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Merge pull request #12 from eugenp/master 

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2
README.md
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@ -14,7 +14,7 @@ Java and Spring Tutorials
================
This project is **a collection of small and focused tutorials** - each covering a single and well defined area of development in the Java ecosystem.
A strong focus of these is, of course, the Spring Framework - Spring, Spring Boot and Spring Securiyt.
A strong focus of these is, of course, the Spring Framework - Spring, Spring Boot and Spring Security.
In additional to Spring, the following technologies are in focus: `core Java`, `Jackson`, `HttpClient`, `Guava`.

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akka-http/README.md Normal file
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@ -0,0 +1,3 @@
## Relevant articles:
- [Introduction to Akka HTTP](https://www.baeldung.com/akka-http)

4
algorithms-miscellaneous-1/README.md
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@ -12,4 +12,6 @@
- [Check If a String Contains All The Letters of The Alphabet](https://www.baeldung.com/java-string-contains-all-letters)
- [Find the Middle Element of a Linked List](http://www.baeldung.com/java-linked-list-middle-element)
- [Calculate Factorial in Java](https://www.baeldung.com/java-calculate-factorial)
- [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)
- [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)
- [Find the Longest Substring without Repeating Characters](https://www.baeldung.com/java-longest-substring-without-repeated-characters)
- [Java Two Pointer Technique](https://www.baeldung.com/java-two-pointer-technique)

123
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/permutation/Permutation.java Normal file
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@ -0,0 +1,123 @@
package com.baeldung.algorithms.permutation;
import java.util.Arrays;
import java.util.Collections;
public class Permutation {
public static <T> void printAllRecursive(T[] elements, char delimiter) {
printAllRecursive(elements.length, elements, delimiter);
}
public static <T> void printAllRecursive(int n, T[] elements, char delimiter) {
if(n == 1) {
printArray(elements, delimiter);
} else {
for(int i = 0; i < n-1; i++) {
printAllRecursive(n - 1, elements, delimiter);
if(n % 2 == 0) {
swap(elements, i, n-1);
} else {
swap(elements, 0, n-1);
}
}
printAllRecursive(n - 1, elements, delimiter);
}
}
public static <T> void printAllIterative(int n, T[] elements, char delimiter) {
int[] indexes = new int[n];
for (int i = 0; i < n; i++) {
indexes[i] = 0;
}
printArray(elements, delimiter);
int i = 0;
while (i < n) {
if (indexes[i] < i) {
swap(elements, i % 2 == 0 ? 0: indexes[i], i);
printArray(elements, delimiter);
indexes[i]++;
i = 0;
}
else {
indexes[i] = 0;
i++;
}
}
}
public static <T extends Comparable<T>> void printAllOrdered(T[] elements, char delimiter) {
Arrays.sort(elements);
boolean hasNext = true;
while(hasNext) {
printArray(elements, delimiter);
int k = 0, l = 0;
hasNext = false;
for (int i = elements.length - 1; i > 0; i--) {
if (elements[i].compareTo(elements[i - 1]) > 0) {
k = i - 1;
hasNext = true;
break;
}
}
for (int i = elements.length - 1; i > k; i--) {
if (elements[i].compareTo(elements[k]) > 0) {
l = i;
break;
}
}
swap(elements, k, l);
Collections.reverse(Arrays.asList(elements).subList(k + 1, elements.length));
}
}
public static <T> void printRandom(T[] elements, char delimiter) {
Collections.shuffle(Arrays.asList(elements));
printArray(elements, delimiter);
}
private static <T> void swap(T[] elements, int a, int b) {
T tmp = elements[a];
elements[a] = elements[b];
elements[b] = tmp;
}
private static <T> void printArray(T[] elements, char delimiter) {
String delimiterSpace = delimiter + " ";
for(int i = 0; i < elements.length; i++) {
System.out.print(elements[i] + delimiterSpace);
}
System.out.print('\n');
}
public static void main(String[] argv) {
Integer[] elements = {1,2,3,4};
System.out.println("Rec:");
printAllRecursive(elements, ';');
System.out.println("Iter:");
printAllIterative(elements.length, elements, ';');
System.out.println("Orderes:");
printAllOrdered(elements, ';');
System.out.println("Random:");
printRandom(elements, ';');
System.out.println("Random:");
printRandom(elements, ';');
}
}

16
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/twopointertechnique/LinkedListFindMiddle.java Normal file
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@ -0,0 +1,16 @@
package com.baeldung.algorithms.twopointertechnique;
public class LinkedListFindMiddle {
public <T> T findMiddle(MyNode<T> head) {
MyNode<T> slowPointer = head;
MyNode<T> fastPointer = head;
while (fastPointer.next != null && fastPointer.next.next != null) {
fastPointer = fastPointer.next.next;
slowPointer = slowPointer.next;
}
return slowPointer.data;
}
}

20
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/twopointertechnique/MyNode.java Normal file
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@ -0,0 +1,20 @@
package com.baeldung.algorithms.twopointertechnique;
public class MyNode<E> {
MyNode<E> next;
E data;
public MyNode(E value) {
data = value;
next = null;
}
public MyNode(E value, MyNode<E> n) {
data = value;
next = n;
}
public void setNext(MyNode<E> n) {
next = n;
}
}

22
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/twopointertechnique/RotateArray.java Normal file
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@ -0,0 +1,22 @@
package com.baeldung.algorithms.twopointertechnique;
public class RotateArray {
public void rotate(int[] input, int step) {
step %= input.length;
reverse(input, 0, input.length - 1);
reverse(input, 0, step - 1);
reverse(input, step, input.length - 1);
}
private void reverse(int[] input, int start, int end) {
while (start < end) {
int temp = input[start];
input[start] = input[end];
input[end] = temp;
start++;
end--;
}
}
}

38
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/twopointertechnique/TwoSum.java Normal file
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@ -0,0 +1,38 @@
package com.baeldung.algorithms.twopointertechnique;
public class TwoSum {
public boolean twoSum(int[] input, int targetValue) {
int pointerOne = 0;
int pointerTwo = input.length - 1;
while (pointerOne < pointerTwo) {
int sum = input[pointerOne] + input[pointerTwo];
if (sum == targetValue) {
return true;
} else if (sum < targetValue) {
pointerOne++;
} else {
pointerTwo--;
}
}
return false;
}
public boolean twoSumSlow(int[] input, int targetValue) {
for (int i = 0; i < input.length; i++) {
for (int j = 1; j < input.length; j++) {
if (input[i] + input[j] == targetValue) {
return true;
}
}
}
return false;
}
}

37
algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/twopointertechnique/LinkedListFindMiddleUnitTest.java Normal file
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@ -0,0 +1,37 @@
package com.baeldung.algorithms.twopointertechnique;
import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;
public class LinkedListFindMiddleUnitTest {
LinkedListFindMiddle linkedListFindMiddle = new LinkedListFindMiddle();
@Test
public void givenLinkedListOfMyNodes_whenLinkedListFindMiddle_thenCorrect() {
MyNode<String> head = createNodesList(8);
assertThat(linkedListFindMiddle.findMiddle(head)).isEqualTo("4");
head = createNodesList(9);
assertThat(linkedListFindMiddle.findMiddle(head)).isEqualTo("5");
}
private static MyNode<String> createNodesList(int n) {
MyNode<String> head = new MyNode<String>("1");
MyNode<String> current = head;
for (int i = 2; i <= n; i++) {
MyNode<String> newNode = new MyNode<String>(String.valueOf(i));
current.setNext(newNode);
current = newNode;
}
return head;
}
}

26
algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/twopointertechnique/RotateArrayUnitTest.java Normal file
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@ -0,0 +1,26 @@
package com.baeldung.algorithms.twopointertechnique;
import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;
public class RotateArrayUnitTest {
private RotateArray rotateArray = new RotateArray();
private int[] inputArray;
private int step;
@Test
public void givenAnArrayOfIntegers_whenRotateKsteps_thenCorrect() {
inputArray = new int[] { 1, 2, 3, 4, 5, 6, 7 };
step = 4;
rotateArray.rotate(inputArray, step);
assertThat(inputArray).containsExactly(new int[] { 4, 5, 6, 7, 1, 2, 3 });
}
}

56
algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/twopointertechnique/TwoSumUnitTest.java Normal file
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@ -0,0 +1,56 @@
package com.baeldung.algorithms.twopointertechnique;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import org.junit.Test;
public class TwoSumUnitTest {
private TwoSum twoSum = new TwoSum();
private int[] sortedArray;
private int targetValue;
@Test
public void givenASortedArrayOfIntegers_whenTwoSumSlow_thenPairExists() {
sortedArray = new int[] { 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9 };
targetValue = 12;
assertTrue(twoSum.twoSumSlow(sortedArray, targetValue));
}
@Test
public void givenASortedArrayOfIntegers_whenTwoSumSlow_thenPairDoesNotExists() {
sortedArray = new int[] { 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9 };
targetValue = 20;
assertFalse(twoSum.twoSumSlow(sortedArray, targetValue));
}
@Test
public void givenASortedArrayOfIntegers_whenTwoSum_thenPairExists() {
sortedArray = new int[] { 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9 };
targetValue = 12;
assertTrue(twoSum.twoSum(sortedArray, targetValue));
}
@Test
public void givenASortedArrayOfIntegers_whenTwoSum_thenPairDoesNotExists() {
sortedArray = new int[] { 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9 };
targetValue = 20;
assertFalse(twoSum.twoSum(sortedArray, targetValue));
}
}

68
apache-spark/pom.xml
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@ -15,16 +15,76 @@
</parent>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.apache.spark/spark-core_2.10 -->
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.10</artifactId>
<artifactId>spark-core_2.11</artifactId>
<version>${org.apache.spark.spark-core.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-sql_2.11</artifactId>
<version>${org.apache.spark.spark-sql.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-streaming_2.11</artifactId>
<version>${org.apache.spark.spark-streaming.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-streaming-kafka-0-10_2.11</artifactId>
<version>${org.apache.spark.spark-streaming-kafka.version}</version>
</dependency>
<dependency>
<groupId>com.datastax.spark</groupId>
<artifactId>spark-cassandra-connector_2.11</artifactId>
<version>${com.datastax.spark.spark-cassandra-connector.version}</version>
</dependency>
<dependency>
<groupId>com.datastax.spark</groupId>
<artifactId>spark-cassandra-connector-java_2.11</artifactId>
<version>${com.datastax.spark.spark-cassandra-connector-java.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<org.apache.spark.spark-core.version>2.2.0</org.apache.spark.spark-core.version>
<org.apache.spark.spark-core.version>2.3.0</org.apache.spark.spark-core.version>
<org.apache.spark.spark-sql.version>2.3.0</org.apache.spark.spark-sql.version>
<org.apache.spark.spark-streaming.version>2.3.0</org.apache.spark.spark-streaming.version>
<org.apache.spark.spark-streaming-kafka.version>2.3.0</org.apache.spark.spark-streaming-kafka.version>
<com.datastax.spark.spark-cassandra-connector.version>2.3.0</com.datastax.spark.spark-cassandra-connector.version>
<com.datastax.spark.spark-cassandra-connector-java.version>1.5.2</com.datastax.spark.spark-cassandra-connector-java.version>
</properties>
</project>

