This commit is contained in:
Jonathan Cook 2020-05-05 09:58:54 +02:00
commit 65b0294435
522 changed files with 6915 additions and 1614 deletions

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@ -15,9 +15,5 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
- [Maximum Subarray Problem](https://www.baeldung.com/java-maximum-subarray)
- [How to Merge Two Sorted Arrays](https://www.baeldung.com/java-merge-sorted-arrays)
- [Median of Stream of Integers using Heap](https://www.baeldung.com/java-stream-integers-median-using-heap)
- [Kruskals Algorithm for Spanning Trees](https://www.baeldung.com/java-spanning-trees-kruskal)
- [Balanced Brackets Algorithm in Java](https://www.baeldung.com/java-balanced-brackets-algorithm)
- [Efficiently Merge Sorted Java Sequences](https://www.baeldung.com/java-merge-sorted-sequences)
- [Introduction to Greedy Algorithms with Java](https://www.baeldung.com/java-greedy-algorithms)
- [The Caesar Cipher in Java](https://www.baeldung.com/java-caesar-cipher)
- More articles: [[<-- prev]](/../algorithms-miscellaneous-4)
- More articles: [[<-- prev]](/../algorithms-miscellaneous-4) [[next -->]](/../algorithms-miscellaneous-6)

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@ -25,12 +25,6 @@
<artifactId>commons-math3</artifactId>
<version>${commons-math3.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>pl.allegro.finance</groupId>
<artifactId>tradukisto</artifactId>

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@ -2,3 +2,9 @@
- [Boruvkas Algorithm for Minimum Spanning Trees](https://www.baeldung.com/java-boruvka-algorithm)
- [Gradient Descent in Java](https://www.baeldung.com/java-gradient-descent)
- [Kruskals Algorithm for Spanning Trees](https://www.baeldung.com/java-spanning-trees-kruskal)
- [Balanced Brackets Algorithm in Java](https://www.baeldung.com/java-balanced-brackets-algorithm)
- [Efficiently Merge Sorted Java Sequences](https://www.baeldung.com/java-merge-sorted-sequences)
- [Introduction to Greedy Algorithms with Java](https://www.baeldung.com/java-greedy-algorithms)
- [The Caesar Cipher in Java](https://www.baeldung.com/java-caesar-cipher)
- More articles: [[<-- prev]](/../algorithms-miscellaneous-5)

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@ -18,10 +18,35 @@
<artifactId>guava</artifactId>
<version>${guava.version}</version>
</dependency>
<dependency>
<groupId>org.junit.platform</groupId>
<artifactId>junit-platform-commons</artifactId>
<version>${junit.platform.version}</version>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${org.assertj.core.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-math3</artifactId>
<version>${commons-math3.version}</version>
</dependency>
</dependencies>
<properties>
<guava.version>28.1-jre</guava.version>
<org.assertj.core.version>3.9.0</org.assertj.core.version>
<junit.platform.version>1.6.0</junit.platform.version>
<commons-math3.version>3.6.1</commons-math3.version>
</properties>
</project>

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@ -1,13 +1,13 @@
package com.baeldung.algorithms.minheapmerge;
public class HeapNode {
int element;
int arrayIndex;
int nextElementIndex = 1;
public HeapNode(int element, int arrayIndex) {
this.element = element;
this.arrayIndex = arrayIndex;
}
}
package com.baeldung.algorithms.minheapmerge;
public class HeapNode {
int element;
int arrayIndex;
int nextElementIndex = 1;
public HeapNode(int element, int arrayIndex) {
this.element = element;
this.arrayIndex = arrayIndex;
}
}

