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

1
algorithms-miscellaneous-1/README.md
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@ -13,3 +13,4 @@
- [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 the Longest Substring without Repeating Characters](https://www.baeldung.com/java-longest-substring-without-repeated-characters)

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algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/permutation/Permutation.java Normal file
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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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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--;
}
}
}

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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;
}
}

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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 });
}
}

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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));
}
}

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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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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.Iterator;
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.JavaPairRDD;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.function.FlatMapFunction;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.api.java.function.Function2;
import org.apache.spark.api.java.function.PairFunction;
import org.apache.spark.api.java.function.VoidFunction;
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 {
@SuppressWarnings("serial")
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(new PairFunction<ConsumerRecord<String, String>, String, String>() {
@Override
public Tuple2<String, String> call(ConsumerRecord<String, String> record) {
return new Tuple2<>(record.key(), record.value());
}
});
JavaDStream<String> lines = results.map(new Function<Tuple2<String, String>, String>() {
@Override
public String call(Tuple2<String, String> tuple2) {
return tuple2._2();
}
});
JavaDStream<String> words = lines.flatMap(new FlatMapFunction<String, String>() {
@Override
public Iterator<String> call(String x) {
return Arrays.asList(x.split("\\s+"))
.iterator();
}
});
JavaPairDStream<String, Integer> wordCounts = words.mapToPair(new PairFunction<String, String, Integer>() {
@Override
public Tuple2<String, Integer> call(String s) {
return new Tuple2<>(s, 1);
}
})
.reduceByKey(new Function2<Integer, Integer, Integer>() {
@Override
public Integer call(Integer i1, Integer i2) {
return i1 + i2;
}
});
wordCounts.foreachRDD(new VoidFunction<JavaPairRDD<String, Integer>>() {
@Override
public void call(JavaPairRDD<String, Integer> javaRdd) throws Exception {
Map<String, Integer> wordCountMap = javaRdd.collectAsMap();
for (String key : wordCountMap.keySet()) {
List<Word> words = Arrays.asList(new Word(key, wordCountMap.get(key)));
JavaRDD<Word> rdd = streamingContext.sparkContext()
.parallelize(words);
javaFunctions(rdd).writerBuilder("vocabulary", "words", mapToRow(Word.class))
.saveToCassandra();
}
}
});
streamingContext.start();
streamingContext.awaitTermination();
}
}

140
apache-spark/src/main/java/com/baeldung/data/pipeline/WordCountingAppWithCheckpoint.java Normal file
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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.Iterator;
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.JavaPairRDD;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.Optional;
import org.apache.spark.api.java.function.FlatMapFunction;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.api.java.function.Function2;
import org.apache.spark.api.java.function.Function3;
import org.apache.spark.api.java.function.PairFunction;
import org.apache.spark.api.java.function.VoidFunction;
import org.apache.spark.streaming.Durations;
import org.apache.spark.streaming.State;
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;
@SuppressWarnings("serial")
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(new PairFunction<ConsumerRecord<String, String>, String, String>() {
@Override
public Tuple2<String, String> call(ConsumerRecord<String, String> record) {
return new Tuple2<>(record.key(), record.value());
}
});
JavaDStream<String> lines = results.map(new Function<Tuple2<String, String>, String>() {
@Override
public String call(Tuple2<String, String> tuple2) {
return tuple2._2();
}
});
JavaDStream<String> words = lines.flatMap(new FlatMapFunction<String, String>() {
@Override
public Iterator<String> call(String x) {
return Arrays.asList(x.split("\\s+"))
.iterator();
}
});
JavaPairDStream<String, Integer> wordCounts = words.mapToPair(new PairFunction<String, String, Integer>() {
@Override
public Tuple2<String, Integer> call(String s) {
return new Tuple2<>(s, 1);
}
})
.reduceByKey(new Function2<Integer, Integer, Integer>() {
@Override
public Integer call(Integer i1, Integer i2) {
return i1 + i2;
}
});
Function3<String, Optional<Integer>, State<Integer>, Tuple2<String, Integer>> mappingFunc = (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;
};
JavaPairRDD<String, Integer> initialRDD = JavaPairRDD.fromJavaRDD(sparkContext.emptyRDD());
JavaMapWithStateDStream<String, Integer, Integer, Tuple2<String, Integer>> cumulativeWordCounts = wordCounts.mapWithState(StateSpec.function(mappingFunc)
.initialState(initialRDD));
cumulativeWordCounts.foreachRDD(new VoidFunction<JavaRDD<Tuple2<String, Integer>>>() {
@Override
public void call(JavaRDD<Tuple2<String, Integer>> javaRdd) throws Exception {
List<Tuple2<String, Integer>> wordCountList = javaRdd.collect();
for (Tuple2<String, Integer> tuple : wordCountList) {
List<Word> words = Arrays.asList(new Word(tuple._1, tuple._2));
JavaRDD<Word> rdd = sparkContext.parallelize(words);
javaFunctions(rdd).writerBuilder("vocabulary", "words", mapToRow(Word.class))
.saveToCassandra();
}
}
});
streamingContext.start();
streamingContext.awaitTermination();
}
}

