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Merge branch 'eugenp:master' into master

This commit is contained in:
Mladen Savic 2021-10-01 12:34:37 +02:00 committed by GitHub
parent f30118469c be966d6d62
commit b75fba6f7f
357 changed files with 7841 additions and 1406 deletions
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2
algorithms-genetic/pom.xml
View File

@ -50,4 +50,4 @@
<commons-codec.version>1.11</commons-codec.version>
</properties>
</project>
</project>

4
algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/prim/PrimUnitTest.java
View File

@ -1,10 +1,10 @@
package com.baeldung.algorithms.prim;
import org.junit.Test;
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
public class PrimUnitTest {
@Test

12
algorithms-searching/src/main/java/com/baeldung/algorithms/dfs/Graph.java
View File

@ -29,11 +29,13 @@ public class Graph {
stack.push(start);
while (!stack.isEmpty()) {
int current = stack.pop();
isVisited[current] = true;
visit(current);
for (int dest : adjVertices.get(current)) {
if (!isVisited[dest])
stack.push(dest);
if(!isVisited[current]){
isVisited[current] = true;
visit(current);
for (int dest : adjVertices.get(current)) {
if (!isVisited[dest])
stack.push(dest);
}
}
}
}

10
algorithms-searching/src/main/java/com/baeldung/algorithms/suffixtree/SuffixTree.java
View File

@ -8,7 +8,9 @@ import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class SuffixTree {
private static final Logger LOGGER = LoggerFactory.getLogger(SuffixTree.class);
private static final String WORD_TERMINATION = "$";
private static final int POSITION_UNDEFINED = -1;
private Node root;
@ -23,7 +25,7 @@ public class SuffixTree {
}
public List<String> searchText(String pattern) {
LOGGER.info("Searching for pattern \"{}\"", pattern);
LOGGER.debug("Searching for pattern \"{}\"", pattern);
List<String> result = new ArrayList<>();
List<Node> nodes = getAllNodesInTraversePath(pattern, root, false);
@ -41,11 +43,11 @@ public class SuffixTree {
}
private void addSuffix(String suffix, int position) {
LOGGER.info(">>>>>>>>>>>> Adding new suffix {}", suffix);
LOGGER.debug(">>>>>>>>>>>> Adding new suffix {}", suffix);
List<Node> nodes = getAllNodesInTraversePath(suffix, root, true);
if (nodes.size() == 0) {
addChildNode(root, suffix, position);
LOGGER.info("{}", printTree());
LOGGER.debug("{}", printTree());
} else {
Node lastNode = nodes.remove(nodes.size() - 1);
String newText = suffix;
@ -58,7 +60,7 @@ public class SuffixTree {
newText = newText.substring(existingSuffixUptoLastNode.length());
}
extendNode(lastNode, newText, position);
LOGGER.info("{}", printTree());
LOGGER.debug("{}", printTree());
}
}

1
algorithms-searching/src/test/java/com/baeldung/algorithms/dfs/GraphUnitTest.java
View File

@ -2,7 +2,6 @@ package com.baeldung.algorithms.dfs;
import java.util.List;
import com.baeldung.algorithms.dfs.Graph;
import org.junit.Test;
public class GraphUnitTest {

30
algorithms-searching/src/test/java/com/baeldung/algorithms/quadtree/QuadTreeSearchUnitTest.java
View File

@ -10,7 +10,7 @@ import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class QuadTreeSearchUnitTest {
private static final Logger LOGGER = LoggerFactory.getLogger(QuadTreeSearchUnitTest.class);
private static QuadTree quadTree;
@ -20,41 +20,41 @@ public class QuadTreeSearchUnitTest {
Region area = new Region(0, 0, 400, 400);
quadTree = new QuadTree(area);
float[][] points = new float[][] { { 21, 25 }, { 55, 53 }, { 70, 318 }, { 98, 302 },
float[][] points = new float[][] { { 21, 25 }, { 55, 53 }, { 70, 318 }, { 98, 302 },
{ 49, 229 }, { 135, 229 }, { 224, 292 }, { 206, 321 }, { 197, 258 }, { 245, 238 } };
for (int i = 0; i < points.length; i++) {
Point point = new Point(points[i][0], points[i][1]);
quadTree.addPoint(point);
}
LOGGER.info("\n" + quadTree.printTree(""));
LOGGER.info("==============================================");
LOGGER.debug("\n" + quadTree.printTree(""));
LOGGER.debug("==============================================");
}
@Test
public void givenQuadTree_whenSearchingForRange_thenReturn1MatchingItem() {
Region searchArea = new Region(200, 200, 250, 250);
List<Point> result = quadTree.search(searchArea, null, "");
LOGGER.info(result.toString());
LOGGER.info(quadTree.printSearchTraversePath());
LOGGER.debug(result.toString());
LOGGER.debug(quadTree.printSearchTraversePath());
Assert.assertEquals(1, result.size());
Assert.assertArrayEquals(new float[] { 245, 238 },
Assert.assertArrayEquals(new float[] { 245, 238 },
new float[]{result.get(0).getX(), result.get(0).getY() }, 0);
}
@Test
public void givenQuadTree_whenSearchingForRange_thenReturn2MatchingItems() {
Region searchArea = new Region(0, 0, 100, 100);
List<Point> result = quadTree.search(searchArea, null, "");
LOGGER.info(result.toString());
LOGGER.info(quadTree.printSearchTraversePath());
LOGGER.debug(result.toString());
LOGGER.debug(quadTree.printSearchTraversePath());
Assert.assertEquals(2, result.size());
Assert.assertArrayEquals(new float[] { 21, 25 },
Assert.assertArrayEquals(new float[] { 21, 25 },
new float[]{result.get(0).getX(), result.get(0).getY() }, 0);
Assert.assertArrayEquals(new float[] { 55, 53 },
Assert.assertArrayEquals(new float[] { 55, 53 },
new float[]{result.get(1).getX(), result.get(1).getY() }, 0);
}
}

5
apache-kafka/README.md
View File

@ -3,7 +3,7 @@
This module contains articles about Apache Kafka.
### Relevant articles
- [Kafka Streams vs Kafka Consumer](https://www.baeldung.com/java-kafka-streams-vs-kafka-consumer)
- [Kafka Streams vs. Kafka Consumer](https://www.baeldung.com/java-kafka-streams-vs-kafka-consumer)
- [Kafka Topic Creation Using Java](https://www.baeldung.com/kafka-topic-creation)
- [Using Kafka MockConsumer](https://www.baeldung.com/kafka-mockconsumer)
- [Using Kafka MockProducer](https://www.baeldung.com/kafka-mockproducer)
@ -12,7 +12,8 @@ This module contains articles about Apache Kafka.
- [Kafka Connect Example with MQTT and MongoDB](https://www.baeldung.com/kafka-connect-mqtt-mongodb)
- [Building a Data Pipeline with Flink and Kafka](https://www.baeldung.com/kafka-flink-data-pipeline)
- [Exactly Once Processing in Kafka with Java](https://www.baeldung.com/kafka-exactly-once)
- [Custom Serializers in Apache Kafka](https://www.baeldung.com/kafka-custom-serializer)
##### Building the project
You can build the project from the command line using: *mvn clean install*, or in an IDE.
You can build the project from the command line using: *mvn clean install*, or in an IDE.

7
apache-kafka/pom.xml
View File

@ -161,6 +161,12 @@
<artifactId>spark-cassandra-connector-java_2.11</artifactId>
<version>${com.datastax.spark.spark-cassandra-connector-java.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
</dependencies>
<properties>
@ -175,6 +181,7 @@
<graphframes.version>0.8.1-spark3.0-s_2.12</graphframes.version>
<com.datastax.spark.spark-cassandra-connector.version>2.5.2</com.datastax.spark.spark-cassandra-connector.version>
<com.datastax.spark.spark-cassandra-connector-java.version>1.6.0-M1</com.datastax.spark.spark-cassandra-connector-java.version>
<lombok.version>1.18.20</lombok.version>
</properties>
</project>

15
apache-kafka/src/main/java/com/baeldung/kafka/dto/MessageDto.java Normal file
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@ -0,0 +1,15 @@
package com.baeldung.kafka.dto;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class MessageDto {
private String message;
private String version;
}

35
apache-kafka/src/main/java/com/baeldung/kafka/serdes/CustomDeserializer.java Normal file
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@ -0,0 +1,35 @@
package com.baeldung.kafka.serdes;
import com.baeldung.kafka.dto.MessageDto;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.kafka.common.errors.SerializationException;
import org.apache.kafka.common.serialization.Deserializer;
import java.util.Map;
public class CustomDeserializer implements Deserializer<MessageDto> {
private ObjectMapper objectMapper = new ObjectMapper();
@Override
public void configure(Map<String, ?> configs, boolean isKey) {
}
@Override
public MessageDto deserialize(String topic, byte[] data) {
try {
if (data == null){
System.out.println("Null received at deserializing");
return null;
}
System.out.println("Deserializing...");
return objectMapper.readValue(new String(data, "UTF-8"), MessageDto.class);
} catch (Exception e) {
throw new SerializationException("Error when deserializing byte[] to MessageDto");
}
}
@Override
public void close() {
}
}

34
apache-kafka/src/main/java/com/baeldung/kafka/serdes/CustomSerializer.java Normal file
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@ -0,0 +1,34 @@
package com.baeldung.kafka.serdes;
import com.baeldung.kafka.dto.MessageDto;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.kafka.common.errors.SerializationException;
import org.apache.kafka.common.serialization.Serializer;
import java.util.Map;
public class CustomSerializer implements Serializer<MessageDto> {
private final ObjectMapper objectMapper = new ObjectMapper();
@Override
public void configure(Map<String, ?> configs, boolean isKey) {
}
@Override
public byte[] serialize(String topic, MessageDto data) {
try {
if (data == null){
System.out.println("Null received at serializing");
return null;
}
System.out.println("Serializing...");
return objectMapper.writeValueAsBytes(data);
} catch (Exception e) {
throw new SerializationException("Error when serializing MessageDto to byte[]");
}
}
@Override
public void close() {
}
}

92
apache-kafka/src/test/java/com/baeldung/kafka/serdes/KafkaSerDesLiveTest.java Normal file
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@ -0,0 +1,92 @@
package com.baeldung.kafka.serdes;
import com.baeldung.kafka.dto.MessageDto;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.junit.Before;
import org.junit.ClassRule;
import org.junit.Test;
import org.testcontainers.containers.KafkaContainer;
import org.testcontainers.utility.DockerImageName;
import java.time.Duration;
import java.util.Arrays;
import java.util.Properties;
import java.util.concurrent.atomic.AtomicReference;
import static org.junit.Assert.assertEquals;
public class KafkaSerDesLiveTest {
private static final String CONSUMER_APP_ID = "consumer_id";
private static final String CONSUMER_GROUP_ID = "group_id";
@ClassRule
public static KafkaContainer kafka = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:5.4.3"));
private final String TOPIC = "mytopic";
private static KafkaConsumer<String, MessageDto> createKafkaConsumer() {
Properties props = new Properties();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, kafka.getBootstrapServers());
props.put(ConsumerConfig.CLIENT_ID_CONFIG, CONSUMER_APP_ID);
props.put(ConsumerConfig.GROUP_ID_CONFIG, CONSUMER_GROUP_ID);
props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "com.baeldung.kafka.serdes.CustomDeserializer");
return new KafkaConsumer<>(props);
}
private static KafkaProducer<String, MessageDto> createKafkaProducer() {
Properties props = new Properties();
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, kafka.getBootstrapServers());
props.put(ProducerConfig.CLIENT_ID_CONFIG, CONSUMER_APP_ID);
props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, "com.baeldung.kafka.serdes.CustomSerializer");
return new KafkaProducer(props);
}
@Before
public void setUp() {
}
@Test
public void givenKafkaClientShouldSerializeAndDeserialize() throws InterruptedException {
MessageDto msgProd = MessageDto.builder().message("test").version("1.0").build();
KafkaProducer<String, MessageDto> producer = createKafkaProducer();
producer.send(new ProducerRecord<String, MessageDto>(TOPIC, "1", msgProd));
System.out.println("Message sent " + msgProd);
producer.close();
Thread.sleep(2000);
AtomicReference<MessageDto> msgCons = new AtomicReference<>();
KafkaConsumer<String, MessageDto> consumer = createKafkaConsumer();
consumer.subscribe(Arrays.asList(TOPIC));
ConsumerRecords<String, MessageDto> records = consumer.poll(Duration.ofSeconds(1));
records.forEach(record -> {
msgCons.set(record.value());
System.out.println("Message received " + record.value());
});
consumer.close();
assertEquals(msgProd, msgCons.get());
}
}

