Merge branch 'eugenp:master' into BAEL-7618

algorithms-modules/algorithms-miscellaneous-7/README.md

@@ -7,4 +7,5 @@
 - [Rotate Arrays in Java](https://www.baeldung.com/java-rotate-arrays)
 - [Find Missing Number From a Given Array in Java](https://www.baeldung.com/java-array-find-missing-number)
 - [Calculate Weighted Mean in Java](https://www.baeldung.com/java-compute-weighted-average)
+- [Check if Two Strings Are Rotations of Each Other](https://www.baeldung.com/java-string-check-strings-rotations)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-6)

apache-libraries/pom.xml

@@ -191,7 +191,7 @@
         <bval.version>2.0.6</bval.version>
         <javax.validation.validation-api.version>2.0.1.Final</javax.validation.validation-api.version>
         <meecrowave-junit.version>1.2.15</meecrowave-junit.version>
-        <okhttp.version>4.12.0</okhttp.version>
+        <okhttp.version>5.0.0-alpha.12</okhttp.version>
         <meecrowave-jpa.version>1.2.15</meecrowave-jpa.version>
         <meecrowave-core.version>1.2.15</meecrowave-core.version>
         <meecrowave-maven-plugin.version>1.2.15</meecrowave-maven-plugin.version>

core-java-modules/core-java-18/README.md

@@ -1,2 +1,3 @@
 ## Relevant Articles
 - [Deprecate Finalization in Java 18](https://www.baeldung.com/java-18-deprecate-finalization)
+- [Simple Web Server in Java 18](https://www.baeldung.com/simple-web-server-java-18)

core-java-modules/core-java-collections-array-list/pom.xml

@@ -22,7 +22,7 @@
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
-            <version>31.1-jre</version>
+            <version>${guava.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>

core-java-modules/core-java-collections-list-6/pom.xml

@@ -29,4 +29,4 @@
     <properties>
         <vavr.version>0.10.4</vavr.version>
     </properties>
-</project>
+</project>

core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/modifyandprint/ModifyAndPrintListElementsUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.modifyandprint;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.collect.Lists;
+
+public class ModifyAndPrintListElementsUnitTest {
+
+    private final Logger log = LoggerFactory.getLogger(ModifyAndPrintListElementsUnitTest.class);
+
+    @Test
+    void whenPrintingInForEach_thenListIsPrinted() {
+        List<String> theList = Lists.newArrayList("Kai", "Liam", "Eric", "Kevin");
+        theList.forEach(element -> log.info(element));
+    }
+
+    @Test
+    void whenUsingModifyAndPrintingSeparately_thenListIsModifiedAndPrinted() {
+        List<String> theList = Lists.newArrayList("Kai", "Liam", "Eric", "Kevin");
+        theList.replaceAll(element -> element.toUpperCase());
+        theList.forEach(element -> log.info(element));
+        assertEquals(List.of("KAI", "LIAM", "ERIC", "KEVIN"), theList);
+    }
+
+    @Test
+    void whenPrintingInMap_thenStreamIsModifiedAndPrinted() {
+        List<String> theList = List.of("Kai", "Liam", "Eric", "Kevin");
+        List<String> newList = theList.stream()
+            .map(element -> {
+                String newElement = element.toUpperCase();
+                log.info(newElement);
+                return newElement;
+            })
+            .collect(Collectors.toList());
+        assertEquals(List.of("KAI", "LIAM", "ERIC", "KEVIN"), newList);
+    }
+
+    @Test
+    void whenPrintingInPeek_thenStreamIsModifiedAndPrinted() {
+        List<String> theList = List.of("Kai", "Liam", "Eric", "Kevin");
+        List<String> newList = theList.stream()
+            .map(element -> element.toUpperCase())
+            .peek(element-> log.info(element))
+            .collect(Collectors.toList());
+        assertEquals(List.of("KAI", "LIAM", "ERIC", "KEVIN"), newList);
+    }
+}