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@ -1,88 +1,88 @@
package com.baeldung.algorithms.minheapmerge;
public class MinHeap {
HeapNode[] heapNodes;
public MinHeap(HeapNode heapNodes[]) {
this.heapNodes = heapNodes;
heapifyFromLastLeafsParent();
}
void heapifyFromLastLeafsParent() {
int lastLeafsParentIndex = getParentNodeIndex(heapNodes.length);
while (lastLeafsParentIndex >= 0) {
heapify(lastLeafsParentIndex);
lastLeafsParentIndex--;
}
}
void heapify(int index) {
int leftNodeIndex = getLeftNodeIndex(index);
int rightNodeIndex = getRightNodeIndex(index);
int smallestElementIndex = index;
if (leftNodeIndex < heapNodes.length && heapNodes[leftNodeIndex].element < heapNodes[index].element) {
smallestElementIndex = leftNodeIndex;
}
if (rightNodeIndex < heapNodes.length && heapNodes[rightNodeIndex].element < heapNodes[smallestElementIndex].element) {
smallestElementIndex = rightNodeIndex;
}
if (smallestElementIndex != index) {
swap(index, smallestElementIndex);
heapify(smallestElementIndex);
}
}
int getParentNodeIndex(int index) {
return (index - 1) / 2;
}
int getLeftNodeIndex(int index) {
return (2 * index + 1);
}
int getRightNodeIndex(int index) {
return (2 * index + 2);
}
HeapNode getRootNode() {
return heapNodes[0];
}
void heapifyFromRoot() {
heapify(0);
}
void swap(int i, int j) {
HeapNode temp = heapNodes[i];
heapNodes[i] = heapNodes[j];
heapNodes[j] = temp;
}
static int[] merge(int[][] array) {
HeapNode[] heapNodes = new HeapNode[array.length];
int resultingArraySize = 0;
for (int i = 0; i < array.length; i++) {
HeapNode node = new HeapNode(array[i][0], i);
heapNodes[i] = node;
resultingArraySize += array[i].length;
}
MinHeap minHeap = new MinHeap(heapNodes);
int[] resultingArray = new int[resultingArraySize];
for (int i = 0; i < resultingArraySize; i++) {
HeapNode root = minHeap.getRootNode();
resultingArray[i] = root.element;
if (root.nextElementIndex < array[root.arrayIndex].length) {
root.element = array[root.arrayIndex][root.nextElementIndex++];
} else {
root.element = Integer.MAX_VALUE;
}
minHeap.heapifyFromRoot();
}
return resultingArray;
}
}
package com.baeldung.algorithms.minheapmerge;
public class MinHeap {
HeapNode[] heapNodes;
public MinHeap(HeapNode heapNodes[]) {
this.heapNodes = heapNodes;
heapifyFromLastLeafsParent();
}
void heapifyFromLastLeafsParent() {
int lastLeafsParentIndex = getParentNodeIndex(heapNodes.length);
while (lastLeafsParentIndex >= 0) {
heapify(lastLeafsParentIndex);
lastLeafsParentIndex--;
}
}
void heapify(int index) {
int leftNodeIndex = getLeftNodeIndex(index);
int rightNodeIndex = getRightNodeIndex(index);
int smallestElementIndex = index;
if (leftNodeIndex < heapNodes.length && heapNodes[leftNodeIndex].element < heapNodes[index].element) {
smallestElementIndex = leftNodeIndex;
}
if (rightNodeIndex < heapNodes.length && heapNodes[rightNodeIndex].element < heapNodes[smallestElementIndex].element) {
smallestElementIndex = rightNodeIndex;
}
if (smallestElementIndex != index) {
swap(index, smallestElementIndex);
heapify(smallestElementIndex);
}
}
int getParentNodeIndex(int index) {
return (index - 1) / 2;
}
int getLeftNodeIndex(int index) {
return (2 * index + 1);
}
int getRightNodeIndex(int index) {
return (2 * index + 2);
}
HeapNode getRootNode() {
return heapNodes[0];
}
void heapifyFromRoot() {
heapify(0);
}
void swap(int i, int j) {
HeapNode temp = heapNodes[i];
heapNodes[i] = heapNodes[j];
heapNodes[j] = temp;
}
static int[] merge(int[][] array) {
HeapNode[] heapNodes = new HeapNode[array.length];
int resultingArraySize = 0;
for (int i = 0; i < array.length; i++) {
HeapNode node = new HeapNode(array[i][0], i);
heapNodes[i] = node;
resultingArraySize += array[i].length;
}
MinHeap minHeap = new MinHeap(heapNodes);
int[] resultingArray = new int[resultingArraySize];
for (int i = 0; i < resultingArraySize; i++) {
HeapNode root = minHeap.getRootNode();
resultingArray[i] = root.element;
if (root.nextElementIndex < array[root.arrayIndex].length) {
root.element = array[root.arrayIndex][root.nextElementIndex++];
} else {
root.element = Integer.MAX_VALUE;
}
minHeap.heapifyFromRoot();
}
return resultingArray;
}
}

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@ -1,22 +1,22 @@
package com.baeldung.algorithms.minheapmerge;
import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import org.junit.Test;
public class MinHeapUnitTest {
private final int[][] inputArray = { { 0, 6 }, { 1, 5, 10, 100 }, { 2, 4, 200, 650 } };
private final int[] expectedArray = { 0, 1, 2, 4, 5, 6, 10, 100, 200, 650 };
@Test
public void givenSortedArrays_whenMerged_thenShouldReturnASingleSortedarray() {
int[] resultArray = MinHeap.merge(inputArray);
assertThat(resultArray.length, is(equalTo(10)));
assertThat(resultArray, is(equalTo(expectedArray)));
}
}
package com.baeldung.algorithms.minheapmerge;
import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import org.junit.Test;
public class MinHeapUnitTest {
private final int[][] inputArray = { { 0, 6 }, { 1, 5, 10, 100 }, { 2, 4, 200, 650 } };
private final int[] expectedArray = { 0, 1, 2, 4, 5, 6, 10, 100, 200, 650 };
@Test
public void givenSortedArrays_whenMerged_thenShouldReturnASingleSortedarray() {
int[] resultArray = MinHeap.merge(inputArray);
assertThat(resultArray.length, is(equalTo(10)));
assertThat(resultArray, is(equalTo(expectedArray)));
}
}

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@ -1,4 +1,4 @@
package com.baeldung.java14.helpfulnullpointerexceptions;
package com.baeldung.java14.npe;
public class HelpfulNullPointerException {

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@ -5,5 +5,5 @@ This module contains articles about sorting arrays in Java
### Relevant Articles:
- [Sorting Arrays in Java](https://www.baeldung.com/java-sorting-arrays)
- [Checking If an Array Is Sorted in Java](https://www.baeldung.com/java-check-sorted-array)
- [How to Reverse an Array in Java](http://www.baeldung.com/java-invert-array)
- [How to Reverse an Array in Java](https://www.baeldung.com/java-invert-array)
- [Arrays.sort vs Arrays.parallelSort](https://www.baeldung.com/java-arrays-sort-vs-parallelsort)

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@ -4,4 +4,5 @@
### Relevant Articles:
- [Using a Mutex Object in Java](https://www.baeldung.com/java-mutex)
- [Testing Multi-Threaded Code in Java] (https://www.baeldung.com/java-testing-multithreaded)