6
apache-libraries/pom.xml
View File

@ -133,6 +133,11 @@
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.jayway.awaitility</groupId>
<artifactId>awaitility</artifactId>
@ -196,7 +201,6 @@
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<avro.version>1.8.2</avro.version>
<slf4j.version>1.7.25</slf4j.version>
<beam.version>2.19.0</beam.version>
<assertj.version>3.9.0</assertj.version>
<bval.version>1.1.2</bval.version>

18
apache-libraries/src/main/resources/log4j2.xml Normal file
View File

@ -0,0 +1,18 @@
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
</Console>
</Appenders>
<Loggers>
<Logger name="org.apache.meecrowave" level="warn">
<AppenderRef ref="Console"/>
</Logger>
<Root level="info">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
</Configuration>

1
apache-libraries/src/test/java/com/baeldung/apache/beam/intro/WordCountUnitTest.java
View File

@ -10,7 +10,6 @@ import com.baeldung.apache.beam.intro.WordCount;
public class WordCountUnitTest {
@Test
// @Ignore
public void givenInputFile_whenWordCountRuns_thenJobFinishWithoutError() {
boolean jobDone = WordCount.wordCount("src/test/resources/wordcount.txt", "target/output");
assertTrue(jobDone);

42
apache-spark/src/main/resources/log4j.properties Normal file
View File

@ -0,0 +1,42 @@
#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Set everything to be logged to the console
log4j.rootCategory=WARN, console
log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.target=System.err
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=%d{yy/MM/dd HH:mm:ss} %p %c{1}: %m%n
# Set the default spark-shell log level to WARN. When running the spark-shell, the
# log level for this class is used to overwrite the root logger's log level, so that
# the user can have different defaults for the shell and regular Spark apps.
log4j.logger.org.apache.spark.repl.Main=WARN
# Settings to quiet third party logs that are too verbose
log4j.logger.org.spark_project.jetty=WARN
log4j.logger.org.spark_project.jetty.util.component.AbstractLifeCycle=ERROR
log4j.logger.org.apache.spark.repl.SparkIMain$exprTyper=INFO
log4j.logger.org.apache.spark.repl.SparkILoop$SparkILoopInterpreter=INFO
# SPARK-9183: Settings to avoid annoying messages when looking up nonexistent UDFs in SparkSQL with Hive support
log4j.logger.org.apache.hadoop.hive.metastore.RetryingHMSHandler=FATAL
log4j.logger.org.apache.hadoop.hive.ql.exec.FunctionRegistry=ERROR
# Parquet related logging
log4j.logger.org.apache.parquet.CorruptStatistics=ERROR
log4j.logger.parquet.CorruptStatistics=ERROR

3
apache-tapestry/pom.xml
View File

@ -32,7 +32,6 @@
<!-- Uncomment this to add support for file uploads: -->
<!-- <dependency> <groupId>org.apache.tapestry</groupId> <artifactId>tapestry-upload</artifactId>
<version>${tapestry-release-version}</version> </dependency> -->
<!-- A dependency on either JUnit or TestNG is required, or the surefire plugin (which runs the
tests) will fail, preventing Maven from packaging the WAR. Tapestry includes a large number of testing
facilities designed for use with TestNG (http://testng.org/), so it's recommended. -->
@ -110,8 +109,6 @@
</plugins>
</build>
<reporting />
<repositories>
<repository>
<id>jboss</id>

3
apache-thrift/pom.xml
View File

@ -29,7 +29,7 @@
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>${org.slf4j.slf4j-simple.version}</version>
<version>${org.slf4j.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
@ -61,7 +61,6 @@
<properties>
<thrift.version>0.10.0</thrift.version>
<maven-thrift.version>0.1.11</maven-thrift.version>
<org.slf4j.slf4j-simple.version>1.7.12</org.slf4j.slf4j-simple.version>
<build-helper-maven-plugin.version>3.0.0</build-helper-maven-plugin.version>
</properties>

2
aws-reactive/pom.xml
View File

@ -93,5 +93,5 @@
<spring.version>2.2.1.RELEASE</spring.version>
<awssdk.version>2.10.27</awssdk.version>
</properties>
</project>

2
aws/README.md
View File

@ -6,7 +6,7 @@ This module contains articles about Amazon Web Services (AWS)
- [AWS Lambda Using DynamoDB With Java](https://www.baeldung.com/aws-lambda-dynamodb-java)
- [AWS S3 with Java](https://www.baeldung.com/aws-s3-java)
- [AWS Lambda With Java](https://www.baeldung.com/java-aws-lambda)
- [A Basic AWS Lambda Example With Java](https://www.baeldung.com/java-aws-lambda)
- [Managing EC2 Instances in Java](https://www.baeldung.com/ec2-java)
- [Multipart Uploads in Amazon S3 with Java](https://www.baeldung.com/aws-s3-multipart-upload)
- [Integration Testing with a Local DynamoDB Instance](https://www.baeldung.com/dynamodb-local-integration-tests)

1
axon/README.md
View File

@ -6,3 +6,4 @@ This module contains articles about Axon
- [A Guide to the Axon Framework](https://www.baeldung.com/axon-cqrs-event-sourcing)
- [Multi-Entity Aggregates in Axon](https://www.baeldung.com/java-axon-multi-entity-aggregates)
- [Snapshotting Aggregates in Axon](https://www.baeldung.com/axon-snapshotting-aggregates)

18
axon/src/main/java/com/baeldung/axon/OrderApplicationConfiguration.java Normal file
View File

@ -0,0 +1,18 @@
package com.baeldung.axon;
import org.axonframework.eventsourcing.EventCountSnapshotTriggerDefinition;
import org.axonframework.eventsourcing.SnapshotTriggerDefinition;
import org.axonframework.eventsourcing.Snapshotter;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class OrderApplicationConfiguration {
@Bean
public SnapshotTriggerDefinition orderAggregateSnapshotTriggerDefinition(Snapshotter snapshotter,
@Value("${axon.aggregate.order.snapshot-threshold:250}") int threshold) {
return new EventCountSnapshotTriggerDefinition(snapshotter, threshold);
}
}

2
axon/src/main/java/com/baeldung/axon/commandmodel/order/OrderAggregate.java
View File

@ -23,7 +23,7 @@ import java.util.Map;
import static org.axonframework.modelling.command.AggregateLifecycle.apply;
@Aggregate
@Aggregate(snapshotTriggerDefinition = "orderAggregateSnapshotTriggerDefinition")
public class OrderAggregate {
@AggregateIdentifier

1
core-groovy-2/pom.xml
View File

@ -166,7 +166,6 @@
<hsqldb.version>2.4.0</hsqldb.version>
<spock-core.version>1.1-groovy-2.4</spock-core.version>
<groovy-wslite.version>1.1.3</groovy-wslite.version>
<logback.version>1.2.3</logback.version>
<groovy.version>2.5.7</groovy.version>
<assembly.plugin.version>3.1.0</assembly.plugin.version>
<compiler.plugin.version>3.8.0</compiler.plugin.version>

1
core-java-modules/core-java-11-2/README.md
View File

@ -8,3 +8,4 @@ This module contains articles about Java 11 core features
- [Guide to Java 8’s Collectors](https://www.baeldung.com/java-8-collectors)
- [New Features in Java 11](https://www.baeldung.com/java-11-new-features)
- [Getting the Java Version at Runtime](https://www.baeldung.com/get-java-version-runtime)
- [Invoking a SOAP Web Service in Java](https://www.baeldung.com/java-soap-web-service)

104
core-java-modules/core-java-12/pom.xml
View File

@ -1,60 +1,60 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-12</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-12</name>
<packaging>jar</packaging>
<url>http://maven.apache.org</url>
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-12</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-12</name>
<packaging>jar</packaging>
<url>http://maven.apache.org</url>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../../</relativePath>
</parent>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../../</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.11.0</version>
</dependency>
</dependencies>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.11.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${maven.compiler.source.version}</source>
<target>${maven.compiler.target.version}</target>
<compilerArgs>--enable-preview</compilerArgs>
</configuration>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<argLine>--enable-preview</argLine>
</configuration>
</plugin>
</plugins>
</build>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${maven.compiler.source.version}</source>
<target>${maven.compiler.target.version}</target>
<compilerArgs>--enable-preview</compilerArgs>
</configuration>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<argLine>--enable-preview</argLine>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<maven.compiler.source.version>12</maven.compiler.source.version>
<maven.compiler.target.version>12</maven.compiler.target.version>
<assertj.version>3.6.1</assertj.version>
</properties>
<properties>
<maven.compiler.source.version>12</maven.compiler.source.version>
<maven.compiler.target.version>12</maven.compiler.target.version>
<assertj.version>3.6.1</assertj.version>
</properties>
</project>

4
core-java-modules/core-java-14/pom.xml
View File

@ -14,7 +14,7 @@
<version>1.0.0-SNAPSHOT</version>
<relativePath>../../</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
@ -35,7 +35,7 @@
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>

4
core-java-modules/core-java-16/README.md
View File

@ -1,3 +1,7 @@
### Relevant articles:
- [Collect a Java Stream to an Immutable Collection](https://www.baeldung.com/java-stream-immutable-collection)
- [Guide to mapMulti in Stream API](https://www.baeldung.com/java-mapmulti)
- [Collecting Stream Elements into a List in Java](https://www.baeldung.com/java-stream-to-list-collecting)
- [New Features in Java 16](https://www.baeldung.com/java-16-new-features)
- [Guide to Java 8 groupingBy Collector](https://www.baeldung.com/java-groupingby-collector)

103
core-java-modules/core-java-16/pom.xml
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@ -1,53 +1,86 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-16</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-16</name>
<packaging>jar</packaging>
<url>http://maven.apache.org</url>
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-16</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-16</name>
<packaging>jar</packaging>
<url>http://maven.apache.org</url>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../../</relativePath>
</parent>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../../</relativePath>
</parent>
<dependencies>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.12.0</version>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit-jupiter.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.12.0</version>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>${junit-jupiter.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
</dependencies>
<build>
<plugins>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<release>${maven.compiler.release}</release>
<compilerArgs>--enable-preview</compilerArgs>
<source>${maven.compiler.source.version}</source>
<target>${maven.compiler.target.version}</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<artifactId>maven-surefire-plugin</artifactId>
<version>${surefire.plugin.version}</version>
<configuration>
<source>${maven.compiler.source.version}</source>
<target>${maven.compiler.target.version}</target>
<argLine>--enable-preview</argLine>
<forkCount>1</forkCount>
</configuration>
<dependencies>
<dependency>
<groupId>org.apache.maven.surefire</groupId>
<artifactId>surefire-api</artifactId>
<version>${surefire.plugin.version}</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</plugins>
</build>
<properties>
<maven.compiler.source.version>16</maven.compiler.source.version>
<maven.compiler.target.version>16</maven.compiler.target.version>
<assertj.version>3.6.1</assertj.version>
</properties>
<properties>
<maven.compiler.source.version>16</maven.compiler.source.version>
<maven.compiler.target.version>16</maven.compiler.target.version>
<maven.compiler.release>16</maven.compiler.release>
<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
<surefire.plugin.version>3.0.0-M5</surefire.plugin.version>
<assertj.version>3.17.2</assertj.version>
</properties>
</project>