core-java-modules/core-java-collections-maps-7/README.md

@@ -8,4 +8,5 @@
 - [How to Sort LinkedHashMap by Values in Java](https://www.baeldung.com/java-sort-linkedhashmap-using-values)
 - [How to Increment a Map Value in Java](https://www.baeldung.com/java-increment-map-value)
 - [Collect Stream of entrySet() to a LinkedHashMap](https://www.baeldung.com/java-linkedhashmap-entryset-stream)
+- [How to Pretty-Print a Map in Java](https://www.baeldung.com/java-map-pretty-print)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-maps-6)

core-java-modules/core-java-collections-set-2/pom.xml

@@ -35,7 +35,7 @@
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
-            <version>32.1.1-jre</version>
+            <version>${guava.version}</version>
         </dependency>
     </dependencies>
 

core-java-modules/core-java-concurrency-2/README.md

@@ -9,3 +9,5 @@
 - [Parallelize for Loop in Java](https://www.baeldung.com/java-for-loop-parallel)
 - [How to Effectively Unit Test CompletableFuture](https://www.baeldung.com/java-completablefuture-unit-test)
 - [How to Collect All Results and Handle Exceptions With CompletableFuture in a Loop](https://www.baeldung.com/java-completablefuture-collect-results-handle-exceptions)
+- [CompletableFuture runAsync() vs. supplyAsync() in Java](https://www.baeldung.com/java-completablefuture-runasync-supplyasync)
+- [Difference Between thenApply() and thenApplyAsync() in CompletableFuture](https://www.baeldung.com/java-completablefuture-thenapply-thenapplyasync)

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

@@ -17,4 +17,5 @@
 - [Validate if a String Is a Valid Geo Coordinate](https://www.baeldung.com/java-geo-coordinates-validation)
 - [Rotate a Vertex Around a Certain Point in Java](https://www.baeldung.com/java-rotate-vertex-around-point)
 - [Calculating the Power of Any Number in Java Without Using Math pow() Method](https://www.baeldung.com/java-calculating-the-power-without-math-pow)
+- [Solving Rod Cutting Problem in Java](https://www.baeldung.com/java-rod-cutting-problem)
 - More articles: [[<-- Prev]](/core-java-modules/core-java-lang-math-2)

core-java-modules/core-java-perf/src/main/java/com/baeldung/outofmemoryerror/OutOfMemoryGCLimitExceed.java

@@ -1,19 +1,21 @@
 package com.baeldung.outofmemoryerror;
 
-import java.util.HashMap;
-import java.util.Map;
+import java.util.LinkedList;
+import java.util.List;
 import java.util.Random;
 
 public class OutOfMemoryGCLimitExceed {
-    public static void addRandomDataToMap() {
-        Map<Integer, String> dataMap = new HashMap<>();
-        Random r = new Random();
+
+    public static final Random RANDOM = new Random();
+
+    public static void addRandomDataToList() {
+        List<String> dataList = new LinkedList<>();
         while (true) {
-            dataMap.put(r.nextInt(), String.valueOf(r.nextInt()));
+            dataList.add(String.valueOf(RANDOM.nextInt()));
         }
     }
 
     public static void main(String[] args) {
-        OutOfMemoryGCLimitExceed.addRandomDataToMap();
+        OutOfMemoryGCLimitExceed.addRandomDataToList();
     }
 }

core-java-modules/core-java-streams-6/REAME.md

@@ -1,3 +1,4 @@
 ## Relevant Articles
 - [Java 8 Stream Operation on the Empty List](https://www.baeldung.com/java-empty-list-stream-ops)
+- [Get a Range of Items from a Stream in Java](https://www.baeldung.com/java-stream-get-range)
 

core-java-modules/core-java-string-algorithms-4/README.md

@@ -6,3 +6,4 @@ This module contains articles about string-related algorithms.
 - [Rotating a Java String By n Characters](https://www.baeldung.com/java-rotate-string-by-n-characters)
 - [Remove Characters From a String That Are in the Other String](https://www.baeldung.com/java-strings-character-difference)
 - [Run-Length Encoding and Decoding in Java](https://www.baeldung.com/java-rle-compression)
+- [Check if a String Is Equal to Its Mirror Reflection](https://www.baeldung.com/java-string-mirror-image-test)

