Merge branch 'master' into BAEL-7278

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

@@ -4,4 +4,5 @@
 - [Find the N Most Frequent Elements in a Java Array](https://www.baeldung.com/java-n-most-frequent-elements-array)
 - [Getting Pixel Array From Image in Java](https://www.baeldung.com/java-getting-pixel-array-from-image)
 - [Calculate Distance Between Two Coordinates in Java](https://www.baeldung.com/java-find-distance-between-points)
+- [Rotate Arrays in Java](https://www.baeldung.com/java-rotate-arrays)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-6)

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/rotatearray/RotateArray.java

@@ -0,0 +1,102 @@
+package com.baeldung.algorithms.rotatearray;
+
+/**
+ *  To speed up the rotation, we narrow k rotations to the remainder of k divided by the array length, or k module the array length.
+ *  Therefore, a large rotation number will be translated into the relative smallest rotation.
+ *  All solutions replace the original array, although they might use an extra array to compute the rotation.
+ */
+public class RotateArray {
+
+    private RotateArray() {
+        throw new IllegalStateException("Rotate array algorithm utility methods class");
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void bruteForce(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k %= arr.length;
+        int temp;
+        int previous;
+        for (int i = 0; i < k; i++) {
+            previous = arr[arr.length - 1];
+            for (int j = 0; j < arr.length; j++) {
+                temp = arr[j];
+                arr[j] = previous;
+                previous = temp;
+            }
+        }
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void withExtraArray(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        int[] extraArray = new int[arr.length];
+        for (int i = 0; i < arr.length; i++) {
+            extraArray[(i + k) % arr.length] = arr[i];
+        }
+        System.arraycopy(extraArray, 0, arr, 0, arr.length);
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void cyclicReplacement(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k = k % arr.length;
+        int count = 0;
+        for (int start = 0; count < arr.length; start++) {
+            int current = start;
+            int prev = arr[start];
+            do {
+                int next = (current + k) % arr.length;
+                int temp = arr[next];
+                arr[next] = prev;
+                prev = temp;
+                current = next;
+                count++;
+            } while (start != current);
+        }
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void reverse(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k %= arr.length;
+        reverse(arr, 0, arr.length - 1);
+        reverse(arr, 0, k - 1);
+        reverse(arr, k, arr.length - 1);
+    }
+
+    private static void reverse(int[] nums, int start, int end) {
+        while (start < end) {
+            int temp = nums[start];
+            nums[start] = nums[end];
+            nums[end] = temp;
+            start++;
+            end--;
+        }
+    }
+
+    private static void checkInvalidInput(int[] arr, int rotation) {
+        if (rotation < 1 || arr == null)
+            throw new IllegalArgumentException("Rotation must be greater than zero or array must be not null");
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/connect4/GameBoard.java

@@ -0,0 +1,129 @@
+package com.baeldung.algorithms.connect4;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class GameBoard {
+    private final List<List<Piece>> columns;
+
+    private final int rows;
+
+    public GameBoard(int columns, int rows) {
+        this.rows = rows;
+        this.columns = new ArrayList<>();
+
+        for (int i = 0; i < columns; ++i) {
+            this.columns.add(new ArrayList<>());
+        }
+    }
+
+    public int getRows() {
+        return rows;
+    }
+
+    public int getColumns() {
+        return columns.size();
+    }
+
+    public Piece getCell(int x, int y) {
+        assert(x >= 0 && x < getColumns());
+        assert(y >= 0 && y < getRows());
+
+        List<Piece> column = columns.get(x);
+
+        if (column.size() > y) {
+            return column.get(y);
+        } else {
+            return null;
+        }
+    }
+
+    public boolean move(int x, Piece player) {
+        assert(x >= 0 && x < getColumns());
+
+        List<Piece> column = columns.get(x);
+
+        if (column.size() >= this.rows) {
+            throw new IllegalArgumentException("That column is full");
+        }
+
+        column.add(player);
+
+        return checkWin(x, column.size() - 1, player);
+    }
+
+    private boolean checkWin(int x, int y, Piece player) {
+        // Vertical line
+        if (checkLine(x, y, 0, -1, player)) {
+            return true;
+        }
+
+        for (int offset = 0; offset < 4; ++offset) {
+            // Horizontal line
+            if (checkLine(x - 3 + offset, y, 1, 0, player)) {
+                return true;
+            }
+
+            // Leading diagonal
+            if (checkLine(x - 3 + offset, y + 3 - offset, 1, -1, player)) {
+                return true;
+            }
+
+            // Trailing diagonal
+            if (checkLine(x - 3 + offset, y - 3 + offset, 1, 1, player)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private boolean checkLine(int x1, int y1, int xDiff, int yDiff, Piece player) {
+        for (int i = 0; i < 4; ++i) {
+            int x = x1 + (xDiff * i);
+            int y = y1 + (yDiff * i);
+
+            if (x < 0 || x > columns.size() - 1) {
+                return false;
+            }
+
+            if (y < 0 || y > rows - 1) {
+                return false;
+            }
+
+            if (player != getCell(x, y)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder result = new StringBuilder();
+
+        for (int y = getRows() - 1; y >= 0; --y) {
+            for (int x = 0; x < getColumns(); ++x) {
+                Piece piece = getCell(x, y);
+
+                result.append("|");
+                if (piece == null) {
+                    result.append(" ");
+                } else if (piece == Piece.PLAYER_1) {
+                    result.append("X");
+                } else if (piece == Piece.PLAYER_2) {
+                    result.append("O");
+                }
+            }
+
+            result.append("|\n");
+            for (int i = 0; i < getColumns(); ++i) {
+                result.append("+-");
+            }
+            result.append("+\n");
+        }
+
+        return result.toString();
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/connect4/GameUnitTest.java