7
core-java-modules/core-java-16/src/main/java/com/baeldung/features/HelloWorld.java Normal file
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@ -0,0 +1,7 @@
package com.baeldung.features;
interface HelloWorld {
default String hello() {
return "world";
}
}

9
core-java-modules/core-java-16/src/main/java/com/baeldung/features/OuterClass.java Normal file
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@ -0,0 +1,9 @@
package com.baeldung.features;
import com.baeldung.features.record.Book;
public class OuterClass {
class InnerClass {
Book book = new Book("Title", "author", "isbn");
}
}

23
core-java-modules/core-java-16/src/main/java/com/baeldung/features/VectorExample.java Normal file
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@ -0,0 +1,23 @@
package com.baeldung.features;
import jdk.incubator.vector.IntVector;
public class VectorExample {
public int[] scalarComputation(int[] a, int[] b) {
var c = new int[a.length];
for (int i = 0; i < a.length; i++) {
c[i] = a[i] * b[i];
}
return c;
}
public int[] vectorComputation(int[] a, int[] b) {
var c = new int[a.length];
var vectorA = IntVector.fromArray(IntVector.SPECIES_128, a, 0);
var vectorB = IntVector.fromArray(IntVector.SPECIES_128, b, 0);
var vectorC = vectorA.mul(vectorB);
vectorC.intoArray(c, 0);
return c;
}
}

44
core-java-modules/core-java-16/src/main/java/com/baeldung/features/model/Book.java Normal file
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@ -0,0 +1,44 @@
package com.baeldung.features.model;
import java.util.Objects;
public final class Book {
private final String title;
private final String author;
private final String isbn;
public Book(String title, String author, String isbn) {
this.title = title;
this.author = author;
this.isbn = isbn;
}
public String getTitle() {
return title;
}
public String getAuthor() {
return author;
}
public String getIsbn() {
return isbn;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Book book = (Book) o;
return Objects.equals(title, book.title) && Objects.equals(author, book.author) && Objects.equals(isbn, book.isbn);
}
@Override
public int hashCode() {
return Objects.hash(title, author, isbn);
}
}

4
core-java-modules/core-java-16/src/main/java/com/baeldung/features/record/Book.java Normal file
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@ -0,0 +1,4 @@
package com.baeldung.features.record;
public record Book(String title, String author, String isbn) {
}

4
core-java-modules/core-java-16/src/main/java/com/baeldung/features/sealed/JungleAnimal.java Normal file
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@ -0,0 +1,4 @@
package com.baeldung.features.sealed;
public sealed interface JungleAnimal permits Monkey, Snake {
}

4
core-java-modules/core-java-16/src/main/java/com/baeldung/features/sealed/Monkey.java Normal file
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@ -0,0 +1,4 @@
package com.baeldung.features.sealed;
public final class Monkey implements JungleAnimal {
}

13
core-java-modules/core-java-16/src/main/java/com/baeldung/features/sealed/Sealed.java Normal file
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@ -0,0 +1,13 @@
package com.baeldung.features.sealed;
public class Sealed {
public static void main(String... args) {
JungleAnimal j = new Monkey();
if (j instanceof Monkey m) {
// do logic
} else if (j instanceof Snake s) {
// do logic
}
}
}

4
core-java-modules/core-java-16/src/main/java/com/baeldung/features/sealed/Snake.java Normal file
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@ -0,0 +1,4 @@
package com.baeldung.features.sealed;
public non-sealed class Snake implements JungleAnimal {
}

49
core-java-modules/core-java-16/src/main/java/com/baeldung/java_16_features/mapmulti/Album.java Normal file
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@ -0,0 +1,49 @@
package com.baeldung.java_16_features.mapmulti;
import java.util.List;
import java.util.function.Consumer;
import java.util.stream.Collectors;
import org.apache.commons.lang3.tuple.ImmutablePair;
import org.apache.commons.lang3.tuple.Pair;
public class Album {
private String albumName;
private int albumCost;
private List<Artist> artists;
Album(String name, int albumCost, List<Artist> artists) {
this.albumName = name;
this.artists = artists;
this.albumCost = albumCost;
}
public void artistAlbumPairsToMajorLabels(Consumer<Pair<String, String>> consumer) {
for (Artist artist : artists) {
if (artist.isAssociatedMajorLabels()) {
String concatLabels = artist.getMajorLabels()
.stream()
.collect(Collectors.joining(","));
consumer.accept(new ImmutablePair<>(artist.getName() + ":" + albumName, concatLabels));
}
}
}
public String getAlbumName() {
return albumName;
}
public int getAlbumCost() {
return albumCost;
}
List<Artist> getArtists() {
return artists;
}
public String toString() {
return albumName;
}
}

50
core-java-modules/core-java-16/src/main/java/com/baeldung/java_16_features/mapmulti/Artist.java Normal file
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@ -0,0 +1,50 @@
package com.baeldung.java_16_features.mapmulti;
import java.util.List;
import java.util.Objects;
public class Artist {
private final String name;
private boolean associatedMajorLabels;
private List<String> majorLabels;
Artist(String name, boolean associatedMajorLabels, List<String> majorLabels) {
this.name = name;
this.associatedMajorLabels = associatedMajorLabels;
this.majorLabels = majorLabels;
}
public String getName() {
return name;
}
public boolean isAssociatedMajorLabels() {
return associatedMajorLabels;
}
public List<String> getMajorLabels() {
return majorLabels;
}
@Override
public int hashCode() {
return Objects.hash(name);
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Artist other = (Artist) obj;
return Objects.equals(name, other.name);
}
public String toString() {
return name;
}
}

4
core-java-modules/core-java-16/src/main/java/module-info.java Normal file
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@ -0,0 +1,4 @@
module core.java {
requires jdk.incubator.vector;
requires org.apache.commons.lang3;
}

24
core-java-modules/core-java-16/src/test/java/com/baeldung/features/DayPeriodSupportUnitTest.java Normal file
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@ -0,0 +1,24 @@
package com.baeldung.features;
import org.junit.jupiter.api.Test;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import static org.assertj.core.api.Assertions.assertThat;
public class DayPeriodSupportUnitTest {
@Test
public void givenASpecificTime_whenFormattingUsingTheBSymbol_thenExpectVerbosePeriodOfDay() {
LocalTime date = LocalTime.parse("15:25:08.690791");
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("h B");
assertThat(date.format(formatter)).isEqualTo("3 in the afternoon");
formatter = DateTimeFormatter.ofPattern("h BBBB");
assertThat(date.format(formatter)).isEqualTo("3 in the afternoon");
formatter = DateTimeFormatter.ofPattern("h BBBBB");
assertThat(date.format(formatter)).isEqualTo("3 in the afternoon");
}
}

28
core-java-modules/core-java-16/src/test/java/com/baeldung/features/HelloWorldUnitTest.java Normal file
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@ -0,0 +1,28 @@
package com.baeldung.features;
import org.junit.jupiter.api.Test;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import static java.lang.ClassLoader.getSystemClassLoader;
import static org.assertj.core.api.Assertions.assertThat;
class HelloWorldUnitTest {
@Test
public void givenAnInterfaceWithDefaulMethod_whenCreatingProxyInstance_thenCanInvokeDefaultMethod() throws Exception {
Object proxy = Proxy.newProxyInstance(getSystemClassLoader(), new Class<?>[] { HelloWorld.class },
(prox, method, args) -> {
if (method.isDefault()) {
return InvocationHandler.invokeDefault(prox, method, args);
}
return method.invoke(prox, args);
}
);
Method method = proxy.getClass().getMethod("hello");
assertThat(method.invoke(proxy)).isEqualTo("world");
}
}

18
core-java-modules/core-java-16/src/test/java/com/baeldung/features/InstanceOfPatternMatchingUnitTest.java Normal file
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@ -0,0 +1,18 @@
package com.baeldung.features;
import org.junit.jupiter.api.Test;
import static org.assertj.core.api.Assertions.assertThat;
public class InstanceOfPatternMatchingUnitTest {
@Test
void givenTheNewPatternMatchingAbility_whenComparingAgainstTheTradiationalApproach_thenBothVariablesAreEqual() {
Object obj = "TEST";
if (obj instanceof String a) {
String b = (String) obj;
assertThat(a).isEqualTo(b);
}
}
}

20
core-java-modules/core-java-16/src/test/java/com/baeldung/features/StreamToListUnitTest.java Normal file
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@ -0,0 +1,20 @@
package com.baeldung.features;
import org.junit.jupiter.api.Test;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import static org.assertj.core.api.Assertions.assertThat;
public class StreamToListUnitTest {
@Test
void givenAStream_whenCreatingANewListFromStream_thenCollectorsOrInbuiltFunctionAreEquivalent() {
List<String> integersAsString = Arrays.asList("1", "2", "3");
List<Integer> ints = integersAsString.stream().map(Integer::parseInt).collect(Collectors.toList());
List<Integer> intsEquivalent = integersAsString.stream().map(Integer::parseInt).toList();
assertThat(ints).isEqualTo(intsEquivalent);
}
}

21
core-java-modules/core-java-16/src/test/java/com/baeldung/features/VectorExampleUnitTest.java Normal file
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@ -0,0 +1,21 @@
package com.baeldung.features;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
class VectorExampleUnitTest {
@Test
void givenAScalarComputation_whenCalculatingUsingVectorAPI_thenResultIsSameAsPreviousMethodOfComputation() {
VectorExample objectUnderTest = new VectorExample();
int[] a = {1, 2, 3, 4};
int[] b = {5, 6, 7, 8};
int[] result = objectUnderTest.scalarComputation(a, b);
int[] result2 = objectUnderTest.vectorComputation(a, b);
assertArrayEquals(result, result2);
}
}