core-java-modules/core-java-string-operations-8/README.md

@@ -1,2 +1,6 @@
 ### Relevant Articles:
 - [Count Uppercase and Lowercase Letters in a String](https://www.baeldung.com/java-string-count-letters-uppercase-lowercase)
+- [Find The Largest Number in a String](https://www.baeldung.com/java-find-largest-number-string)
+- [Check if String is Base64 Encoded](https://www.baeldung.com/java-check-string-base64-encoding)
+- [Find an Unique Email Address in a List](https://www.baeldung.com/java-find-unique-email-address)
+- [Get First n Characters in a String in Java](https://www.baeldung.com/get-first-n-characters-in-a-string-in-java)

core-java-modules/core-java-uuid/src/main/java/com/baeldung/uuid/UUIDPositiveLongGenerator.java

@@ -1,83 +0,0 @@
-package com.baeldung.uuid;
-
-import java.nio.ByteBuffer;
-import java.security.SecureRandom;
-import java.util.UUID;
-
-/**
- * Methods are called by reflection in the unit test
- */
-@SuppressWarnings("unused")
-public class UUIDPositiveLongGenerator {
-    public long getLeastSignificantBits() {
-        return Math.abs(UUID.randomUUID().getLeastSignificantBits());
-    }
-
-    public long getMostSignificantBits() {
-        return Math.abs(UUID.randomUUID().getMostSignificantBits());
-    }
-
-    public long combineByteBuffer() {
-        UUID uuid = UUID.randomUUID();
-        ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
-        bb.putLong(uuid.getMostSignificantBits());
-        bb.putLong(uuid.getLeastSignificantBits());
-        bb.rewind();
-        return Math.abs(bb.getLong());
-    }
-
-    public long combineBitwise() {
-        UUID uniqueUUID = UUID.randomUUID();
-        long mostSignificantBits = uniqueUUID.getMostSignificantBits();
-        long leastSignificantBits = uniqueUUID.getLeastSignificantBits();
-        return Math.abs((mostSignificantBits << 32) | (leastSignificantBits & 0xFFFFFFFFL));
-    }
-
-    public long combineDirect() {
-        UUID uniqueUUID = UUID.randomUUID();
-        long mostSignificantBits = uniqueUUID.getMostSignificantBits();
-        long leastSignificantBits = uniqueUUID.getLeastSignificantBits();
-        return Math.abs(mostSignificantBits ^ (leastSignificantBits >> 1));
-    }
-
-    public long combinePermutation() {
-        UUID uuid = UUID.randomUUID();
-        long mostSigBits = uuid.getMostSignificantBits();
-        long leastSigBits = uuid.getLeastSignificantBits();
-        byte[] uuidBytes = new byte[16];
-
-        for (int i = 0; i < 8; i++) {
-            uuidBytes[i] = (byte) (mostSigBits >>> (8 * (7 - i)));
-            uuidBytes[i + 8] = (byte) (leastSigBits >>> (8 * (7 - i)));
-        }
-
-        long result = 0;
-        for (byte b : uuidBytes) {
-            result = (result << 8) | (b & 0xFF);
-        }
-        return Math.abs(result);
-    }
-
-    public long combineWithSecureRandom() {
-        UUID uniqueUUID = UUID.randomUUID();
-        SecureRandom secureRandom = new SecureRandom();
-        long randomBits = secureRandom.nextLong();
-
-        long mostSignificantBits = uniqueUUID.getMostSignificantBits() ^ randomBits;
-        long leastSignificantBits = uniqueUUID.getLeastSignificantBits();
-
-        return Math.abs((mostSignificantBits << 32) | (leastSignificantBits & 0xFFFFFFFFL));
-    }
-
-    public long combineWithNanoTime() {
-        UUID uniqueUUID = UUID.randomUUID();
-        long nanoTime = System.nanoTime();
-
-        long mostSignificantBits = uniqueUUID.getMostSignificantBits() ^ nanoTime;
-        long leastSignificantBits = uniqueUUID.getLeastSignificantBits();
-
-        return Math.abs((mostSignificantBits << 32) | (leastSignificantBits & 0xFFFFFFFFL));
-    }
-
-
-}