2
core-java-11/README.md
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@ -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)

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)

1
core-java-collections-list/README.md
View File

@ -25,3 +25,4 @@
- [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)
- [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)

19
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>());
}
@ -22,12 +22,13 @@ public class ArrayListOfArrayList {
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);
}
}
}

2
core-java-collections/README.md
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@ -29,3 +29,5 @@
- [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 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

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
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@ -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>

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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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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0
core-java/src/test/resources/META-INF/mime.types → core-java-io/src/test/resources/META-INF/mime.types
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0
core-java/src/test/resources/product.png → core-java-io/src/test/resources/product.png
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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)

0
core-java/native/nativedatetimeutils.dll → core-java-lang/native/nativedatetimeutils.dll
View File

0
core-java/src/main/java/com/baeldung/nativekeyword/DateTimeUtils.java → core-java-lang/src/main/java/com/baeldung/nativekeyword/DateTimeUtils.java
View File

0
core-java/src/main/java/com/baeldung/nativekeyword/NativeMainApp.java → core-java-lang/src/main/java/com/baeldung/nativekeyword/NativeMainApp.java
View File

0
core-java/src/test/java/com/baeldung/nativekeyword/DateTimeUtilsManualTest.java → core-java-lang/src/test/java/com/baeldung/nativekeyword/DateTimeUtilsManualTest.java
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11
core-java-security/README.md Normal file
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@ -0,0 +1,11 @@
## Core Java Security
### Relevant Articles:
- [MD5 Hashing in Java](http://www.baeldung.com/java-md5)
- [Guide to the Cipher Class](http://www.baeldung.com/java-cipher-class)
- [Introduction to SSL in Java](http://www.baeldung.com/java-ssl)
- [Java KeyStore API](http://www.baeldung.com/java-keystore)
- [Encrypting and Decrypting Files in Java](http://www.baeldung.com/java-cipher-input-output-stream)
- [Hashing a Password in Java](https://www.baeldung.com/java-password-hashing)
- [SSL Handshake Failures](https://www.baeldung.com/java-ssl-handshake-failures)
- [SHA-256 Hashing in Java](https://www.baeldung.com/sha-256-hashing-java)

55
core-java-security/pom.xml Normal file
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@ -0,0 +1,55 @@
<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>
<groupId>com.baeldung</groupId>
<artifactId>core-java-security</artifactId>
<version>0.1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>core-java-security</name>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../parent-java</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj-core.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>${commons-codec.version}</version>
</dependency>
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcprov-jdk15on</artifactId>
<version>${bouncycastle.version}</version>
</dependency>
</dependencies>
<properties>
<!-- util -->
<commons-lang3.version>3.8.1</commons-lang3.version>
<bouncycastle.version>1.55</bouncycastle.version>
<commons-codec.version>1.10</commons-codec.version>
<!-- testing -->
<assertj-core.version>3.10.0</assertj-core.version>
</properties>
</project>

0
core-java/src/main/java/com/baeldung/cipher/Encryptor.java → core-java-security/src/main/java/com/baeldung/cipher/Encryptor.java
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0
core-java/src/main/java/com/baeldung/encrypt/FileEncrypterDecrypter.java → core-java-security/src/main/java/com/baeldung/encrypt/FileEncrypterDecrypter.java
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0
core-java/src/main/java/com/baeldung/hashing/SHA256Hashing.java → core-java-security/src/main/java/com/baeldung/hashing/SHA256Hashing.java
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0
core-java/src/main/java/com/baeldung/keystore/JavaKeyStore.java → core-java-security/src/main/java/com/baeldung/keystore/JavaKeyStore.java
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0
core-java/src/main/java/com/baeldung/passwordhashing/PBKDF2Hasher.java → core-java-security/src/main/java/com/baeldung/passwordhashing/PBKDF2Hasher.java
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0
core-java/src/main/java/com/baeldung/passwordhashing/SHA512Hasher.java → core-java-security/src/main/java/com/baeldung/passwordhashing/SHA512Hasher.java
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0
core-java/src/main/java/com/baeldung/passwordhashing/SimplePBKDF2Hasher.java → core-java-security/src/main/java/com/baeldung/passwordhashing/SimplePBKDF2Hasher.java
View File

0
core-java/src/main/java/com/baeldung/ssl/SecureConnection.java → core-java-security/src/main/java/com/baeldung/ssl/SecureConnection.java
View File