@@ -0,0 +1,40 @@
+package com.baeldung.algorithms.connect4;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class GameUnitTest {
+    @Test
+    public void blankGame() {
+        GameBoard gameBoard = new GameBoard(8, 6);
+
+        System.out.println(gameBoard);
+    }
+
+    @Test
+    public void playedGame() {
+        GameBoard gameBoard = new GameBoard(8, 6);
+
+        assertFalse(gameBoard.move(3, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(2, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(4, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(3, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(5, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(6, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(5, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(4, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(5, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(5, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(6, Piece.PLAYER_1));
+        assertTrue(gameBoard.move(4, Piece.PLAYER_2));
+
+        System.out.println(gameBoard);
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/connect4/Piece.java

@@ -0,0 +1,6 @@
+package com.baeldung.algorithms.connect4;
+
+public enum Piece {
+    PLAYER_1,
+    PLAYER_2
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/connect4/README.md

@@ -0,0 +1,2 @@
+## Relevant Articles
+- [Implement Connect 4 Game with Java](https://www.baeldung.com/java-connect-4-game)

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/rotatearray/RotateArrayUnitTest.java

@@ -0,0 +1,124 @@
+package com.baeldung.algorithms.rotatearray;
+
+import static com.baeldung.algorithms.rotatearray.RotateArray.bruteForce;
+import static com.baeldung.algorithms.rotatearray.RotateArray.cyclicReplacement;
+import static com.baeldung.algorithms.rotatearray.RotateArray.reverse;
+import static com.baeldung.algorithms.rotatearray.RotateArray.withExtraArray;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class RotateArrayUnitTest {
+
+    private final int[] arr = { 1, 2, 3, 4, 5, 6 };
+    private final int rotationLtArrayLength = 1;
+    private final int rotationGtArrayLength = arr.length + 2;
+    private final int[] ltArrayLengthRotation = { 6, 1, 2, 3, 4, 5 };
+    private final int[] gtArrayLengthRotation = { 5, 6, 1, 2, 3, 4 };
+
+    @Test
+    void givenInputArray_whenNoRotationOrEmptyArray_thenThrowIllegalArgumentException() {
+        final int noRotation = 0;
+        final int someRotation = arr.length - 1;
+
+        assertThrows(IllegalArgumentException.class, () -> bruteForce(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> withExtraArray(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> cyclicReplacement(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> reverse(arr, noRotation));
+
+        assertThrows(IllegalArgumentException.class, () -> bruteForce(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> withExtraArray(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> cyclicReplacement(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> reverse(null, someRotation));
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationLtArrayLength_thenRotateArrayOk() {
+
+        bruteForce(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationGtArrayLength_thenRotateArrayOk() {
+
+        bruteForce(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationEqArrayLength_thenDoNothing() {
+        int[] expected = arr.clone();
+
+        bruteForce(arr, arr.length);
+        assertArrayEquals(expected, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayRotationLtArrayLength_thenRotateArrayOk() {
+
+        withExtraArray(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayRotationGtArrayLength_thenRotateArrayOk() {
+
+        withExtraArray(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayWithRotationEqArrayLength_thenDoNothing() {
+        int[] clone = arr.clone();
+
+        withExtraArray(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationLtArrayLength_thenRotateArrayOk() {
+
+        cyclicReplacement(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationGtArrayLength_thenRotateArrayOk() {
+
+        cyclicReplacement(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationEqArrayLength_thenDoNothing() {
+        int[] clone = arr.clone();
+
+        cyclicReplacement(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationLtArrayLength_thenRotateArrayOk() {
+
+        reverse(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationGtArrayLength_thenRotateArrayOk() {
+
+        reverse(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationEqArrayLength_thenDoNothing() {
+
+        int[] clone = arr.clone();
+
+        reverse(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+}

