From be2a321118d39f4e0acb32e75ed08205a707fc09 Mon Sep 17 00:00:00 2001
From: Ivan Semkiv <ivansemkiv@MacBook-Air-Ivan.local>
Date: Thu, 12 Sep 2024 09:58:18 +0200
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
---
.../com/bobocode/intro/ExerciseIntroduction.java | 14 +++++++-------
1 file changed, 7 insertions(+), 7 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..0b758fe7d 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
@@ -1,5 +1,5 @@
package com.bobocode.intro;
-
+import java.util.Base64;
import com.bobocode.util.ExerciseNotCompletedException;
/**
@@ -23,9 +23,9 @@ 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
- throw new ExerciseNotCompletedException();
+ return "The key to efficient learning is practice!";
}
+
/**
* Method encodeMessage accepts one {@link String} parameter and returns encoded {@link String}.
@@ -38,8 +38,8 @@ public String getWelcomeMessage() {
* @param message input message
* @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();
- }
+
+public String encodeMessage(String message) {
+ return Base64.getEncoder().encodeToString(message.getBytes());
}
+}
\ No newline at end of file
From 8c0c8c7d9d272bcffd18458e773a200a2a589aa9 Mon Sep 17 00:00:00 2001
From: Ivan Semkiv <ivansemkiv@MacBook-Air-Ivan.local>
Date: Fri, 1 Nov 2024 03:33:54 +0100
Subject: [PATCH 2/2] =?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
---
.../main/java/com/bobocode/basics/Box.java | 12 +-
.../com/bobocode/basics/CrazyGenerics.java | 110 ++++++++++++------
2 files changed, 78 insertions(+), 44 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..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
@@ -7,18 +7,18 @@
* <p>
* 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<T> {
+ 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;
}
-}
+}
\ No newline at end of file
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..ea0252325 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 +1,11 @@
package com.bobocode.basics;
import com.bobocode.basics.util.BaseEntity;
-import com.bobocode.util.ExerciseNotCompletedException;
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 +30,8 @@ public class CrazyGenerics {
* @param <T> – 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<T> { // todo: refactor class to introduce type parameter and make value generic
+ private T value;
private String source;
}
@@ -45,11 +42,11 @@ public static class Sourced { // todo: refactor class to introduce type paramete
* @param <T> – actual, min and max type
*/
@Data
- public static class Limited {
+ public static class Limited<T extends Number> {
// 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 +56,9 @@ public static class Limited {
* @param <T> – source object type
* @param <R> - converted result type
*/
- public interface Converter { // todo: introduce type parameters
+ public interface Converter<T, R> { // todo: introduce type parameters
// todo: add convert method
+ R convert(T param);
}
/**
@@ -70,10 +68,10 @@ public interface Converter { // todo: introduce type parameters
*
* @param <T> – value type
*/
- public static class MaxHolder { // todo: refactor class to make it generic
- private Object max;
+ public static class MaxHolder<T extends Comparable<? super T>> { // todo: refactor class to make it generic
+ private T max;
- public MaxHolder(Object max) {
+ public MaxHolder(T max) {
this.max = max;
}
@@ -82,11 +80,13 @@ 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;
+ } // todo: update parameter and implement the method
}
- public Object getMax() {
+ public T getMax() {
return max;
}
}
@@ -97,8 +97,8 @@ public Object getMax() {
*
* @param <T> – the type of objects that can be processed
*/
- interface StrictProcessor { // todo: make it generic
- void process(Object obj);
+ interface StrictProcessor<T extends Serializable & Comparable<? super T>> { // todo: make it generic
+ void process(T obj);
}
/**
@@ -108,19 +108,19 @@ interface StrictProcessor { // todo: make it generic
* @param <T> – a type of the entity that should be a subclass of {@link BaseEntity}
* @param <C> – a type of any collection
*/
- interface CollectionRepository { // todo: update interface according to the javadoc
- void save(Object entity);
+ interface CollectionRepository<T extends BaseEntity, C extends Collection<T>> { // todo: update interface according to the javadoc
+ void save(T entity);
- Collection<Object> getEntityCollection();
+ C getEntityCollection();
}
/**
* {@link ListRepository} extends {@link CollectionRepository} but specifies the underlying collection as
- * {@link java.util.List}.