core-java-modules/core-java-uuid/src/test/java/com/baeldung/uuid/UUIDPositiveLongGeneratorUnitTest.java

@@ -2,42 +2,21 @@ package com.baeldung.uuid;
 
 import org.junit.jupiter.api.Test;
 
-import java.lang.reflect.Method;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.UUID;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class UUIDPositiveLongGeneratorUnitTest {
 
-    private final UUIDPositiveLongGenerator uuidLongGenerator = new UUIDPositiveLongGenerator();
-
-    private final Set<Long> uniqueValues = new HashSet<>();
-
     @Test
-    void whenForeachMethods_thenRetryWhileNotUnique() throws Exception {
-        for (Method method : uuidLongGenerator.getClass().getDeclaredMethods()) {
-            long uniqueValue;
-            do uniqueValue = (long) method.invoke(uuidLongGenerator); while (!isUnique(uniqueValue));
-            assertThat(uniqueValue).isPositive();
-        }
+    public void whenGetMostSignificantBits_thenAssertPositive() {
+        long randomPositiveLong = Math.abs(UUID.randomUUID().getMostSignificantBits());
+        assertThat(randomPositiveLong).isNotNegative();
     }
 
     @Test
-    void whenGivenLongValue_thenCheckUniqueness() {
-        long uniqueValue = generateUniqueLong();
-        assertThat(uniqueValue).isPositive();
+    public void whenGetLeastSignificantBits_thenAssertPositive() {
+        long randomPositiveLong = Math.abs(UUID.randomUUID().getLeastSignificantBits());
+        assertThat(randomPositiveLong).isNotNegative();
     }
-
-    private long generateUniqueLong() {
-        long uniqueValue;
-        do uniqueValue = uuidLongGenerator.combineBitwise(); while (!isUnique(uniqueValue));
-        return uniqueValue;
-    }
-
-    private boolean isUnique(long value) {
-        // Implement uniqueness checking logic, for example, by checking in the database
-        return uniqueValues.add(value);
-    }
-
 }

core-java-modules/java-spi/exchange-rate-impl/pom.xml

@@ -66,7 +66,7 @@
 
     <properties>
         <exchange-rate-api.version>1.0.0-SNAPSHOT</exchange-rate-api.version>
-        <okhttp.version>4.12.0</okhttp.version>
+        <okhttp.version>5.0.0-alpha.12</okhttp.version>
         <javax.json.bind-api.version>1.0</javax.json.bind-api.version>
         <yasson.version>1.0.1</yasson.version>
         <javax.json.version>1.1.2</javax.json.version>

docker-modules/docker-caching/multi-module-caching/core-module/pom.xml

@@ -15,12 +15,14 @@
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
         </dependency>
     </dependencies>
 
     <properties>
         <maven.compiler.source>8</maven.compiler.source>
         <maven.compiler.target>8</maven.compiler.target>
+        <guava.version>33.0.0-jre</guava.version>
     </properties>
 
 </project>

docker-modules/docker-spring-boot/pom.xml

@@ -9,9 +9,9 @@
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-boot-2</artifactId>
+        <artifactId>parent-boot-3</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../../parent-boot-2</relativePath>
+        <relativePath>../../parent-boot-3</relativePath>
     </parent>
 
     <dependencies>

docker-modules/docker-spring-boot/src/main/docker/Dockerfile

@@ -2,12 +2,12 @@
 #
 # docker build -f src/main/docker/Dockerfile .
 
