Merge branch 'master' of https://github.com/eugenp/tutorials

core-java-modules/core-java-10/README.md

@@ -10,3 +10,4 @@ This module contains articles about Java 10 core features
 - [Deep Dive Into the New Java JIT Compiler – Graal](https://www.baeldung.com/graal-java-jit-compiler)
 - [Copying Sets in Java](https://www.baeldung.com/java-copy-sets)
 - [Converting between a List and a Set in Java](https://www.baeldung.com/convert-list-to-set-and-set-to-list)
+- [Java IndexOutOfBoundsException “Source Does Not Fit in Dest”](https://www.baeldung.com/java-indexoutofboundsexception)

core-java-modules/core-java-exceptions-3/README.md

@@ -4,3 +4,5 @@
 - [IllegalArgumentException or NullPointerException for a Null Parameter?](https://www.baeldung.com/java-illegalargumentexception-or-nullpointerexception)
 - [IllegalMonitorStateException in Java](https://www.baeldung.com/java-illegalmonitorstateexception)
 - [AbstractMethodError in Java](https://www.baeldung.com/java-abstractmethoderror)
+- [Java IndexOutOfBoundsException “Source Does Not Fit in Dest”](https://www.baeldung.com/java-indexoutofboundsexception)
+- [Localizing Exception Messages in Java](https://www.baeldung.com/java-localize-exception-messages)

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exception/indexoutofbounds/CopyListUsingAddAllMethodDemo.java

@@ -0,0 +1,14 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CopyListUsingAddAllMethodDemo {
+    static List<Integer> copyList(List<Integer> source) {
+        List<Integer> destination =  new ArrayList<>();
+
+        destination.addAll(source);
+
+        return destination;
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exception/indexoutofbounds/CopyListUsingCollectionsCopyMethodDemo.java

@@ -0,0 +1,10 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import java.util.Collections;
+import java.util.List;
+
+public class CopyListUsingCollectionsCopyMethodDemo {
+    static void copyList(List<Integer> source, List<Integer> destination) {
+        Collections.copy(destination, source);
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exception/indexoutofbounds/CopyListUsingConstructorDemo.java

@@ -0,0 +1,10 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CopyListUsingConstructorDemo {
+    static List<Integer> copyList(List<Integer> source) {
+        return new ArrayList<>(source);
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exception/indexoutofbounds/CopyListUsingJava8StreamDemo.java

@@ -0,0 +1,12 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class CopyListUsingJava8StreamDemo {
+    static List<Integer> copyList(List<Integer> source) {
+        return source
+                .stream()
+                .collect(Collectors.toList());
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exception/indexoutofbounds/IndexOutOfBoundsExceptionDemo.java

@@ -0,0 +1,13 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class IndexOutOfBoundsExceptionDemo {
+    static List<Integer> copyList(List<Integer> source) {
+        List<Integer> destination = new ArrayList<>(source.size());
+        Collections.copy(destination, source);
+        return destination;
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/localization/LocalizedException.java

@@ -0,0 +1,47 @@
+package com.baeldung.exceptions.localization;
+
+import java.util.Locale;
+
+public class LocalizedException extends Exception {
+    
+    private static final long serialVersionUID = 1L;
+
+    private final String messageKey;
+    private final Locale locale;
+
+    public LocalizedException(String messageKey) {
+        this(messageKey, Locale.getDefault());
+    }
+
+    public LocalizedException(String messageKey, Locale locale) {
+        this.messageKey = messageKey;
+        this.locale = locale;
+    }
+
+    /**
+     * @return a localized message based on the messageKey provided at instantiation.
+     */
+    public String getMessage() {
+
+        /*
+         * This is a deliberate role reversal of the default implementation of getLocalizedMessage.
+         * some logging frameworks like Log4J 1 & 2 and Logback will use getMessage instead of
+         * getLocalizedMessage when logging Throwables. If we want to use these frameworks in client
+         * applications to log localized messages, then we'll need to override getMessage in a
+         * similar fashion to return the appropriate content.  Or, you can call getLocalizedMessage
+         * on your own to create the log content.
+         */
+        return getLocalizedMessage();
+    }
+
+    /**
+     * @return a localized message based on the messageKey provided at instantiation.
+     */
+    public String getLocalizedMessage() {
+
+        /*
+         * java.util.logging uses getLocalizedMessage when logging Throwables.
+         */
+        return Messages.getMessageForLocale(messageKey, locale);
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/localization/Messages.java

@@ -0,0 +1,27 @@
+package com.baeldung.exceptions.localization;
+
+import java.util.Locale;
+import java.util.ResourceBundle;
+
+public class Messages {
+
+    /**
+     * Retrieves the value for the messageKey from the locale-specific messages.properties, or from
+     * the base messages.properties for unsupported locales.
+     *
+     * @param messageKey The key for the message in the messages.properties ResourceBundle.
+     * @param locale The locale to search the message key.
+     * @return The value defined for the messageKey in the provided locale.
+     */
+    public static String getMessageForLocale(String messageKey, Locale locale) {
+
+        /*
+         * For more complex implementations, you will want a var-args parameter for MessageFormat
+         * substitutions. Then we can read the value from the bundle and pass the value with the
+         * substitutions to MessageFormat to create the final message value.
+         */
+        return ResourceBundle.getBundle("messages", locale)
+            .getString(messageKey);
+    }
+
+}

core-java-modules/core-java-exceptions-3/src/main/resources/messages.properties

@@ -0,0 +1 @@
+message.exception = I am an exception.

core-java-modules/core-java-exceptions-3/src/main/resources/messages_fr.properties

@@ -0,0 +1 @@
+message.exception = Je suis une exception.