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apache-spark/src/main/java/com/baeldung/data/pipeline/Word.java Normal file
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@ -0,0 +1,25 @@
package com.baeldung.data.pipeline;
import java.io.Serializable;
public class Word implements Serializable {
private static final long serialVersionUID = 1L;
private String word;
private int count;
Word(String word, int count) {
this.word = word;
this.count = count;
}
public String getWord() {
return word;
}
public void setWord(String word) {
this.word = word;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
}

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apache-spark/src/main/java/com/baeldung/data/pipeline/WordCountingApp.java Normal file
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@ -0,0 +1,80 @@
package com.baeldung.data.pipeline;
import static com.datastax.spark.connector.japi.CassandraJavaUtil.javaFunctions;
import static com.datastax.spark.connector.japi.CassandraJavaUtil.mapToRow;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.streaming.Durations;
import org.apache.spark.streaming.api.java.JavaDStream;
import org.apache.spark.streaming.api.java.JavaInputDStream;
import org.apache.spark.streaming.api.java.JavaPairDStream;
import org.apache.spark.streaming.api.java.JavaStreamingContext;
import org.apache.spark.streaming.kafka010.ConsumerStrategies;
import org.apache.spark.streaming.kafka010.KafkaUtils;
import org.apache.spark.streaming.kafka010.LocationStrategies;
import scala.Tuple2;
public class WordCountingApp {
public static void main(String[] args) throws InterruptedException {
Logger.getLogger("org")
.setLevel(Level.OFF);
Logger.getLogger("akka")
.setLevel(Level.OFF);
Map<String, Object> kafkaParams = new HashMap<>();
kafkaParams.put("bootstrap.servers", "localhost:9092");
kafkaParams.put("key.deserializer", StringDeserializer.class);
kafkaParams.put("value.deserializer", StringDeserializer.class);
kafkaParams.put("group.id", "use_a_separate_group_id_for_each_stream");
kafkaParams.put("auto.offset.reset", "latest");
kafkaParams.put("enable.auto.commit", false);
Collection<String> topics = Arrays.asList("messages");
SparkConf sparkConf = new SparkConf();
sparkConf.setMaster("local[2]");
sparkConf.setAppName("WordCountingApp");
sparkConf.set("spark.cassandra.connection.host", "127.0.0.1");
JavaStreamingContext streamingContext = new JavaStreamingContext(sparkConf, Durations.seconds(1));
JavaInputDStream<ConsumerRecord<String, String>> messages = KafkaUtils.createDirectStream(streamingContext, LocationStrategies.PreferConsistent(), ConsumerStrategies.<String, String> Subscribe(topics, kafkaParams));
JavaPairDStream<String, String> results = messages.mapToPair(record -> new Tuple2<>(record.key(), record.value()));
JavaDStream<String> lines = results.map(tuple2 -> tuple2._2());
JavaDStream<String> words = lines.flatMap(x -> Arrays.asList(x.split("\\s+"))
.iterator());
JavaPairDStream<String, Integer> wordCounts = words.mapToPair(s -> new Tuple2<>(s, 1))
.reduceByKey((i1, i2) -> i1 + i2);
wordCounts.foreachRDD(javaRdd -> {
Map<String, Integer> wordCountMap = javaRdd.collectAsMap();
for (String key : wordCountMap.keySet()) {
List<Word> wordList = Arrays.asList(new Word(key, wordCountMap.get(key)));
JavaRDD<Word> rdd = streamingContext.sparkContext()
.parallelize(wordList);
javaFunctions(rdd).writerBuilder("vocabulary", "words", mapToRow(Word.class))
.saveToCassandra();
}
});
streamingContext.start();
streamingContext.awaitTermination();
}
}

97
apache-spark/src/main/java/com/baeldung/data/pipeline/WordCountingAppWithCheckpoint.java Normal file
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@ -0,0 +1,97 @@
package com.baeldung.data.pipeline;
import static com.datastax.spark.connector.japi.CassandraJavaUtil.javaFunctions;
import static com.datastax.spark.connector.japi.CassandraJavaUtil.mapToRow;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.function.Function2;
import org.apache.spark.streaming.Durations;
import org.apache.spark.streaming.StateSpec;
import org.apache.spark.streaming.api.java.JavaDStream;
import org.apache.spark.streaming.api.java.JavaInputDStream;
import org.apache.spark.streaming.api.java.JavaMapWithStateDStream;
import org.apache.spark.streaming.api.java.JavaPairDStream;
import org.apache.spark.streaming.api.java.JavaStreamingContext;
import org.apache.spark.streaming.kafka010.ConsumerStrategies;
import org.apache.spark.streaming.kafka010.KafkaUtils;
import org.apache.spark.streaming.kafka010.LocationStrategies;
import scala.Tuple2;
public class WordCountingAppWithCheckpoint {
public static JavaSparkContext sparkContext;
public static void main(String[] args) throws InterruptedException {
Logger.getLogger("org")
.setLevel(Level.OFF);
Logger.getLogger("akka")
.setLevel(Level.OFF);
Map<String, Object> kafkaParams = new HashMap<>();
kafkaParams.put("bootstrap.servers", "localhost:9092");
kafkaParams.put("key.deserializer", StringDeserializer.class);
kafkaParams.put("value.deserializer", StringDeserializer.class);
kafkaParams.put("group.id", "use_a_separate_group_id_for_each_stream");
kafkaParams.put("auto.offset.reset", "latest");
kafkaParams.put("enable.auto.commit", false);
Collection<String> topics = Arrays.asList("messages");
SparkConf sparkConf = new SparkConf();
sparkConf.setMaster("local[2]");
sparkConf.setAppName("WordCountingAppWithCheckpoint");
sparkConf.set("spark.cassandra.connection.host", "127.0.0.1");
JavaStreamingContext streamingContext = new JavaStreamingContext(sparkConf, Durations.seconds(1));
sparkContext = streamingContext.sparkContext();
streamingContext.checkpoint("./.checkpoint");
JavaInputDStream<ConsumerRecord<String, String>> messages = KafkaUtils.createDirectStream(streamingContext, LocationStrategies.PreferConsistent(), ConsumerStrategies.<String, String> Subscribe(topics, kafkaParams));
JavaPairDStream<String, String> results = messages.mapToPair(record -> new Tuple2<>(record.key(), record.value()));
JavaDStream<String> lines = results.map(tuple2 -> tuple2._2());
JavaDStream<String> words = lines.flatMap(x -> Arrays.asList(x.split("\\s+"))
.iterator());
JavaPairDStream<String, Integer> wordCounts = words.mapToPair(s -> new Tuple2<>(s, 1))
.reduceByKey((Function2<Integer, Integer, Integer>) (i1, i2) -> i1 + i2);
JavaMapWithStateDStream<String, Integer, Integer, Tuple2<String, Integer>> cumulativeWordCounts = wordCounts.mapWithState(StateSpec.function((word, one, state) -> {
int sum = one.orElse(0) + (state.exists() ? state.get() : 0);
Tuple2<String, Integer> output = new Tuple2<>(word, sum);
state.update(sum);
return output;
}));
cumulativeWordCounts.foreachRDD(javaRdd -> {
List<Tuple2<String, Integer>> wordCountList = javaRdd.collect();
for (Tuple2<String, Integer> tuple : wordCountList) {
List<Word> wordList = Arrays.asList(new Word(tuple._1, tuple._2));
JavaRDD<Word> rdd = sparkContext.parallelize(wordList);
javaFunctions(rdd).writerBuilder("vocabulary", "words", mapToRow(Word.class))
.saveToCassandra();
}
});
streamingContext.start();
streamingContext.awaitTermination();
}
}

46
axon/pom.xml
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@ -4,29 +4,61 @@
<modelVersion>4.0.0</modelVersion>
<artifactId>axon</artifactId>
<name>axon</name>
<description>Basic Axon Framework with Spring Boot configuration tutorial</description>
<parent>
<artifactId>parent-modules</artifactId>
<groupId>com.baeldung</groupId>
<version>1.0.0-SNAPSHOT</version>
<artifactId>parent-boot-2</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../parent-boot-2</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.axonframework</groupId>
<artifactId>axon-spring-boot-starter</artifactId>
<version>${axon.version}</version>
<exclusions>
<exclusion>
<groupId>org.axonframework</groupId>
<artifactId>axon-server-connector</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.axonframework</groupId>
<artifactId>axon-test</artifactId>
<version>${axon.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.axonframework</groupId>
<artifactId>axon-core</artifactId>
<version>${axon.version}</version>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-autoconfigure</artifactId>
<version>2.1.1.RELEASE</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
</dependencies>
<properties>
<axon.version>3.0.2</axon.version>
<axon.version>4.0.3</axon.version>
</properties>
</project>

54
axon/src/main/java/com/baeldung/axon/MessagesRunner.java
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@ -1,54 +0,0 @@
package com.baeldung.axon;
import com.baeldung.axon.aggregates.MessagesAggregate;
import com.baeldung.axon.commands.CreateMessageCommand;
import com.baeldung.axon.commands.MarkReadMessageCommand;
import com.baeldung.axon.eventhandlers.MessagesEventHandler;
import org.axonframework.commandhandling.AggregateAnnotationCommandHandler;
import org.axonframework.commandhandling.CommandBus;
import org.axonframework.commandhandling.SimpleCommandBus;
import org.axonframework.commandhandling.gateway.CommandGateway;
import org.axonframework.commandhandling.gateway.DefaultCommandGateway;
import org.axonframework.eventhandling.AnnotationEventListenerAdapter;
import org.axonframework.eventsourcing.EventSourcingRepository;
import org.axonframework.eventsourcing.eventstore.EmbeddedEventStore;
import org.axonframework.eventsourcing.eventstore.EventStore;
import org.axonframework.eventsourcing.eventstore.inmemory.InMemoryEventStorageEngine;
import java.util.UUID;
public class MessagesRunner {
public static void main(String[] args) {
CommandBus commandBus = new SimpleCommandBus();
CommandGateway commandGateway = new DefaultCommandGateway(commandBus);
EventStore eventStore = new EmbeddedEventStore(new InMemoryEventStorageEngine());
EventSourcingRepository<MessagesAggregate> repository =
new EventSourcingRepository<>(MessagesAggregate.class, eventStore);
AggregateAnnotationCommandHandler<MessagesAggregate> messagesAggregateAggregateAnnotationCommandHandler =
new AggregateAnnotationCommandHandler<MessagesAggregate>(MessagesAggregate.class, repository);
messagesAggregateAggregateAnnotationCommandHandler.subscribe(commandBus);
final AnnotationEventListenerAdapter annotationEventListenerAdapter =
new AnnotationEventListenerAdapter(new MessagesEventHandler());
eventStore.subscribe(eventMessages -> eventMessages.forEach(e -> {
try {
annotationEventListenerAdapter.handle(e);
} catch (Exception e1) {
throw new RuntimeException(e1);
}
}
));
final String itemId = UUID.randomUUID().toString();
commandGateway.send(new CreateMessageCommand(itemId, "Hello, how is your day? :-)"));
commandGateway.send(new MarkReadMessageCommand(itemId));
}
}