0
core-java/src/main/java/com/baeldung/ssl/example/SimpleClient.java → core-java-security/src/main/java/com/baeldung/ssl/example/SimpleClient.java
View File

0
core-java/src/main/java/com/baeldung/ssl/example/SimpleServer.java → core-java-security/src/main/java/com/baeldung/ssl/example/SimpleServer.java
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19
core-java-security/src/main/resources/logback.xml Normal file
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@ -0,0 +1,19 @@
<?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>

0
core-java/src/test/java/com/baeldung/cipher/EncryptorUnitTest.java → core-java-security/src/test/java/com/baeldung/cipher/EncryptorUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/encrypt/FileEncrypterDecrypterIntegrationTest.java → core-java-security/src/test/java/com/baeldung/encrypt/FileEncrypterDecrypterIntegrationTest.java
View File

0
core-java/src/test/java/com/baeldung/hashing/SHA256HashingUnitTest.java → core-java-security/src/test/java/com/baeldung/hashing/SHA256HashingUnitTest.java
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0
core-java/src/test/java/com/baeldung/keystore/JavaKeyStoreUnitTest.java → core-java-security/src/test/java/com/baeldung/keystore/JavaKeyStoreUnitTest.java
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0
core-java/src/test/java/com/baeldung/passwordhashing/PBKDF2HasherUnitTest.java → core-java-security/src/test/java/com/baeldung/passwordhashing/PBKDF2HasherUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/passwordhashing/SHA512HasherUnitTest.java → core-java-security/src/test/java/com/baeldung/passwordhashing/SHA512HasherUnitTest.java
View File

0
core-java/src/test/java/org/baeldung/java/md5/JavaMD5UnitTest.java → core-java-security/src/test/java/org/baeldung/java/md5/JavaMD5UnitTest.java
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0
core-java/src/test/resources/test_md5.txt → core-java-security/src/test/resources/test_md5.txt
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22
core-java/README.md
View File

@ -5,7 +5,6 @@
### Relevant Articles:
- [Java Timer](http://www.baeldung.com/java-timer-and-timertask)
- [How to Run a Shell Command in Java](http://www.baeldung.com/run-shell-command-in-java)
- [MD5 Hashing in Java](http://www.baeldung.com/java-md5)
- [How to Print Screen in Java](http://www.baeldung.com/print-screen-in-java)
- [A Guide To Java Regular Expressions API](http://www.baeldung.com/regular-expressions-java)
- [Getting Started with Java Properties](http://www.baeldung.com/java-properties)
@ -23,44 +22,27 @@
- [Difference between URL and URI](http://www.baeldung.com/java-url-vs-uri)
- [Creating a Java Compiler Plugin](http://www.baeldung.com/java-build-compiler-plugin)
- [Quick Guide to Java Stack](http://www.baeldung.com/java-stack)
- [Guide to java.util.Formatter](http://www.baeldung.com/java-string-formatter)
- [Guide to the Cipher Class](http://www.baeldung.com/java-cipher-class)
- [Compiling Java *.class Files with javac](http://www.baeldung.com/javac)
- [A Guide to Iterator in Java](http://www.baeldung.com/java-iterator)
- [Introduction to Javadoc](http://www.baeldung.com/javadoc)
- [Guide to the Externalizable Interface in Java](http://www.baeldung.com/java-externalizable)
- [A Practical Guide to DecimalFormat](http://www.baeldung.com/java-decimalformat)
- [How to Detect the OS Using Java](http://www.baeldung.com/java-detect-os)
- [ASCII Art in Java](http://www.baeldung.com/ascii-art-in-java)
- [What is the serialVersionUID?](http://www.baeldung.com/java-serial-version-uid)
- [A Guide to the ResourceBundle](http://www.baeldung.com/java-resourcebundle)
- [Class Loaders in Java](http://www.baeldung.com/java-classloaders)
- [Introduction to SSL in Java](http://www.baeldung.com/java-ssl)
- [Java KeyStore API](http://www.baeldung.com/java-keystore)
- [Double-Checked Locking with Singleton](http://www.baeldung.com/java-singleton-double-checked-locking)
- [Guide to Java Clock Class](http://www.baeldung.com/java-clock)
- [Importance of Main Manifest Attribute in a Self-Executing JAR](http://www.baeldung.com/java-jar-executable-manifest-main-class)
- [How to Get the File Extension of a File in Java](http://www.baeldung.com/java-file-extension)
- [Java Global Exception Handler](http://www.baeldung.com/java-global-exception-handler)
- [Encrypting and Decrypting Files in Java](http://www.baeldung.com/java-cipher-input-output-stream)
- [How to Get the Size of an Object in Java](http://www.baeldung.com/java-size-of-object)
- [Guide to Java Instrumentation](http://www.baeldung.com/java-instrumentation)
- [Getting a File’s Mime Type in Java](http://www.baeldung.com/java-file-mime-type)
- [Common Java Exceptions](http://www.baeldung.com/java-common-exceptions)
- [Throw Exception in Optional in Java 8](https://www.baeldung.com/java-optional-throw-exception)
- [Add a Character to a String at a Given Position](https://www.baeldung.com/java-add-character-to-string)
- [Calculating the nth Root in Java](https://www.baeldung.com/java-nth-root)
- [Convert Double to String, Removing Decimal Places](https://www.baeldung.com/java-double-to-string)
- [ZoneOffset in Java](https://www.baeldung.com/java-zone-offset)
- [Hashing a Password in Java](https://www.baeldung.com/java-password-hashing)
- [Merging java.util.Properties Objects](https://www.baeldung.com/java-merging-properties)
- [A Guide to SimpleDateFormat](https://www.baeldung.com/java-simple-date-format)
- [SSL Handshake Failures](https://www.baeldung.com/java-ssl-handshake-failures)
- [Changing the Order in a Sum Operation Can Produce Different Results?](https://www.baeldung.com/java-floating-point-sum-order)
- [Merging java.util.Properties Objects](https://www.baeldung.com/java-merging-properties)
- [Java – Try with Resources](https://www.baeldung.com/java-try-with-resources)
- [Abstract Classes in Java](https://www.baeldung.com/java-abstract-class)
- [Guide to Character Encoding](https://www.baeldung.com/java-char-encoding)
- [Calculate the Area of a Circle in Java](https://www.baeldung.com/java-calculate-circle-area)
- [A Guide to the Java Math Class](https://www.baeldung.com/java-lang-math)
- [Graphs in Java](https://www.baeldung.com/java-graphs)
- [Console I/O in Java](http://www.baeldung.com/java-console-input-output)
- [Formatting with printf() in Java](https://www.baeldung.com/java-printstream-printf)