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exception/indexoutofbounds/CopyListUsingAddAllMethodDemoUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CopyListUsingAddAllMethodDemoUnitTest {
+
+    @Test
+    void whenPassValidArrayList_thenCopyListUsingAddAllMethod() {
+        List<Integer> source = Arrays.asList(11, 22, 33);
+
+        assertEquals(source, CopyListUsingAddAllMethodDemo.copyList(source));
+    }
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exception/indexoutofbounds/CopyListUsingCollectionsCopyMethodDemoUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class CopyListUsingCollectionsCopyMethodDemoUnitTest {
+    @Test
+    void whenCopyListUsingCollectionsCopy_thenOverrideAllDestinationListValues() {
+        List<Integer> source = Arrays.asList(11, 22, 33);
+        List<Integer> destination = Arrays.asList(1, 2, 3);
+
+        CopyListUsingCollectionsCopyMethodDemo.copyList(source, destination);
+
+        assertEquals(source, destination);
+    }
+
+    @Test
+    void whenCopyListUsingCollectionsCopy_thenOverrideInitialDestinationValuesAndOthersShouldBeUnchanged(){
+        List<Integer> source = Arrays.asList(11, 22, 33);
+        List<Integer> destination = Arrays.asList(1, 2, 3, 4, 5);
+        List<Integer> expectedList = Arrays.asList(11, 22, 33, 4, 5);
+
+        CopyListUsingCollectionsCopyMethodDemo.copyList(source, destination);
+
+        assertEquals(expectedList, destination);
+    }
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exception/indexoutofbounds/CopyListUsingConstructorDemoUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CopyListUsingConstructorDemoUnitTest {
+
+    @Test
+    void whenCopyListUsingConstructor_thenMakeACopyOfList() {
+        List<Integer> source = Arrays.asList(11, 22, 33);
+
+        assertEquals(source, CopyListUsingConstructorDemo.copyList(source));
+    }
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exception/indexoutofbounds/CopyListUsingJava8StreamDemoUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CopyListUsingJava8StreamDemoUnitTest {
+
+    @Test
+    void whenCopyListUsingStream_thenMakeACopyOfArrayList() {
+        List<Integer> source = Arrays.asList(11, 22, 33);
+
+        assertEquals(source, CopyListUsingJava8StreamDemo.copyList(source));
+    }
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exception/indexoutofbounds/IndexOutOfBoundsExceptionDemoUnitTest.java

@@ -0,0 +1,28 @@
+package com.baeldung.exception.indexoutofbounds;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+
+class IndexOutOfBoundsExceptionDemoUnitTest {
+
+    @Test
+    void givenDestinationArrayListSizeIsZero_whenCopySourceArrayListToDestination_thenShouldThrowIndexOutOfBoundsException() {
+        List<Integer> source = Arrays.asList(1, 2, 3, 4, 5);
+
+        assertThrows(IndexOutOfBoundsException.class, () -> IndexOutOfBoundsExceptionDemo.copyList(source));
+    }
+
+    @Test
+    void givenSourceAndDestinationListSizeIsEqual_whenCopySourceArrayListToDestination_thenShouldNotThrowIndexOutOfBoundsException() {
+        List<Integer> source = Collections.emptyList();
+
+        assertEquals(source, IndexOutOfBoundsExceptionDemo.copyList(source));
+    }
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/localization/LocalizedExceptionUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.exceptions.localization;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.Locale;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class LocalizedExceptionUnitTest {
+
+    private Locale originalDefaultLocale;
+
+    @Before
+    public void saveOriginalDefaultLocale() {
+        originalDefaultLocale = Locale.getDefault();
+    }
+
+    @After
+    public void restoreOriginalDefaultLocale() {
+        Locale.setDefault(originalDefaultLocale);
+    }
+
+    @Test
+    public void givenUsEnglishDefaultLocale_whenLocalizingMessage_thenMessageComesFromDefaultMessages() {
+        Locale.setDefault(Locale.US);
+
+        LocalizedException localizedException = new LocalizedException("message.exception");
+        String usEnglishLocalizedExceptionMessage = localizedException.getLocalizedMessage();
+
+        assertThat(usEnglishLocalizedExceptionMessage).isEqualTo("I am an exception.");
+    }
+
+    @Test
+    public void givenFranceFrenchDefaultLocale_whenLocalizingMessage_thenMessageComesFromFrenchTranslationMessages() {
+        Locale.setDefault(Locale.FRANCE);
+
+        LocalizedException localizedException = new LocalizedException("message.exception");
+        String franceFrenchLocalizedExceptionMessage = localizedException.getLocalizedMessage();
+
+        assertThat(franceFrenchLocalizedExceptionMessage).isEqualTo("Je suis une exception.");
+    }
+
+    @Test
+    public void givenUsEnglishProvidedLocale_whenLocalizingMessage_thenMessageComesFromDefaultMessage() {
+        LocalizedException localizedException = new LocalizedException("message.exception", Locale.US);
+        String usEnglishLocalizedExceptionMessage = localizedException.getLocalizedMessage();
+
+        assertThat(usEnglishLocalizedExceptionMessage).isEqualTo("I am an exception.");
+    }
+
+    @Test
+    public void givenFranceFrenchProvidedLocale_whenLocalizingMessage_thenMessageComesFromFrenchTranslationMessages() {
+        LocalizedException localizedException = new LocalizedException("message.exception", Locale.FRANCE);
+        String franceFrenchLocalizedExceptionMessage = localizedException.getLocalizedMessage();
+
+        assertThat(franceFrenchLocalizedExceptionMessage).isEqualTo("Je suis une exception.");
+    }
+
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/localization/MessagesUnitTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.exceptions.localization;
+
+import org.junit.Test;
+
+import java.util.Locale;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class MessagesUnitTest {
+
+    @Test
+    public void givenUsEnglishLocale_whenRetrievingMessage_thenEnglishTranslationIsReturned() {
+        String translatedMessage = Messages.getMessageForLocale("message.exception", Locale.US);
+
+        assertThat(translatedMessage).isEqualTo("I am an exception.");
+    }
+
+    @Test
+    public void givenFranceFrenchLocale_whenRetrievingMessage_thenFrenchTranslationIsReturned() {
+        String translatedMessage = Messages.getMessageForLocale("message.exception", Locale.FRANCE);
+
+        assertThat(translatedMessage).isEqualTo("Je suis une exception.");
+    }
+
+}