algorithms-modules/pom.xml

@@ -28,7 +28,7 @@
     </modules>
 
     <properties>
-        <commons-codec.version>1.11</commons-codec.version>
+        <commons-codec.version>1.16.0</commons-codec.version>
         <commons-math3.version>3.6.1</commons-math3.version>
         <cobertura.plugin.version>2.7</cobertura.plugin.version>
         <tradukisto.version>1.0.1</tradukisto.version>

apache-httpclient/pom.xml

@@ -58,7 +58,7 @@
         </dependency>
 
         <dependency>
-            <groupId>com.github.tomakehurst</groupId>
+            <groupId>org.wiremock</groupId>
             <artifactId>wiremock</artifactId>
             <version>${wiremock.version}</version>
             <scope>test</scope>
@@ -77,11 +77,11 @@
 
     <properties>
         <mockserver.version>5.6.1</mockserver.version>
-        <wiremock.version>2.5.1</wiremock.version>
+        <wiremock.version>3.3.1</wiremock.version>
         <!-- http client & core 5 -->
-        <httpcore5.version>5.2</httpcore5.version>
-        <httpclient5.version>5.2</httpclient5.version>
-        <httpclient5-fluent.version>5.2</httpclient5-fluent.version>
+        <httpcore5.version>5.2.2</httpcore5.version>
+        <httpclient5.version>5.2.2</httpclient5.version>
+        <httpclient5-fluent.version>5.2.2</httpclient5-fluent.version>
     </properties>
 
 </project>

apache-httpclient/src/test/java/com/baeldung/httpclient/GetRequestMockServer.java

@@ -8,7 +8,7 @@ import static org.mockserver.model.HttpResponse.response;
 import java.io.IOException;
 import java.net.ServerSocket;
 
-import org.apache.http.HttpStatus;
+import org.apache.hc.core5.http.HttpStatus;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 import org.mockserver.client.MockServerClient;

apache-httpclient/src/test/java/com/baeldung/httpclient/HttpAsyncClientLiveTest.java

@@ -25,6 +25,7 @@ import org.apache.hc.client5.http.impl.nio.PoolingAsyncClientConnectionManagerBu
 import org.apache.hc.client5.http.impl.routing.DefaultProxyRoutePlanner;
 import org.apache.hc.client5.http.protocol.HttpClientContext;
 import org.apache.hc.client5.http.ssl.ClientTlsStrategyBuilder;
+import org.apache.hc.client5.http.ssl.NoopHostnameVerifier;
 import org.apache.hc.core5.http.HttpHost;
 import org.apache.hc.core5.http.HttpResponse;
 import org.apache.hc.core5.http.nio.ssl.TlsStrategy;
@@ -33,13 +34,10 @@ import org.apache.hc.core5.http.protocol.HttpContext;
 import org.apache.hc.core5.reactor.IOReactorConfig;
 import org.apache.hc.core5.ssl.SSLContexts;
 import org.apache.hc.core5.ssl.TrustStrategy;
-import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
 import org.junit.jupiter.api.Test;
 
 
 class HttpAsyncClientLiveTest extends GetRequestMockServer {
-
-    private static final String HOST = "http://www.google.com";
     private static final String HOST_WITH_SSL = "https://mms.nw.ru/";
     private static final String HOST_WITH_PROXY = "http://httpbin.org/";
     private static final String URL_SECURED_BY_BASIC_AUTHENTICATION = "http://browserspy.dk/password-ok.php";// "http://localhost:8080/spring-security-rest-basic-auth/api/foos/1";
@@ -122,7 +120,7 @@ class HttpAsyncClientLiveTest extends GetRequestMockServer {
             .build();
 
         final TlsStrategy tlsStrategy = ClientTlsStrategyBuilder.create()
-            .setHostnameVerifier(SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER)
+            .setHostnameVerifier(NoopHostnameVerifier.INSTANCE)
             .setSslContext(sslContext)
             .build();
 
@@ -136,7 +134,7 @@ class HttpAsyncClientLiveTest extends GetRequestMockServer {
 
         client.start();
 