-FROM adoptopenjdk:11-jre-hotspot as builder
+FROM openjdk:17-jdk-alpine as builder
 ARG JAR_FILE=target/*.jar
 COPY ${JAR_FILE} application.jar
 RUN java -Djarmode=layertools -jar application.jar extract
 
-FROM adoptopenjdk:11-jre-hotspot
+FROM openjdk:17-jdk-alpine
 COPY --from=builder dependencies/ ./
 COPY --from=builder spring-boot-loader/ ./
 COPY --from=builder internal-dependencies/ ./

docker-modules/docker-spring-boot/src/main/docker/springprofile/Dockerfile

@@ -6,6 +6,6 @@
 # To run with profiles:
 # docker run -e "SPRING_PROFILES_ACTIVE=test1,test2,test3" docker-with-spring-profile:latest
 
-FROM openjdk:11
+FROM openjdk:17-jdk-alpine
 COPY target/*.jar app.jar
 ENTRYPOINT ["java", "-jar", "/app.jar"]

jackson-modules/jackson-custom-conversions/README.md

@@ -8,3 +8,4 @@ This module contains articles about Jackson custom conversions.
 - [Serialize Only Fields That Meet a Custom Criteria With Jackson](https://www.baeldung.com/jackson-serialize-field-custom-criteria)
 - [Calling Default Serializer from Custom Serializer in Jackson](https://www.baeldung.com/jackson-call-default-serializer-from-custom-serializer)
 - [OffsetDateTime Serialization With Jackson](https://www.baeldung.com/java-jackson-offsetdatetime)
+- [Create JavaType From Class with Jackson](https://www.baeldung.com/java-javatype-class-jackson)

libraries-data-io/README.md

@@ -11,3 +11,4 @@ This module contains articles about IO data processing libraries.
 - [Introduction To Docx4J](https://www.baeldung.com/docx4j)
 - [Breaking YAML Strings Over Multiple Lines](https://www.baeldung.com/yaml-multi-line)
 - [Different Serialization Approaches for Java](https://www.baeldung.com/java-serialization-approaches)
+- [A Guide to etcd](https://www.baeldung.com/java-etcd-guide)

libraries-http-2/pom.xml

@@ -109,9 +109,9 @@
     </build>
 
     <properties>
-        <okhttp.version>4.12.0</okhttp.version>
+        <okhttp.version>5.0.0-alpha.12</okhttp.version>
         <gson.version>2.10.1</gson.version>
-        <mockwebserver.version>4.9.1</mockwebserver.version>
+        <mockwebserver.version>5.0.0-alpha.12</mockwebserver.version>
         <jetty.httpclient.version>1.0.3</jetty.httpclient.version>
         <jetty.server.version>9.4.19.v20190610</jetty.server.version>
         <rxjava2.version>2.2.11</rxjava2.version>

libraries-http-2/src/test/java/com/baeldung/okhttp/download/BinaryFileDownloaderUnitTest.java

@@ -52,17 +52,10 @@ public class BinaryFileDownloaderUnitTest {
         verify(writer).close();
     }
 
-    @Test(expected = IllegalStateException.class)
-    public void givenUrlAndResponseWithNullBody_whenDownload_thenExpectIllegalStateException() throws Exception {
+    @Test(expected = NullPointerException.class)
+    public void givenUrlAndResponseWithNullBody_whenDownload_thenExpectNullPointerException() throws Exception {
         String url = "http://example.com/file";
-        Call call = mock(Call.class);
-        when(client.newCall(any(Request.class))).thenReturn(call);
         Response response = createResponse(url, null);
-        when(call.execute()).thenReturn(response);
-
-        tested.download(url);
-
-        verify(writer, times(0)).write(any(InputStream.class), anyDouble());
     }
 