core-java-modules/core-java-functional/README.md

@@ -1 +1,3 @@
 ## Relevant articles:
+
+- [Functional Programming in Java](https://www.baeldung.com/java-functional-programming)

core-java-modules/core-java-lang-3/README.md

@@ -8,4 +8,5 @@ This module contains articles about core features in the Java language
 - [Checking if a Class Exists in Java](https://www.baeldung.com/java-check-class-exists)
 - [The Difference Between a.getClass() and A.class in Java](https://www.baeldung.com/java-getclass-vs-class)
 - [Constants in Java: Patterns and Anti-Patterns](https://www.baeldung.com/java-constants-good-practices)
+- [The transient Keyword in Java](https://www.baeldung.com/java-transient-keyword)
 - [[<-- Prev]](/core-java-modules/core-java-lang-2)

core-java-modules/core-java-lang-oop-types/README.md

@@ -12,3 +12,4 @@ This module contains articles about types in Java
 - [Attaching Values to Java Enum](https://www.baeldung.com/java-enum-values)
 - [A Guide to Java Enums](https://www.baeldung.com/a-guide-to-java-enums)
 - [Determine if an Object is of Primitive Type](https://www.baeldung.com/java-object-primitive-type)
+- [Extending Enums in Java](https://www.baeldung.com/java-extending-enums)

core-java-modules/core-java-string-operations-3/README.md

@@ -1,3 +1,4 @@
 ### Relevant Articles:
 
 - [Version Comparison in Java](https://www.baeldung.com/java-comparing-versions)
+- [Java (String) or .toString()?](https://www.baeldung.com/java-string-casting-vs-tostring)

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/BufferedChannel.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import kotlinx.coroutines.cancelChildren
 import kotlinx.coroutines.channels.Channel

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/ConflatedChannel.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import kotlinx.coroutines.cancelChildren
 import kotlinx.coroutines.channels.Channel

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/PizzaPipeline.kt

@@ -1,6 +1,6 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
-import com.baeldung.channles.OrderStatus.*
+import com.baeldung.channels.OrderStatus.*
 import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.ReceiveChannel
 import kotlinx.coroutines.channels.produce

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/ProducerConsumer.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.ExperimentalCoroutinesApi

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/RendezvousChannel.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.Channel

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/SeveralProducersOneConsumer.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import kotlinx.coroutines.cancelChildren
 import kotlinx.coroutines.channels.Channel

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/SingleProducerSeveralConsumers.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.ReceiveChannel

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/TickerChannel.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import kotlinx.coroutines.channels.ticker
 import kotlinx.coroutines.delay

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/UnlimitedChannel.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import kotlinx.coroutines.cancelChildren
 import kotlinx.coroutines.channels.Channel

core-kotlin-modules/core-kotlin-concurrency/src/main/kotlin/com/baeldung/channels/logger.kt

@@ -1,4 +1,4 @@
-package com.baeldung.channles
+package com.baeldung.channels
 
 import java.text.SimpleDateFormat
 import java.util.*

discord4j/.gitignore

@@ -0,0 +1,33 @@
+README.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

discord4j/pom.xml

@@ -0,0 +1,63 @@
+<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.3.5.RELEASE</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>com.baeldung</groupId>
+	<artifactId>discord4j-bot</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>discord4j-bot</name>
+	<description>Demo Discord bot using Discord4J + Spring Boot</description>
+
+	<properties>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+			<exclusions>
+				<exclusion>
+					<groupId>org.junit.vintage</groupId>
+					<artifactId>junit-vintage-engine</artifactId>
+				</exclusion>
+			</exclusions>
+		</dependency>
+
+		<dependency>
+			<groupId>com.discord4j</groupId>
+			<artifactId>discord4j-core</artifactId>
+			<version>3.1.1</version>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-compiler-plugin</artifactId>
+				<configuration>
+					<source>1.8</source>
+					<target>1.8</target>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

discord4j/src/main/java/com/baeldung/discordbot/BotConfiguration.java

@@ -0,0 +1,48 @@
+package com.baeldung.discordbot;
+
+import com.baeldung.discordbot.events.EventListener;
+import discord4j.core.DiscordClientBuilder;
+import discord4j.core.GatewayDiscordClient;
+import discord4j.core.event.domain.Event;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import java.util.List;
+
+@Configuration
+public class BotConfiguration {
+
+    private static final Logger log = LoggerFactory.getLogger( BotConfiguration.class );
+
+    @Value("${token}")
+    private String token;
+
+    @Bean
+    public <T extends Event> GatewayDiscordClient gatewayDiscordClient(List<EventListener<T>> eventListeners) {
+        GatewayDiscordClient client = null;
+
+        try {
+            client = DiscordClientBuilder.create(token)
+              .build()
+              .login()
+              .block();
+
+            for(EventListener<T> listener : eventListeners) {
+                client.on(listener.getEventType())
+                  .flatMap(listener::execute)
+                  .onErrorResume(listener::handleError)
+                  .subscribe();
+            }
+
+            client.onDisconnect().block();
+        }
+        catch ( Exception exception ) {
+            log.error( "Be sure to use a valid bot token!", exception );
+        }
+
+        return client;
+    }
+}