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@ -15,6 +15,38 @@
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.googlecode.thread-weaver</groupId>
<artifactId>threadweaver</artifactId>
<version>0.2</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.code.tempus-fugit</groupId>
<artifactId>tempus-fugit</artifactId>
<version>1.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.googlecode.multithreadedtc</groupId>
<artifactId>multithreadedtc</artifactId>
<version>1.01</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.openjdk.jcstress</groupId>
<artifactId>jcstress-core</artifactId>
<version>0.5</version>
</dependency>
</dependencies>
<build>
<finalName>core-java-concurrency-2</finalName>
@ -24,6 +56,51 @@
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<compilerVersion>${javac.target}</compilerVersion>
<source>${javac.target}</source>
<target>${javac.target}</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.2</version>
<executions>
<execution>
<id>main</id>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<finalName>jcstress</finalName>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>org.openjdk.jcstress.Main</mainClass>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/TestList</resource>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<properties>
<javac.target>1.8</javac.target>
</properties>
</project>

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@ -1,5 +1,6 @@
package com.baeldung.concurrent;
import org.junit.Ignore;
import org.junit.Test;
import edu.umd.cs.mtc.MultithreadedTestCase;
@ -25,9 +26,10 @@ public class MyCounterMultithreadedTCUnitTest extends MultithreadedTestCase {
@SuppressWarnings("deprecation")
@Override
public void finish() {
assertEquals(2, counter.getCount());
assertEquals(2, counter.getCount());
}
@Ignore
@Test
public void testCounter() throws Throwable {
TestFramework.runManyTimes(new MyCounterMultithreadedTCUnitTest(), 1000);

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@ -6,6 +6,7 @@ import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.junit.Ignore;
import org.junit.Test;
public class MyCounterSimpleUnitTest {
@ -18,7 +19,8 @@ public class MyCounterSimpleUnitTest {
assertEquals(500, counter.getCount());
}
// @Test
@Ignore
@Test
public void testCounterWithConcurrency() throws InterruptedException {
int numberOfThreads = 100;
ExecutorService service = Executors.newFixedThreadPool(10);
@ -34,7 +36,8 @@ public class MyCounterSimpleUnitTest {
assertEquals(numberOfThreads, counter.getCount());
}
// @Test
@Ignore
@Test
public void testSummationWithConcurrencyAndWait() throws InterruptedException {
int numberOfThreads = 2;
ExecutorService service = Executors.newFixedThreadPool(10);

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@ -3,6 +3,7 @@ package com.baeldung.concurrent;
import static org.junit.Assert.assertEquals;
import org.junit.AfterClass;
import org.junit.Ignore;
import org.junit.Rule;
import org.junit.Test;
@ -20,6 +21,7 @@ public class MyCounterTempusFugitUnitTest {
private static MyCounter counter = new MyCounter();
@Ignore
@Test
@Concurrent(count = 2)
@Repeating(repetition = 10)

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@ -2,6 +2,7 @@ package com.baeldung.concurrent;
import static org.junit.Assert.assertEquals;
import org.junit.Ignore;
import org.junit.Test;
import com.google.testing.threadtester.AnnotatedTestRunner;
@ -34,6 +35,7 @@ public class MyCounterThreadWeaverUnitTest {
assertEquals(2, counter.getCount());
}
@Ignore
@Test
public void testCounter() {
new AnnotatedTestRunner().runTests(this.getClass(), MyCounter.class);

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@ -0,0 +1,60 @@
package com.baeldung.deadlockAndLivelock;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class DeadlockExample {
private Lock lock1 = new ReentrantLock(true);
private Lock lock2 = new ReentrantLock(true);
public static void main(String[] args) {
DeadlockExample deadlock = new DeadlockExample();
new Thread(deadlock::operation1, "T1").start();
new Thread(deadlock::operation2, "T2").start();
}
public void operation1() {
lock1.lock();
print("lock1 acquired, waiting to acquire lock2.");
sleep(50);
lock2.lock();
print("lock2 acquired");
print("executing first operation.");
lock2.unlock();
lock1.unlock();
}
public void operation2() {
lock2.lock();
print("lock2 acquired, waiting to acquire lock1.");
sleep(50);
lock1.lock();
print("lock1 acquired");
print("executing second operation.");
lock1.unlock();
lock2.unlock();
}
public void print(String message) {
System.out.println("Thread " + Thread.currentThread()
.getName() + ": " + message);
}
public void sleep(long millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}

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@ -0,0 +1,86 @@
package com.baeldung.deadlockAndLivelock;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class LivelockExample {
private Lock lock1 = new ReentrantLock(true);
private Lock lock2 = new ReentrantLock(true);
public static void main(String[] args) {
LivelockExample livelock = new LivelockExample();
new Thread(livelock::operation1, "T1").start();
new Thread(livelock::operation2, "T2").start();
}
public void operation1() {
while (true) {
tryLock(lock1, 50);
print("lock1 acquired, trying to acquire lock2.");
sleep(50);
if (tryLock(lock2)) {
print("lock2 acquired.");
} else {
print("cannot acquire lock2, releasing lock1.");
lock1.unlock();
continue;
}
print("executing first operation.");
break;
}
lock2.unlock();
lock1.unlock();
}
public void operation2() {
while (true) {
tryLock(lock2, 50);
print("lock2 acquired, trying to acquire lock1.");
sleep(50);
if (tryLock(lock1)) {
print("lock1 acquired.");
} else {
print("cannot acquire lock1, releasing lock2.");
lock2.unlock();
continue;
}
print("executing second operation.");
break;
}
lock1.unlock();
lock2.unlock();
}
public void print(String message) {
System.out.println("Thread " + Thread.currentThread()
.getName() + ": " + message);
}
public void sleep(long millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void tryLock(Lock lock, long millis) {
try {
lock.tryLock(10, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public boolean tryLock(Lock lock) {
return lock.tryLock();
}
}