27
core-java/pom.xml
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@ -24,11 +24,6 @@
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcprov-jdk15on</artifactId>
<version>${bouncycastle.version}</version>
</dependency>
<dependency>
<groupId>org.unix4j</groupId>
<artifactId>unix4j-command</artifactId>
@ -75,12 +70,6 @@
<version>${assertj-core.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>${commons-codec.version}</version>
</dependency>
<dependency>
<groupId>org.javamoney</groupId>
<artifactId>moneta</artifactId>
@ -126,17 +115,6 @@
<artifactId>h2</artifactId>
<version>${h2database.version}</version>
</dependency>
<!-- Mime Type Resolution Libraries -->
<dependency>
<groupId>org.apache.tika</groupId>
<artifactId>tika-core</artifactId>
<version>${tika.version}</version>
</dependency>
<dependency>
<groupId>net.sf.jmimemagic</groupId>
<artifactId>jmimemagic</artifactId>
<version>${jmime-magic.version}</version>
</dependency>
<!-- instrumentation -->
<dependency>
<groupId>org.javassist</groupId>
@ -477,8 +455,6 @@
<!-- util -->
<commons-lang3.version>3.5</commons-lang3.version>
<bouncycastle.version>1.55</bouncycastle.version>
<commons-codec.version>1.10</commons-codec.version>
<commons-io.version>2.5</commons-io.version>
<commons-math3.version>3.6.1</commons-math3.version>
<decimal4j.version>1.0.3</decimal4j.version>
@ -509,9 +485,6 @@
<spring-boot-maven-plugin.version>2.0.3.RELEASE</spring-boot-maven-plugin.version>
<exec-maven-plugin.version>1.6.0</exec-maven-plugin.version>
<icu4j.version>61.1</icu4j.version>
<!-- Mime Type Libraries -->
<tika.version>1.18</tika.version>
<jmime-magic.version>0.1.5</jmime-magic.version>
<!-- instrumentation -->
<javaassist.version>3.21.0-GA</javaassist.version>

29
core-java/src/main/java/com/baeldung/curltojava/JavaCurlExamples.java Normal file
View File

@ -0,0 +1,29 @@
package com.baeldung.curltojava;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.logging.Level;
import java.util.logging.Logger;
public class JavaCurlExamples {
public static String inputStreamToString(InputStream inputStream) {
final int bufferSize = 8 * 1024;
byte[] buffer = new byte[bufferSize];
final StringBuilder builder = new StringBuilder();
try (BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream, bufferSize)) {
while (bufferedInputStream.read(buffer) != -1) {
builder.append(new String(buffer));
}
} catch (IOException ex) {
Logger.getLogger(JavaCurlExamples.class.getName()).log(Level.SEVERE, null, ex);
}
return builder.toString();
}
public static void consumeInputStream(InputStream inputStream) {
inputStreamToString(inputStream);
}
}