discord4j/src/main/java/com/baeldung/discordbot/DiscordBotApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.discordbot;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class DiscordBotApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(DiscordBotApplication.class, args);
+	}
+}

discord4j/src/main/java/com/baeldung/discordbot/events/EventListener.java

@@ -0,0 +1,19 @@
+package com.baeldung.discordbot.events;
+
+import discord4j.core.event.domain.Event;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import reactor.core.publisher.Mono;
+
+public interface EventListener<T extends Event> {
+
+    Logger LOG = LoggerFactory.getLogger(EventListener.class);
+
+    Class<T> getEventType();
+    Mono<Void> execute(T event);
+
+    default Mono<Void> handleError(Throwable error) {
+        LOG.error("Unable to process " + getEventType().getSimpleName(), error);
+        return Mono.empty();
+    }
+}

discord4j/src/main/java/com/baeldung/discordbot/events/MessageCreateListener.java

@@ -0,0 +1,19 @@
+package com.baeldung.discordbot.events;
+
+import discord4j.core.event.domain.message.MessageCreateEvent;
+import org.springframework.stereotype.Service;
+import reactor.core.publisher.Mono;
+
+@Service
+public class MessageCreateListener extends MessageListener implements EventListener<MessageCreateEvent> {
+
+    @Override
+    public Class<MessageCreateEvent> getEventType() {
+        return MessageCreateEvent.class;
+    }
+
+    @Override
+    public Mono<Void> execute(MessageCreateEvent event) {
+        return processCommand(event.getMessage());
+    }
+}

discord4j/src/main/java/com/baeldung/discordbot/events/MessageListener.java

@@ -0,0 +1,19 @@
+package com.baeldung.discordbot.events;
+
+import discord4j.core.object.entity.Message;
+import reactor.core.publisher.Mono;
+
+public abstract class MessageListener {
+
+    public Mono<Void> processCommand(Message eventMessage) {
+        return Mono.just(eventMessage)
+           .filter(message -> message.getAuthor().map(user -> !user.isBot()).orElse(false))
+           .filter(message -> message.getContent().equalsIgnoreCase("!todo"))
+           .flatMap(Message::getChannel)
+           .flatMap(channel -> channel.createMessage("Things to do today:\n" +
+                                                     " - write a bot\n" +
+                                                     " - eat lunch\n" +
+                                                     " - play a game"))
+           .then();
+    }
+}

discord4j/src/main/java/com/baeldung/discordbot/events/MessageUpdateListener.java

@@ -0,0 +1,22 @@
+package com.baeldung.discordbot.events;
+
+import discord4j.core.event.domain.message.MessageUpdateEvent;
+import org.springframework.stereotype.Service;
+import reactor.core.publisher.Mono;
+
+@Service
+public class MessageUpdateListener extends MessageListener implements EventListener<MessageUpdateEvent> {
+
+    @Override
+    public Class<MessageUpdateEvent> getEventType() {
+        return MessageUpdateEvent.class;
+    }
+
+    @Override
+    public Mono<Void> execute(MessageUpdateEvent event) {
+        return Mono.just(event)
+           .filter(MessageUpdateEvent::isContentChanged)
+           .flatMap(MessageUpdateEvent::getMessage)
+           .flatMap(super::processCommand);
+    }
+}

discord4j/src/main/resources/application.yml

@@ -0,0 +1 @@
+token: 'our-token-here'

discord4j/src/test/java/com/baeldung/discordbot/DiscordBotLiveTest.java

@@ -0,0 +1,12 @@
+package com.baeldung.discordbot;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+public class DiscordBotLiveTest {
+
+    @Test
+    public void contextTest() {
+    }
+}

java-native/README.md

@@ -6,3 +6,4 @@ This module contains articles about the Java Native Interface (JNI).
 
 - [Guide to JNI (Java Native Interface)](https://www.baeldung.com/jni)
 - [Using JNA to Access Native Dynamic Libraries](https://www.baeldung.com/java-jna-dynamic-libraries)
+- [Check if a Java Program Is Running in 64-Bit or 32-Bit JVM](https://www.baeldung.com/java-detect-jvm-64-or-32-bit)

persistence-modules/java-jpa-3/README.md

@@ -5,3 +5,4 @@ This module contains articles about the Java Persistence API (JPA) in Java.
 ### Relevant Articles:
 
 - [JPA Entity Equality](https://www.baeldung.com/jpa-entity-equality)
+- [Ignoring Fields With the JPA @Transient Annotation](https://www.baeldung.com/jpa-transient-ignore-field)

persistence-modules/java-jpa-3/pom.xml

@@ -27,7 +27,21 @@
             <artifactId>h2</artifactId>
             <version>${h2.version}</version>
         </dependency>
-
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <version>8.0.21</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>2.11.3</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.datatype</groupId>
+            <artifactId>jackson-datatype-hibernate5</artifactId>
+            <version>2.9.8</version>
+        </dependency>
         <!--Compile time JPA API -->
         <dependency>
             <groupId>javax.persistence</groupId>

persistence-modules/java-jpa-3/src/main/java/com/baeldung/ignorable/fields/HibernateConfig.java