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@ -1,7 +0,0 @@
=========
## Core Java Concurrency Testing Examples
### Relevant Articles:
- [Testing Multi-Threaded Code in Java](https://www.baeldung.com/java-testing-multithreaded)

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@ -1,93 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-concurrency-testing</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-concurrency-testing</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.googlecode.thread-weaver</groupId>
<artifactId>threadweaver</artifactId>
<version>0.2</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.code.tempus-fugit</groupId>
<artifactId>tempus-fugit</artifactId>
<version>1.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.googlecode.multithreadedtc</groupId>
<artifactId>multithreadedtc</artifactId>
<version>1.01</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.openjdk.jcstress</groupId>
<artifactId>jcstress-core</artifactId>
<version>0.5</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<compilerVersion>${javac.target}</compilerVersion>
<source>${javac.target}</source>
<target>${javac.target}</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.2</version>
<executions>
<execution>
<id>main</id>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<finalName>jcstress</finalName>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>org.openjdk.jcstress.Main</mainClass>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/TestList</resource>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

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@ -1,19 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
</pattern>
</encoder>
</appender>
<logger name="org.springframework" level="WARN" />
<logger name="org.springframework.transaction" level="WARN" />
<!-- in order to debug some marshalling issues, this needs to be TRACE -->
<logger name="org.springframework.web.servlet.mvc" level="WARN" />
<root level="INFO">
<appender-ref ref="STDOUT" />
</root>
</configuration>

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@ -1,13 +0,0 @@
*.class
#folders#
/target
/neoDb*
/data
/src/main/webapp/WEB-INF/classes
*/META-INF/*
# Packaged files #
*.jar
*.war
*.ear

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@ -29,6 +29,11 @@
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons.lang3.version}</version>
</dependency>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
@ -40,6 +45,7 @@
<properties>
<javax.mail.version>1.5.0-b01</javax.mail.version>
<commons.lang3.version>3.10</commons.lang3.version>
<!-- testing -->
<assertj-core.version>3.10.0</assertj-core.version>
</properties>

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@ -0,0 +1,20 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Arithmetic {
private static Logger LOGGER = LoggerFactory.getLogger(Arithmetic.class);
public static void main(String[] args) {
try {
int result = 30 / 0; // Trying to divide by zero
} catch (ArithmeticException e) {
LOGGER.error("ArithmeticException caught!");
}
}
}

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@ -0,0 +1,24 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class ArrayIndexOutOfBounds {
private static Logger LOGGER = LoggerFactory.getLogger(ArrayIndexOutOfBounds.class);
public static void main(String[] args) {
int[] nums = new int[] { 1, 2, 3 };
try {
int numFromNegativeIndex = nums[-1]; // Trying to access at negative index
int numFromGreaterIndex = nums[4]; // Trying to access at greater index
int numFromLengthIndex = nums[3]; // Trying to access at index equal to size of the array
} catch (ArrayIndexOutOfBoundsException e) {
LOGGER.error("ArrayIndexOutOfBoundsException caught");
}
}
}

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@ -0,0 +1,36 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
class Animal {
}
class Dog extends Animal {
}
class Lion extends Animal {
}
public class ClassCast {
private static Logger LOGGER = LoggerFactory.getLogger(ClassCast.class);
public static void main(String[] args) {
try {
Animal animalOne = new Dog(); // At runtime the instance is dog
Dog bruno = (Dog) animalOne; // Downcasting
Animal animalTwo = new Lion(); // At runtime the instance is animal
Dog tommy = (Dog) animalTwo; // Downcasting
} catch (ClassCastException e) {
LOGGER.error("ClassCastException caught!");
}
}
}

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package com.baeldung.exceptions.globalexceptionhandler;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class FileNotFound {
private static Logger LOGGER = LoggerFactory.getLogger(FileNotFound.class);
public static void main(String[] args) {
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader(new File("/invalid/file/location")));
} catch (FileNotFoundException e) {
LOGGER.error("FileNotFoundException caught!");
}
}
}

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package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class GlobalExceptionHandler {
public static void main(String[] args) {
Handler globalExceptionHandler = new Handler();
Thread.setDefaultUncaughtExceptionHandler(globalExceptionHandler);
new GlobalExceptionHandler().performArithmeticOperation(10, 0);
}
public int performArithmeticOperation(int num1, int num2) {
return num1/num2;
}
}
class Handler implements Thread.UncaughtExceptionHandler {
private static Logger LOGGER = LoggerFactory.getLogger(Handler.class);
public void uncaughtException(Thread t, Throwable e) {
LOGGER.info("Unhandled exception caught!");
}
}

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@ -0,0 +1,18 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class IllegalArgument {
private static Logger LOGGER = LoggerFactory.getLogger(IllegalArgument.class);
public static void main(String[] args) {
try {
Thread.sleep(-1000);
} catch (InterruptedException e) {
LOGGER.error("IllegalArgumentException caught!");
}
}
}