13
axon/src/main/java/com/baeldung/axon/OrderApplication.java Normal file
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@ -0,0 +1,13 @@
package com.baeldung.axon;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class OrderApplication {
public static void main(String[] args) {
SpringApplication.run(OrderApplication.class, args);
}
}

36
axon/src/main/java/com/baeldung/axon/aggregates/MessagesAggregate.java
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@ -1,36 +0,0 @@
package com.baeldung.axon.aggregates;
import com.baeldung.axon.commands.CreateMessageCommand;
import com.baeldung.axon.commands.MarkReadMessageCommand;
import com.baeldung.axon.events.MessageCreatedEvent;
import com.baeldung.axon.events.MessageReadEvent;
import org.axonframework.commandhandling.CommandHandler;
import org.axonframework.commandhandling.model.AggregateIdentifier;
import org.axonframework.eventhandling.EventHandler;
import static org.axonframework.commandhandling.model.AggregateLifecycle.apply;
public class MessagesAggregate {
@AggregateIdentifier
private String id;
public MessagesAggregate() {
}
@CommandHandler
public MessagesAggregate(CreateMessageCommand command) {
apply(new MessageCreatedEvent(command.getId(), command.getText()));
}
@EventHandler
public void on(MessageCreatedEvent event) {
this.id = event.getId();
}
@CommandHandler
public void markRead(MarkReadMessageCommand command) {
apply(new MessageReadEvent(id));
}
}

58
axon/src/main/java/com/baeldung/axon/commandmodel/OrderAggregate.java Normal file
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@ -0,0 +1,58 @@
package com.baeldung.axon.commandmodel;
import static org.axonframework.modelling.command.AggregateLifecycle.apply;
import org.axonframework.commandhandling.CommandHandler;
import org.axonframework.eventsourcing.EventSourcingHandler;
import org.axonframework.modelling.command.AggregateIdentifier;
import org.axonframework.spring.stereotype.Aggregate;
import com.baeldung.axon.coreapi.commands.ConfirmOrderCommand;
import com.baeldung.axon.coreapi.commands.PlaceOrderCommand;
import com.baeldung.axon.coreapi.commands.ShipOrderCommand;
import com.baeldung.axon.coreapi.events.OrderConfirmedEvent;
import com.baeldung.axon.coreapi.events.OrderPlacedEvent;
import com.baeldung.axon.coreapi.events.OrderShippedEvent;
@Aggregate
public class OrderAggregate {
@AggregateIdentifier
private String orderId;
private boolean orderConfirmed;
@CommandHandler
public OrderAggregate(PlaceOrderCommand command) {
apply(new OrderPlacedEvent(command.getOrderId(), command.getProduct()));
}
@CommandHandler
public void handle(ConfirmOrderCommand command) {
apply(new OrderConfirmedEvent(orderId));
}
@CommandHandler
public void handle(ShipOrderCommand command) {
if (!orderConfirmed) {
throw new IllegalStateException("Cannot ship an order which has not been confirmed yet.");
}
apply(new OrderShippedEvent(orderId));
}
@EventSourcingHandler
public void on(OrderPlacedEvent event) {
this.orderId = event.getOrderId();
orderConfirmed = false;
}
@EventSourcingHandler
public void on(OrderConfirmedEvent event) {
orderConfirmed = true;
}
protected OrderAggregate() {
// Required by Axon to build a default Aggregate prior to Event Sourcing
}
}

24
axon/src/main/java/com/baeldung/axon/commands/CreateMessageCommand.java
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@ -1,24 +0,0 @@
package com.baeldung.axon.commands;
import org.axonframework.commandhandling.TargetAggregateIdentifier;
public class CreateMessageCommand {
@TargetAggregateIdentifier
private final String id;
private final String text;
public CreateMessageCommand(String id, String text) {
this.id = id;
this.text = text;
}
public String getId() {
return id;
}
public String getText() {
return text;
}
}

18
axon/src/main/java/com/baeldung/axon/commands/MarkReadMessageCommand.java
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@ -1,18 +0,0 @@
package com.baeldung.axon.commands;
import org.axonframework.commandhandling.TargetAggregateIdentifier;
public class MarkReadMessageCommand {
@TargetAggregateIdentifier
private final String id;
public MarkReadMessageCommand(String id) {
this.id = id;
}
public String getId() {
return id;
}
}

43
axon/src/main/java/com/baeldung/axon/coreapi/commands/ConfirmOrderCommand.java Normal file
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@ -0,0 +1,43 @@
package com.baeldung.axon.coreapi.commands;
import org.axonframework.modelling.command.TargetAggregateIdentifier;
import java.util.Objects;
public class ConfirmOrderCommand {
@TargetAggregateIdentifier
private final String orderId;
public ConfirmOrderCommand(String orderId) {
this.orderId = orderId;
}
public String getOrderId() {
return orderId;
}
@Override
public int hashCode() {
return Objects.hash(orderId);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
final ConfirmOrderCommand other = (ConfirmOrderCommand) obj;
return Objects.equals(this.orderId, other.orderId);
}
@Override
public String toString() {
return "ConfirmOrderCommand{" +
"orderId='" + orderId + '\'' +
'}';
}
}

51
axon/src/main/java/com/baeldung/axon/coreapi/commands/PlaceOrderCommand.java Normal file
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@ -0,0 +1,51 @@
package com.baeldung.axon.coreapi.commands;
import java.util.Objects;
import org.axonframework.modelling.command.TargetAggregateIdentifier;
public class PlaceOrderCommand {
@TargetAggregateIdentifier
private final String orderId;
private final String product;
public PlaceOrderCommand(String orderId, String product) {
this.orderId = orderId;
this.product = product;
}
public String getOrderId() {
return orderId;
}
public String getProduct() {
return product;
}
@Override
public int hashCode() {
return Objects.hash(orderId, product);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
final PlaceOrderCommand other = (PlaceOrderCommand) obj;
return Objects.equals(this.orderId, other.orderId)
&& Objects.equals(this.product, other.product);
}
@Override
public String toString() {
return "PlaceOrderCommand{" +
"orderId='" + orderId + '\'' +
", product='" + product + '\'' +
'}';
}
}

43
axon/src/main/java/com/baeldung/axon/coreapi/commands/ShipOrderCommand.java Normal file
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@ -0,0 +1,43 @@
package com.baeldung.axon.coreapi.commands;
import java.util.Objects;
import org.axonframework.modelling.command.TargetAggregateIdentifier;
public class ShipOrderCommand {
@TargetAggregateIdentifier
private final String orderId;
public ShipOrderCommand(String orderId) {
this.orderId = orderId;
}
public String getOrderId() {
return orderId;
}
@Override
public int hashCode() {
return Objects.hash(orderId);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
final ShipOrderCommand other = (ShipOrderCommand) obj;
return Objects.equals(this.orderId, other.orderId);
}
@Override
public String toString() {
return "ShipOrderCommand{" +
"orderId='" + orderId + '\'' +
'}';
}
}

40
axon/src/main/java/com/baeldung/axon/coreapi/events/OrderConfirmedEvent.java Normal file
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@ -0,0 +1,40 @@
package com.baeldung.axon.coreapi.events;
import java.util.Objects;
public class OrderConfirmedEvent {
private final String orderId;
public OrderConfirmedEvent(String orderId) {
this.orderId = orderId;
}
public String getOrderId() {
return orderId;
}
@Override
public int hashCode() {
return Objects.hash(orderId);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
final OrderConfirmedEvent other = (OrderConfirmedEvent) obj;
return Objects.equals(this.orderId, other.orderId);
}
@Override
public String toString() {
return "OrderConfirmedEvent{" +
"orderId='" + orderId + '\'' +
'}';
}
}

48
axon/src/main/java/com/baeldung/axon/coreapi/events/OrderPlacedEvent.java Normal file
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@ -0,0 +1,48 @@
package com.baeldung.axon.coreapi.events;
import java.util.Objects;
public class OrderPlacedEvent {
private final String orderId;
private final String product;
public OrderPlacedEvent(String orderId, String product) {
this.orderId = orderId;
this.product = product;
}
public String getOrderId() {
return orderId;
}
public String getProduct() {
return product;
}
@Override
public int hashCode() {
return Objects.hash(orderId, product);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
final OrderPlacedEvent other = (OrderPlacedEvent) obj;
return Objects.equals(this.orderId, other.orderId)
&& Objects.equals(this.product, other.product);
}
@Override
public String toString() {
return "OrderPlacedEvent{" +
"orderId='" + orderId + '\'' +
", product='" + product + '\'' +
'}';
}
}

40
axon/src/main/java/com/baeldung/axon/coreapi/events/OrderShippedEvent.java Normal file
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@ -0,0 +1,40 @@
package com.baeldung.axon.coreapi.events;
import java.util.Objects;
public class OrderShippedEvent {
private final String orderId;
public OrderShippedEvent(String orderId) {
this.orderId = orderId;
}
public String getOrderId() {
return orderId;
}
@Override
public int hashCode() {
return Objects.hash(orderId);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
final OrderShippedEvent other = (OrderShippedEvent) obj;
return Objects.equals(this.orderId, other.orderId);
}
@Override
public String toString() {
return "OrderShippedEvent{" +
"orderId='" + orderId + '\'' +
'}';
}
}

5
axon/src/main/java/com/baeldung/axon/coreapi/queries/FindAllOrderedProductsQuery.java Normal file
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@ -0,0 +1,5 @@
package com.baeldung.axon.coreapi.queries;
public class FindAllOrderedProductsQuery {
}

7
axon/src/main/java/com/baeldung/axon/coreapi/queries/OrderStatus.java Normal file
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@ -0,0 +1,7 @@
package com.baeldung.axon.coreapi.queries;
public enum OrderStatus {
PLACED, CONFIRMED, SHIPPED
}