     @NotNull

libraries-http/pom.xml

@@ -13,13 +13,11 @@
     </parent>
 
     <dependencies>
-        <!-- Dependencies for response decoder with okhttp -->
         <dependency>
             <groupId>com.squareup.okhttp3</groupId>
             <artifactId>okhttp</artifactId>
             <version>${com.squareup.okhttp3.version}</version>
         </dependency>
-        <!-- Dependencies for google http client -->
         <dependency>
             <groupId>com.google.http-client</groupId>
             <artifactId>google-http-client</artifactId>
@@ -30,7 +28,6 @@
             <artifactId>google-http-client-jackson2</artifactId>
             <version>${googleclient.version}</version>
         </dependency>
-        <!-- Retrofit -->
         <dependency>
             <groupId>com.squareup.retrofit2</groupId>
             <artifactId>retrofit</artifactId>
@@ -46,7 +43,6 @@
             <artifactId>adapter-rxjava</artifactId>
             <version>${retrofit.version}</version>
         </dependency>
-        <!-- https://mvnrepository.com/artifact/org.asynchttpclient/async-http-client -->
         <dependency>
             <groupId>org.asynchttpclient</groupId>
             <artifactId>async-http-client</artifactId>
@@ -68,7 +64,6 @@
             <artifactId>unirest-java</artifactId>
             <version>${unirest.version}</version>
         </dependency>
-        <!-- javalin -->
         <dependency>
             <groupId>io.javalin</groupId>
             <artifactId>javalin</artifactId>
@@ -105,7 +100,7 @@
     <properties>
         <gson.version>2.10.1</gson.version>
         <httpclient.version>4.5.3</httpclient.version>
-        <com.squareup.okhttp3.version>4.12.0</com.squareup.okhttp3.version>
+        <com.squareup.okhttp3.version>5.0.0-alpha.12</com.squareup.okhttp3.version>
         <googleclient.version>1.23.0</googleclient.version>
         <async.http.client.version>2.2.0</async.http.client.version>
         <retrofit.version>2.3.0</retrofit.version>

libraries-server-2/pom.xml

@@ -30,6 +30,12 @@
             <artifactId>jetty-webapp</artifactId>
             <version>${jetty.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.netty</groupId>
+            <artifactId>netty-all</artifactId>
+            <version>${netty.version}</version>
+        </dependency>
+
     </dependencies>
 
     <build>
@@ -73,6 +79,7 @@
     <properties>
         <jetty.version>9.4.27.v20200227</jetty.version>
         <alpn.version>8.1.11.v20170118</alpn.version>
+        <netty.version>4.1.104.Final</netty.version>
     </properties>
 
 </project>

libraries-server-2/src/main/java/com/baeldung/netty/customhandlersandlisteners/ChatClientMain.java

@@ -0,0 +1,77 @@
+package com.baeldung.netty.customhandlersandlisteners;
+
+import java.util.Scanner;
+
+import com.baeldung.netty.customhandlersandlisteners.handler.ClientEventHandler;
+import com.baeldung.netty.customhandlersandlisteners.listener.ChannelInfoListener;
+
+import io.netty.bootstrap.Bootstrap;
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelFuture;
+import io.netty.channel.ChannelInitializer;
+import io.netty.channel.EventLoopGroup;
+import io.netty.channel.nio.NioEventLoopGroup;
+import io.netty.channel.socket.SocketChannel;
+import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.handler.codec.string.StringDecoder;
+import io.netty.handler.codec.string.StringEncoder;
+
+public class ChatClientMain {
+
+    private static final String SYSTEM_USER = System.getProperty("user.name");
+    private static String user;
+
+    public static void main(String[] args) {
+        EventLoopGroup group = new NioEventLoopGroup();
+        try (Scanner scanner = new Scanner(System.in)) {
+            Bootstrap bootstrap = new Bootstrap();
+            bootstrap.group(group)
+                .channel(NioSocketChannel.class)
+                .handler(new ChannelInitializer<SocketChannel>() {
+                    @Override
+                    public void initChannel(SocketChannel channel) throws Exception {
+                        channel.pipeline()
+                            .addFirst(new StringDecoder(), new ClientEventHandler(), new StringEncoder());
+                    }
+                });
+
+            ChannelFuture future = bootstrap.connect(ChatServerMain.HOST, ChatServerMain.PORT)
+                .sync();
+
+            future.addListener(new ChannelInfoListener("connected to server"));
+            Channel channel = future.sync()
+                .channel();
+
+            messageLoop(scanner, channel);
+
+            channel.close();
+        } catch (Throwable e) {
+            e.printStackTrace();
+            Thread.currentThread().interrupt();
+        } finally {
+            group.shutdownGracefully();
+        }
+    }
+
+    private static void messageLoop(Scanner scanner, Channel channel) throws InterruptedException {
+        Thread.sleep(50);
+
+        if (user == null) {
+            System.out.printf("your name [%s]: ", SYSTEM_USER);
+            user = scanner.nextLine();
+            if (user.isEmpty())
+                user = SYSTEM_USER;
+        }
+
+        System.out.print("> ");
+        while (scanner.hasNext()) {
+            String message = scanner.nextLine();
+            if (message.equals("exit"))
+                break;
+
+            ChannelFuture sent = channel.writeAndFlush(user + ";" + message);
+            sent.addListener(new ChannelInfoListener("message sent"));
+            sent.addListener(future -> System.out.print("> "));
+        }
+    }
+}