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package com.baeldung.exceptions.globalexceptionhandler;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class IllegalState {
private static Logger LOGGER = LoggerFactory.getLogger(IllegalState.class);
public static void main(String[] args) {
List<Integer> intList = new ArrayList<>();
for (int i = 0; i < 10; i++) {
intList.add(i);
}
Iterator<Integer> intListIterator = intList.iterator(); // Initialized with index at -1
try {
intListIterator.remove(); // IllegalStateException
} catch (IllegalStateException e) {
LOGGER.error("IllegalStateException caught!");
}
}
}

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@ -0,0 +1,28 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
class ChildThread extends Thread {
private static Logger LOGGER = LoggerFactory.getLogger(ChildThread.class);
public void run() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
LOGGER.error("InterruptedException caught!");
}
}
}
public class InterruptedExceptionExample {
public static void main(String[] args) throws InterruptedException {
ChildThread childThread = new ChildThread();
childThread.start();
childThread.interrupt();
}
}

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@ -0,0 +1,25 @@
package com.baeldung.exceptions.globalexceptionhandler;
import java.net.MalformedURLException;
import java.net.URL;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class MalformedURL {
private static Logger LOGGER = LoggerFactory.getLogger(MalformedURL.class);
public static void main(String[] args) {
URL baeldungURL = null;
try {
baeldungURL = new URL("malformedurl");
} catch (MalformedURLException e) {
LOGGER.error("MalformedURLException caught!");
}
}
}

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@ -0,0 +1,36 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class NullPointer {
private static Logger LOGGER = LoggerFactory.getLogger(NullPointer.class);
public static void main(String[] args) {
Person personObj = null;
try {
String name = personObj.personName; // Accessing the field of a null object
personObj.personName = "Jon Doe"; // Modifying the field of a null object
} catch (NullPointerException e) {
LOGGER.error("NullPointerException caught!");
}
}
}
class Person {
public String personName;
public String getPersonName() {
return personName;
}
public void setPersonName(String personName) {
this.personName = personName;
}
}

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@ -0,0 +1,23 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class NumberFormat {
private static Logger LOGGER = LoggerFactory.getLogger(NumberFormat.class);
public static void main(String[] args) {
String str1 = "100ABCD";
try {
int x = Integer.parseInt(str1); // Converting string with inappropriate format
int y = Integer.valueOf(str1);
} catch (NumberFormatException e) {
LOGGER.error("NumberFormatException caught!");
}
}
}

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@ -0,0 +1,25 @@
package com.baeldung.exceptions.globalexceptionhandler;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class ParseExceptionExample {
private static Logger LOGGER = LoggerFactory.getLogger(ParseExceptionExample.class);
public static void main(String[] args) {
DateFormat format = new SimpleDateFormat("MM, dd, yyyy");
try {
format.parse("01, , 2010");
} catch (ParseException e) {
LOGGER.error("ParseException caught!");
}
}
}

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@ -0,0 +1,23 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class StringIndexOutOfBounds {
private static Logger LOGGER = LoggerFactory.getLogger(StringIndexOutOfBounds.class);
public static void main(String[] args) {
String str = "Hello World";
try {
char charAtNegativeIndex = str.charAt(-1); // Trying to access at negative index
char charAtLengthIndex = str.charAt(11); // Trying to access at index equal to size of the string
} catch (StringIndexOutOfBoundsException e) {
LOGGER.error("StringIndexOutOfBoundsException caught");
}
}
}

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@ -0,0 +1,95 @@
package com.baeldung.exceptions.rootcausefinder;
import java.time.LocalDate;
import java.time.Period;
import java.time.format.DateTimeParseException;
import java.util.Objects;
/**
* Utility class to find root cause exceptions.
*/
public class RootCauseFinder {
public static Throwable findCauseUsingPlainJava(Throwable throwable) {
Objects.requireNonNull(throwable);
Throwable rootCause = throwable;
while (rootCause.getCause() != null) {
rootCause = rootCause.getCause();
}
return rootCause;
}
/**
* Calculates the age of a person from a given date.
*/
static class AgeCalculator {
private AgeCalculator() {
}
public static int calculateAge(String birthDate) throws CalculationException {
if (birthDate == null || birthDate.isEmpty()) {
throw new IllegalArgumentException();
}
try {
return Period
.between(parseDate(birthDate), LocalDate.now())
.getYears();
} catch (DateParseException ex) {
throw new CalculationException(ex);
}
}
private static LocalDate parseDate(String birthDateAsString) throws DateParseException {
LocalDate birthDate;
try {
birthDate = LocalDate.parse(birthDateAsString);
} catch (DateTimeParseException ex) {
throw new InvalidFormatException(birthDateAsString, ex);
}
if (birthDate.isAfter(LocalDate.now())) {
throw new DateOutOfRangeException(birthDateAsString);
}
return birthDate;
}
}
static class CalculationException extends Exception {
CalculationException(DateParseException ex) {
super(ex);
}
}
static class DateParseException extends Exception {
DateParseException(String input) {
super(input);
}
DateParseException(String input, Throwable thr) {
super(input, thr);
}
}
static class InvalidFormatException extends DateParseException {
InvalidFormatException(String input, Throwable thr) {
super("Invalid date format: " + input, thr);
}
}
static class DateOutOfRangeException extends DateParseException {
DateOutOfRangeException(String date) {
super("Date out of range: " + date);
}
}
}