55
core-java/src/test/java/com/baeldung/curltojava/JavaCurlExamplesUnitTest.java Normal file
View File

@ -0,0 +1,55 @@
package com.baeldung.curltojava;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import org.junit.Assert;
import org.junit.Test;
public class JavaCurlExamplesUnitTest {
@Test
public void givenCommand_whenCalled_thenProduceZeroExitCode() throws IOException {
String command = "curl --location --request GET \"https://postman-echo.com/get?foo1=bar1&foo2=bar2\"";
ProcessBuilder processBuilder = new ProcessBuilder(command.replaceAll("\"", "").split(" "));
processBuilder.directory(new File("/home/"));
Process process = processBuilder.start();
InputStream inputStream = process.getInputStream();
// Consume the inputStream so the process can exit
JavaCurlExamples.consumeInputStream(inputStream);
int exitCode = process.exitValue();
Assert.assertEquals(0, exitCode);
}
@Test
public void givenNewCommands_whenCalled_thenCheckIfIsAlive() throws IOException {
String command = "curl --location --request GET \"https://postman-echo.com/get?foo1=bar1&foo2=bar2\"";
ProcessBuilder processBuilder = new ProcessBuilder(command.replaceAll("\"", "").split(" "));
processBuilder.directory(new File("/home/"));
Process process = processBuilder.start();
// Re-use processBuilder
processBuilder.command(new String[]{"newCommand", "arguments"});
Assert.assertEquals(true, process.isAlive());
}
@Test
public void whenRequestGet_thenReturnSuccessResponseCode() throws IOException {
String url = "https://postman-echo.com/get?foo1=bar1&foo2=bar2";
URL urlObj = new URL(url);
HttpURLConnection connection = (HttpURLConnection) urlObj.openConnection();
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(false);
connection.setRequestMethod("GET");
connection.connect();
Assert.assertEquals(HttpURLConnection.HTTP_OK, connection.getResponseCode());
}
}

83
core-java/src/test/java/com/baeldung/string/StringReplaceAndRemoveUnitTest.java
View File

@ -1,83 +0,0 @@
package com.baeldung.string;
import org.apache.commons.lang3.StringUtils;
import org.junit.Test;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
public class StringReplaceAndRemoveUnitTest {
@Test
public void givenTestStrings_whenReplace_thenProcessedString() {
String master = "Hello World Baeldung!";
String target = "Baeldung";
String replacement = "Java";
String processed = master.replace(target, replacement);
assertTrue(processed.contains(replacement));
assertFalse(processed.contains(target));
}
@Test
public void givenTestStrings_whenReplaceAll_thenProcessedString() {
String master2 = "Welcome to Baeldung, Hello World Baeldung";
String regexTarget= "(Baeldung)$";
String replacement = "Java";
String processed2 = master2.replaceAll(regexTarget, replacement);
assertTrue(processed2.endsWith("Java"));
}
@Test
public void givenTestStrings_whenStringBuilderMethods_thenProcessedString() {
String master = "Hello World Baeldung!";
String target = "Baeldung";
String replacement = "Java";
int startIndex = master.indexOf(target);
int stopIndex = startIndex + target.length();
StringBuilder builder = new StringBuilder(master);
builder.delete(startIndex, stopIndex);
assertFalse(builder.toString().contains(target));
builder.replace(startIndex, stopIndex, replacement);
assertTrue(builder.toString().contains(replacement));
}
@Test
public void givenTestStrings_whenStringUtilsMethods_thenProcessedStrings() {
String master = "Hello World Baeldung!";
String target = "Baeldung";
String replacement = "Java";
String processed = StringUtils.replace(master, target, replacement);
assertTrue(processed.contains(replacement));
String master2 = "Hello World Baeldung!";
String target2 = "baeldung";
String processed2 = StringUtils.replaceIgnoreCase(master2, target2, replacement);
assertFalse(processed2.contains(target));
}
}

4
core-kotlin/README.md
View File

@ -47,3 +47,7 @@
- [Dependency Injection for Kotlin with Injekt](https://www.baeldung.com/kotlin-dependency-injection-with-injekt)
- [Implementing a Binary Tree in Kotlin](https://www.baeldung.com/kotlin-binary-tree)
- [Generate a Random Alphanumeric String in Kotlin](https://www.baeldung.com/kotlin-random-alphanumeric-string)
- [Kotlin Contracts](https://www.baeldung.com/kotlin-contracts)
- [Operator Overloading in Kotlin](https://www.baeldung.com/kotlin-operator-overloading)
- [Inline Classes in Kotlin](https://www.baeldung.com/kotlin-inline-classes)
- [Creating Java static final Equivalents in Kotlin](https://www.baeldung.com/kotlin-java-static-final)