+ * {@link List}.
*
* @param <T> – a type of the entity that should be a subclass of {@link BaseEntity}
*/
- interface ListRepository { // todo: update interface according to the javadoc
+ interface ListRepository<T extends BaseEntity> extends CollectionRepository<T, List<T>> { // todo: update interface according to the javadoc
}
/**
@@ -133,7 +133,10 @@ interface ListRepository { // todo: update interface according to the javadoc
*
* @param <E> a type of collection elements
*/
- interface ComparableCollection { // todo: refactor it to make generic and provide a default impl of compareTo
+ interface ComparableCollection<E> extends Collection<E>, Comparable<Collection<?>> { // todo: refactor it to make generic and provide a default impl of compareTo
+ default int compareTo(Collection<?> other) {
+ return Integer.compare(this.size(), other.size());
+ }
}
/**
@@ -147,7 +150,7 @@ static class CollectionUtil {
*
* @param list
*/
- public static void print(List<Integer> 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 +163,13 @@ public static void print(List<Integer> list) {
* @param entities provided collection of entities
* @return true if at least one of the elements has null id
*/
- public static boolean hasNewEntities(Collection<BaseEntity> entities) {
- throw new ExerciseNotCompletedException(); // todo: refactor parameter and implement method
+ public static boolean hasNewEntities(Collection<? extends BaseEntity> entities) {
+ for (BaseEntity e : entities) {
+ if (e.getUuid() == null) {
+ return true; // todo: refactor parameter and implement method
+ }
+ }
+ return false; // todo: refactor parameter and implement method
}
/**
@@ -173,8 +181,10 @@ public static boolean hasNewEntities(Collection<BaseEntity> 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<? extends BaseEntity> entities, Predicate<? super BaseEntity> validationPredicate) {
+ return entities.stream()
+ .allMatch(validationPredicate);
+
}
/**
@@ -187,8 +197,10 @@ public static boolean isValidCollection() {
* @param <T> 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 <T extends BaseEntity> boolean hasDuplicates(List<T> entities, T targetEntity) {
+ return entities.stream()
+ .filter(entity -> entity.getUuid().equals(targetEntity.getUuid()))
+ .count() > 1;
}
/**
@@ -202,10 +214,23 @@ public static boolean hasDuplicates() {
*/
// todo: create a method and implement its logic manually without using util method from JDK
+ public static <T> Optional<T> findMax(Iterable<T> elements, Comparator<? super T> comparator) {
+ if (elements.iterator().hasNext()) {
+ T max = elements.iterator().next();
+ for (T e : elements) {
+ if (comparator.compare(e, max) > 0) {
+ max = e;
+ }
+ }
+ return Optional.of(max);
+ }
+ return Optional.empty();
+ }
+
/**
* findMostRecentlyCreatedEntity is a generic util method that accepts a collection of entities and returns the
* one that is the most recently created. If collection is empty,
- * it throws {@link java.util.NoSuchElementException}.
+ * it throws {@link NoSuchElementException}.
* <p>
* This method reuses findMax method and passes entities along with prepare comparator instance,
* that is stored as constant CREATED_ON_COMPARATOR.
@@ -216,6 +241,11 @@ public static boolean hasDuplicates() {
*/
// todo: create a method according to JavaDoc and implement it using previous method
+ public static <T extends BaseEntity> T findMostRecentlyCreatedEntity(Collection<T> 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
* i will be located on index j, and the element with index j, will be located on the index i.
@@ -226,10 +256,14 @@ public static boolean hasDuplicates() {
* @param j index of the other element to swap
*/
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 <T> void swapHelper(List<T> 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