134
core-java-modules/core-java-16/src/test/java/com/baeldung/java_16_features/mapmulti/JavaStreamMapMultiUnitTest.java Normal file
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@ -0,0 +1,134 @@
package com.baeldung.java_16_features.mapmulti;
import static java.util.stream.Collectors.toList;
import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.offset;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.Arrays;
import java.util.List;
import org.apache.commons.lang3.tuple.ImmutablePair;
import org.apache.commons.lang3.tuple.Pair;
import org.junit.jupiter.api.Test;
public class JavaStreamMapMultiUnitTest {
private static final List<Album> albums = Arrays.asList(new Album("album1", 10, Arrays.asList(new Artist("bob", true, Arrays.asList("label1", "label3")), new Artist("tom", true, Arrays.asList("label2", "label3")))),
new Album("album2", 20, Arrays.asList(new Artist("bill", true, Arrays.asList("label2", "label3")), new Artist("tom", true, Arrays.asList("label2", "label4")))));
@Test
public void givenAListOfintegers_whenMapMulti_thenGetListOfOfEvenDoublesPlusPercentage() {
List<Integer> integers = Arrays.asList(1, 2, 3, 4, 5);
double percentage = .01;
List<Double> evenDoubles = integers.stream()
.<Double> mapMulti((integer, consumer) -> {
if (integer % 2 == 0) {
consumer.accept((double) integer * (1 + percentage));
}
})
.collect(toList());
assertThat(evenDoubles).containsAll(Arrays.asList(2.02D, 4.04D));
}
@Test
public void givenAListOfintegers_whenFilterMap_thenGetListOfOfEvenDoublesPlusPercentage() {
List<Integer> integers = Arrays.asList(1, 2, 3, 4, 5);
double percentage = .01;
List<Double> evenDoubles = integers.stream()
.filter(integer -> integer % 2 == 0)
.<Double> map(integer -> ((double) integer * (1 + percentage)))
.collect(toList());
assertThat(evenDoubles).containsAll(Arrays.asList(2.02D, 4.04D));
}
@Test
public void givenAListOfintegers_whenMapMultiToDouble_thenGetSumOfEvenNumbersAfterApplyPercentage() {
List<Integer> integers = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
double percentage = .01;
double sum = integers.stream()
.mapMultiToDouble((integer, consumer) -> {
if (integer % 2 == 0) {
consumer.accept(integer * (1 + percentage));
}
})
.sum();
assertThat(sum).isEqualTo(12.12, offset(0.001d));
}
@Test
public void givenAListOfAlbums_whenFlatMap_thenGetListOfArtistAlbumPairs() {
List<Pair<String, String>> artistAlbum = albums.stream()
.flatMap(album -> album.getArtists()
.stream()
.map(artist -> new ImmutablePair<String, String>(artist.getName(), album.getAlbumName())))
.collect(toList());
assertThat(artistAlbum).contains(new ImmutablePair<String, String>("bob", "album1"), new ImmutablePair<String,
String>("tom", "album1"), new ImmutablePair<String, String>("bill", "album2"), new ImmutablePair<String, String>("tom", "album2"));
}
@Test
public void givenAListOfAlbums_whenMapMulti_thenGetListOfPairsOfArtistAlbum() {
List<Pair<String, String>> artistAlbum = albums.stream()
.<Pair<String, String>> mapMulti((album, consumer) -> {
for (Artist artist : album.getArtists()) {
consumer.accept(new ImmutablePair<String, String>(artist.getName(), album.getAlbumName()));
}
})
.collect(toList());
assertThat(artistAlbum).contains(new ImmutablePair<String, String>("bob", "album1"), new ImmutablePair<String, String>("tom", "album1"),
new ImmutablePair<String, String>("bill", "album2"), new ImmutablePair<String, String>("tom", "album2"));
}
@Test
public void givenAListOfAlbums_whenFlatMap_thenGetListOfArtistAlbumjPairsBelowGivenCost() {
int upperCost = 9;
List<Pair<String, String>> artistAlbum = albums.stream()
.flatMap(album -> album.getArtists()
.stream()
.filter(artist -> upperCost > album.getAlbumCost())
.map(artist -> new ImmutablePair<String, String>(artist.getName(), album.getAlbumName())))
.collect(toList());
assertTrue(artistAlbum.isEmpty());
}
@Test
public void givenAListOfAlbums_whenMapMulti_thenGetListOfArtistAlbumPairsBelowGivenCost() {
int upperCost = 9;
List<Pair<String, String>> artistAlbum = albums.stream()
.<Pair<String, String>> mapMulti((album, consumer) -> {
if (album.getAlbumCost() < upperCost) {
for (Artist artist : album.getArtists()) {
consumer.accept(new ImmutablePair<String, String>(artist.getName(), album.getAlbumName()));
}
}
})
.collect(toList());
assertTrue(artistAlbum.isEmpty());
}
@Test
public void givenAListOfAlbums_whenMapMulti_thenGetPairsOfArtistMajorLabelsUsingMethodReference() {
List<Pair<String, String>> artistLabels = albums.stream()
.mapMulti(Album::artistAlbumPairsToMajorLabels)
.collect(toList());
assertThat(artistLabels).contains(new ImmutablePair<String, String>("bob:album1", "label1,label3"), new ImmutablePair<String, String>("tom:album1", "label2,label3"),
new ImmutablePair<String, String>("bill:album2", "label2,label3"), new ImmutablePair<String, String>("tom:album2", "label2,label4"));
}
}

128
core-java-modules/core-java-16/src/test/java/com/baeldung/streams/StreamToListComparisonWithCollectorsToListUnitTest.java Normal file
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@ -0,0 +1,128 @@
package com.baeldung.streams;
import java.util.List;
import java.util.Locale;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
public class StreamToListComparisonWithCollectorsToListUnitTest {
@Test
public void whenAddingtoCollectToList_thenSuccess() {
List<String> result = Stream.of(Locale.getISOCountries())
.collect(Collectors.toList());
Assertions.assertDoesNotThrow(() -> {
result.add("test");
});
}
@Test
public void whenSortingtoCollectToList_thenSuccess() {
List<String> result = Stream.of(Locale.getISOCountries())
.collect(Collectors.toList());
Assertions.assertDoesNotThrow(() -> {
result.sort(String::compareToIgnoreCase);
});
}
@Test
public void whenAddingCollectUnmodifiableToList_thenException() {
List<String> result = Stream.of(Locale.getISOCountries())
.collect(Collectors.toUnmodifiableList());
Assertions.assertThrows(UnsupportedOperationException.class, () -> {
result.add("test");
});
}
@Test
public void whenSortingCollectUnmodifiableToList_thenSortException() {
List<String> result = Stream.of(Locale.getISOCountries())
.collect(Collectors.toUnmodifiableList());
Assertions.assertThrows(UnsupportedOperationException.class, () -> {
result.sort(String::compareToIgnoreCase);
});
}
@Test
public void whenAddingStreamToList_thenException() {
List<String> result = Stream.of(Locale.getISOCountries())
.toList();
Assertions.assertThrows(UnsupportedOperationException.class, () -> {
result.add("test");
});
}
@Test
public void whenSortingStreamToList_thenException() {
List<String> result = Stream.of(Locale.getISOCountries())
.toList();
Assertions.assertThrows(UnsupportedOperationException.class, () -> {
result.sort(String::compareToIgnoreCase);
});
}
@Test
public void whenComparingStreamToList_withCollectToList_thenEqual() {
List<String> streamToList = Stream.of(Locale.getISOCountries())
.toList();
List<String> collectToList = Stream.of(Locale.getISOCountries())
.collect(Collectors.toList());
Assertions.assertEquals(streamToList, collectToList);
}
@Test
public void whenComparingStreamToList_withUnmodifiedCollectToList_thenEqual() {
List<String> streamToList = Stream.of(Locale.getISOCountries())
.toList();
List<String> collectToUnmodifiableList = Stream.of(Locale.getISOCountries())
.collect(Collectors.toUnmodifiableList());
Assertions.assertEquals(streamToList, collectToUnmodifiableList);
}
@Test
public void whenNullCollectorsToList_thenSuccess() {
Assertions.assertDoesNotThrow(() -> {
Stream.of(null, null)
.collect(Collectors.toList());
});
}
@Test
public void whenNullCollectorsUnmodifiableToList_thenException() {
Assertions.assertThrows(NullPointerException.class, () -> {
Stream.of(null, null)
.collect(Collectors.toUnmodifiableList());
});
}
@Test
public void whenNullStreamToList_thenSuccess() {
Assertions.assertDoesNotThrow(() -> {
Stream.of(null, null)
.toList();
});
}
}

2
core-java-modules/core-java-8-2/pom.xml
View File

@ -7,7 +7,7 @@
<version>0.1.0-SNAPSHOT</version>
<name>core-java-8-2</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>

2
core-java-modules/core-java-8-datetime-2/pom.xml
View File

@ -7,7 +7,7 @@
<version>${project.parent.version}</version>
<name>core-java-8-datetime-2</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>

2
core-java-modules/core-java-8-datetime/pom.xml
View File

@ -7,7 +7,7 @@
<version>${project.parent.version}</version>
<name>core-java-8-datetime</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>

1
core-java-modules/core-java-8/README.md
View File

@ -4,7 +4,6 @@ This module contains articles about Java 8 core features
### Relevant Articles:
- [New Features in Java 8](https://www.baeldung.com/java-8-new-features)
- [Guide to Java 8 groupingBy Collector](https://www.baeldung.com/java-groupingby-collector)
- [Strategy Design Pattern in Java 8](https://www.baeldung.com/java-strategy-pattern)
- [Guide to Java 8 Comparator.comparing()](https://www.baeldung.com/java-8-comparator-comparing)
- [Guide to the Java 8 forEach](https://www.baeldung.com/foreach-java)

2
core-java-modules/core-java-8/pom.xml
View File

@ -7,7 +7,7 @@
<version>0.1.0-SNAPSHOT</version>
<name>core-java-8</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>

36
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/groupingby/BlogPost.java
View File

@ -1,36 +0,0 @@
package com.baeldung.java_8_features.groupingby;
public class BlogPost {
private String title;
private String author;
private BlogPostType type;
private int likes;
public BlogPost(String title, String author, BlogPostType type, int likes) {
this.title = title;
this.author = author;
this.type = type;
this.likes = likes;
}
public String getTitle() {
return title;
}
public String getAuthor() {
return author;
}
public BlogPostType getType() {
return type;
}
public int getLikes() {
return likes;
}
@Override
public String toString() {
return "BlogPost{" + "title='" + title + '\'' + ", type=" + type + ", likes=" + likes + '}';
}
}

5
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/groupingby/BlogPostType.java
View File

@ -1,5 +0,0 @@
package com.baeldung.java_8_features.groupingby;
public enum BlogPostType {
NEWS, REVIEW, GUIDE
}

41
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/groupingby/Tuple.java
View File

@ -1,41 +0,0 @@
package com.baeldung.java_8_features.groupingby;
import java.util.Objects;
public class Tuple {
private final BlogPostType type;
private final String author;
public Tuple(BlogPostType type, String author) {
this.type = type;
this.author = author;
}
public BlogPostType getType() {
return type;
}
public String getAuthor() {
return author;
}
@Override
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
Tuple tuple = (Tuple) o;
return type == tuple.type && author.equals(tuple.author);
}
@Override
public int hashCode() {
return Objects.hash(type, author);
}
@Override
public String toString() {
return "Tuple{" + "type=" + type + ", author='" + author + '\'' + '}';
}
}

215
core-java-modules/core-java-8/src/test/java/com/baeldung/java_8_features/groupingby/Java8GroupingByCollectorUnitTest.java
View File

