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Merge branch 'master' into thombergs-patch-4

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Loredana Crusoveanu
2019-01-05 18:53:15 +02:00
committed by GitHub
parent 6c60462000 5a4ac6201b
commit 544e7b2d22
187 changed files with 2600 additions and 254 deletions
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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`.
akka-http/README.md
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### Relevant articles
## Relevant articles:
- [Introduction to Akka HTTP](https://www.baeldung.com/akka-http)
algorithms-miscellaneous-1/README.md
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- [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)
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/permutation/Permutation.java
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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, ';');
}
}
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/twopointertechnique/LinkedListFindMiddle.java
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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;
}
}
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/twopointertechnique/MyNode.java
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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;
}
}
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/twopointertechnique/RotateArray.java
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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--;
}
}
}
algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/twopointertechnique/TwoSum.java
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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;
}
}
algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/twopointertechnique/LinkedListFindMiddleUnitTest.java
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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;
}
}
algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/twopointertechnique/RotateArrayUnitTest.java
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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 });
}
}
algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/twopointertechnique/TwoSumUnitTest.java
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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));
}
}
apache-spark/pom.xml
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</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>
apache-spark/src/main/java/com/baeldung/data/pipeline/Word.java
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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;
}
}
apache-spark/src/main/java/com/baeldung/data/pipeline/WordCountingApp.java
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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();
}
}
apache-spark/src/main/java/com/baeldung/data/pipeline/WordCountingAppWithCheckpoint.java
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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();
}
}
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)
core-java-8/README.md
+5
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@@ -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)
core-java-9/src/main/java/com/baeldung/java9/set/UnmodifiableSet.java
+44
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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);
}
}
core-java-9/src/test/java/com/baeldung/java9/SetExamplesUnitTest.java
+12
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@@ -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");
}
}
core-java-arrays/README.md
+1
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@@ -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)
core-java-collections-list/README.md
+2 -1
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)
core-java-collections-list/src/main/java/com/baeldung/list/multidimensional/ArrayListOfArrayList.java
+11 -10
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);
}
}
}
core-java-collections-list/src/main/java/com/baeldung/list/multidimensional/ThreeDimensionalArrayList.java
+5 -5
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));
}
}
core-java-collections/README.md
+3 -1
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)
core-java/src/main/java/com/baeldung/iteratorguide/IteratorGuide.java → core-java-collections/src/main/java/com/baeldung/iteratorguide/IteratorGuide.java
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core-java-io/README.md
+2
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)
core-java-io/pom.xml
+14
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>
core-java/src/main/java/com/baeldung/extension/Extension.java → core-java-io/src/main/java/com/baeldung/extension/Extension.java
View File
core-java/src/test/java/com/baeldung/extension/ExtensionUnitTest.java → core-java-io/src/test/java/com/baeldung/extension/ExtensionUnitTest.java
View File
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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