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@ -0,0 +1,64 @@
package com.baeldung.exceptions.globalexceptionhandler;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.ArgumentCaptor;
import org.mockito.Captor;
import org.mockito.Mock;
import org.mockito.junit.MockitoJUnitRunner;
import org.slf4j.LoggerFactory;
import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.classic.spi.LoggingEvent;
import ch.qos.logback.core.Appender;
import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.Mockito.verify;
@RunWith(MockitoJUnitRunner.class)
public class GlobalExceptionHandlerUnitTest {
@Mock
private Appender<ILoggingEvent> mockAppender;
@Captor
private ArgumentCaptor<LoggingEvent> captorLoggingEvent;
@Before
public void setup() {
final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
logger.addAppender(mockAppender);
Handler globalExceptionHandler = new Handler();
Thread.setDefaultUncaughtExceptionHandler(globalExceptionHandler);
}
@After
public void teardown() {
final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
logger.detachAppender(mockAppender);
}
@Test
public void whenArithmeticException_thenUseUncaughtExceptionHandler() throws InterruptedException {
Thread globalExceptionHandlerThread = new Thread() {
public void run() {
GlobalExceptionHandler globalExceptionHandlerObj = new GlobalExceptionHandler();
globalExceptionHandlerObj.performArithmeticOperation(99, 0);
}
};
globalExceptionHandlerThread.start();
globalExceptionHandlerThread.join();
verify(mockAppender).doAppend(captorLoggingEvent.capture());
LoggingEvent loggingEvent = captorLoggingEvent.getValue();
assertThat(loggingEvent.getLevel()).isEqualTo(Level.INFO);
assertThat(loggingEvent.getFormattedMessage()).isEqualTo("Unhandled exception caught!");
}
}

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package com.baeldung.exceptions.rootcausefinder;
import com.baeldung.exceptions.rootcausefinder.RootCauseFinder.CalculationException;
import com.baeldung.exceptions.rootcausefinder.RootCauseFinder.DateOutOfRangeException;
import com.google.common.base.Throwables;
import org.apache.commons.lang3.exception.ExceptionUtils;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import java.time.LocalDate;
import java.time.format.DateTimeParseException;
import java.time.temporal.ChronoUnit;
import static com.baeldung.exceptions.rootcausefinder.RootCauseFinder.AgeCalculator;
import static com.baeldung.exceptions.rootcausefinder.RootCauseFinder.findCauseUsingPlainJava;
import static org.junit.jupiter.api.Assertions.assertTrue;
/**
* Tests the {@link RootCauseFinder}.
*/
public class RootCauseFinderUnitTest {
@Test
public void givenBirthDate_whenCalculatingAge_thenAgeReturned() {
try {
int age = AgeCalculator.calculateAge("1990-01-01");
Assertions.assertEquals(1990, LocalDate
.now()
.minus(age, ChronoUnit.YEARS)
.getYear());
} catch (CalculationException e) {
Assertions.fail(e.getMessage());
}
}
@Test
public void givenWrongFormatDate_whenFindingRootCauseUsingJava_thenRootCauseFound() {
try {
AgeCalculator.calculateAge("010102");
} catch (CalculationException ex) {
assertTrue(findCauseUsingPlainJava(ex) instanceof DateTimeParseException);
}
}
@Test
public void givenOutOfRangeDate_whenFindingRootCauseUsingJava_thenRootCauseFound() {
try {
AgeCalculator.calculateAge("2020-04-04");
} catch (CalculationException ex) {
assertTrue(findCauseUsingPlainJava(ex) instanceof DateOutOfRangeException);
}
}
@Test
public void givenNullDate_whenFindingRootCauseUsingJava_thenRootCauseFound() {
try {
AgeCalculator.calculateAge(null);
} catch (Exception ex) {
assertTrue(findCauseUsingPlainJava(ex) instanceof IllegalArgumentException);
}
}
@Test
public void givenWrongFormatDate_whenFindingRootCauseUsingApacheCommons_thenRootCauseFound() {
try {
AgeCalculator.calculateAge("010102");
} catch (CalculationException ex) {
assertTrue(ExceptionUtils.getRootCause(ex) instanceof DateTimeParseException);
}
}
@Test
public void givenOutOfRangeDate_whenFindingRootCauseUsingApacheCommons_thenRootCauseFound() {
try {
AgeCalculator.calculateAge("2020-04-04");
} catch (CalculationException ex) {
assertTrue(ExceptionUtils.getRootCause(ex) instanceof DateOutOfRangeException);
}
}
@Test
public void givenWrongFormatDate_whenFindingRootCauseUsingGuava_thenRootCauseFound() {
try {
AgeCalculator.calculateAge("010102");
} catch (CalculationException ex) {
assertTrue(Throwables.getRootCause(ex) instanceof DateTimeParseException);
}
}
@Test
public void givenOutOfRangeDate_whenFindingRootCauseUsingGuava_thenRootCauseFound() {
try {
AgeCalculator.calculateAge("2020-04-04");
} catch (CalculationException ex) {
assertTrue(Throwables.getRootCause(ex) instanceof DateOutOfRangeException);
}
}
}