@ -1,215 +0,0 @@
package com.baeldung.java_8_features.groupingby;
import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.averagingInt;
import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.groupingByConcurrent;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.mapping;
import static java.util.stream.Collectors.maxBy;
import static java.util.stream.Collectors.summarizingInt;
import static java.util.stream.Collectors.summingInt;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;
import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import java.util.Arrays;
import java.util.EnumMap;
import java.util.IntSummaryStatistics;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;
import org.junit.Test;
public class Java8GroupingByCollectorUnitTest {
private static final List<BlogPost> posts = Arrays.asList(new BlogPost("News item 1", "Author 1", BlogPostType.NEWS, 15), new BlogPost("Tech review 1", "Author 2", BlogPostType.REVIEW, 5),
new BlogPost("Programming guide", "Author 1", BlogPostType.GUIDE, 20), new BlogPost("News item 2", "Author 2", BlogPostType.NEWS, 35), new BlogPost("Tech review 2", "Author 1", BlogPostType.REVIEW, 15));
@Test
public void givenAListOfPosts_whenGroupedByType_thenGetAMapBetweenTypeAndPosts() {
Map<BlogPostType, List<BlogPost>> postsPerType = posts.stream()
.collect(groupingBy(BlogPost::getType));
assertEquals(2, postsPerType.get(BlogPostType.NEWS)
.size());
assertEquals(1, postsPerType.get(BlogPostType.GUIDE)
.size());
assertEquals(2, postsPerType.get(BlogPostType.REVIEW)
.size());
}
@Test
public void givenAListOfPosts_whenGroupedByTypeAndTheirTitlesAreJoinedInAString_thenGetAMapBetweenTypeAndCsvTitles() {
Map<BlogPostType, String> postsPerType = posts.stream()
.collect(groupingBy(BlogPost::getType, mapping(BlogPost::getTitle, joining(", ", "Post titles: [", "]"))));
assertEquals("Post titles: [News item 1, News item 2]", postsPerType.get(BlogPostType.NEWS));
assertEquals("Post titles: [Programming guide]", postsPerType.get(BlogPostType.GUIDE));
assertEquals("Post titles: [Tech review 1, Tech review 2]", postsPerType.get(BlogPostType.REVIEW));
}
@Test
public void givenAListOfPosts_whenGroupedByTypeAndSumTheLikes_thenGetAMapBetweenTypeAndPostLikes() {
Map<BlogPostType, Integer> likesPerType = posts.stream()
.collect(groupingBy(BlogPost::getType, summingInt(BlogPost::getLikes)));
assertEquals(50, likesPerType.get(BlogPostType.NEWS)
.intValue());
assertEquals(20, likesPerType.get(BlogPostType.REVIEW)
.intValue());
assertEquals(20, likesPerType.get(BlogPostType.GUIDE)
.intValue());
}
@Test
public void givenAListOfPosts_whenGroupedByTypeInAnEnumMap_thenGetAnEnumMapBetweenTypeAndPosts() {
EnumMap<BlogPostType, List<BlogPost>> postsPerType = posts.stream()
.collect(groupingBy(BlogPost::getType, () -> new EnumMap<>(BlogPostType.class), toList()));
assertEquals(2, postsPerType.get(BlogPostType.NEWS)
.size());
assertEquals(1, postsPerType.get(BlogPostType.GUIDE)
.size());
assertEquals(2, postsPerType.get(BlogPostType.REVIEW)
.size());
}
@Test
public void givenAListOfPosts_whenGroupedByTypeInSets_thenGetAMapBetweenTypesAndSetsOfPosts() {
Map<BlogPostType, Set<BlogPost>> postsPerType = posts.stream()
.collect(groupingBy(BlogPost::getType, toSet()));
assertEquals(2, postsPerType.get(BlogPostType.NEWS)
.size());
assertEquals(1, postsPerType.get(BlogPostType.GUIDE)
.size());
assertEquals(2, postsPerType.get(BlogPostType.REVIEW)
.size());
}
@Test
public void givenAListOfPosts_whenGroupedByTypeConcurrently_thenGetAMapBetweenTypeAndPosts() {
ConcurrentMap<BlogPostType, List<BlogPost>> postsPerType = posts.parallelStream()
.collect(groupingByConcurrent(BlogPost::getType));
assertEquals(2, postsPerType.get(BlogPostType.NEWS)
.size());
assertEquals(1, postsPerType.get(BlogPostType.GUIDE)
.size());
assertEquals(2, postsPerType.get(BlogPostType.REVIEW)
.size());
}
@Test
public void givenAListOfPosts_whenGroupedByTypeAndAveragingLikes_thenGetAMapBetweenTypeAndAverageNumberOfLikes() {
Map<BlogPostType, Double> averageLikesPerType = posts.stream()
.collect(groupingBy(BlogPost::getType, averagingInt(BlogPost::getLikes)));
assertEquals(25, averageLikesPerType.get(BlogPostType.NEWS)
.intValue());
assertEquals(20, averageLikesPerType.get(BlogPostType.GUIDE)
.intValue());
assertEquals(10, averageLikesPerType.get(BlogPostType.REVIEW)
.intValue());
}
@Test
public void givenAListOfPosts_whenGroupedByTypeAndCounted_thenGetAMapBetweenTypeAndNumberOfPosts() {
Map<BlogPostType, Long> numberOfPostsPerType = posts.stream()
.collect(groupingBy(BlogPost::getType, counting()));
assertEquals(2, numberOfPostsPerType.get(BlogPostType.NEWS)
.intValue());
assertEquals(1, numberOfPostsPerType.get(BlogPostType.GUIDE)
.intValue());
assertEquals(2, numberOfPostsPerType.get(BlogPostType.REVIEW)
.intValue());
}
@Test
public void givenAListOfPosts_whenGroupedByTypeAndMaxingLikes_thenGetAMapBetweenTypeAndMaximumNumberOfLikes() {
Map<BlogPostType, Optional<BlogPost>> maxLikesPerPostType = posts.stream()
.collect(groupingBy(BlogPost::getType, maxBy(comparingInt(BlogPost::getLikes))));
assertTrue(maxLikesPerPostType.get(BlogPostType.NEWS)
.isPresent());
assertEquals(35, maxLikesPerPostType.get(BlogPostType.NEWS)
.get()
.getLikes());
assertTrue(maxLikesPerPostType.get(BlogPostType.GUIDE)
.isPresent());
assertEquals(20, maxLikesPerPostType.get(BlogPostType.GUIDE)
.get()
.getLikes());
assertTrue(maxLikesPerPostType.get(BlogPostType.REVIEW)
.isPresent());
assertEquals(15, maxLikesPerPostType.get(BlogPostType.REVIEW)
.get()
.getLikes());
}
@Test
public void givenAListOfPosts_whenGroupedByAuthorAndThenByType_thenGetAMapBetweenAuthorAndMapsBetweenTypeAndBlogPosts() {
Map<String, Map<BlogPostType, List<BlogPost>>> map = posts.stream()
.collect(groupingBy(BlogPost::getAuthor, groupingBy(BlogPost::getType)));
assertEquals(1, map.get("Author 1")
.get(BlogPostType.NEWS)
.size());
assertEquals(1, map.get("Author 1")
.get(BlogPostType.GUIDE)
.size());
assertEquals(1, map.get("Author 1")
.get(BlogPostType.REVIEW)
.size());
assertEquals(1, map.get("Author 2")
.get(BlogPostType.NEWS)
.size());
assertEquals(1, map.get("Author 2")
.get(BlogPostType.REVIEW)
.size());
assertNull(map.get("Author 2")
.get(BlogPostType.GUIDE));
}
@Test
public void givenAListOfPosts_whenGroupedByTypeAndSummarizingLikes_thenGetAMapBetweenTypeAndSummary() {
Map<BlogPostType, IntSummaryStatistics> likeStatisticsPerType = posts.stream()
.collect(groupingBy(BlogPost::getType, summarizingInt(BlogPost::getLikes)));
IntSummaryStatistics newsLikeStatistics = likeStatisticsPerType.get(BlogPostType.NEWS);
assertEquals(2, newsLikeStatistics.getCount());
assertEquals(50, newsLikeStatistics.getSum());
assertEquals(25.0, newsLikeStatistics.getAverage(), 0.001);
assertEquals(35, newsLikeStatistics.getMax());
assertEquals(15, newsLikeStatistics.getMin());
}
@Test
public void givenAListOfPosts_whenGroupedByComplexMapKeyType_thenGetAMapBetweenTupleAndList() {
Map<Tuple, List<BlogPost>> postsPerTypeAndAuthor = posts.stream()
.collect(groupingBy(post -> new Tuple(post.getType(), post.getAuthor())));
List<BlogPost> result = postsPerTypeAndAuthor.get(new Tuple(BlogPostType.GUIDE, "Author 1"));
assertThat(result.size()).isEqualTo(1);
BlogPost blogPost = result.get(0);
assertThat(blogPost.getTitle()).isEqualTo("Programming guide");
assertThat(blogPost.getType()).isEqualTo(BlogPostType.GUIDE);
assertThat(blogPost.getAuthor()).isEqualTo("Author 1");
}
}

4
core-java-modules/core-java-9-new-features/pom.xml
View File

@ -39,7 +39,7 @@
<scope>test</scope>
</dependency>
</dependencies>
<profiles>
<profile>
<id>incubator-features</id>
@ -131,7 +131,7 @@
</build>
</profile>
</profiles>
<build>
<finalName>core-java-9-new-features</finalName>
<plugins>

1
core-java-modules/core-java-arrays-operations-advanced/README.md
View File

@ -10,3 +10,4 @@ This module contains articles about advanced operations on arrays in Java. They
- [Intersection Between two Integer Arrays](https://www.baeldung.com/java-array-intersection)
- [Comparing Arrays in Java](https://www.baeldung.com/java-comparing-arrays)
- [Concatenate Two Arrays in Java](https://www.baeldung.com/java-concatenate-arrays)
- [Performance of System.arraycopy() vs. Arrays.copyOf()](https://www.baeldung.com/java-system-arraycopy-arrays-copyof-performance)

40
core-java-modules/core-java-arrays-operations-advanced/pom.xml
View File

@ -26,10 +26,50 @@
<version>${assertj-core.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>${jmh.version}</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>${jmh.version}</version>
</dependency>
</dependencies>
<properties>
<assertj-core.version>3.10.0</assertj-core.version>
<jmh.version>1.33</jmh.version>
</properties>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>com.baeldung.copyarraymethodsperformance.BenchmarkRunner</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

11
core-java-modules/core-java-arrays-operations-advanced/src/main/java/com/baeldung/copyarraymethodsperformance/BenchmarkRunner.java Normal file
View File

@ -0,0 +1,11 @@
package com.baeldung.copyarraymethodsperformance;
public class BenchmarkRunner {
public static void main(String[] args) throws Exception {
org.openjdk.jmh.Main.main(args);
}
}

42
core-java-modules/core-java-arrays-operations-advanced/src/main/java/com/baeldung/copyarraymethodsperformance/ObjectsCopyBenchmark.java Normal file
View File

@ -0,0 +1,42 @@
package com.baeldung.copyarraymethodsperformance;
import org.openjdk.jmh.annotations.*;
import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.TimeUnit;
@BenchmarkMode(Mode.AverageTime)
@State(Scope.Thread)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 10)
@Fork(1)
@Measurement(iterations = 100)
public class ObjectsCopyBenchmark {
@Param({ "10", "1000000" })
public int SIZE;
Integer[] src;
@Setup
public void setup() {
Random r = new Random();
src = new Integer[SIZE];
for (int i = 0; i < SIZE; i++) {
src[i] = r.nextInt();
}
}
@Benchmark
public Integer[] systemArrayCopyBenchmark() {
Integer[] target = new Integer[SIZE];
System.arraycopy(src, 0, target, 0, SIZE);
return target;
}
@Benchmark
public Integer[] arraysCopyOfBenchmark() {
return Arrays.copyOf(src, SIZE);
}
}

43
core-java-modules/core-java-arrays-operations-advanced/src/main/java/com/baeldung/copyarraymethodsperformance/PrimitivesCopyBenchmark.java Normal file
View File

@ -0,0 +1,43 @@
package com.baeldung.copyarraymethodsperformance;
import org.openjdk.jmh.annotations.*;
import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.TimeUnit;
@BenchmarkMode(Mode.AverageTime)
@State(Scope.Thread)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 10)
@Fork(1)
@Measurement(iterations = 100)
public class PrimitivesCopyBenchmark {
@Param({ "10", "1000000" })
public int SIZE;
int[] src;
@Setup
public void setup() {
Random r = new Random();
src = new int[SIZE];
for (int i = 0; i < SIZE; i++) {
src[i] = r.nextInt();
}
}
@Benchmark
public int[] systemArrayCopyBenchmark() {
int[] target = new int[SIZE];
System.arraycopy(src, 0, target, 0, SIZE);
return target;
}
@Benchmark
public int[] arraysCopyOfBenchmark() {
return Arrays.copyOf(src, SIZE);
}
}