1
gson/README.md
View File

@ -9,3 +9,4 @@
- [Exclude Fields from Serialization in Gson](http://www.baeldung.com/gson-exclude-fields-serialization)
- [Save Data to a JSON File with Gson](https://www.baeldung.com/gson-save-file)
- [Convert JSON to a Map Using Gson](https://www.baeldung.com/gson-json-to-map)
- [Working with Primitive Values in Gson](https://www.baeldung.com/java-gson-primitives)

1
guava/README.md
View File

@ -18,4 +18,3 @@
- [Hamcrest Text Matchers](http://www.baeldung.com/hamcrest-text-matchers)
- [Quick Guide to the Guava RateLimiter](http://www.baeldung.com/guava-rate-limiter)
- [Hamcrest File Matchers](https://www.baeldung.com/hamcrest-file-matchers)
- [SHA-256 Hashing in Java](https://www.baeldung.com/sha-256-hashing-java)

2
java-collections-maps/README.md
View File

@ -17,3 +17,5 @@
- [Finding the Highest Value in a Java Map](https://www.baeldung.com/java-find-map-max)
- [Merging Two Maps with Java 8](https://www.baeldung.com/java-merge-maps)
- [How to Check If a Key Exists in a Map](https://www.baeldung.com/java-map-key-exists)
- [Comparing Two HashMaps in Java](https://www.baeldung.com/java-compare-hashmaps)
- [Immutable Map Implementations in Java](https://www.baeldung.com/java-immutable-maps)

2
java-dates/README.md
View File

@ -26,3 +26,5 @@
- [Format ZonedDateTime to String](https://www.baeldung.com/java-format-zoned-datetime-string)
- [Convert Between java.time.Instant and java.sql.Timestamp](https://www.baeldung.com/java-time-instant-to-java-sql-timestamp)
- [Convert between String and Timestamp](https://www.baeldung.com/java-string-to-timestamp)
- [A Guide to SimpleDateFormat](https://www.baeldung.com/java-simple-date-format)
- [ZoneOffset in Java](https://www.baeldung.com/java-zone-offset)

0
core-java/src/main/java/com/baeldung/zoneddatetime/OffsetDateTimeExample.java → java-dates/src/main/java/com/baeldung/zoneddatetime/OffsetDateTimeExample.java
View File

0
core-java/src/main/java/com/baeldung/zoneddatetime/OffsetTimeExample.java → java-dates/src/main/java/com/baeldung/zoneddatetime/OffsetTimeExample.java
View File

0
core-java/src/main/java/com/baeldung/zoneddatetime/ZoneDateTimeExample.java → java-dates/src/main/java/com/baeldung/zoneddatetime/ZoneDateTimeExample.java
View File

2
java-dates/src/test/java/com/baeldung/date/DateDiffUnitTest.java
View File

@ -8,6 +8,8 @@ import java.time.Duration;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.Period;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoUnit;
import java.util.Date;
import java.util.Locale;

0
core-java/src/test/java/com/baeldung/simpledateformat/SimpleDateFormatUnitTest.java → java-dates/src/test/java/com/baeldung/simpledateformat/SimpleDateFormatUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/zoneddatetime/OffsetDateTimeExampleUnitTest.java → java-dates/src/test/java/com/baeldung/zoneddatetime/OffsetDateTimeExampleUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/zoneddatetime/OffsetTimeExampleUnitTest.java → java-dates/src/test/java/com/baeldung/zoneddatetime/OffsetTimeExampleUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/zoneddatetime/ZoneDateTimeExampleUnitTest.java → java-dates/src/test/java/com/baeldung/zoneddatetime/ZoneDateTimeExampleUnitTest.java
View File

6
java-numbers/README.md
View File

@ -13,3 +13,9 @@
- [Find All Pairs of Numbers in an Array That Add Up to a Given Sum](http://www.baeldung.com/java-algorithm-number-pairs-sum)
- [Java – Random Long, Float, Integer and Double](http://www.baeldung.com/java-generate-random-long-float-integer-double)
- [Using Math.sin with Degrees](https://www.baeldung.com/java-math-sin-degrees)
- [A Practical Guide to DecimalFormat](http://www.baeldung.com/java-decimalformat)
- [Calculating the nth Root in Java](https://www.baeldung.com/java-nth-root)
- [Convert Double to String, Removing Decimal Places](https://www.baeldung.com/java-double-to-string)
- [Changing the Order in a Sum Operation Can Produce Different Results?](https://www.baeldung.com/java-floating-point-sum-order)
- [Calculate the Area of a Circle in Java](https://www.baeldung.com/java-calculate-circle-area)
- [A Guide to the Java Math Class](https://www.baeldung.com/java-lang-math)

0
core-java/src/main/java/com/baeldung/area/circle/Circle.java → java-numbers/src/main/java/com/baeldung/area/circle/Circle.java
View File