64
axon/src/main/java/com/baeldung/axon/coreapi/queries/OrderedProduct.java Normal file
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@ -0,0 +1,64 @@
package com.baeldung.axon.coreapi.queries;
import java.util.Objects;
public class OrderedProduct {
private final String orderId;
private final String product;
private OrderStatus orderStatus;
public OrderedProduct(String orderId, String product) {
this.orderId = orderId;
this.product = product;
orderStatus = OrderStatus.PLACED;
}
public String getOrderId() {
return orderId;
}
public String getProduct() {
return product;
}
public OrderStatus getOrderStatus() {
return orderStatus;
}
public void setOrderConfirmed() {
this.orderStatus = OrderStatus.CONFIRMED;
}
public void setOrderShipped() {
this.orderStatus = OrderStatus.SHIPPED;
}
@Override
public int hashCode() {
return Objects.hash(orderId, product, orderStatus);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
final OrderedProduct other = (OrderedProduct) obj;
return Objects.equals(this.orderId, other.orderId)
&& Objects.equals(this.product, other.product)
&& Objects.equals(this.orderStatus, other.orderStatus);
}
@Override
public String toString() {
return "OrderedProduct{" +
"orderId='" + orderId + '\'' +
", product='" + product + '\'' +
", orderStatus=" + orderStatus +
'}';
}
}

19
axon/src/main/java/com/baeldung/axon/eventhandlers/MessagesEventHandler.java
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@ -1,19 +0,0 @@
package com.baeldung.axon.eventhandlers;
import com.baeldung.axon.events.MessageReadEvent;
import com.baeldung.axon.events.MessageCreatedEvent;
import org.axonframework.eventhandling.EventHandler;
public class MessagesEventHandler {
@EventHandler
public void handle(MessageCreatedEvent event) {
System.out.println("Message received: " + event.getText() + " (" + event.getId() + ")");
}
@EventHandler
public void handle(MessageReadEvent event) {
System.out.println("Message read: " + event.getId());
}
}

20
axon/src/main/java/com/baeldung/axon/events/MessageCreatedEvent.java
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@ -1,20 +0,0 @@
package com.baeldung.axon.events;
public class MessageCreatedEvent {
private final String id;
private final String text;
public MessageCreatedEvent(String id, String text) {
this.id = id;
this.text = text;
}
public String getId() {
return id;
}
public String getText() {
return text;
}
}

14
axon/src/main/java/com/baeldung/axon/events/MessageReadEvent.java
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@ -1,14 +0,0 @@
package com.baeldung.axon.events;
public class MessageReadEvent {
private final String id;
public MessageReadEvent(String id) {
this.id = id;
}
public String getId() {
return id;
}
}

52
axon/src/main/java/com/baeldung/axon/gui/OrderRestEndpoint.java Normal file
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@ -0,0 +1,52 @@
package com.baeldung.axon.gui;
import java.util.List;
import java.util.UUID;
import org.axonframework.commandhandling.gateway.CommandGateway;
import org.axonframework.messaging.responsetypes.ResponseTypes;
import org.axonframework.queryhandling.QueryGateway;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import com.baeldung.axon.coreapi.commands.ConfirmOrderCommand;
import com.baeldung.axon.coreapi.commands.PlaceOrderCommand;
import com.baeldung.axon.coreapi.commands.ShipOrderCommand;
import com.baeldung.axon.coreapi.queries.FindAllOrderedProductsQuery;
import com.baeldung.axon.coreapi.queries.OrderedProduct;
@RestController
public class OrderRestEndpoint {
private final CommandGateway commandGateway;
private final QueryGateway queryGateway;
public OrderRestEndpoint(CommandGateway commandGateway, QueryGateway queryGateway) {
this.commandGateway = commandGateway;
this.queryGateway = queryGateway;
}
@PostMapping("/ship-order")
public void shipOrder() {
String orderId = UUID.randomUUID().toString();
commandGateway.send(new PlaceOrderCommand(orderId, "Deluxe Chair"));
commandGateway.send(new ConfirmOrderCommand(orderId));
commandGateway.send(new ShipOrderCommand(orderId));
}
@PostMapping("/ship-unconfirmed-order")
public void shipUnconfirmedOrder() {
String orderId = UUID.randomUUID().toString();
commandGateway.send(new PlaceOrderCommand(orderId, "Deluxe Chair"));
// This throws an exception, as an Order cannot be shipped if it has not been confirmed yet.
commandGateway.send(new ShipOrderCommand(orderId));
}
@GetMapping("/all-orders")
public List<OrderedProduct> findAllOrderedProducts() {
return queryGateway.query(new FindAllOrderedProductsQuery(), ResponseTypes.multipleInstancesOf(OrderedProduct.class))
.join();
}
}

50
axon/src/main/java/com/baeldung/axon/querymodel/OrderedProductsEventHandler.java Normal file
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@ -0,0 +1,50 @@
package com.baeldung.axon.querymodel;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.axonframework.eventhandling.EventHandler;
import org.axonframework.queryhandling.QueryHandler;
import org.springframework.stereotype.Service;
import com.baeldung.axon.coreapi.events.OrderConfirmedEvent;
import com.baeldung.axon.coreapi.events.OrderPlacedEvent;
import com.baeldung.axon.coreapi.events.OrderShippedEvent;
import com.baeldung.axon.coreapi.queries.FindAllOrderedProductsQuery;
import com.baeldung.axon.coreapi.queries.OrderedProduct;
@Service
public class OrderedProductsEventHandler {
private final Map<String, OrderedProduct> orderedProducts = new HashMap<>();
@EventHandler
public void on(OrderPlacedEvent event) {
String orderId = event.getOrderId();
orderedProducts.put(orderId, new OrderedProduct(orderId, event.getProduct()));
}
@EventHandler
public void on(OrderConfirmedEvent event) {
orderedProducts.computeIfPresent(event.getOrderId(), (orderId, orderedProduct) -> {
orderedProduct.setOrderConfirmed();
return orderedProduct;
});
}
@EventHandler
public void on(OrderShippedEvent event) {
orderedProducts.computeIfPresent(event.getOrderId(), (orderId, orderedProduct) -> {
orderedProduct.setOrderShipped();
return orderedProduct;
});
}
@QueryHandler
public List<OrderedProduct> handle(FindAllOrderedProductsQuery query) {
return new ArrayList<>(orderedProducts.values());
}
}

11
axon/src/main/resources/order-api.http Normal file
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@ -0,0 +1,11 @@
POST http://localhost:8080/ship-order
###
POST http://localhost:8080/ship-unconfirmed-order
###
GET http://localhost:8080/all-orders
###

42
axon/src/test/java/com/baeldung/axon/MessagesAggregateIntegrationTest.java
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@ -1,42 +0,0 @@
package com.baeldung.axon;
import com.baeldung.axon.aggregates.MessagesAggregate;
import com.baeldung.axon.commands.CreateMessageCommand;
import com.baeldung.axon.commands.MarkReadMessageCommand;
import com.baeldung.axon.events.MessageCreatedEvent;
import com.baeldung.axon.events.MessageReadEvent;
import org.axonframework.test.aggregate.AggregateTestFixture;
import org.axonframework.test.aggregate.FixtureConfiguration;
import org.junit.Before;
import org.junit.Test;
import java.util.UUID;
public class MessagesAggregateIntegrationTest {
private FixtureConfiguration<MessagesAggregate> fixture;
@Before
public void setUp() throws Exception {
fixture = new AggregateTestFixture<MessagesAggregate>(MessagesAggregate.class);
}
@Test
public void giveAggregateRoot_whenCreateMessageCommand_thenShouldProduceMessageCreatedEvent() throws Exception {
String eventText = "Hello, how is your day?";
String id = UUID.randomUUID().toString();
fixture.given()
.when(new CreateMessageCommand(id, eventText))
.expectEvents(new MessageCreatedEvent(id, eventText));
}
@Test
public void givenMessageCreatedEvent_whenReadMessageCommand_thenShouldProduceMessageReadEvent() throws Exception {
String id = UUID.randomUUID().toString();
fixture.given(new MessageCreatedEvent(id, "Hello :-)"))
.when(new MarkReadMessageCommand(id))
.expectEvents(new MessageReadEvent(id));
}
}

61
axon/src/test/java/com/baeldung/axon/commandmodel/OrderAggregateUnitTest.java Normal file
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@ -0,0 +1,61 @@
package com.baeldung.axon.commandmodel;
import java.util.UUID;
import org.axonframework.test.aggregate.AggregateTestFixture;
import org.axonframework.test.aggregate.FixtureConfiguration;
import org.junit.*;
import com.baeldung.axon.coreapi.commands.ConfirmOrderCommand;
import com.baeldung.axon.coreapi.commands.PlaceOrderCommand;
import com.baeldung.axon.coreapi.commands.ShipOrderCommand;
import com.baeldung.axon.coreapi.events.OrderConfirmedEvent;
import com.baeldung.axon.coreapi.events.OrderPlacedEvent;
import com.baeldung.axon.coreapi.events.OrderShippedEvent;
public class OrderAggregateUnitTest {
private FixtureConfiguration<OrderAggregate> fixture;
@Before
public void setUp() {
fixture = new AggregateTestFixture<>(OrderAggregate.class);
}
@Test
public void giveNoPriorActivity_whenPlaceOrderCommand_thenShouldPublishOrderPlacedEvent() {
String orderId = UUID.randomUUID().toString();
String product = "Deluxe Chair";
fixture.givenNoPriorActivity()
.when(new PlaceOrderCommand(orderId, product))
.expectEvents(new OrderPlacedEvent(orderId, product));
}
@Test
public void givenOrderPlacedEvent_whenConfirmOrderCommand_thenShouldPublishOrderConfirmedEvent() {
String orderId = UUID.randomUUID().toString();
String product = "Deluxe Chair";
fixture.given(new OrderPlacedEvent(orderId, product))
.when(new ConfirmOrderCommand(orderId))
.expectEvents(new OrderConfirmedEvent(orderId));
}
@Test
public void givenOrderPlacedEvent_whenShipOrderCommand_thenShouldThrowIllegalStateException() {
String orderId = UUID.randomUUID().toString();
String product = "Deluxe Chair";
fixture.given(new OrderPlacedEvent(orderId, product))
.when(new ShipOrderCommand(orderId))
.expectException(IllegalStateException.class);
}
@Test
public void givenOrderPlacedEventAndOrderConfirmedEvent_whenShipOrderCommand_thenShouldPublishOrderShippedEvent() {
String orderId = UUID.randomUUID().toString();
String product = "Deluxe Chair";
fixture.given(new OrderPlacedEvent(orderId, product), new OrderConfirmedEvent(orderId))
.when(new ShipOrderCommand(orderId))
.expectEvents(new OrderShippedEvent(orderId));
}
}

2
core-java-11/README.md
View File

@ -2,4 +2,4 @@
- [Java 11 Single File Source Code](https://www.baeldung.com/java-single-file-source-code)
- [Java 11 Local Variable Syntax for Lambda Parameters](https://www.baeldung.com/java-var-lambda-params)
- [Java 11 String API Additions](https://www.baeldung.com/java-11-string-api)