1
core-java-modules/core-java-arrays-sorting/pom.xml
View File

@ -78,4 +78,5 @@
<guava.version>28.2-jre</guava.version>
<assertj-core.version>3.10.0</assertj-core.version>
</properties>
</project>

2
core-java-modules/core-java-char/pom.xml
View File

@ -7,7 +7,7 @@
<version>0.1.0-SNAPSHOT</version>
<name>core-java-char</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>

2
core-java-modules/core-java-collections-2/pom.xml
View File

@ -6,7 +6,7 @@
<artifactId>core-java-collections-2</artifactId>
<name>core-java-collections-2</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>

2
core-java-modules/core-java-collections-3/pom.xml
View File

@ -7,7 +7,7 @@
<version>0.1.0-SNAPSHOT</version>
<name>core-java-collections-3</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>

48
core-java-modules/core-java-collections-4/pom.xml
View File

@ -1,31 +1,31 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-collections-4</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-collections-4</name>
<packaging>jar</packaging>
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-collections-4</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-collections-4</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath>
</parent>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<properties>
<assertj.version>3.19.0</assertj.version>
</properties>
<properties>
<assertj.version>3.19.0</assertj.version>
</properties>
</project>

2
core-java-modules/core-java-collections-maps-3/README.md
View File

@ -8,5 +8,5 @@ This module contains articles about Map data structures in Java.
- [The Map.computeIfAbsent() Method](https://www.baeldung.com/java-map-computeifabsent)
- [Collections.synchronizedMap vs. ConcurrentHashMap](https://www.baeldung.com/java-synchronizedmap-vs-concurrenthashmap)
- [Java HashMap Load Factor](https://www.baeldung.com/java-hashmap-load-factor)
- [Converting java.util.Properties to HashMap](https://www.baeldung.com/java-convert-properties-to-hashmap)
- [Converting Java Properties to HashMap](https://www.baeldung.com/java-convert-properties-to-hashmap)
- More articles: [[<-- prev]](/core-java-modules/core-java-collections-maps-2)

6
core-java-modules/core-java-collections-maps-4/README.md Normal file
View File

@ -0,0 +1,6 @@
## Java Collections Cookbooks and Examples
This module contains articles about Map data structures in Java.
### Relevant Articles:
- [Using a Custom Class as a Key in a Java HashMap](https://www.baeldung.com/custom-key-hashmap)

34
core-java-modules/core-java-collections-maps-4/pom.xml Normal file
View File

@ -0,0 +1,34 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-collections-maps-4</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-collections-maps-4</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath>
</parent>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>3.0.0-M5</version>
<configuration>
<!-- those tests are not made for CI purposes, but for manual testing -->
<groups>!performance</groups>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>

39
core-java-modules/core-java-collections-maps-4/src/main/java/com/baeldung/maps/CoordinateKey.java Normal file
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@ -0,0 +1,39 @@
package com.baeldung.maps;
import java.util.Objects;
public class CoordinateKey {
private final int x;
private final int y;
private final int hashCode;
public CoordinateKey(int x, int y) {
this.x = x;
this.y = y;
this.hashCode = Objects.hash(x, y);
}
public int getX() {
return x;
}
public int getY() {
return y;
}
@Override
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
CoordinateKey that = (CoordinateKey) o;
return x == that.x && y == that.y;
}
@Override
public int hashCode() {
return this.hashCode;
}
}

45
core-java-modules/core-java-collections-maps-4/src/main/java/com/baeldung/maps/CoordinateMutableKey.java Normal file
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@ -0,0 +1,45 @@
package com.baeldung.maps;
import java.util.Objects;
public class CoordinateMutableKey {
private int x;
private int y;
public CoordinateMutableKey(int x, int y) {
this.x = x;
this.y = y;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
@Override
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
CoordinateMutableKey that = (CoordinateMutableKey) o;
return x == that.x && y == that.y;
}
@Override
public int hashCode() {
return Objects.hash(x, y);
}
}

13
core-java-modules/core-java-collections-maps-4/src/main/java/com/baeldung/maps/CoordinateSlowKey.java Normal file
View File

@ -0,0 +1,13 @@
package com.baeldung.maps;
public class CoordinateSlowKey extends CoordinateKey {
public CoordinateSlowKey(int x, int y) {
super(x, y);
}
@Override
public int hashCode() {
return 1;
}
}

80
core-java-modules/core-java-collections-maps-4/src/test/java/com/baeldung/maps/CoordinateKeyUnitTest.java Normal file
View File

@ -0,0 +1,80 @@
package com.baeldung.maps;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;
import java.awt.*;
import java.util.HashMap;
import java.util.Map;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
public class CoordinateKeyUnitTest {
private Map<CoordinateKey, Color> pixels = new HashMap<>();
@Test
void testOptimalKey() {
// setup
CoordinateKey coord = new CoordinateKey(1, 2);
pixels.put(coord, Color.CYAN);
// read out color correctly
assertEquals(Color.CYAN, pixels.get(coord));
}
@Test
void testSlowKey() {
// setup
CoordinateKey coord = new CoordinateSlowKey(1, 2);
pixels.put(coord, Color.CYAN);
// read out color correctly
assertEquals(Color.CYAN, pixels.get(coord));
}
// Performance Test Parameters - change here
private static final int MAX_X = 100;
private static final int MAX_Y = 100;
private static final int COUNT_OF_QUERIES = 1000;
private static final int QUERY_X = 1;
private static final int QUERY_Y = 1;
@Tag("performance")
@Test
void testKeyPerformance() {
// generate some sample keys and values
for (int x = 0; x < MAX_X; x++) {
for (int y = 0; y < MAX_Y; y++) {
pixels.put(new CoordinateKey(x, y), new Color(x % 255, y % 255, (x + y) % 255));
}
}
// read out multiple times and measure time
CoordinateKey coord = new CoordinateKey(QUERY_X, QUERY_Y);
long t1 = System.currentTimeMillis();
for (int i = 0; i < COUNT_OF_QUERIES; i++) {
assertNotNull(pixels.get(coord));
}
long t2 = System.currentTimeMillis();
System.out.printf("Optimal key performance: %d ms%n", t2 - t1);
}
@Tag("performance")
@Test
void testSlowKeyPerformance() {
// generate some sample keys and values
for (int x = 0; x < MAX_X; x++) {
for (int y = 0; y < MAX_Y; y++) {
pixels.put(new CoordinateSlowKey(x, y), new Color(x % 255, y % 255, (x + y) % 255));
}
}
// read out multiple times and measure time
CoordinateKey coord = new CoordinateSlowKey(QUERY_X, QUERY_Y);
long t1 = System.currentTimeMillis();
for (int i = 0; i < COUNT_OF_QUERIES; i++) {
assertNotNull(pixels.get(coord));
}
long t2 = System.currentTimeMillis();
System.out.printf("Slow key performance: %d ms%n", t2 - t1);
}
}

27
core-java-modules/core-java-collections-maps-4/src/test/java/com/baeldung/maps/CoordinateMutableKeyUnitTest.java Normal file
View File

@ -0,0 +1,27 @@
package com.baeldung.maps;
import org.junit.jupiter.api.Test;
import java.awt.*;
import java.util.HashMap;
import java.util.Map;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNull;
public class CoordinateMutableKeyUnitTest {
@Test
void testKeyMutable() {
// setup
Map<CoordinateMutableKey, Color> pixels = new HashMap<>();
CoordinateMutableKey coord = new CoordinateMutableKey(1, 2);
pixels.put(coord, Color.CYAN);
// read out color correctly
assertEquals(Color.CYAN, pixels.get(coord));
// change key's hashcode should result in null value
coord.setX(10);
assertNull(pixels.get(coord));
}
}

4
core-java-modules/core-java-collections-maps/pom.xml
View File

@ -33,5 +33,5 @@
<commons-collections4.version>4.1</commons-collections4.version>
<assertj.version>3.6.1</assertj.version>
</properties>
</project>
</project>

2
core-java-modules/core-java-collections/pom.xml
View File

@ -7,7 +7,7 @@
<version>0.1.0-SNAPSHOT</version>
<name>core-java-collections</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>

2
core-java-modules/core-java-console/README.md
View File

@ -3,6 +3,6 @@
### Relevant Articles:
- [Read and Write User Input in Java](http://www.baeldung.com/java-console-input-output)
- [Formatting with printf() in Java](https://www.baeldung.com/java-printstream-printf)
- [Formatting Output with printf() in Java](https://www.baeldung.com/java-printstream-printf)
- [ASCII Art in Java](http://www.baeldung.com/ascii-art-in-java)
- [System.console() vs. System.out](https://www.baeldung.com/java-system-console-vs-system-out)

1
core-java-modules/core-java-date-operations-1/pom.xml
View File

@ -26,7 +26,6 @@
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>

1
core-java-modules/core-java-datetime-string/README.md
View File

@ -11,3 +11,4 @@ This module contains articles about parsing and formatting Java date and time ob
- [Display All Time Zones With GMT And UTC in Java](http://www.baeldung.com/java-time-zones)
- [Convert between String and Timestamp](https://www.baeldung.com/java-string-to-timestamp)
- [Convert String to Date in Java](http://www.baeldung.com/java-string-to-date)
- [Format a Milliseconds Duration to HH:MM:SS](https://www.baeldung.com/java-ms-to-hhmmss)

1
core-java-modules/core-java-exceptions-3/pom.xml
View File

@ -36,4 +36,5 @@
<!-- testing -->
<assertj-core.version>3.10.0</assertj-core.version>
</properties>
</project>

1
core-java-modules/core-java-io-conversions/README.md
View File

@ -13,4 +13,5 @@ This module contains articles about core Java input/output(IO) conversions.
- [Java – Write a Reader to File](https://www.baeldung.com/java-write-reader-to-file)
- [Java – Reader to Byte Array](https://www.baeldung.com/java-convert-reader-to-byte-array)
- [Java – Reader to InputStream](https://www.baeldung.com/java-convert-reader-to-inputstream)
- [Java String to InputStream](https://www.baeldung.com/convert-string-to-input-stream)
- More articles: [[next -->]](/core-java-modules/core-java-io-conversions-2)

1
core-java-modules/core-java-io/src/main/resources/logback.xml
View File

@ -9,6 +9,7 @@
<logger name="org.springframework" level="WARN" />
<logger name="org.springframework.transaction" level="WARN" />
<logger name="net.sf.jmimemagic" level="WARN" />
<!-- in order to debug some marshalling issues, this needs to be TRACE -->
<logger name="org.springframework.web.servlet.mvc" level="WARN" />

4
core-java-modules/core-java-jar/pom.xml
View File

@ -76,6 +76,7 @@
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>${maven-dependency-plugin.version}</version>
<executions>
<execution>
<id>copy-dependencies</id>
@ -106,6 +107,7 @@
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>${maven-assembly-plugin.version}</version>
<executions>
<execution>
<phase>package</phase>
@ -383,6 +385,8 @@
<maven-jar-plugin.version>3.0.2</maven-jar-plugin.version>
<onejar-maven-plugin.version>1.4.4</onejar-maven-plugin.version>
<maven-shade-plugin.version>3.1.1</maven-shade-plugin.version>
<maven-assembly-plugin.version>3.3.0</maven-assembly-plugin.version>
<maven-dependency-plugin.version>3.2.0</maven-dependency-plugin.version>
<spring-boot-maven-plugin.version>2.0.3.RELEASE</spring-boot-maven-plugin.version>
<source.version>1.8</source.version>
<target.version>1.8</target.version>