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package com.baeldung.exceptions;
import java.time.LocalDate;
import java.time.Period;
import java.time.format.DateTimeParseException;
import java.util.Objects;
/**
* Utility class to find root cause exceptions.
*/
public class RootCauseFinder {
public static Throwable findCauseUsingPlainJava(Throwable throwable) {
Objects.requireNonNull(throwable);
Throwable rootCause = throwable;
while (rootCause.getCause() != null) {
rootCause = rootCause.getCause();
}
return rootCause;
}
/**
* Calculates the age of a person from a given date.
*/
static class AgeCalculator {
private AgeCalculator() {
}
public static int calculateAge(String birthDate) throws CalculationException {
if (birthDate == null || birthDate.isEmpty()) {
throw new IllegalArgumentException();
}
try {
return Period
.between(parseDate(birthDate), LocalDate.now())
.getYears();
} catch (DateParseException ex) {
throw new CalculationException(ex);
}
}
private static LocalDate parseDate(String birthDateAsString) throws DateParseException {
LocalDate birthDate;
try {
birthDate = LocalDate.parse(birthDateAsString);
} catch (DateTimeParseException ex) {
throw new InvalidFormatException(birthDateAsString, ex);
}
if (birthDate.isAfter(LocalDate.now())) {
throw new DateOutOfRangeException(birthDateAsString);
}
return birthDate;
}
}
static class CalculationException extends Exception {
CalculationException(DateParseException ex) {
super(ex);
}
}
static class DateParseException extends Exception {
DateParseException(String input) {
super(input);
}
DateParseException(String input, Throwable thr) {
super(input, thr);
}
}
static class InvalidFormatException extends DateParseException {
InvalidFormatException(String input, Throwable thr) {
super("Invalid date format: " + input, thr);
}
}
static class DateOutOfRangeException extends DateParseException {
DateOutOfRangeException(String date) {
super("Date out of range: " + date);
}
}
}

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@ -1,4 +0,0 @@
target/
.idea/
bin/
*.iml

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@ -1,18 +0,0 @@
## Core Java Lang OOP (Part 2)
This module contains articles about Object-oriented programming (OOP) in Java
### Relevant Articles:
- [Generic Constructors in Java](https://www.baeldung.com/java-generic-constructors)
- [Cannot Reference “X” Before Supertype Constructor Has Been Called](https://www.baeldung.com/java-cannot-reference-x-before-supertype-constructor-error)
- [Anonymous Classes in Java](https://www.baeldung.com/java-anonymous-classes)
- [Raw Types in Java](https://www.baeldung.com/raw-types-java)
- [Marker Interfaces in Java](https://www.baeldung.com/java-marker-interfaces)
- [Java equals() and hashCode() Contracts](https://www.baeldung.com/java-equals-hashcode-contracts)
- [Immutable Objects in Java](https://www.baeldung.com/java-immutable-object)
- [Inheritance and Composition (Is-a vs Has-a relationship) in Java](https://www.baeldung.com/java-inheritance-composition)
- [A Guide to Constructors in Java](https://www.baeldung.com/java-constructors)
- [Static and Default Methods in Interfaces in Java](https://www.baeldung.com/java-static-default-methods)
- [Java Copy Constructor](https://www.baeldung.com/java-copy-constructor)
- [Abstract Classes in Java](https://www.baeldung.com/java-abstract-class)
- [[<-- Prev]](/core-java-modules/core-java-lang-oop)[[More -->]](/core-java-modules/core-java-lang-oop-3)

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@ -1,51 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-lang-oop-2</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-lang-oop-2</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj-core.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>nl.jqno.equalsverifier</groupId>
<artifactId>equalsverifier</artifactId>
<version>${equalsverifier.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>core-java-lang-oop-2</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
</build>
<properties>
<!-- testing -->
<assertj-core.version>3.10.0</assertj-core.version>
<equalsverifier.version>3.0.3</equalsverifier.version>
</properties>
</project>

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@ -1,16 +0,0 @@
## Core Java Lang OOP (Part 3)
This module contains articles about Object-oriented programming (OOP) in Java
### Relevant Articles:
- [Pass-By-Value as a Parameter Passing Mechanism in Java](https://www.baeldung.com/java-pass-by-value-or-pass-by-reference)
- [Access Modifiers in Java](https://www.baeldung.com/java-access-modifiers)
- [Guide to the super Java Keyword](https://www.baeldung.com/java-super)
- [Guide to the this Java Keyword](https://www.baeldung.com/java-this)
- [Java public Access Modifier](https://www.baeldung.com/java-public-keyword)
- [Composition, Aggregation, and Association in Java](https://www.baeldung.com/java-composition-aggregation-association)
- [Nested Classes in Java](https://www.baeldung.com/java-nested-classes)
- [A Guide to Inner Interfaces in Java](https://www.baeldung.com/java-inner-interfaces)
- [Java Classes and Objects](https://www.baeldung.com/java-classes-objects)
- [Java Interfaces](https://www.baeldung.com/java-interfaces)
- [[<-- Prev]](/core-java-modules/core-java-lang-oop-2)[[More -->]](/core-java-modules/core-java-lang-oop-4)

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@ -1,60 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-lang-oop-3</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-lang-oop-3</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<!-- logging -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
<version>${org.slf4j.version}</version>
</dependency>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj-core.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>${h2.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>core-java-lang-oop-3</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
</build>
<properties>
<assertj-core.version>3.10.0</assertj-core.version>
</properties>
</project>

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@ -1,9 +0,0 @@
## Core Java Lang OOP (Part 4)
This module contains articles about Object-oriented programming (OOP) in Java
### Relevant Articles:
- [Static and Dynamic Binding in Java](https://www.baeldung.com/java-static-dynamic-binding)
- [Methods in Java](https://www.baeldung.com/java-methods)
- [Java private Access Modifier](https://www.baeldung.com/java-private-keyword)
- [[<-- Prev]](/core-java-modules/core-java-lang-oop-3)