5
core-java-8/README.md
View File

@ -33,3 +33,8 @@
- [Java Primitives versus Objects](https://www.baeldung.com/java-primitives-vs-objects)
- [How to Use if/else Logic in Java 8 Streams](https://www.baeldung.com/java-8-streams-if-else-logic)
- [How to Replace Many if Statements in Java](https://www.baeldung.com/java-replace-if-statements)
- [Java @Override Annotation](https://www.baeldung.com/java-override)
- [Java @SuppressWarnings Annotation](https://www.baeldung.com/java-suppresswarnings)
- [Java @SafeVarargs Annotation](https://www.baeldung.com/java-safevarargs)
- [Java @Deprecated Annotation](https://www.baeldung.com/java-deprecated)
- [Java 8 Predicate Chain](https://www.baeldung.com/java-predicate-chain)

22
core-java-8/src/main/java/com/baeldung/interfaces/Electronic.java
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@ -1,22 +0,0 @@
package com.baeldung.interfaces;
public interface Electronic {
//Constant variable
public static final String LED = "LED";
//Abstract method
public int getElectricityUse();
// Static method
public static boolean isEnergyEfficient(String electtronicType) {
if (electtronicType.equals(LED)) {
return true;
}
return false;
}
//Default method
public default void printDescription() {
System.out.println("Electronic Description");
}
}

10
core-java-8/src/main/java/com/baeldung/interfaces/Motorcycle.java
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@ -1,10 +0,0 @@
package com.baeldung.interfaces;
import com.baeldung.interfaces.multiinheritance.Transform;
public class Motorcycle implements Transform {
@Override
public void transform() {
// Implementation
}
}

8
core-java-8/src/main/java/com/baeldung/interfaces/Truck.java
View File

@ -1,8 +0,0 @@
package com.baeldung.interfaces;
public class Truck extends Vehicle {
@Override
public void transform() {
// implementation
}
}

6
core-java-8/src/main/java/com/baeldung/interfaces/Vehicle.java
View File

@ -1,6 +0,0 @@
package com.baeldung.interfaces;
import com.baeldung.interfaces.multiinheritance.Transform;
public abstract class Vehicle implements Transform {
}

13
core-java-8/src/main/java/com/baeldung/interfaces/multiinheritance/Vehicle.java
View File

@ -1,13 +0,0 @@
package com.baeldung.interfaces.multiinheritance;
public class Vehicle implements Fly, Transform {
@Override
public void fly() {
System.out.println("I can Fly!!");
}
@Override
public void transform() {
System.out.println("I can Transform!!");
}
}

25
core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/Circle.java
View File

@ -1,25 +0,0 @@
package com.baeldung.interfaces.polymorphysim;
public class Circle implements Shape {
private double radius;
public Circle(double radius){
this.radius = radius;
}
@Override
public String name() {
return "Circle";
}
@Override
public double area() {
return Math.PI * (radius * radius);
}
@Override
public String getColor() {
return "green";
}
}

26
core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/DisplayShape.java
View File

@ -1,26 +0,0 @@
package com.baeldung.interfaces.polymorphysim;
import java.util.ArrayList;
public class DisplayShape {
private ArrayList<Shape> shapes;
public ArrayList<Shape> getShapes() {
return shapes;
}
public DisplayShape() {
shapes = new ArrayList<>();
}
public void add(Shape shape) {
shapes.add(shape);
}
public void display() {
for (Shape shape : shapes) {
System.out.println(shape.name() + " area: " + shape.area());
}
}
}

23
core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/FunctionalMain.java
View File

@ -1,23 +0,0 @@
package com.baeldung.interfaces.polymorphysim;
import java.util.function.Predicate;
public class FunctionalMain {
public static void main(String[] args) {
Shape circleShape = new Circle(2);
Shape squareShape = new Square(2);
DisplayShape DisplayShape = new DisplayShape();
DisplayShape.add(circleShape);
DisplayShape.add(squareShape);
Predicate<Shape> checkArea = (shape) -> shape.area() < 5;
for (Shape shape : DisplayShape.getShapes()) {
if (checkArea.test(shape)) {
System.out.println(shape.name() + " " + shape.area());
}
}
}
}

15
core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/MainPolymorphic.java
View File

@ -1,15 +0,0 @@
package com.baeldung.interfaces.polymorphysim;
public class MainPolymorphic {
public static void main(String[] args){
Shape circleShape = new Circle(2);
Shape squareShape = new Square(2);
DisplayShape displayShape = new DisplayShape();
displayShape.add(circleShape);
displayShape.add(squareShape);
displayShape.display();
}
}

9
core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/Shape.java
View File

@ -1,9 +0,0 @@
package com.baeldung.interfaces.polymorphysim;
import com.baeldung.interfaces.HasColor;
public interface Shape extends HasColor {
public abstract String name();
public abstract double area();
}

25
core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/Square.java
View File

@ -1,25 +0,0 @@
package com.baeldung.interfaces.polymorphysim;
public class Square implements Shape {
private double width;
public Square(double width) {
this.width = width;
}
@Override
public String name() {
return "Square";
}
@Override
public double area() {
return width * width;
}
@Override
public String getColor() {
return "red";
}
}

26
core-java-8/src/test/java/com/baeldung/interfaces/PolymorphysimUnitTest.java
View File

@ -1,26 +0,0 @@
package com.baeldung.interfaces;
import com.baeldung.interfaces.polymorphysim.Circle;
import com.baeldung.interfaces.polymorphysim.Shape;
import com.baeldung.interfaces.polymorphysim.Square;
import org.assertj.core.api.Assertions;
import org.junit.Test;
public class PolymorphysimUnitTest {
@Test
public void whenInterfacePointsToCircle_CircleAreaMethodisBeingCalled(){
double expectedArea = 12.566370614359172;
Shape circle = new Circle(2);
double actualArea = circle.area();
Assertions.assertThat(actualArea).isEqualTo(expectedArea);
}
@Test
public void whenInterfacePointsToSquare_SquareAreaMethodisBeingCalled(){
double expectedArea = 4;
Shape square = new Square(2);
double actualArea = square.area();
Assertions.assertThat(actualArea).isEqualTo(expectedArea);
}
}

44
core-java-9/src/main/java/com/baeldung/java9/set/UnmodifiableSet.java Normal file
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@ -0,0 +1,44 @@
package com.baeldung.java9.set;
import com.google.common.collect.ImmutableSet;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
public class UnmodifiableSet {
public static void main(String[] args) {
Set<String> set = new HashSet<>();
set.add("Canada");
set.add("USA");
coreJDK(set);
guavaOf();
copyOf(set);
java9Of();
}
private static void java9Of() {
Set<String> immutable = Set.of("Canada", "USA");
System.out.println(immutable);
}
private static void guavaOf() {
Set<String> immutable = ImmutableSet.of("Canada", "USA");
System.out.println(immutable);
}
private static void copyOf(Set<String> set) {
Set<String> immutable = ImmutableSet.copyOf(set);
set.add("Costa Rica");
System.out.println(immutable);
}
private static void coreJDK(Set<String> set) {
Set<String> unmodifiableSet = Collections.unmodifiableSet(set);
set.add("Costa Rica");
System.out.println(unmodifiableSet);
}
}

12
core-java-9/src/test/java/com/baeldung/java9/SetExamplesUnitTest.java
View File

@ -1,5 +1,7 @@
package com.baeldung.java9;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import org.junit.Test;
@ -23,4 +25,14 @@ public class SetExamplesUnitTest {
Set<Integer> intSet = Set.of(intArray);
assertEquals(intSet.size(), intArray.length);
}
@Test(expected = UnsupportedOperationException.class)
public void testUnmodifiableSet() {
Set<String> set = new HashSet<>();
set.add("Canada");
set.add("USA");
Set<String> unmodifiableSet = Collections.unmodifiableSet(set);
unmodifiableSet.add("Costa Rica");
}
}

1
core-java-arrays/README.md
View File

@ -13,3 +13,4 @@
- [How to Invert an Array in Java](http://www.baeldung.com/java-invert-array)
- [Array Operations in Java](http://www.baeldung.com/java-common-array-operations)
- [Intersection Between two Integer Arrays](https://www.baeldung.com/java-array-intersection)
- [Sorting Arrays in Java](https://www.baeldung.com/java-sorting-arrays)

3
core-java-collections-list/README.md
View File

@ -24,4 +24,5 @@
- [Java List Initialization in One Line](https://www.baeldung.com/java-init-list-one-line)
- [Ways to Iterate Over a List in Java](https://www.baeldung.com/java-iterate-list)
- [ClassCastException: Arrays$ArrayList cannot be cast to ArrayList](https://www.baeldung.com/java-classcastexception-arrays-arraylist)
- [Flattening Nested Collections in Java](http://www.baeldung.com/java-flatten-nested-collections)
- [Flattening Nested Collections in Java](http://www.baeldung.com/java-flatten-nested-collections)
- [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)

21
core-java-collections-list/src/main/java/com/baeldung/list/multidimensional/ArrayListOfArrayList.java
View File

@ -6,11 +6,11 @@ public class ArrayListOfArrayList {
public static void main(String args[]) {
int numVertices = 3;
ArrayList<ArrayList<Integer>> graph = new ArrayList<>(numVertices);
int vertexCount = 3;
ArrayList<ArrayList<Integer>> graph = new ArrayList<>(vertexCount);
//Initializing each element of ArrayList with ArrayList
for(int i=0; i< numVertices; i++) {
for(int i = 0; i< vertexCount; i++) {
graph.add(new ArrayList<Integer>());
}
@ -21,13 +21,14 @@ public class ArrayListOfArrayList {
graph.get(1).add(0);
graph.get(2).add(1);
graph.get(0).add(2);
//Printing all the edges
for(int vertexNo=0; vertexNo<numVertices; vertexNo++) {
int edgeCount = graph.get(vertexNo).size();
ArrayList<Integer> listOfVertices = graph.get(vertexNo);
for(int i=0; i<edgeCount; i++) {
System.out.println("Vertex "+vertexNo+" is connected to vetex "+listOfVertices.get(i));
vertexCount = graph.size();
for(int i = 0; i < vertexCount; i++) {
int edgeCount = graph.get(i).size();
for(int j = 0; j < edgeCount; j++) {
Integer startVertex = i;
Integer endVertex = graph.get(i).get(j);
System.out.printf("Vertex %d is connected to vertex %d%n", startVertex, endVertex);
}
}
}

10
core-java-collections-list/src/main/java/com/baeldung/list/multidimensional/ThreeDimensionalArrayList.java
View File

@ -12,9 +12,9 @@ public class ThreeDimensionalArrayList {
ArrayList< ArrayList< ArrayList<String> > > space = new ArrayList<>(x_axis_length);
//Initializing each element of ArrayList with ArrayList< ArrayList<String> >
for(int i=0; i< x_axis_length; i++) {
for(int i = 0; i < x_axis_length; i++) {
space.add(new ArrayList< ArrayList<String> >(y_axis_length));
for(int j =0; j< y_axis_length; j++) {
for(int j = 0; j < y_axis_length; j++) {
space.get(i).add(new ArrayList<String>(z_axis_length));
}
}
@ -33,9 +33,9 @@ public class ThreeDimensionalArrayList {
space.get(1).get(1).add(1,"Yellow");
//Printing colors for all the points
for(int i=0; i<x_axis_length; i++) {
for(int j=0; j<y_axis_length; j++) {
for(int k=0; k<z_axis_length; k++) {
for(int i = 0; i < x_axis_length; i++) {
for(int j = 0; j < y_axis_length; j++) {
for(int k = 0; k < z_axis_length; k++) {
System.out.println("Color of point ("+i+","+j+","+k+") is :"+space.get(i).get(j).get(k));
}
}

