java.util.*; +import java.util.function.Predicate; /** * {@link CrazyGenerics} is an exercise class. It consists of classes, interfaces and methods that should be updated @@ -33,8 +31,8 @@ public class CrazyGenerics { * @param – value type */ @Data - public static class Sourced { // todo: refactor class to introduce type parameter and make value generic - private Object value; + public static class Sourced { // todo: refactor class to introduce type parameter and make value generic + private T value; private String source; } @@ -45,11 +43,11 @@ public static class Sourced { // todo: refactor class to introduce type paramete * @param – actual, min and max type */ @Data - public static class Limited { + public static class Limited { // todo: refactor class to introduce type param bounded by number and make fields generic numbers - private final Object actual; - private final Object min; - private final Object max; + private final T actual; + private final T min; + private final T max; } /** @@ -59,8 +57,9 @@ public static class Limited { * @param – source object type * @param - converted result type */ - public interface Converter { // todo: introduce type parameters + public interface Converter { // todo: introduce type parameters // todo: add convert method + R convert(T obj); } /** @@ -70,10 +69,10 @@ public interface Converter { // todo: introduce type parameters * * @param – value type */ - public static class MaxHolder { // todo: refactor class to make it generic - private Object max; + public static class MaxHolder> { // todo: refactor class to make it generic + private T max; - public MaxHolder(Object max) { + public MaxHolder(T max) { this.max = max; } @@ -82,11 +81,14 @@ public MaxHolder(Object max) { * * @param val a new value */ - public void put(Object val) { - throw new ExerciseNotCompletedException(); // todo: update parameter and implement the method + public void put(T val) { + // throw new ExerciseNotCompletedException(); // todo: update parameter and implement the method + if(val.compareTo(max) > 0){ + max = val; + } } - public Object getMax() { + public T getMax() { return max; } } @@ -97,8 +99,8 @@ public Object getMax() { * * @param – the type of objects that can be processed */ - interface StrictProcessor { // todo: make it generic - void process(Object obj); + interface StrictProcessor> { // todo: make it generic + void process(T obj); } /** @@ -108,10 +110,9 @@ interface StrictProcessor { // todo: make it generic * @param – a type of the entity that should be a subclass of {@link BaseEntity} * @param – a type of any collection */ - interface CollectionRepository { // todo: update interface according to the javadoc - void save(Object entity); - - Collection getEntityCollection(); + interface CollectionRepository> { // todo: update interface according to the javadoc + void save(T entity); + C getEntityCollection(); } /** @@ -120,7 +121,7 @@ interface CollectionRepository { // todo: update interface according to the java * * @param – a type of the entity that should be a subclass of {@link BaseEntity} */ - interface ListRepository { // todo: update interface according to the javadoc + interface ListRepository extends CollectionRepository> { // todo: update interface according to the javadoc } /** @@ -133,7 +134,11 @@ interface ListRepository { // todo: update interface according to the javadoc * * @param a type of collection elements */ - interface ComparableCollection { // todo: refactor it to make generic and provide a default impl of compareTo + interface ComparableCollection extends Collection, Comparable> { // todo: refactor it to make generic and provide a default impl of compareTo + @Override + default int compareTo(Collection o){ + return Integer.compare(this.size(), o.size()) + } } /** @@ -147,7 +152,7 @@ static class CollectionUtil { * * @param list */ - public static void print(List list) { + public static void print(List list) { // todo: refactor it so the list of any type can be printed, not only integers list.forEach(element -> System.out.println(" – " + element)); } @@ -160,8 +165,10 @@ public static void print(List list) { * @param entities provided collection of entities * @return true if at least one of the elements has null id */ - public static boolean hasNewEntities(Collection entities) { - throw new ExerciseNotCompletedException(); // todo: refactor parameter and implement method + public static boolean hasNewEntities(Collection entities) { + //throw new ExerciseNotCompletedException(); // todo: refactor parameter and implement method + return entities.stream() + .anyMatch(e -> e.getUuid() == null); } /** @@ -173,8 +180,10 @@ public static boolean hasNewEntities(Collection entities) { * @param validationPredicate criteria for validation * @return true if all entities fit validation criteria */ - public static boolean isValidCollection() { - throw new ExerciseNotCompletedException(); // todo: add method parameters and implement the logic + public static boolean isValidCollection(Collection entities, Predicate validationPredicate) { + //throw new ExerciseNotCompletedException(); // todo: add method parameters and implement the logic + return entities.stream() + .allMatch(validationPredicate); } /** @@ -187,8 +196,11 @@ public static boolean isValidCollection() { * @param entity type * @return true if entities list contains target entity more than once */ - public static boolean hasDuplicates() { - throw new ExerciseNotCompletedException(); // todo: update method signature and implement it + public static boolean hasDuplicates(Collection entities, T targetEntity) { + //throw new ExerciseNotCompletedException(); // todo: update method signature and implement it + return entities.stream() + .filter(e -> e.getUuid().equals(targetEntity.getUuid())) + .count() > 1; } /** @@ -201,6 +213,20 @@ public static boolean hasDuplicates() { * @return optional max value */ // todo: create a method and implement its logic manually without using util method from JDK + public static Optional findMax(Iterable elements, Comparator comparator){ + var iterator = elements.iterator(); + if(!iterator.hasNext()){ + return Optional.empty(); + } + var max = iterator.next(); + while(iterator.hasNext()){ + var element = iterator.next(); + if(comparator.compare(element, max) > 0){ + max = element; + } + } + return Optional.of(max); + } /** * findMostRecentlyCreatedEntity is a generic util method that accepts a collection of entities and returns the @@ -215,6 +241,10 @@ public static boolean hasDuplicates() { * @return an entity from the given collection that has the max createdOn value */ // todo: create a method according to JavaDoc and implement it using previous method + public static T findMostRecentlyCreatedEntity(Collection entities){ + return findMax(entities, CREATED_ON_COMPARATOR) + .orElseThrow(); + } /** * An util method that allows to swap two elements of any list. It changes the list so the element with the index @@ -228,7 +258,14 @@ public static boolean hasDuplicates() { public static void swap(List elements, int i, int j) { Objects.checkIndex(i, elements.size()); Objects.checkIndex(j, elements.size()); - throw new ExerciseNotCompletedException(); // todo: complete method implementation + //throw new ExerciseNotCompletedException(); // todo: complete method implementation + swapHelper(elements, i, j); + } + + private static void swapHelper(List elements, int i, int j){ + T temp = elements.get(i); + elements.set(i, elements.get(j)); + elements.set(j, temp); } }