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@ -1,60 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-lang-oop-4</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-lang-oop-4</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<!-- logging -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
<version>${org.slf4j.version}</version>
</dependency>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj-core.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>${h2.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>core-java-lang-oop-4</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
</build>
<properties>
<assertj-core.version>3.10.0</assertj-core.version>
</properties>
</project>

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@ -0,0 +1,8 @@
## Core Java Lang OOP - Constructors
This module contains article about constructors in Java
### Relevant Articles:
- [A Guide to Constructors in Java](https://www.baeldung.com/java-constructors)
- [Java Copy Constructor](https://www.baeldung.com/java-copy-constructor)
- [Cannot Reference “X” Before Supertype Constructor Has Been Called](https://www.baeldung.com/java-cannot-reference-x-before-supertype-constructor-error)

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@ -0,0 +1,28 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>core-java-modules</artifactId>
<groupId>com.baeldung.core-java-modules</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-lang-oop-constructors</artifactId>
<name>core-java-lang-oop-constructors</name>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj-core.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<properties>
<assertj-core.version>3.10.0</assertj-core.version>
</properties>
</project>

View File

@ -6,7 +6,7 @@ class BankAccount {
String name;
LocalDateTime opened;
double balance;
@Override
public String toString() {
return String.format("%s, %s, %f", this.name, this.opened.toString(), this.balance);
@ -47,14 +47,13 @@ class BankAccountCopyConstructor extends BankAccount {
this.opened = opened;
this.balance = balance;
}
public BankAccountCopyConstructor(BankAccount other) {
this.name = other.name;
this.opened = LocalDateTime.now();
this.balance = 0.0f;
}
}
class BankAccountChainedConstructors extends BankAccount {
public BankAccountChainedConstructors(String name, LocalDateTime opened, double balance) {
this.name = name;
@ -65,4 +64,4 @@ class BankAccountChainedConstructors extends BankAccount {
public BankAccountChainedConstructors(String name) {
this(name, LocalDateTime.now(), 0.0f);
}
}
}

View File

@ -1,20 +1,19 @@
package com.baeldung.constructors;
import org.assertj.core.api.Assertions;
import org.junit.Test;
import java.time.LocalDateTime;
import java.time.Month;
import java.util.logging.Logger;
import static org.assertj.core.api.Assertions.*;
import static org.assertj.core.api.Assertions.assertThat;
public class ConstructorUnitTest {
final static Logger LOGGER = Logger.getLogger(ConstructorUnitTest.class.getName());
@Test
public void givenNoExplicitContructor_whenUsed_thenFails() {
BankAccount account = new BankAccount();
assertThatThrownBy(() -> {
Assertions.assertThatThrownBy(() -> {
account.toString();
}).isInstanceOf(Exception.class);
}
@ -22,7 +21,7 @@ public class ConstructorUnitTest {
@Test
public void givenNoArgumentConstructor_whenUsed_thenSucceeds() {
BankAccountEmptyConstructor account = new BankAccountEmptyConstructor();
assertThatCode(() -> {
Assertions.assertThatCode(() -> {
account.toString();
}).doesNotThrowAnyException();
}
@ -33,7 +32,7 @@ public class ConstructorUnitTest {
BankAccountParameterizedConstructor account =
new BankAccountParameterizedConstructor("Tom", opened, 1000.0f);
assertThatCode(() -> {
Assertions.assertThatCode(() -> {
account.toString();
}).doesNotThrowAnyException();
}

View File

@ -0,0 +1,8 @@
## Core Java Lang OOP - Generics
This module contains articles about generics in Java
### Relevant Articles:
- [Generic Constructors in Java](https://www.baeldung.com/java-generic-constructors)
- [Type Erasure in Java Explained](https://www.baeldung.com/java-type-erasure)
- [Raw Types in Java](https://www.baeldung.com/raw-types-java)

View File

@ -0,0 +1,16 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>core-java-modules</artifactId>
<groupId>com.baeldung.core-java-modules</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-lang-oop-generics</artifactId>
<name>core-java-lang-oop-generics</name>
<packaging>jar</packaging>
</project>

View File

@ -0,0 +1,13 @@
package com.baeldung.typeerasure;
public class Example {
public static <E> boolean containsElement(E [] elements, E element){
for (E e : elements){
if(e.equals(element)){
return true;
}
}
return false;
}
}

View File

@ -0,0 +1,14 @@
## Core Java Lang OOP - Inheritance
This module contains articles about inheritance in Java
### Relevant Articles:
- [Java Interfaces](https://www.baeldung.com/java-interfaces)
- [Abstract Classes in Java](https://www.baeldung.com/java-abstract-class)
- [A Guide to Inner Interfaces in Java](https://www.baeldung.com/java-inner-interfaces)
- [Guide to the super Java Keyword](https://www.baeldung.com/java-super)
- [Anonymous Classes in Java](https://www.baeldung.com/java-anonymous-classes)
- [Polymorphism in Java](https://www.baeldung.com/java-polymorphism)
- [Guide to Inheritance in Java](https://www.baeldung.com/java-inheritance)
- [Object Type Casting in Java](https://www.baeldung.com/java-type-casting)
- [Variable and Method Hiding in Java](https://www.baeldung.com/java-variable-method-hiding)

View File

@ -0,0 +1,28 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>core-java-modules</artifactId>
<groupId>com.baeldung.core-java-modules</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-lang-oop-inheritance</artifactId>
<name>core-java-lang-oop-inheritance</name>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj-core.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<properties>
<assertj-core.version>3.10.0</assertj-core.version>
</properties>
</project>

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