4
core-java-collections/README.md
View File

@ -28,4 +28,6 @@
- [Combining Different Types of Collections in Java](https://www.baeldung.com/java-combine-collections)
- [Sorting in Java](http://www.baeldung.com/java-sorting)
- [Join and Split Arrays and Collections in Java](http://www.baeldung.com/java-join-and-split)
- [A Guide to EnumMap](https://www.baeldung.com/java-enum-map)
- [A Guide to EnumMap](https://www.baeldung.com/java-enum-map)
- [A Guide to Iterator in Java](http://www.baeldung.com/java-iterator)
- [Differences Between HashMap and Hashtable](https://www.baeldung.com/hashmap-hashtable-differences)

0
core-java/src/main/java/com/baeldung/iteratorguide/IteratorGuide.java → core-java-collections/src/main/java/com/baeldung/iteratorguide/IteratorGuide.java
View File

27
core-java-collections/src/main/java/com/baeldung/java/list/VectorExample.java Normal file
View File

@ -0,0 +1,27 @@
package com.baeldung.java.list;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Vector;
public class VectorExample {
public static void main(String[] args) {
Vector<String> vector = new Vector<>();
vector.add("baeldung");
vector.add("Vector");
vector.add("example");
Enumeration e = vector.elements();
while(e.hasMoreElements()){
System.out.println(e.nextElement());
}
Iterator<String> iterator = vector.iterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
}
}

25
core-java-collections/src/main/java/com/baeldung/performance/ArrayListBenchmark.java
View File

@ -9,7 +9,7 @@ import java.util.*;
import java.util.concurrent.TimeUnit;
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 10)
public class ArrayListBenchmark {
@ -17,6 +17,7 @@ public class ArrayListBenchmark {
public static class MyState {
List<Employee> employeeList = new ArrayList<>();
Vector<Employee> employeeVector = new Vector<>();
//LinkedList<Employee> employeeList = new LinkedList<>();
long iterations = 100000;
@ -29,9 +30,11 @@ public class ArrayListBenchmark {
public void setUp() {
for (long i = 0; i < iterations; i++) {
employeeList.add(new Employee(i, "John"));
employeeVector.add(new Employee(i, "John"));
}
employeeList.add(employee);
employeeVector.add(employee);
employeeIndex = employeeList.indexOf(employee);
}
}
@ -46,6 +49,11 @@ public class ArrayListBenchmark {
return state.employeeList.contains(state.employee);
}
@Benchmark
public boolean testContainsVector(ArrayListBenchmark.MyState state) {
return state.employeeVector.contains(state.employee);
}
@Benchmark
public int testIndexOf(ArrayListBenchmark.MyState state) {
return state.employeeList.indexOf(state.employee);
@ -56,19 +64,24 @@ public class ArrayListBenchmark {
return state.employeeList.get(state.employeeIndex);
}
@Benchmark
public Employee testVectorGet(ArrayListBenchmark.MyState state) {
return state.employeeVector.get(state.employeeIndex);
}
@Benchmark
public boolean testRemove(ArrayListBenchmark.MyState state) {
return state.employeeList.remove(state.employee);
}
// @Benchmark
// public void testAdd(ArrayListBenchmark.MyState state) {
// state.employeeList.add(new Employee(state.iterations + 1, "John"));
// }
@Benchmark
public void testAdd(ArrayListBenchmark.MyState state) {
state.employeeList.add(new Employee(state.iterations + 1, "John"));
}
public static void main(String[] args) throws Exception {
Options options = new OptionsBuilder()
.include(ArrayListBenchmark.class.getSimpleName()).threads(1)
.include(ArrayListBenchmark.class.getSimpleName()).threads(3)
.forks(1).shouldFailOnError(true)
.shouldDoGC(true)
.jvmArgs("-server").build();

48
core-java-collections/src/main/java/com/baeldung/queueInterface/CustomBaeldungQueue.java Normal file
View File

@ -0,0 +1,48 @@
package com.baeldung.queueinterface;
import java.util.AbstractQueue;
import java.util.Iterator;
import java.util.LinkedList;
public class CustomBaeldungQueue<T> extends AbstractQueue<T> {
private LinkedList<T> elements;
public CustomBaeldungQueue() {
this.elements = new LinkedList<T>();
}
@Override
public Iterator<T> iterator() {
return elements.iterator();
}
@Override
public int size() {
return elements.size();
}
@Override
public boolean offer(T t) {
if(t == null) return false;
elements.add(t);
return true;
}
@Override
public T poll() {
Iterator<T> iter = elements.iterator();
T t = iter.next();
if(t != null){
iter.remove();
return t;
}
return null;
}
@Override
public T peek() {
return elements.getFirst();
}
}

53
core-java-collections/src/test/java/com/baeldung/queueInterface/PriorityQueueUnitTest.java Normal file
View File

@ -0,0 +1,53 @@
package com.baeldung.queueinterface;
import org.junit.Before;
import org.junit.Test;
import java.util.PriorityQueue;
import static org.junit.Assert.assertEquals;
public class PriorityQueueUnitTest {
@Test
public void givenIntegerQueue_whenIntegersOutOfOrder_checkRetrievalOrderIsNatural() {
PriorityQueue<Integer> integerQueue = new PriorityQueue<>();
integerQueue.add(9);
integerQueue.add(2);
integerQueue.add(4);
int first = integerQueue.poll();
int second = integerQueue.poll();
int third = integerQueue.poll();
assertEquals(2, first);
assertEquals(4, second);
assertEquals(9, third);
}
@Test
public void givenStringQueue_whenStringsAddedOutOfNaturalOrder_checkRetrievalOrderNatural() {
PriorityQueue<String> stringQueue = new PriorityQueue<>();
stringQueue.add("banana");
stringQueue.add("apple");
stringQueue.add("cherry");
String first = stringQueue.poll();
String second = stringQueue.poll();
String third = stringQueue.poll();
assertEquals("apple", first);
assertEquals("banana", second);
assertEquals("cherry", third);
}
}

30
core-java-collections/src/test/java/com/baeldung/queueinterface/CustomBaeldungQueueUnitTest.java Normal file
View File

@ -0,0 +1,30 @@
package com.baeldung.queueinterface;
import org.junit.Before;
import org.junit.Test;
import static org.junit.Assert.*;
public class CustomBaeldungQueueUnitTest {
private CustomBaeldungQueue<Integer> customQueue;
@Before
public void setUp() throws Exception {
customQueue = new CustomBaeldungQueue<>();
}
@Test
public void givenQueueWithTwoElements_whenElementsRetrieved_checkRetrievalCorrect() {
customQueue.add(7);
customQueue.add(5);
int first = customQueue.poll();
int second = customQueue.poll();
assertEquals(7, first);
assertEquals(5, second);
}
}

86
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/application/Application.java Normal file
View File

@ -0,0 +1,86 @@
package com.baeldung.concurrent.threadsafety.application;
import com.baeldung.concurrent.threadsafety.callables.AtomicCounterCallable;
import com.baeldung.concurrent.threadsafety.mathutils.MathUtils;
import com.baeldung.concurrent.threadsafety.callables.CounterCallable;
import com.baeldung.concurrent.threadsafety.callables.ExtrinsicLockCounterCallable;
import com.baeldung.concurrent.threadsafety.callables.MessageServiceCallable;
import com.baeldung.concurrent.threadsafety.callables.ReentranReadWriteLockCounterCallable;
import com.baeldung.concurrent.threadsafety.callables.ReentrantLockCounterCallable;
import com.baeldung.concurrent.threadsafety.services.AtomicCounter;
import com.baeldung.concurrent.threadsafety.services.Counter;
import com.baeldung.concurrent.threadsafety.services.ExtrinsicLockCounter;
import com.baeldung.concurrent.threadsafety.services.MessageService;
import com.baeldung.concurrent.threadsafety.services.ReentrantLockCounter;
import com.baeldung.concurrent.threadsafety.services.ReentrantReadWriteLockCounter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class Application {
public static void main(String[] args) throws InterruptedException, ExecutionException {
new Thread(() -> {
System.out.println(MathUtils.factorial(10));
}).start();
new Thread(() -> {
System.out.println(MathUtils.factorial(5));
}).start();
ExecutorService executorService = Executors.newFixedThreadPool(10);
MessageService messageService = new MessageService("Welcome to Baeldung!");
Future<String> future1 = (Future<String>) executorService.submit(new MessageServiceCallable(messageService));
Future<String> future2 = (Future<String>) executorService.submit(new MessageServiceCallable(messageService));
System.out.println(future1.get());
System.out.println(future2.get());
Counter counter = new Counter();
Future<Integer> future3 = (Future<Integer>) executorService.submit(new CounterCallable(counter));
Future<Integer> future4 = (Future<Integer>) executorService.submit(new CounterCallable(counter));
System.out.println(future3.get());
System.out.println(future4.get());
ExtrinsicLockCounter extrinsicLockCounter = new ExtrinsicLockCounter();
Future<Integer> future5 = (Future<Integer>) executorService.submit(new ExtrinsicLockCounterCallable(extrinsicLockCounter));
Future<Integer> future6 = (Future<Integer>) executorService.submit(new ExtrinsicLockCounterCallable(extrinsicLockCounter));
System.out.println(future5.get());
System.out.println(future6.get());
ReentrantLockCounter reentrantLockCounter = new ReentrantLockCounter();
Future<Integer> future7 = (Future<Integer>) executorService.submit(new ReentrantLockCounterCallable(reentrantLockCounter));
Future<Integer> future8 = (Future<Integer>) executorService.submit(new ReentrantLockCounterCallable(reentrantLockCounter));
System.out.println(future7.get());
System.out.println(future8.get());
ReentrantReadWriteLockCounter reentrantReadWriteLockCounter = new ReentrantReadWriteLockCounter();
Future<Integer> future9 = (Future<Integer>) executorService.submit(new ReentranReadWriteLockCounterCallable(reentrantReadWriteLockCounter));
Future<Integer> future10 = (Future<Integer>) executorService.submit(new ReentranReadWriteLockCounterCallable(reentrantReadWriteLockCounter));
System.out.println(future9.get());
System.out.println(future10.get());
AtomicCounter atomicCounter = new AtomicCounter();
Future<Integer> future11 = (Future<Integer>) executorService.submit(new AtomicCounterCallable(atomicCounter));
Future<Integer> future12 = (Future<Integer>) executorService.submit(new AtomicCounterCallable(atomicCounter));
System.out.println(future11.get());
System.out.println(future12.get());
Collection<Integer> syncCollection = Collections.synchronizedCollection(new ArrayList<>());
Thread thread11 = new Thread(() -> syncCollection.addAll(Arrays.asList(1, 2, 3, 4, 5, 6)));
Thread thread12 = new Thread(() -> syncCollection.addAll(Arrays.asList(1, 2, 3, 4, 5, 6)));
thread11.start();
thread12.start();
Map<String,String> concurrentMap = new ConcurrentHashMap<>();
concurrentMap.put("1", "one");
concurrentMap.put("2", "two");
concurrentMap.put("3", "three");
}
}