0
core-java/src/main/java/com/baeldung/area/circle/CircleArea.java → java-numbers/src/main/java/com/baeldung/area/circle/CircleArea.java
View File

0
core-java/src/main/java/com/baeldung/nth/root/calculator/NthRootCalculator.java → java-numbers/src/main/java/com/baeldung/nth/root/calculator/NthRootCalculator.java
View File

0
core-java/src/main/java/com/baeldung/nth/root/main/Main.java → java-numbers/src/main/java/com/baeldung/nth/root/main/Main.java
View File

0
core-java/src/test/java/com/baeldung/decimalformat/DecimalFormatExamplesUnitTest.java → java-numbers/src/test/java/com/baeldung/decimalformat/DecimalFormatExamplesUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/java/math/MathUnitTest.java → java-numbers/src/test/java/com/baeldung/java/math/MathUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/nth/root/calculator/NthRootCalculatorUnitTest.java → java-numbers/src/test/java/com/baeldung/nth/root/calculator/NthRootCalculatorUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/nth/root/main/MainUnitTest.java → java-numbers/src/test/java/com/baeldung/nth/root/main/MainUnitTest.java
View File

0
core-java/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsManualTest.java → java-numbers/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsManualTest.java
View File

0
core-java/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsUnitTest.java → java-numbers/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsUnitTest.java
View File

1
java-streams/README.md
View File

@ -14,3 +14,4 @@
- [Primitive Type Streams in Java 8](http://www.baeldung.com/java-8-primitive-streams)
- [Stream Ordering in Java](https://www.baeldung.com/java-stream-ordering)
- [Introduction to Protonpack](https://www.baeldung.com/java-protonpack)
- [Java Stream Filter with Lambda Expression](https://www.baeldung.com/java-stream-filter-lambda)

4
java-strings/README.md
View File

@ -45,3 +45,7 @@
- [Remove or Replace part of a String in Java](https://www.baeldung.com/java-remove-replace-string-part)
- [Replace a Character at a Specific Index in a String in Java](https://www.baeldung.com/java-replace-character-at-index)
- [Convert a Comma Separated String to a List in Java](https://www.baeldung.com/java-string-with-separator-to-list)
- [Guide to java.util.Formatter](http://www.baeldung.com/java-string-formatter)
- [Add a Character to a String at a Given Position](https://www.baeldung.com/java-add-character-to-string)
- [Remove Leading and Trailing Characters from a String](https://www.baeldung.com/java-remove-trailing-characters)
- [Concatenating Strings In Java](https://www.baeldung.com/java-strings-concatenation)

0
core-java/src/main/java/com/baeldung/string/AppendCharAtPositionX.java → java-strings/src/main/java/com/baeldung/string/AppendCharAtPositionX.java
View File

0
core-java/src/test/java/com/baeldung/string/AppendCharAtPositionXUnitTest.java → java-strings/src/test/java/com/baeldung/string/AppendCharAtPositionXUnitTest.java
View File

9
java-strings/src/test/java/com/baeldung/string/formatter/DateToStringFormatterUnitTest.java
View File

@ -1,7 +1,6 @@
package com.baeldung.string.formatter;
import org.junit.BeforeClass;
import org.junit.Test;
import static org.junit.Assert.assertEquals;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
@ -11,9 +10,11 @@ import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
import static org.junit.Assert.assertEquals;
import org.junit.BeforeClass;
import org.junit.Test;
public class DateToStringFormatterUnitTest {
@ -40,7 +41,7 @@ public class DateToStringFormatterUnitTest {
@Test
public void whenDateConvertedUsingDateFormatToString_thenCorrect() {
String formattedDate = DateFormat
.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.SHORT)
.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.SHORT, Locale.US)
.format(date);
assertEquals(EXPECTED_STRING_DATE, formattedDate);

19
java-strings/src/test/java/com/baeldung/string/interview/LocaleUnitTest.java Normal file
View File

@ -0,0 +1,19 @@
package com.baeldung.string.interview;
import java.math.BigDecimal;
import java.text.NumberFormat;
import java.util.Locale;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class LocaleUnitTest {
@Test
public void whenUsingLocal_thenCorrectResultsForDifferentLocale() {
Locale usLocale = Locale.US;
BigDecimal number = new BigDecimal(102_300.456d);
NumberFormat usNumberFormat = NumberFormat.getCurrencyInstance(usLocale);
assertEquals(usNumberFormat.format(number), "$102,300.46");
}
}

29
java-strings/src/test/java/com/baeldung/string/interview/StringAnagramUnitTest.java Normal file
View File