@@ -0,0 +1,37 @@
+package com.baeldung.ignorable.fields;
+
+import java.util.Properties;
+
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.cfg.Configuration;
+import org.hibernate.cfg.Environment;
+import org.hibernate.service.ServiceRegistry;
+
+public class HibernateConfig {
+    private static SessionFactory sessionFactory;
+
+    public static SessionFactory getSessionFactory() {
+        if (sessionFactory == null) {
+            Configuration configuration = new Configuration();
+
+            Properties settings = new Properties();
+            settings.put(Environment.DRIVER, "com.mysql.cj.jdbc.Driver");
+            settings.put(Environment.URL, "jdbc:mysql://localhost:3306/app_db?useSSL=false");
+            settings.put(Environment.USER, "root");
+            settings.put(Environment.PASS, "password");
+            settings.put(Environment.DIALECT, "org.hibernate.dialect.MySQL5Dialect");
+            settings.put(Environment.CURRENT_SESSION_CONTEXT_CLASS, "thread");
+            configuration.setProperties(settings);
+
+            configuration.addAnnotatedClass(User.class);
+
+            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
+              .applySettings(configuration.getProperties())
+              .build();
+
+            sessionFactory = configuration.buildSessionFactory(serviceRegistry);
+        }
+        return sessionFactory;
+    }
+}

persistence-modules/java-jpa-3/src/main/java/com/baeldung/ignorable/fields/User.java

@@ -0,0 +1,80 @@
+package com.baeldung.ignorable.fields;
+
+import java.io.Serializable;
+import java.util.StringJoiner;
+
+import javax.persistence.*;
+
+@Entity
+@Table(name = "Users")
+public class User implements Serializable {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Integer id;
+    private String email;
+    private String password;
+    @Transient
+    private String currentDevice;
+
+    // Needed for Hibernate mapping
+    public User() {
+    }
+
+    public User(String email, String password, String currentDevice) {
+        this.email = email;
+        this.password = password;
+        this.currentDevice = currentDevice;
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public String getCurrentDevice() {
+        return currentDevice;
+    }
+
+    public void setCurrentDevice(String currentDevice) {
+        this.currentDevice = currentDevice;
+    }
+
+    @Override
+    public String toString() {
+        return new StringJoiner(", ", User.class.getSimpleName() + "[", "]").add("id=" + id)
+          .add("email='" + email + "'")
+          .add("password='" + password + "'")
+          .add("currentDevice='" + currentDevice + "'")
+          .toString();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (!(o instanceof User))
+            return false;
+        User user = (User) o;
+        return email.equals(user.email);
+    }
+}

persistence-modules/java-jpa-3/src/main/java/com/baeldung/ignorable/fields/UserDao.java

@@ -0,0 +1,28 @@
+package com.baeldung.ignorable.fields;
+
+import java.util.List;
+
+import org.hibernate.Session;
+import org.hibernate.Transaction;
+
+public class UserDao {
+
+    public void saveUser(User user) {
+        Transaction transaction = null;
+        try (Session session = HibernateConfig.getSessionFactory().openSession()) {
+            transaction = session.beginTransaction();
+            session.save(user);
+            transaction.commit();
+        } catch (Exception e) {
+            if (transaction != null) {
+                transaction.rollback();
+            }
+        }
+    }
+
+    public List<User> getUsers() {
+        try (Session session = HibernateConfig.getSessionFactory().openSession()) {
+            return session.createQuery("from User", User.class).list();
+        }
+    }
+}

persistence-modules/java-jpa-3/src/main/java/com/baeldung/jpa/removal/LineItem.java

@@ -0,0 +1,45 @@
+package com.baeldung.jpa.removal;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.ManyToOne;
+import java.util.Objects;
+
+@Entity
+public class LineItem {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    private String name;
+
+    @ManyToOne
+    private OrderRequest orderRequest;
+
+    public LineItem(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+
+        LineItem lineItem = (LineItem) o;
+
+        return Objects.equals(id, lineItem.id);
+    }
+
+    @Override
+    public int hashCode() {
+        return id != null ? id.hashCode() : 0;
+    }
+
+    protected LineItem() {
+    }
+}

persistence-modules/java-jpa-3/src/main/java/com/baeldung/jpa/removal/OrderRequest.java

@@ -0,0 +1,43 @@
+package com.baeldung.jpa.removal;
+
+import javax.persistence.CascadeType;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+import javax.persistence.OneToOne;
+import java.util.List;
+
+@Entity
+public class OrderRequest {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    @OneToOne(cascade = { CascadeType.REMOVE, CascadeType.PERSIST })
+    private ShipmentInfo shipmentInfo;
+
+    @OneToMany(orphanRemoval = true, cascade = CascadeType.PERSIST, mappedBy = "orderRequest")
+    private List<LineItem> lineItems;
+
+    public OrderRequest(ShipmentInfo shipmentInfo) {
+        this.shipmentInfo = shipmentInfo;
+    }
+
+    public OrderRequest(List<LineItem> lineItems) {
+        this.lineItems = lineItems;
+    }
+
+    public void removeLineItem(LineItem lineItem) {
+        lineItems.remove(lineItem);
+    }
+
+    public void setLineItems(List<LineItem> lineItems) {
+        this.lineItems = lineItems;
+    }
+
+    protected OrderRequest() {
+    }
+}

persistence-modules/java-jpa-3/src/main/java/com/baeldung/jpa/removal/ShipmentInfo.java