19
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/callables/AtomicCounterCallable.java Normal file
View File

@ -0,0 +1,19 @@
package com.baeldung.concurrent.threadsafety.callables;
import com.baeldung.concurrent.threadsafety.services.AtomicCounter;
import java.util.concurrent.Callable;
public class AtomicCounterCallable implements Callable<Integer> {
private final AtomicCounter counter;
public AtomicCounterCallable(AtomicCounter counter) {
this.counter = counter;
}
@Override
public Integer call() throws Exception {
counter.incrementCounter();
return counter.getCounter();
}
}

19
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/callables/CounterCallable.java Normal file
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@ -0,0 +1,19 @@
package com.baeldung.concurrent.threadsafety.callables;
import com.baeldung.concurrent.threadsafety.services.Counter;
import java.util.concurrent.Callable;
public class CounterCallable implements Callable<Integer> {
private final Counter counter;
public CounterCallable(Counter counter) {
this.counter = counter;
}
@Override
public Integer call() throws Exception {
counter.incrementCounter();
return counter.getCounter();
}
}

19
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/callables/ExtrinsicLockCounterCallable.java Normal file
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@ -0,0 +1,19 @@
package com.baeldung.concurrent.threadsafety.callables;
import com.baeldung.concurrent.threadsafety.services.ExtrinsicLockCounter;
import java.util.concurrent.Callable;
public class ExtrinsicLockCounterCallable implements Callable<Integer> {
private final ExtrinsicLockCounter counter;
public ExtrinsicLockCounterCallable(ExtrinsicLockCounter counter) {
this.counter = counter;
}
@Override
public Integer call() throws Exception {
counter.incrementCounter();
return counter.getCounter();
}
}

19
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/callables/MessageServiceCallable.java Normal file
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@ -0,0 +1,19 @@
package com.baeldung.concurrent.threadsafety.callables;
import com.baeldung.concurrent.threadsafety.services.MessageService;
import java.util.concurrent.Callable;
public class MessageServiceCallable implements Callable<String> {
private final MessageService messageService;
public MessageServiceCallable(MessageService messageService) {
this.messageService = messageService;
}
@Override
public String call() {
return messageService.getMesssage();
}
}

20
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/callables/ReentranReadWriteLockCounterCallable.java Normal file
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@ -0,0 +1,20 @@
package com.baeldung.concurrent.threadsafety.callables;
import com.baeldung.concurrent.threadsafety.services.ReentrantReadWriteLockCounter;
import java.util.concurrent.Callable;
public class ReentranReadWriteLockCounterCallable implements Callable<Integer> {
private final ReentrantReadWriteLockCounter counter;
public ReentranReadWriteLockCounterCallable(ReentrantReadWriteLockCounter counter) {
this.counter = counter;
}
@Override
public Integer call() throws Exception {
counter.incrementCounter();
return counter.getCounter();
}
}

19
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/callables/ReentrantLockCounterCallable.java Normal file
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@ -0,0 +1,19 @@
package com.baeldung.concurrent.threadsafety.callables;
import com.baeldung.concurrent.threadsafety.services.ReentrantLockCounter;
import java.util.concurrent.Callable;
public class ReentrantLockCounterCallable implements Callable<Integer> {
private final ReentrantLockCounter counter;
public ReentrantLockCounterCallable(ReentrantLockCounter counter) {
this.counter = counter;
}
@Override
public Integer call() throws Exception {
counter.incrementCounter();
return counter.getCounter();
}
}

14
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/mathutils/MathUtils.java Normal file
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@ -0,0 +1,14 @@
package com.baeldung.concurrent.threadsafety.mathutils;
import java.math.BigInteger;
public class MathUtils {
public static BigInteger factorial(int number) {
BigInteger f = new BigInteger("1");
for (int i = 2; i <= number; i++) {
f = f.multiply(BigInteger.valueOf(i));
}
return f;
}
}

18
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/services/AtomicCounter.java Normal file
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@ -0,0 +1,18 @@
package com.baeldung.concurrent.threadsafety.services;
import java.util.concurrent.atomic.AtomicInteger;
public class AtomicCounter {
private final AtomicInteger counter = new AtomicInteger();
public AtomicCounter() {}
public void incrementCounter() {
counter.incrementAndGet();
}
public synchronized int getCounter() {
return counter.get();
}
}

18
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/services/Counter.java Normal file
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@ -0,0 +1,18 @@
package com.baeldung.concurrent.threadsafety.services;
public class Counter {
private volatile int counter;
public Counter() {
this.counter = 0;
}
public synchronized void incrementCounter() {
counter += 1;
}
public int getCounter() {
return counter;
}
}

23
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/services/ExtrinsicLockCounter.java Normal file
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@ -0,0 +1,23 @@
package com.baeldung.concurrent.threadsafety.services;
public class ExtrinsicLockCounter {
private int counter;
private final Object lock = new Object();
public ExtrinsicLockCounter() {
this.counter = 0;
}
public void incrementCounter() {
synchronized (lock) {
counter += 1;
}
}
public int getCounter() {
synchronized (lock) {
return counter;
}
}
}

14
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/services/MessageService.java Normal file
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@ -0,0 +1,14 @@
package com.baeldung.concurrent.threadsafety.services;
public class MessageService {
private final String message;
public MessageService(String message) {
this.message = message;
}
public String getMesssage() {
return message;
}
}

26
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/services/ReentrantLockCounter.java Normal file
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@ -0,0 +1,26 @@
package com.baeldung.concurrent.threadsafety.services;
import java.util.concurrent.locks.ReentrantLock;
public class ReentrantLockCounter {
private int counter;
private final ReentrantLock reLock = new ReentrantLock(true);
public ReentrantLockCounter() {
this.counter = 0;
}
public void incrementCounter() {
reLock.lock();
try {
counter += 1;
} finally {
reLock.unlock();
}
}
public int getCounter() {
return counter;
}
}

34
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/services/ReentrantReadWriteLockCounter.java Normal file
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@ -0,0 +1,34 @@
package com.baeldung.concurrent.threadsafety.services;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
public class ReentrantReadWriteLockCounter {
private int counter;
private final ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock();
private final Lock readLock = rwLock.readLock();
private final Lock writeLock = rwLock.writeLock();
public ReentrantReadWriteLockCounter() {
this.counter = 0;
}
public void incrementCounter() {
writeLock.lock();
try {
counter += 1;
} finally {
writeLock.unlock();
}
}
public int getCounter() {
readLock.lock();
try {
return counter;
} finally {
readLock.unlock();
}
}
}

14
core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/threadsafety/services/StateHolder.java Normal file
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@ -0,0 +1,14 @@
package com.baeldung.concurrent.threadsafety.services;
public class StateHolder {
private final String state;
public StateHolder(String state) {
this.state = state;
}
public String getState() {
return state;
}
}

23
core-java-concurrency-basic/src/test/com/baeldung/concurrent/threadsafety/tests/CounterTest.java Normal file
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@ -0,0 +1,23 @@
package com.baeldung.concurrent.threadsafety.tests;
import org.junit.Test;
import static org.assertj.core.api.Assertions.assertThat;
import com.baeldung.concurrent.threadsafety.callables.CounterCallable;
import com.baeldung.concurrent.threadsafety.services.Counter;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class CounterTest {
@Test
public void whenCalledIncrementCounter_thenCorrect() throws Exception {
ExecutorService executorService = Executors.newFixedThreadPool(2);
Counter counter = new Counter();
Future<Integer> future1 = (Future<Integer>) executorService.submit(new CounterCallable(counter));
Future<Integer> future2 = (Future<Integer>) executorService.submit(new CounterCallable(counter));
assertThat(future1.get()).isEqualTo(1);
assertThat(future2.get()).isEqualTo(2);
}
}

23
core-java-concurrency-basic/src/test/com/baeldung/concurrent/threadsafety/tests/ExtrinsicLockCounterTest.java Normal file
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@ -0,0 +1,23 @@
package com.baeldung.concurrent.threadsafety.tests;
import org.junit.Test;
import static org.assertj.core.api.Assertions.assertThat;
import com.baeldung.concurrent.threadsafety.callables.ExtrinsicLockCounterCallable;
import com.baeldung.concurrent.threadsafety.services.ExtrinsicLockCounter;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class ExtrinsicLockCounterTest {
@Test
public void whenCalledIncrementCounter_thenCorrect() throws Exception {
ExecutorService executorService = Executors.newFixedThreadPool(2);
ExtrinsicLockCounter counter = new ExtrinsicLockCounter();
Future<Integer> future1 = (Future<Integer>) executorService.submit(new ExtrinsicLockCounterCallable(counter));
Future<Integer> future2 = (Future<Integer>) executorService.submit(new ExtrinsicLockCounterCallable(counter));
assertThat(future1.get()).isEqualTo(1);
assertThat(future2.get()).isEqualTo(2);
}
}

13
core-java-concurrency-basic/src/test/com/baeldung/concurrent/threadsafety/tests/MathUtilsTest.java Normal file
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@ -0,0 +1,13 @@
package com.baeldung.concurrent.threadsafety.tests;
import com.baeldung.concurrent.threadsafety.mathutils.MathUtils;
import org.junit.Test;
import static org.assertj.core.api.Assertions.assertThat;
public class MathUtilsTest {
@Test
public void whenCalledFactorialMethod_thenCorrect() {
assertThat(MathUtils.factorial(2)).isEqualTo(2);
}
}

23
core-java-concurrency-basic/src/test/com/baeldung/concurrent/threadsafety/tests/MessageServiceTest.java Normal file
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@ -0,0 +1,23 @@
package com.baeldung.concurrent.threadsafety.tests;
import org.junit.Test;
import static org.assertj.core.api.Assertions.assertThat;
import com.baeldung.concurrent.threadsafety.callables.MessageServiceCallable;
import com.baeldung.concurrent.threadsafety.services.MessageService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class MessageServiceTest {
@Test
public void whenCalledgetMessage_thenCorrect() throws Exception {
ExecutorService executorService = Executors.newFixedThreadPool(2);
MessageService messageService = new MessageService("Welcome to Baeldung!");
Future<String> future1 = (Future<String>) executorService.submit(new MessageServiceCallable(messageService));
Future<String> future2 = (Future<String>) executorService.submit(new MessageServiceCallable(messageService));
assertThat(future1.get()).isEqualTo("Welcome to Baeldung!");
assertThat(future2.get()).isEqualTo("Welcome to Baeldung!");
}
}