libraries-server-2/src/main/java/com/baeldung/netty/customhandlersandlisteners/ChatServerMain.java

@@ -0,0 +1,53 @@
+package com.baeldung.netty.customhandlersandlisteners;
+
+import com.baeldung.netty.customhandlersandlisteners.handler.ServerEventHandler;
+import com.baeldung.netty.customhandlersandlisteners.listener.ChannelInfoListener;
+
+import io.netty.bootstrap.ServerBootstrap;
+import io.netty.channel.ChannelFuture;
+import io.netty.channel.ChannelInitializer;
+import io.netty.channel.EventLoopGroup;
+import io.netty.channel.nio.NioEventLoopGroup;
+import io.netty.channel.socket.SocketChannel;
+import io.netty.channel.socket.nio.NioServerSocketChannel;
+import io.netty.handler.codec.string.StringDecoder;
+import io.netty.handler.codec.string.StringEncoder;
+
+public final class ChatServerMain {
+
+    public static final String HOST = "localhost";
+    public static final int PORT = 8081;
+
+    public static void main(String[] args) {
+        EventLoopGroup serverGroup = new NioEventLoopGroup(1);
+        EventLoopGroup clientGroup = new NioEventLoopGroup();
+        try {
+            ServerBootstrap bootstrap = new ServerBootstrap();
+            bootstrap.group(serverGroup, clientGroup)
+                .channel(NioServerSocketChannel.class)
+                .childHandler(new ChannelInitializer<SocketChannel>() {
+                    @Override
+                    public void initChannel(SocketChannel channel) throws Exception {
+                        channel.pipeline()
+                            .addFirst(new StringDecoder(), new ServerEventHandler(), new StringEncoder());
+                    }
+                });
+
+            ChannelFuture future = bootstrap.bind(HOST, PORT)
+                .sync();
+
+            System.out.println("chat server started. ready to accept clients.");
+            future.addListener(new ChannelInfoListener("server online"));
+
+            future.channel()
+                .closeFuture()
+                .sync();
+        } catch (Throwable e) {
+            e.printStackTrace();
+            Thread.currentThread().interrupt();
+        } finally {
+            serverGroup.shutdownGracefully();
+            clientGroup.shutdownGracefully();
+        }
+    }
+}

libraries-server-2/src/main/java/com/baeldung/netty/customhandlersandlisteners/handler/ClientEventHandler.java

@@ -0,0 +1,12 @@
+package com.baeldung.netty.customhandlersandlisteners.handler;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.SimpleChannelInboundHandler;
+
+public class ClientEventHandler extends SimpleChannelInboundHandler<String> {
+
+    @Override
+    protected void channelRead0(ChannelHandlerContext context, String msg) {
+        System.out.println(msg);
+    }
+}