@@ -0,0 +1,23 @@
+package com.baeldung.jpa.removal;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+
+@Entity
+public class ShipmentInfo {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    private String name;
+
+    public ShipmentInfo(String name) {
+        this.name = name;
+    }
+
+    protected ShipmentInfo() {
+    }
+}

persistence-modules/java-jpa-3/src/main/resources/META-INF/persistence.xml

@@ -1,25 +1,43 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
+             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
              http://xmlns.jcp.org/xml/ns/persistence/persistence_2_2.xsd"
-	version="2.2">
-	<persistence-unit name="jpa-h2-equality">
-		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-		<class>com.baeldung.jpa.equality.EqualByJavaDefault</class>
-		<class>com.baeldung.jpa.equality.EqualById</class>
-		<class>com.baeldung.jpa.equality.EqualByBusinessKey</class>
-		<exclude-unlisted-classes>true</exclude-unlisted-classes>
-		<properties>
-			<property name="javax.persistence.jdbc.driver" value="org.h2.Driver" />
-			<property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test" />
-			<property name="javax.persistence.jdbc.user" value="sa" />
-			<property name="javax.persistence.jdbc.password" value="" />
-			<property name="javax.persistence.jdbc.driver" value="org.h2.Driver" />
-			<property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
-			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
-			<property name="show_sql" value="false" />
-			<property name="hibernate.temp.use_jdbc_metadata_defaults" value="false" />
-		</properties>
-	</persistence-unit>
+             version="2.2">
+    <persistence-unit name="jpa-h2-equality">
+        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+        <class>com.baeldung.jpa.equality.EqualByJavaDefault</class>
+        <class>com.baeldung.jpa.equality.EqualById</class>
+        <class>com.baeldung.jpa.equality.EqualByBusinessKey</class>
+        <exclude-unlisted-classes>true</exclude-unlisted-classes>
+        <properties>
+            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
+            <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test"/>
+            <property name="javax.persistence.jdbc.user" value="sa"/>
+            <property name="javax.persistence.jdbc.password" value=""/>
+            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
+            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
+            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
+            <property name="show_sql" value="false"/>
+            <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
+        </properties>
+    </persistence-unit>
+    <persistence-unit name="jpa-h2-removal">
+        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+        <class>com.baeldung.jpa.removal.ShipmentInfo</class>
+        <class>com.baeldung.jpa.removal.LineItem</class>
+        <class>com.baeldung.jpa.removal.OrderRequest</class>
+        <exclude-unlisted-classes>true</exclude-unlisted-classes>
+        <properties>
+            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
+            <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test"/>
+            <property name="javax.persistence.jdbc.user" value="sa"/>
+            <property name="javax.persistence.jdbc.password" value=""/>
+            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
+            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
+            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
+            <property name="show_sql" value="false"/>
+            <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
+        </properties>
+    </persistence-unit>
 </persistence>

persistence-modules/java-jpa-3/src/test/java/com/baeldung/ignorable/fields/TransientFieldUnitTest.java

@@ -0,0 +1,79 @@
+package com.baeldung.ignorable.fields;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import java.io.*;
+import java.util.List;
+import java.util.Random;
+
+import org.junit.Test;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.MapperFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.datatype.hibernate5.Hibernate5Module;
+
+public class TransientFieldUnitTest {
+
+    private final UserDao userDao = new UserDao();
+
+    private final int randInt = new Random().nextInt();
+
+    private final User user = new User("user" + randInt + "@bar.com", "hunter2", "MacOSX");
+
+    @Test
+    public void givenFieldWithTransientAnnotation_whenSavingViaJPA_thenFieldIgnored() {
+        userDao.saveUser(user);
+        List<User> allUsers = userDao.getUsers();
+        User savedUser = allUsers.get(allUsers.indexOf(user));
+
+        assertNull(savedUser.getCurrentDevice());
+    }
+
+    @Test
+    public void givenFieldWithTransientAnnotation_whenSerializingObject_thenFieldSerialized() throws IOException, ClassNotFoundException {
+
+        FileOutputStream fout = new FileOutputStream("test.obj");
+        ObjectOutputStream out = new ObjectOutputStream(fout);
+        out.writeObject(user);
+        out.flush();
+        out.close();
+
+        FileInputStream fin = new FileInputStream("test.obj");
+        ObjectInputStream in = new ObjectInputStream(fin);
+        User savedUser = (User) in.readObject();
+        in.close();
+
+        assertEquals(user.getCurrentDevice(), savedUser.getCurrentDevice());
+    }
+
+    @Test
+    public void givenFieldWithTransientAnnotation_whenSerializingToJSON_thenFieldSerialized() throws JsonProcessingException {
+        ObjectMapper objectMapper = new ObjectMapper();
+        String json = objectMapper.writeValueAsString(user);
+        User savedUser = objectMapper.readValue(json, User.class);
+
+        assertEquals(user.getCurrentDevice(), savedUser.getCurrentDevice());
+    }
+
+    @Test
+    public void givenJacksonHibernate5Module_whenSerializingTransientAnnotation_thenFieldIgnored() throws JsonProcessingException {
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.registerModule(new Hibernate5Module());
+        String json = objectMapper.writeValueAsString(user);
+        User savedUser = objectMapper.readValue(json, User.class);
+
+        assertNull(savedUser.getCurrentDevice());
+    }
+
+    @Test
+    public void givenPropagateTransientFieldFlag_whenSerializingTransientAnnotation_thenFieldSerialized() throws JsonProcessingException {
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.configure(MapperFeature.PROPAGATE_TRANSIENT_MARKER, true);
+        String json = objectMapper.writeValueAsString(user);
+        User savedUser = objectMapper.readValue(json, User.class);
+
+        assertEquals(user.getCurrentDevice(), savedUser.getCurrentDevice());
+    }
+}

persistence-modules/java-jpa-3/src/test/java/com/baeldung/jpa/removal/CascadeTypeRemoveIntegrationTest.java