@ -0,0 +1,29 @@
package com.baeldung.string.interview;
import static org.assertj.core.api.Assertions.assertThat;
import java.util.Arrays;
import org.junit.Test;
public class StringAnagramUnitTest {
public boolean isAnagram(String s1, String s2) {
if(s1.length() != s2.length())
return false;
char[] arr1 = s1.toCharArray();
char[] arr2 = s2.toCharArray();
Arrays.sort(arr1);
Arrays.sort(arr2);
return Arrays.equals(arr1, arr2);
}
@Test
public void whenTestAnagrams_thenTestingCorrectly() {
assertThat(isAnagram("car", "arc")).isTrue();
assertThat(isAnagram("west", "stew")).isTrue();
assertThat(isAnagram("west", "east")).isFalse();
}
}

20
java-strings/src/test/java/com/baeldung/string/interview/StringChangeCaseUnitTest.java Normal file
View File

@ -0,0 +1,20 @@
package com.baeldung.string.interview;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class StringChangeCaseUnitTest {
@Test
public void givenString_whenChangingToUppercase_thenCaseChanged() {
String s = "Welcome to Baeldung!";
assertEquals("WELCOME TO BAELDUNG!", s.toUpperCase());
}
@Test
public void givenString_whenChangingToLowerrcase_thenCaseChanged() {
String s = "Welcome to Baeldung!";
assertEquals("welcome to baeldung!", s.toLowerCase());
}
}

28
java-strings/src/test/java/com/baeldung/string/interview/StringCountOccurrencesUnitTest.java Normal file
View File

@ -0,0 +1,28 @@
package com.baeldung.string.interview;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class StringCountOccurrencesUnitTest {
public int countOccurrences(String s, char c) {
int count = 0;
for (int i = 0; i < s.length(); i++) {
if (s.charAt(i) == c) {
count++;
}
}
return count;
}
@Test
public void givenString_whenCountingFrequencyOfChar_thenCountCorrect() {
assertEquals(3, countOccurrences("united states", 't'));
}
public void givenString_whenUsingJava8_thenCountingOfCharCorrect() {
String str = "united states";
long count = str.chars().filter(ch -> (char)ch == 't').count();
assertEquals(3, count);
}
}

14
java-strings/src/test/java/com/baeldung/string/interview/StringFormatUnitTest.java Normal file
View File

@ -0,0 +1,14 @@
package com.baeldung.string.interview;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class StringFormatUnitTest {
@Test
public void givenString_whenUsingStringFormat_thenStringFormatted() {
String title = "Baeldung";
String formatted = String.format("Title is %s", title);
assertEquals(formatted, "Title is Baeldung");
}
}

17
java-strings/src/test/java/com/baeldung/string/interview/StringInternUnitTest.java Normal file
View File

@ -0,0 +1,17 @@
package com.baeldung.string.interview;
import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;
public class StringInternUnitTest {
@Test
public void whenCallingStringIntern_thenStringsInterned() {
String s1 = "Baeldung";
String s2 = new String("Baeldung");
String s3 = new String("Baeldung").intern();
assertThat(s1 == s2).isFalse();
assertThat(s1 == s3).isTrue();
}
}

18
java-strings/src/test/java/com/baeldung/string/interview/StringJoinerUnitTest.java Normal file
View File

@ -0,0 +1,18 @@
package com.baeldung.string.interview;
import java.util.StringJoiner;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class StringJoinerUnitTest {
@Test
public void whenUsingStringJoiner_thenStringsJoined() {
StringJoiner joiner = new StringJoiner(",", "[", "]");
joiner.add("Red")
.add("Green")
.add("Blue");
assertEquals(joiner.toString(), "[Red,Green,Blue]");
}
}

29
java-strings/src/test/java/com/baeldung/string/interview/StringPalindromeUnitTest.java Normal file
View File

@ -0,0 +1,29 @@
package com.baeldung.string.interview;
import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;
public class StringPalindromeUnitTest {
public boolean isPalindrome(String text) {
int forward = 0;
int backward = text.length() - 1;
while (backward > forward) {
char forwardChar = text.charAt(forward++);
char backwardChar = text.charAt(backward--);
if (forwardChar != backwardChar)
return false;
}
return true;
}
@Test
public void givenIsPalindromeMethod_whenCheckingString_thenFindIfPalindrome() {
assertThat(isPalindrome("madam")).isTrue();
assertThat(isPalindrome("radar")).isTrue();
assertThat(isPalindrome("level")).isTrue();
assertThat(isPalindrome("baeldung")).isFalse();
}
}

13
java-strings/src/test/java/com/baeldung/string/interview/StringReverseUnitTest.java Normal file
View File

@ -0,0 +1,13 @@
package com.baeldung.string.interview;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class StringReverseUnitTest {
@Test
public void whenUsingInbuildMethods_thenStringReversed() {
String reversed = new StringBuilder("baeldung").reverse().toString();
assertEquals("gnudleab", reversed);
}
}

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