23
core-java-concurrency-basic/src/test/com/baeldung/concurrent/threadsafety/tests/ReentrantLockCounterTest.java Normal file
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@ -0,0 +1,23 @@
package com.baeldung.concurrent.threadsafety.tests;
import com.baeldung.concurrent.threadsafety.callables.ReentrantLockCounterCallable;
import com.baeldung.concurrent.threadsafety.services.ReentrantLockCounter;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;
public class ReentrantLockCounterTest {
@Test
public void whenCalledIncrementCounter_thenCorrect() throws Exception {
ExecutorService executorService = Executors.newFixedThreadPool(2);
ReentrantLockCounter counter = new ReentrantLockCounter();
Future<Integer> future1 = (Future<Integer>) executorService.submit(new ReentrantLockCounterCallable(counter));
Future<Integer> future2 = (Future<Integer>) executorService.submit(new ReentrantLockCounterCallable(counter));
assertThat(future1.get()).isEqualTo(1);
assertThat(future2.get()).isEqualTo(2);
}
}

24
core-java-concurrency-basic/src/test/com/baeldung/concurrent/threadsafety/tests/ReentrantReadWriteLockCounterTest.java Normal file
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@ -0,0 +1,24 @@
package com.baeldung.concurrent.threadsafety.tests;
import com.baeldung.concurrent.threadsafety.callables.ReentranReadWriteLockCounterCallable;
import com.baeldung.concurrent.threadsafety.services.ReentrantReadWriteLockCounter;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;
public class ReentrantReadWriteLockCounterTest {
@Test
public void whenCalledIncrementCounter_thenCorrect() throws Exception {
ExecutorService executorService = Executors.newFixedThreadPool(2);
ReentrantReadWriteLockCounter counter = new ReentrantReadWriteLockCounter();
Future<Integer> future1 = (Future<Integer>) executorService.submit(new ReentranReadWriteLockCounterCallable(counter));
Future<Integer> future2 = (Future<Integer>) executorService.submit(new ReentranReadWriteLockCounterCallable(counter));
assertThat(future1.get()).isEqualTo(1);
assertThat(future2.get()).isEqualTo(2);
}
}

2
core-java-io/README.md
View File

@ -35,3 +35,5 @@
- [Guide to Java OutputStream](https://www.baeldung.com/java-outputstream)
- [Reading a CSV File into an Array](https://www.baeldung.com/java-csv-file-array)
- [Guide to BufferedReader](https://www.baeldung.com/java-buffered-reader)
- [How to Get the File Extension of a File in Java](http://www.baeldung.com/java-file-extension)
- [Getting a File’s Mime Type in Java](http://www.baeldung.com/java-file-mime-type)

14
core-java-io/pom.xml
View File

@ -160,6 +160,17 @@
<version>${opencsv.version}</version>
<scope>test</scope>
</dependency>
<!-- Mime Type Resolution Libraries -->
<dependency>
<groupId>org.apache.tika</groupId>
<artifactId>tika-core</artifactId>
<version>${tika.version}</version>
</dependency>
<dependency>
<groupId>net.sf.jmimemagic</groupId>
<artifactId>jmimemagic</artifactId>
<version>${jmime-magic.version}</version>
</dependency>
</dependencies>
<build>
@ -264,6 +275,9 @@
<esapi.version>2.1.0.1</esapi.version>
<jmh-generator-annprocess.version>1.19</jmh-generator-annprocess.version>
<async-http-client.version>2.4.5</async-http-client.version>
<!-- Mime Type Libraries -->
<tika.version>1.18</tika.version>
<jmime-magic.version>0.1.5</jmime-magic.version>
</properties>
</project>

26
core-java-io/src/main/java/com/baeldung/csv/WriteCsvFileExample.java Normal file
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@ -0,0 +1,26 @@
package com.baeldung.csv;
public class WriteCsvFileExample {
public String convertToCSV(String[] data) {
StringBuilder csvLine = new StringBuilder();
for (int i = 0; i < data.length; i++) {
if (i > 0) {
csvLine.append(",");
}
csvLine.append(escapeSpecialCharacters(data[i]));
}
return csvLine.toString();
}
public String escapeSpecialCharacters(String data) {
String escapedData = data.replaceAll("\\R", " ");
if (data.contains(",") || data.contains("\"") || data.contains("'")) {
data = data.replace("\"", "\"\"");
escapedData = "\"" + data + "\"";
}
return escapedData;
}
}

0
core-java/src/main/java/com/baeldung/extension/Extension.java → core-java-io/src/main/java/com/baeldung/extension/Extension.java
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84
core-java-io/src/test/java/com/baeldung/csv/WriteCsvFileExampleUnitTest.java Normal file
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@ -0,0 +1,84 @@
package com.baeldung.csv;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import org.junit.Before;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class WriteCsvFileExampleUnitTest {
private static final Logger LOG = LoggerFactory.getLogger(WriteCsvFileExampleUnitTest.class);
private static final String CSV_FILE_NAME = "src/test/resources/exampleOutput.csv";
private WriteCsvFileExample csvExample;
@Before
public void setupClass() {
csvExample = new WriteCsvFileExample();
}
@Test
public void givenCommaContainingData_whenEscapeSpecialCharacters_stringReturnedInQuotes() {
String data = "three,two,one";
String escapedData = csvExample.escapeSpecialCharacters(data);
String expectedData = "\"three,two,one\"";
assertEquals(expectedData, escapedData);
}
@Test
public void givenQuoteContainingData_whenEscapeSpecialCharacters_stringReturnedFormatted() {
String data = "She said \"Hello\"";
String escapedData = csvExample.escapeSpecialCharacters(data);
String expectedData = "\"She said \"\"Hello\"\"\"";
assertEquals(expectedData, escapedData);
}
@Test
public void givenNewlineContainingData_whenEscapeSpecialCharacters_stringReturnedInQuotes() {
String dataNewline = "This contains\na newline";
String dataCarriageReturn = "This contains\r\na newline and carriage return";
String escapedDataNl = csvExample.escapeSpecialCharacters(dataNewline);
String escapedDataCr = csvExample.escapeSpecialCharacters(dataCarriageReturn);
String expectedData = "This contains a newline";
assertEquals(expectedData, escapedDataNl);
String expectedDataCr = "This contains a newline and carriage return";
assertEquals(expectedDataCr, escapedDataCr);
}
@Test
public void givenNonSpecialData_whenEscapeSpecialCharacters_stringReturnedUnchanged() {
String data = "This is nothing special";
String returnedData = csvExample.escapeSpecialCharacters(data);
assertEquals(data, returnedData);
}
@Test
public void givenBufferedWriter_whenWriteLine_thenOutputCreated() {
List<String[]> dataLines = new ArrayList<String[]>();
dataLines.add(new String[] { "John", "Doe", "38", "Comment Data\nAnother line of comment data" });
dataLines.add(new String[] { "Jane", "Doe, Jr.", "19", "She said \"I'm being quoted\"" });
File csvOutputFile = new File(CSV_FILE_NAME);
try (PrintWriter pw = new PrintWriter(csvOutputFile)) {
dataLines.stream()
.map(csvExample::convertToCSV)
.forEach(pw::println);
} catch (FileNotFoundException e) {
LOG.error("IOException " + e.getMessage());
}
assertTrue(csvOutputFile.exists());
}
}

0
core-java/src/test/java/com/baeldung/extension/ExtensionUnitTest.java → core-java-io/src/test/java/com/baeldung/extension/ExtensionUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/java/mimetype/MimeTypeUnitTest.java → core-java-io/src/test/java/com/baeldung/java/mimetype/MimeTypeUnitTest.java
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60
core-java-io/src/test/java/org/baeldung/java/io/InputStreamToByteBufferUnitTest.java Normal file
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@ -0,0 +1,60 @@
package org.baeldung.java.io;
import com.google.common.io.ByteStreams;
import org.apache.commons.io.IOUtils;
import org.junit.jupiter.api.Test;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
import static org.junit.jupiter.api.Assertions.assertEquals;
class InputStreamToByteBufferUnitTest {
@Test
public void givenUsingCoreClasses_whenWritingAFileIntoAByteBuffer_thenBytesLengthMustMatch() throws IOException {
File inputFile = getFile();
ByteBuffer bufferByte = ByteBuffer.allocate((int) inputFile.length());
FileInputStream in = new FileInputStream(inputFile);
in.getChannel().read(bufferByte);
assertEquals(bufferByte.position(), inputFile.length());
}
@Test
public void givenUsingCommonsIo_whenWritingAFileIntoAByteBuffer_thenBytesLengthMustMatch() throws IOException {
File inputFile = getFile();
ByteBuffer bufferByte = ByteBuffer.allocateDirect((int) inputFile.length());
ReadableByteChannel readableByteChannel = new FileInputStream(inputFile).getChannel();
IOUtils.readFully(readableByteChannel, bufferByte);
assertEquals(bufferByte.position(), inputFile.length());
}
@Test
public void givenUsingGuava_whenWritingAFileIntoAByteBuffer_thenBytesLengthMustMatch() throws IOException {
File inputFile = getFile();
FileInputStream in = new FileInputStream(inputFile);
byte[] targetArray = ByteStreams.toByteArray(in);
ByteBuffer bufferByte = ByteBuffer.wrap(targetArray);
bufferByte.rewind();
while (bufferByte.hasRemaining()) {
bufferByte.get();
}
assertEquals(bufferByte.position(), inputFile.length());
}
private File getFile() {
ClassLoader classLoader = new InputStreamToByteBufferUnitTest().getClass().getClassLoader();
String fileName = "frontenac-2257154_960_720.jpg";
return new File(classLoader.getResource(fileName).getFile());
}
}

0
core-java/src/test/resources/META-INF/mime.types → core-java-io/src/test/resources/META-INF/mime.types
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2
core-java-io/src/test/resources/exampleOutput.csv Normal file
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@ -0,0 +1,2 @@
John,Doe,38,Comment Data Another line of comment data
Jane,"Doe, Jr.",19,"She said ""I'm being quoted"""
1 John Doe 38 Comment Data Another line of comment data
2 Jane Doe, Jr. 19 She said "I'm being quoted"

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2
core-java-lang/README.md
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@ -33,3 +33,5 @@
- [How to Separate Double into Integer and Decimal Parts](https://www.baeldung.com/java-separate-double-into-integer-decimal-parts)
- [“Sneaky Throws” in Java](http://www.baeldung.com/java-sneaky-throws)
- [Retrieving a Class Name in Java](https://www.baeldung.com/java-class-name)
- [Java Compound Operators](https://www.baeldung.com/java-compound-operators)
- [Guide to Java Packages](https://www.baeldung.com/java-packages)

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