@@ -0,0 +1,73 @@
+package com.baeldung.jpa.removal;
+
+import org.junit.Assert;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.Persistence;
+import javax.persistence.TypedQuery;
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Root;
+import java.util.List;
+
+public class CascadeTypeRemoveIntegrationTest {
+
+    private static EntityManagerFactory factory;
+    private static EntityManager entityManager;
+
+    @BeforeClass
+    public static void setup() {
+        factory = Persistence.createEntityManagerFactory("jpa-h2-removal");
+        entityManager = factory.createEntityManager();
+    }
+
+    @Test
+    public void whenOrderRequestIsDeleted_thenDeleteShipmentInfo() {
+        createOrderRequestWithShipmentInfo();
+
+        OrderRequest orderRequest = entityManager.find(OrderRequest.class, 1L);
+
+        entityManager.getTransaction().begin();
+        entityManager.remove(orderRequest);
+        entityManager.getTransaction().commit();
+
+        Assert.assertEquals(0, findAllOrderRequest().size());
+        Assert.assertEquals(0, findAllShipmentInfo().size());
+    }
+
+    private void createOrderRequestWithShipmentInfo() {
+        ShipmentInfo shipmentInfo = new ShipmentInfo("name");
+        OrderRequest orderRequest = new OrderRequest(shipmentInfo);
+
+        entityManager.getTransaction().begin();
+        entityManager.persist(orderRequest);
+        entityManager.getTransaction().commit();
+
+        Assert.assertEquals(1, findAllOrderRequest().size());
+        Assert.assertEquals(1, findAllShipmentInfo().size());
+    }
+
+    private List<OrderRequest> findAllOrderRequest() {
+        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
+        CriteriaQuery<OrderRequest> cq = cb.createQuery(OrderRequest.class);
+        Root<OrderRequest> root = cq.from(OrderRequest.class);
+        CriteriaQuery<OrderRequest> findAll = cq.select(root);
+        TypedQuery<OrderRequest> findAllQuery = entityManager.createQuery(findAll);
+
+        return findAllQuery.getResultList();
+    }
+
+    private List<ShipmentInfo> findAllShipmentInfo() {
+        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
+        CriteriaQuery<ShipmentInfo> cq = cb.createQuery(ShipmentInfo.class);
+        Root<ShipmentInfo> root = cq.from(ShipmentInfo.class);
+        CriteriaQuery<ShipmentInfo> findAll = cq.select(root);
+        TypedQuery<ShipmentInfo> findAllQuery = entityManager.createQuery(findAll);
+
+        return findAllQuery.getResultList();
+    }
+
+}

persistence-modules/java-jpa-3/src/test/java/com/baeldung/jpa/removal/OrphanRemovalIntegrationTest.java

@@ -0,0 +1,92 @@
+package com.baeldung.jpa.removal;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.Persistence;
+import javax.persistence.PersistenceException;
+import javax.persistence.TypedQuery;
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Root;
+import java.util.ArrayList;
+import java.util.List;
+
+public class OrphanRemovalIntegrationTest {
+
+    private static EntityManagerFactory factory;
+    private static EntityManager entityManager;
+
+    @Before
+    public void setup() {
+        factory = Persistence.createEntityManagerFactory("jpa-h2-removal");
+        entityManager = factory.createEntityManager();
+    }
+
+    @Test
+    public void whenLineItemIsRemovedFromOrderRequest_thenDeleteOrphanedLineItem() {
+        createOrderRequestWithLineItems();
+
+        OrderRequest orderRequest = entityManager.find(OrderRequest.class, 1L);
+        LineItem lineItem = entityManager.find(LineItem.class, 2L);
+        orderRequest.removeLineItem(lineItem);
+
+        entityManager.getTransaction().begin();
+        entityManager.merge(orderRequest);
+        entityManager.getTransaction().commit();
+
+        Assert.assertEquals(1, findAllOrderRequest().size());
+        Assert.assertEquals(2, findAllLineItem().size());
+    }
+
+    @Test(expected = PersistenceException.class)
+    public void whenLineItemsIsReassigned_thenThrowAnException() {
+        createOrderRequestWithLineItems();
+
+        OrderRequest orderRequest = entityManager.find(OrderRequest.class, 1L);
+        orderRequest.setLineItems(new ArrayList<>());
+
+        entityManager.getTransaction().begin();
+        entityManager.merge(orderRequest);
+        entityManager.getTransaction().commit();
+    }
+
+    private void createOrderRequestWithLineItems() {
+        List<LineItem> lineItems = new ArrayList<>();
+        lineItems.add(new LineItem("line item 1"));
+        lineItems.add(new LineItem("line item 2"));
+        lineItems.add(new LineItem("line item 3"));
+
+        OrderRequest orderRequest = new OrderRequest(lineItems);
+
+        entityManager.getTransaction().begin();
+        entityManager.persist(orderRequest);
+        entityManager.getTransaction().commit();
+
+        Assert.assertEquals(1, findAllOrderRequest().size());
+        Assert.assertEquals(3, findAllLineItem().size());
+    }
+
+    private List<OrderRequest> findAllOrderRequest() {
+        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
+        CriteriaQuery<OrderRequest> cq = cb.createQuery(OrderRequest.class);
+        Root<OrderRequest> root = cq.from(OrderRequest.class);
+        CriteriaQuery<OrderRequest> findAll = cq.select(root);
+        TypedQuery<OrderRequest> findAllQuery = entityManager.createQuery(findAll);
+
+        return findAllQuery.getResultList();
+    }
+
+    private List<LineItem> findAllLineItem() {
+        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
+        CriteriaQuery<LineItem> cq = cb.createQuery(LineItem.class);
+        Root<LineItem> root = cq.from(LineItem.class);
+        CriteriaQuery<LineItem> findAll = cq.select(root);
+        TypedQuery<LineItem> findAllQuery = entityManager.createQuery(findAll);
+
+        return findAllQuery.getResultList();
+    }
+}