74
core-java-modules/core-java-lang-3/src/test/java/com/baeldung/isinstancevsisassignablefrom/IsInstanceIsAssignableFromUnitTest.java
View File

@ -6,57 +6,80 @@ import static org.junit.Assert.assertTrue;
import org.junit.Test;
public class IsInstanceIsAssignableFromUnitTest {
@Test
public void whenUsingIsInstanceProperly_desiredResultsHappen() {
public void whenUsingInstanceOfProperly_thenDesiredResultsHappen() {
Shape shape = new Triangle();
Triangle triangle = new Triangle();
IsoscelesTriangle isoscelesTriangle = new IsoscelesTriangle();
Shape nonspecificShape = null;
assertTrue(shape instanceof Shape);
assertTrue(triangle instanceof Shape);
assertTrue(isoscelesTriangle instanceof Shape);
assertFalse(nonspecificShape instanceof Shape);
assertTrue(shape instanceof Triangle);
assertTrue(triangle instanceof Triangle);
assertTrue(isoscelesTriangle instanceof Triangle);
assertFalse(nonspecificShape instanceof Triangle);
assertFalse(shape instanceof IsoscelesTriangle);
assertFalse(triangle instanceof IsoscelesTriangle);
assertTrue(isoscelesTriangle instanceof IsoscelesTriangle);
assertFalse(nonspecificShape instanceof IsoscelesTriangle);
}
@Test
public void whenUsingIsInstanceProperly_thenDesiredResultsHappen() {
Shape shape = new Triangle();
Triangle triangle = new Triangle();
IsoscelesTriangle isoscelesTriangle = new IsoscelesTriangle();
Triangle isoscelesTriangle2 = new IsoscelesTriangle();
Shape nonspecificShape = null;
assertTrue(Shape.class.isInstance(shape));
assertTrue(Shape.class.isInstance(triangle));
assertTrue(Shape.class.isInstance(isoscelesTriangle));
assertTrue(Shape.class.isInstance(isoscelesTriangle2));
assertFalse(Shape.class.isInstance(nonspecificShape));
assertTrue(Triangle.class.isInstance(shape));
assertTrue(Triangle.class.isInstance(triangle));
assertTrue(Triangle.class.isInstance(isoscelesTriangle));
assertTrue(Triangle.class.isInstance(isoscelesTriangle2));
assertFalse(IsoscelesTriangle.class.isInstance(shape));
assertFalse(IsoscelesTriangle.class.isInstance(triangle));
assertTrue(IsoscelesTriangle.class.isInstance(isoscelesTriangle));
assertTrue(IsoscelesTriangle.class.isInstance(isoscelesTriangle2));
assertTrue(IsoscelesTriangle.class.isInstance(isoscelesTriangle2));
}
@Test
public void whenUsingIsAssignableFromProperly_desiredResultsHappen() {
public void whenUsingIsAssignableFromProperly_thenDesiredResultsHappen() {
Shape shape = new Triangle();
Triangle triangle = new Triangle();
IsoscelesTriangle isoscelesTriangle = new IsoscelesTriangle();
Triangle isoscelesTriangle2 = new IsoscelesTriangle();
assertFalse(shape.getClass().isAssignableFrom(Shape.class));
assertTrue(shape.getClass().isAssignableFrom(shape.getClass()));
assertTrue(shape.getClass().isAssignableFrom(triangle.getClass()));
assertTrue(shape.getClass().isAssignableFrom(isoscelesTriangle.getClass()));
assertTrue(shape.getClass().isAssignableFrom(isoscelesTriangle2.getClass()));
assertFalse(triangle.getClass().isAssignableFrom(Shape.class));
assertTrue(triangle.getClass().isAssignableFrom(shape.getClass()));
assertTrue(triangle.getClass().isAssignableFrom(triangle.getClass()));
assertTrue(triangle.getClass().isAssignableFrom(isoscelesTriangle.getClass()));
assertTrue(triangle.getClass().isAssignableFrom(isoscelesTriangle2.getClass()));
assertFalse(isoscelesTriangle.getClass().isAssignableFrom(Shape.class));
assertFalse(isoscelesTriangle.getClass().isAssignableFrom(shape.getClass()));
assertFalse(isoscelesTriangle.getClass().isAssignableFrom(triangle.getClass()));
assertTrue(isoscelesTriangle.getClass().isAssignableFrom(isoscelesTriangle.getClass()));
assertTrue(isoscelesTriangle.getClass().isAssignableFrom(isoscelesTriangle2.getClass()));
assertFalse(isoscelesTriangle2.getClass().isAssignableFrom(Shape.class));
assertFalse(isoscelesTriangle2.getClass().isAssignableFrom(shape.getClass()));
assertFalse(isoscelesTriangle2.getClass().isAssignableFrom(triangle.getClass()));
@ -64,4 +87,31 @@ public class IsInstanceIsAssignableFromUnitTest {
assertTrue(isoscelesTriangle2.getClass().isAssignableFrom(isoscelesTriangle2.getClass()));
}
@Test(expected = NullPointerException.class)
public void whenUsingNull_thenDesiredResultsHappen() {
assertFalse(null instanceof Shape);
assertFalse(Shape.class.isInstance(null));
assertFalse(Shape.class.isAssignableFrom(null)); // NullPointerException
}
@Test
public void whenUsingPrimitiveType_thenDesiredResultsHappen() {
//assertFalse(10 instanceof int); // illegal
assertFalse(int.class.isInstance(10));
assertTrue(Integer.class.isInstance(10));
assertTrue(int.class.isAssignableFrom(int.class));
assertFalse(float.class.isAssignableFrom(int.class));
}
@Test
public void whenUsingClassInstanceVariable_thenDesiredResultsHappen() {
Shape shape = new Triangle();
Triangle triangle = new Triangle();
Class<?> clazz = shape.getClass();
//assertFalse(triangle instanceof clazz); // illegal
assertTrue(clazz.isInstance(triangle));
assertTrue(clazz.isAssignableFrom(triangle.getClass()));
}
}

1
core-java-modules/core-java-lang-4/README.md
View File

@ -8,3 +8,4 @@ This module contains articles about core features in the Java language
- [Java Objects.hash() vs Objects.hashCode()](https://www.baeldung.com/java-objects-hash-vs-objects-hashcode)
- [Referencing a Method in Javadoc Comments](https://www.baeldung.com/java-method-in-javadoc)
- [Tiered Compilation in JVM](https://www.baeldung.com/jvm-tiered-compilation)
- [Fixing the “Declared package does not match the expected package” Error](https://www.baeldung.com/java-declared-expected-package-error)

21
core-java-modules/core-java-lang-4/src/main/java/com/baeldung/bookstore/Book.java Normal file
View File

@ -0,0 +1,21 @@
// The next line is commented out to avoid the code to fail the build.
// package com.baeldung;
/**
* If the below package declaration is commented out and the above incorrect package
* declaration is uncommented, then the problem will replicate.
*/
package com.baeldung.bookstore;
public class Book {
private String title;
private String author;
private long isbn;
public Book(String title, String author, long isbn) {
this.title = title;
this.author = author;
this.isbn = isbn;
}
}

14
core-java-modules/core-java-lang-4/src/main/java/com/baeldung/bookstore/LibraryAdmin.java Normal file
View File

@ -0,0 +1,14 @@
package com.baeldung.bookstore;
import java.util.Random;
public class LibraryAdmin {
public Book createBook(String title, String author) {
final long isbn = new Random().nextLong();
return new Book(title, author, isbn);
}
}

1
core-java-modules/core-java-lang-oop-types/pom.xml
View File

@ -25,6 +25,7 @@
<version>${commons-codec.version}</version>
</dependency>
</dependencies>
<properties>
<commons-codec.version>1.15</commons-codec.version>
</properties>

1
core-java-modules/core-java-networking-3/README.md
View File

@ -8,4 +8,5 @@ This module contains articles about networking in Java
- [Downloading Email Attachments in Java](https://www.baeldung.com/java-download-email-attachments)
- [Connection Timeout vs. Read Timeout for Java Sockets](https://www.baeldung.com/java-socket-connection-read-timeout)
- [Find Whether an IP Address Is in the Specified Range or Not in Java](https://www.baeldung.com/java-check-ip-address-range)
- [Find the IP Address of a Client Connected to a Server](https://www.baeldung.com/java-client-get-ip-address)
- [[<-- Prev]](/core-java-modules/core-java-networking-2)

39
core-java-modules/core-java-networking-3/src/main/java/com/baeldung/clientaddress/ApplicationClient.java Normal file
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@ -0,0 +1,39 @@
package com.baeldung.clientaddress;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
public class ApplicationClient {
private Socket clientSocket;
private PrintWriter out;
private BufferedReader in;
public void connect(String ip, int port) throws IOException {
clientSocket = new Socket(ip, port);
out = new PrintWriter(clientSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
}
public void sendGreetings(String msg) throws IOException {
out.println(msg);
String reply = in.readLine();
System.out.println("Reply received from the server :: " + reply);
}
public void disconnect() throws IOException {
in.close();
out.close();
clientSocket.close();
}
public static void main(String[] args) throws IOException {
ApplicationClient client = new ApplicationClient();
client.connect(args[0], Integer.parseInt(args[1])); // IP address and port number of the server
client.sendGreetings(args[2]); // greetings message
client.disconnect();
}
}

51
core-java-modules/core-java-networking-3/src/main/java/com/baeldung/clientaddress/ApplicationServer.java Normal file
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@ -0,0 +1,51 @@
package com.baeldung.clientaddress;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
public class ApplicationServer {
private ServerSocket serverSocket;
private Socket connectedSocket;
private PrintWriter out;
private BufferedReader in;
public void startServer(int port) throws IOException {
serverSocket = new ServerSocket(port);
connectedSocket = serverSocket.accept();
InetSocketAddress socketAddress = (InetSocketAddress) connectedSocket.getRemoteSocketAddress();
String clientIpAddress = socketAddress.getAddress()
.getHostAddress();
System.out.println("IP address of the connected client :: " + clientIpAddress);
out = new PrintWriter(connectedSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(connectedSocket.getInputStream()));
String msg = in.readLine();
System.out.println("Message received from the client :: " + msg);
out.println("Hello Client !!");
closeIO();
stopServer();
}
private void closeIO() throws IOException {
in.close();
out.close();
}
private void stopServer() throws IOException {
connectedSocket.close();
serverSocket.close();
}
public static void main(String[] args) throws IOException {
ApplicationServer server = new ApplicationServer();
server.startServer(5000);
}
}

1
core-java-modules/core-java-os/README.md
View File

@ -13,5 +13,6 @@ This module contains articles about working with the operating system (OS) in Ja
- [Pattern Search with Grep in Java](http://www.baeldung.com/grep-in-java)
- [How to Run a Shell Command in Java](http://www.baeldung.com/run-shell-command-in-java)
- [Taking Screenshots Using Java](https://www.baeldung.com/java-taking-screenshots)
- [Java Sound API – Capturing Microphone](https://www.baeldung.com/java-sound-api-capture-mic)
This module uses Java 9, so make sure to have the JDK 9 installed to run it.

