From 311a58f9c04e63bdfa22f3c46fb11697a6695c62 Mon Sep 17 00:00:00 2001 From: unknown Date: Thu, 2 Oct 2025 10:11:35 +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 | 3 ++- .../src/main/java/com/bobocode/basics/Box.java | 10 +++++----- .../src/main/java/com/bobocode/basics/BoxDemoApp.java | 7 ++++--- 3 files changed, 11 insertions(+), 9 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..5bcdea3c2 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 @@ -24,7 +24,8 @@ public class ExerciseIntroduction { */ public String getWelcomeMessage() { // todo: implement a method and return a message according to javadoc - throw new ExerciseNotCompletedException(); + return "The key to efficient learning is practice!"; + } /** 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/1-3-0-hello-generics/src/main/java/com/bobocode/basics/BoxDemoApp.java b/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/BoxDemoApp.java index bc12174ee..a104ffa62 100644 --- a/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/BoxDemoApp.java +++ b/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/BoxDemoApp.java @@ -9,13 +9,14 @@ */ public class BoxDemoApp { public static void main(String[] args) { - Box intBox = new Box(123); - Box intBox2 = new Box(321); - System.out.println((int) intBox.getValue() + (int) intBox2.getValue()); + Box intBox = new Box<>(123); + Box intBox2 = new Box<>(321); + System.out.println(intBox.getValue() + intBox2.getValue()); intBox.setValue(222); intBox.setValue("abc"); // this should not be allowed // the following code will compile, but will throw runtime exception System.out.println((int) intBox.getValue() + (int) intBox2.getValue()); + } } From 811f969254f6fe1534a10900d552e464a13c48c6 Mon Sep 17 00:00:00 2001 From: unknown Date: Wed, 15 Oct 2025 19:59:44 +0300 Subject: [PATCH 2/2] I did hw '06. java-fundamentals-exercises - 1-0-java-basics' --- .../bobocode/intro/ExerciseIntroduction.java | 11 +- .../main/java/com/bobocode/basics/Box.java | 2 +- .../java/com/bobocode/basics/BoxDemoApp.java | 2 +- .../com/bobocode/basics/CrazyGenerics.java | 110 +++++++++++------- 4 files changed, 74 insertions(+), 51 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 5bcdea3c2..d00613f68 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 @@ -1,6 +1,6 @@ package com.bobocode.intro; -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. @@ -23,9 +23,7 @@ public class ExerciseIntroduction { * @return "The key to efficient learning is practice!" */ public String getWelcomeMessage() { - // todo: implement a method and return a message according to javadoc - return "The key to efficient learning is practice!"; - + return "The key to efficient learning is practice!"; } /** @@ -40,7 +38,6 @@ public String getWelcomeMessage() { * @return encoded message */ public String encodeMessage(String message) { - // todo: switch to branch "completed" in order to see how it should be implemented - throw new ExerciseNotCompletedException(); + return Base64.getEncoder().encodeToString(message.getBytes()); } -} +} \ No newline at end of file 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 180603a28..1613fcfc3 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 @@ -21,4 +21,4 @@ public T getValue() { public void setValue(T value) { this.value = value; } -} +} \ No newline at end of file diff --git a/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/BoxDemoApp.java b/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/BoxDemoApp.java index a104ffa62..f45534e5d 100644 --- a/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/BoxDemoApp.java +++ b/1-0-java-basics/1-3-0-hello-generics/src/main/java/com/bobocode/basics/BoxDemoApp.java @@ -14,7 +14,7 @@ public static void main(String[] args) { System.out.println(intBox.getValue() + intBox2.getValue()); intBox.setValue(222); - intBox.setValue("abc"); // this should not be allowed + //intBox.setValue("abc"); // this should not be allowed // the following code will compile, but will throw runtime exception System.out.println((int) intBox.getValue() + (int) intBox2.getValue()); 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..669615826 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 @@ -1,14 +1,12 @@ package com.bobocode.basics; import com.bobocode.basics.util.BaseEntity; -import com.bobocode.util.ExerciseNotCompletedException; import lombok.Data; +import lombok.val; 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 { + private T value; private String source; } @@ -45,11 +43,10 @@ public static class Sourced { // todo: refactor class to introduce type paramete * @param – actual, min and max type */ @Data - 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; + public static class Limited { + private final T actual; + private final T min; + private final T max; } /** @@ -59,8 +56,8 @@ public static class Limited { * @param – source object type * @param - converted result type */ - public interface Converter { // todo: introduce type parameters - // todo: add convert method + public interface Converter { + R convert(T obj); } /** @@ -70,10 +67,10 @@ 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 +79,13 @@ 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) { + if (val.compareTo(max) > 0) { + max = val; + } } - public Object getMax() { + public T getMax() { return max; } } @@ -97,8 +96,8 @@ 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 +107,10 @@ 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); + interface CollectionRepository> { // todo: update interface according to the javadoc + void save(T entity); - Collection getEntityCollection(); + C getEntityCollection(); } /** @@ -120,7 +119,7 @@ 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 } /** @@ -133,12 +132,14 @@ 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> { + + @Override + default int compareTo(Collection o) { + return Integer.compare(this.size(), o.size()); + } } - /** - * {@link CollectionUtil} is an util class that provides various generic helper methods. - */ static class CollectionUtil { static final Comparator CREATED_ON_COMPARATOR = Comparator.comparing(BaseEntity::getCreatedOn); @@ -147,8 +148,7 @@ static class CollectionUtil { * * @param list */ - public static void print(List list) { - // todo: refactor it so the list of any type can be printed, not only integers + public static void print(List list) { list.forEach(element -> System.out.println(" – " + element)); } @@ -160,8 +160,9 @@ 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) { + return entities.stream() + .anyMatch(e -> e.getUuid() == null); } /** @@ -173,8 +174,10 @@ 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) { + return entities.stream() + .allMatch(validationPredicate); } /** @@ -187,8 +190,10 @@ 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) { + return entities.stream() + .filter(e -> e.getUuid().equals(targetEntity.getUuid())) + .count() > 1; } /** @@ -200,7 +205,20 @@ public static boolean hasDuplicates() { * @param type of elements * @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 @@ -214,7 +232,10 @@ public static boolean hasDuplicates() { * @param entity type * @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 @@ -228,8 +249,13 @@ 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 + 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); + } } -} +} \ No newline at end of file