pom.xml

@@ -397,6 +397,7 @@
                 <module>ddd</module>
                 <!-- <module>ddd-modules</module>--> <!-- we haven't upgraded to Java 9 -->
                 <module>deeplearning4j</module>
+                <module>discord4j</module>
                 <module>disruptor</module>
                 <module>dozer</module>
                 <module>drools</module>
@@ -909,6 +910,7 @@
                 <module>ddd</module>
                 <!-- <module>ddd-modules</module>--> <!-- we haven't upgraded to Java 9 -->
                 <module>deeplearning4j</module>
+                <module>discord4j</module>
                 <module>disruptor</module>
                 <module>dozer</module>
                 <module>drools</module>

spring-5-reactive/src/test/java/com/baeldung/reactive/Spring5ReactiveServerClientIntegrationTest.java

@@ -1,97 +0,0 @@
-package com.baeldung.reactive;
-
-import static org.springframework.web.reactive.function.server.RequestPredicates.GET;
-import static org.springframework.web.reactive.function.server.RequestPredicates.POST;
-
-import java.time.Duration;
-
-import org.junit.jupiter.api.AfterAll;
-import org.junit.jupiter.api.BeforeAll;
-import org.springframework.http.server.reactive.HttpHandler;
-import org.springframework.http.server.reactive.ReactorHttpHandlerAdapter;
-import org.springframework.web.reactive.function.server.RouterFunction;
-import org.springframework.web.reactive.function.server.RouterFunctions;
-import org.springframework.web.reactive.function.server.ServerResponse;
-
-import com.baeldung.web.reactive.Task;
-
-import reactor.core.publisher.Flux;
-import reactor.core.publisher.Mono;
-import reactor.netty.DisposableServer;
-import reactor.netty.http.server.HttpServer;
-
-public class Spring5ReactiveServerClientIntegrationTest {
-    private static DisposableServer disposableServer;
-
-    @BeforeAll
-    public static void setUp() throws Exception {
-        HttpServer server = HttpServer.create()
-            .host("localhost")
-            .port(8080);
-        RouterFunction<?> route = RouterFunctions.route(POST("/task/process"), request -> ServerResponse.ok()
-            .body(request.bodyToFlux(Task.class)
-                .map(ll -> new Task("TaskName", 1)), Task.class))
-            .and(RouterFunctions.route(GET("/task"), request -> ServerResponse.ok()
-                .body(Mono.just("server is alive"), String.class)));
-        HttpHandler httpHandler = RouterFunctions.toHttpHandler(route);
-        ReactorHttpHandlerAdapter adapter = new ReactorHttpHandlerAdapter(httpHandler);
-        disposableServer = server.handle(adapter)
-            .bindNow();
-    }
-
-    @AfterAll
-    public static void shutDown() {
-        disposableServer.disposeNow();
-    }
-
-    // @Test
-    // public void givenCheckTask_whenServerHandle_thenServerResponseALiveString() throws Exception {
-    // WebClient client = WebClient.create("http://localhost:8080");
-    // Mono<String> result = client
-    // .get()
-    // .uri("/task")
-    // .exchange()
-    // .then(response -> response.bodyToMono(String.class));
-    //
-    // assertThat(result.block()).isInstanceOf(String.class);
-    // }
-
-    // @Test
-    // public void givenThreeTasks_whenServerHandleTheTasks_thenServerResponseATask() throws Exception {
-    // URI uri = URI.create("http://localhost:8080/task/process");
-    // ExchangeFunction exchange = ExchangeFunctions.create(new ReactorClientHttpConnector());
-    // ClientRequest request = ClientRequest
-    // .method(HttpMethod.POST, uri)
-    // .body(BodyInserters.fromPublisher(getLatLngs(), Task.class))
-    // .build();
-    //
-    // Flux<Task> taskResponse = exchange
-    // .exchange(request)
-    // .flatMap(response -> response.bodyToFlux(Task.class));
-    //
-    // assertThat(taskResponse.blockFirst()).isInstanceOf(Task.class);
-    // }
-
-    // @Test
-    // public void givenCheckTask_whenServerHandle_thenOragicServerResponseALiveString() throws Exception {
-    // URI uri = URI.create("http://localhost:8080/task");
-    // ExchangeFunction exchange = ExchangeFunctions.create(new ReactorClientHttpConnector());
-    // ClientRequest request = ClientRequest
-    // .method(HttpMethod.GET, uri)
-    // .body(BodyInserters.fromPublisher(getLatLngs(), Task.class))
-    // .build();
-    //
-    // Flux<String> taskResponse = exchange
-    // .exchange(request)
-    // .flatMap(response -> response.bodyToFlux(String.class));
-    //
-    // assertThat(taskResponse.blockFirst()).isInstanceOf(String.class);
-    // }
-
-    private static Flux<Task> getLatLngs() {
-        return Flux.range(0, 3)
-            .zipWith(Flux.interval(Duration.ofSeconds(1)))
-            .map(x -> new Task("taskname", 1))
-            .doOnNext(ll -> System.out.println("Produced: {}" + ll));
-    }
-}