177
core-java-modules/core-java-os/pom.xml
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@ -1,93 +1,100 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-os</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-os</name>
<packaging>jar</packaging>
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-os</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-os</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../</relativePath>
</parent>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>${commons-collections4.version}</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>${commons-io.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.unix4j</groupId>
<artifactId>unix4j-command</artifactId>
<version>${unix4j.version}</version>
</dependency>
<dependency>
<groupId>com.googlecode.grep4j</groupId>
<artifactId>grep4j</artifactId>
<version>${grep4j.version}</version>
</dependency>
</dependencies>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit-jupiter-engine.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>${commons-collections4.version}</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>${commons-io.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.unix4j</groupId>
<artifactId>unix4j-command</artifactId>
<version>${unix4j.version}</version>
</dependency>
<dependency>
<groupId>com.googlecode.grep4j</groupId>
<artifactId>grep4j</artifactId>
<version>${grep4j.version}</version>
</dependency>
</dependencies>
<build>
<finalName>core-java-os</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${maven.compiler.source}</source>
<target>${maven.compiler.target}</target>
</configuration>
</plugin>
</plugins>
</build>
<build>
<finalName>core-java-os</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${maven.compiler.source}</source>
<target>${maven.compiler.target}</target>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<!-- util -->
<commons-collections4.version>4.1</commons-collections4.version>
<collections-generic.version>4.01</collections-generic.version>
<!-- testing -->
<assertj.version>3.6.1</assertj.version>
<asspectj.version>1.8.9</asspectj.version>
<maven.compiler.source>1.9</maven.compiler.source>
<maven.compiler.target>1.9</maven.compiler.target>
<guava.version>25.1-jre</guava.version>
<unix4j.version>0.4</unix4j.version>
<grep4j.version>1.8.7</grep4j.version>
</properties>
<properties>
<!-- util -->
<commons-collections4.version>4.1</commons-collections4.version>
<collections-generic.version>4.01</collections-generic.version>
<!-- testing -->
<assertj.version>3.6.1</assertj.version>
<asspectj.version>1.8.9</asspectj.version>
<maven.compiler.source>1.9</maven.compiler.source>
<maven.compiler.target>1.9</maven.compiler.target>
<guava.version>25.1-jre</guava.version>
<unix4j.version>0.4</unix4j.version>
<grep4j.version>1.8.7</grep4j.version>
<junit-jupiter-engine.version>5.7.2</junit-jupiter-engine.version>
</properties>
</project>

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core-java-modules/core-java-os/src/main/java/com/baeldung/example/soundapi/App.java Normal file
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package com.baeldung.example.soundapi;
import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioFormat;
public class App {
public static void main(String[] args) throws Exception {
AudioFormat format = buildAudioFormatInstance();
SoundRecorder soundRecorder = new SoundRecorder();
soundRecorder.build(format);
System.out.println("Start recording ....");
soundRecorder.start();
Thread.sleep(20000);
soundRecorder.stop();
WaveDataUtil wd = new WaveDataUtil();
Thread.sleep(3000);
wd.saveToFile("/SoundClip", AudioFileFormat.Type.WAVE, soundRecorder.getAudioInputStream());
}
public static AudioFormat buildAudioFormatInstance() {
ApplicationProperties aConstants = new ApplicationProperties();
AudioFormat.Encoding encoding = aConstants.ENCODING;
float rate = aConstants.RATE;
int channels = aConstants.CHANNELS;
int sampleSize = aConstants.SAMPLE_SIZE;
boolean bigEndian = aConstants.BIG_ENDIAN;
return new AudioFormat(encoding, rate, sampleSize, channels, (sampleSize / 8) * channels, rate, bigEndian);
}
}

10
core-java-modules/core-java-os/src/main/java/com/baeldung/example/soundapi/ApplicationProperties.java Normal file
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package com.baeldung.example.soundapi;
import javax.sound.sampled.AudioFormat;
public class ApplicationProperties {
public final AudioFormat.Encoding ENCODING = AudioFormat.Encoding.PCM_SIGNED;
public final float RATE = 44100.0f;
public final int CHANNELS = 1;
public final int SAMPLE_SIZE = 16;
public final boolean BIG_ENDIAN = true;
}

123
core-java-modules/core-java-os/src/main/java/com/baeldung/example/soundapi/SoundRecorder.java Normal file
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package com.baeldung.example.soundapi;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.TargetDataLine;
public class SoundRecorder implements Runnable {
private AudioInputStream audioInputStream;
private AudioFormat format;
public Thread thread;
private double duration;
public SoundRecorder() {
super();
}
public SoundRecorder(AudioFormat format) {
this.format = format;
}
public SoundRecorder build(AudioFormat format) {
this.format = format;
return this;
}
public void start() {
thread = new Thread(this);
thread.setName("Capture Microphone");
thread.start();
}
public void stop() {
thread = null;
}
@Override
public void run() {
duration = 0;
try (final ByteArrayOutputStream out = new ByteArrayOutputStream(); final TargetDataLine line = getTargetDataLineForRecord();) {
int frameSizeInBytes = format.getFrameSize();
int bufferLengthInFrames = line.getBufferSize() / 8;
final int bufferLengthInBytes = bufferLengthInFrames * frameSizeInBytes;
buildByteOutputStream(out, line, frameSizeInBytes, bufferLengthInBytes);
this.audioInputStream = new AudioInputStream(line);
setAudioInputStream(convertToAudioIStream(out, frameSizeInBytes));
audioInputStream.reset();
} catch (IOException ex) {
ex.printStackTrace();
} catch (Exception ex) {
ex.printStackTrace();
return;
}
}
public void buildByteOutputStream(final ByteArrayOutputStream out, final TargetDataLine line, int frameSizeInBytes, final int bufferLengthInBytes) throws IOException {
final byte[] data = new byte[bufferLengthInBytes];
int numBytesRead;
line.start();
while (thread != null) {
if ((numBytesRead = line.read(data, 0, bufferLengthInBytes)) == -1) {
break;
}
out.write(data, 0, numBytesRead);
}
}
private void setAudioInputStream(AudioInputStream aStream) {
this.audioInputStream = aStream;
}
public AudioInputStream convertToAudioIStream(final ByteArrayOutputStream out, int frameSizeInBytes) {
byte audioBytes[] = out.toByteArray();
ByteArrayInputStream bais = new ByteArrayInputStream(audioBytes);
AudioInputStream audioStream = new AudioInputStream(bais, format, audioBytes.length / frameSizeInBytes);
long milliseconds = (long) ((audioInputStream.getFrameLength() * 1000) / format.getFrameRate());
duration = milliseconds / 1000.0;
System.out.println("Recorded duration in seconds:" + duration);
return audioStream;
}
public TargetDataLine getTargetDataLineForRecord() {
TargetDataLine line;
DataLine.Info info = new DataLine.Info(TargetDataLine.class, format);
if (!AudioSystem.isLineSupported(info)) {
return null;
}
try {
line = (TargetDataLine) AudioSystem.getLine(info);
line.open(format, line.getBufferSize());
} catch (final Exception ex) {
return null;
}
return line;
}
public AudioInputStream getAudioInputStream() {
return audioInputStream;
}
public AudioFormat getFormat() {
return format;
}
public void setFormat(AudioFormat format) {
this.format = format;
}
public Thread getThread() {
return thread;
}
public double getDuration() {
return duration;
}
}

34
core-java-modules/core-java-os/src/main/java/com/baeldung/example/soundapi/WaveDataUtil.java Normal file
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package com.baeldung.example.soundapi;
import java.io.File;
import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
public class WaveDataUtil {
public boolean saveToFile(String name, AudioFileFormat.Type fileType, AudioInputStream audioInputStream) {
System.out.println("Saving...");
if (null == name || null == fileType || audioInputStream == null) {
return false;
}
File myFile = new File(name + "." + fileType.getExtension());
try {
audioInputStream.reset();
} catch (Exception e) {
return false;
}
int i = 0;
while (myFile.exists()) {
String temp = "" + i + myFile.getName();
myFile = new File(temp);
}
try {
AudioSystem.write(audioInputStream, fileType, myFile);
} catch (Exception ex) {
return false;
}
System.out.println("Saved " + myFile.getAbsolutePath());
return true;
}
}

101
core-java-modules/core-java-os/src/main/java/com/baeldung/java9/process/ProcessAPIEnhancements.java Normal file
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package com.baeldung.java9.process;
import java.io.IOException;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.stream.Stream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class ProcessAPIEnhancements {
static Logger log = LoggerFactory.getLogger(ProcessAPIEnhancements.class);
public static void main(String[] args) throws IOException, InterruptedException, ExecutionException {
infoOfCurrentProcess();
infoOfLiveProcesses();
infoOfSpawnProcess();
infoOfExitCallback();
infoOfChildProcess();
}
private static void infoOfCurrentProcess() {
ProcessHandle processHandle = ProcessHandle.current();
ProcessHandle.Info processInfo = processHandle.info();
log.info("PID: " + processHandle.pid());
log.info("Arguments: " + processInfo.arguments());
log.info("Command: " + processInfo.command());
log.info("Instant: " + processInfo.startInstant());
log.info("Total CPU duration: " + processInfo.totalCpuDuration());
log.info("User: " + processInfo.user());
}
private static void infoOfSpawnProcess() throws IOException {
String javaCmd = ProcessUtils.getJavaCmd().getAbsolutePath();
ProcessBuilder processBuilder = new ProcessBuilder(javaCmd, "-version");
Process process = processBuilder.inheritIO().start();
ProcessHandle processHandle = process.toHandle();
ProcessHandle.Info processInfo = processHandle.info();
log.info("PID: " + processHandle.pid());
log.info("Arguments: " + processInfo.arguments());
log.info("Command: " + processInfo.command());
log.info("Instant: " + processInfo.startInstant());
log.info("Total CPU duration: " + processInfo.totalCpuDuration());
log.info("User: " + processInfo.user());
}
private static void infoOfLiveProcesses() {
Stream<ProcessHandle> liveProcesses = ProcessHandle.allProcesses();
liveProcesses.filter(ProcessHandle::isAlive)
.forEach(ph -> {
log.info("PID: " + ph.pid());
log.info("Instance: " + ph.info().startInstant());
log.info("User: " + ph.info().user());
});
}
private static void infoOfChildProcess() throws IOException {
int childProcessCount = 5;
for (int i = 0; i < childProcessCount; i++) {
String javaCmd = ProcessUtils.getJavaCmd()
.getAbsolutePath();
ProcessBuilder processBuilder
= new ProcessBuilder(javaCmd, "-version");
processBuilder.inheritIO().start();
}
Stream<ProcessHandle> children = ProcessHandle.current()
.children();
children.filter(ProcessHandle::isAlive)
.forEach(ph -> log.info("PID: {}, Cmd: {}", ph.pid(), ph.info()
.command()));
Stream<ProcessHandle> descendants = ProcessHandle.current()
.descendants();
descendants.filter(ProcessHandle::isAlive)
.forEach(ph -> log.info("PID: {}, Cmd: {}", ph.pid(), ph.info()
.command()));
}
private static void infoOfExitCallback() throws IOException, InterruptedException, ExecutionException {
String javaCmd = ProcessUtils.getJavaCmd()
.getAbsolutePath();
ProcessBuilder processBuilder
= new ProcessBuilder(javaCmd, "-version");
Process process = processBuilder.inheritIO()
.start();
ProcessHandle processHandle = process.toHandle();
log.info("PID: {} has started", processHandle.pid());
CompletableFuture<ProcessHandle> onProcessExit = processHandle.onExit();
onProcessExit.get();
log.info("Alive: " + processHandle.isAlive());
onProcessExit.thenAccept(ph -> {
log.info("PID: {} has stopped", ph.pid());
});
}
}

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