-        final SimpleHttpRequest request = new SimpleHttpRequest("GET",HOST_WITH_SSL);
+        final SimpleHttpRequest request = new SimpleHttpRequest("GET", HOST_WITH_SSL);
         final Future<SimpleHttpResponse> future = client.execute(request, null);
 
         final HttpResponse response = future.get();
@@ -201,7 +199,7 @@ class HttpAsyncClientLiveTest extends GetRequestMockServer {
         @Override
         public void run() {
             try {
-                final Future<SimpleHttpResponse> future = client.execute(SimpleHttpRequest.copy(request), context, null);
+                final Future<SimpleHttpResponse> future = client.execute(SimpleRequestBuilder.copy(request).build(), context, null);
                 final HttpResponse response = future.get();
                 assertThat(response.getCode(), equalTo(200));
             } catch (final Exception ex) {

apache-httpclient/src/test/java/com/baeldung/httpclient/ResponseUtil.java

@@ -1,10 +1,10 @@
 package com.baeldung.httpclient;
 
-import org.apache.http.HttpEntity;
-import org.apache.http.client.methods.CloseableHttpResponse;
-
 import java.io.IOException;
 
+import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
+import org.apache.hc.core5.http.HttpEntity;
+
 public final class ResponseUtil {
     private ResponseUtil() {
     }

apache-httpclient/src/test/java/com/baeldung/httpclient/advancedconfig/HttpClientAdvancedConfigurationIntegrationTest.java

@@ -103,7 +103,7 @@ class HttpClientAdvancedConfigurationIntegrationTest {
     void givenServerThatIsBehindProxy_whenClientIsConfiguredToSendRequestViaProxy_shouldReturn200() throws IOException {
         //given
         proxyMock.stubFor(get(urlMatching(".*"))
-          .willReturn(aResponse().proxiedFrom("http://localhost:8089/")));
+          .willReturn(aResponse().proxiedFrom("http://localhost:8089")));
 
         serviceMock.stubFor(get(urlEqualTo("/private"))
           .willReturn(aResponse().withStatus(200)));
@@ -129,7 +129,7 @@ class HttpClientAdvancedConfigurationIntegrationTest {
     public void givenServerThatIsBehindAuthorizationProxy_whenClientSendRequest_shouldAuthorizeProperly() throws IOException {
         //given
         proxyMock.stubFor(get(urlMatching("/private"))
-          .willReturn(aResponse().proxiedFrom("http://localhost:8089/")));
+          .willReturn(aResponse().proxiedFrom("http://localhost:8089")));
         serviceMock.stubFor(get(urlEqualTo("/private"))
           .willReturn(aResponse().withStatus(200)));
 

apache-httpclient4/pom.xml

@@ -158,7 +158,7 @@
             <version>${mockserver.version}</version>
         </dependency>
         <dependency>
-            <groupId>com.github.tomakehurst</groupId>
+            <groupId>org.wiremock</groupId>
             <artifactId>wiremock</artifactId>
             <version>${wiremock.version}</version>
             <scope>test</scope>
@@ -234,10 +234,10 @@
 
     <properties>
         <!-- util -->
-        <commons-codec.version>1.10</commons-codec.version>
+        <commons-codec.version>1.16.0</commons-codec.version>
         <httpasyncclient.version>4.1.5</httpasyncclient.version>
         <!-- testing -->
-        <wiremock.version>2.5.1</wiremock.version>
+        <wiremock.version>3.3.1</wiremock.version>
         <httpcore.version>4.4.16</httpcore.version>
         <httpclient.version>4.5.14</httpclient.version>
         <mockserver.version>5.11.2</mockserver.version>

apache-httpclient4/src/main/java/com/baeldung/filter/CustomWebSecurityConfigurerAdapter.java

@@ -7,14 +7,14 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
-import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
 import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
 import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.security.web.SecurityFilterChain;
 import org.springframework.security.web.authentication.www.BasicAuthenticationFilter;
 
 @Configuration
 @EnableWebSecurity
-public class CustomWebSecurityConfigurerAdapter extends WebSecurityConfigurerAdapter {
+public class CustomWebSecurityConfigurerAdapter {
 
     @Autowired private RestAuthenticationEntryPoint authenticationEntryPoint;
 
@@ -27,8 +27,8 @@ public class CustomWebSecurityConfigurerAdapter extends WebSecurityConfigurerAda
           .authorities("ROLE_USER");
     }
 
-    @Override
-    protected void configure(HttpSecurity http) throws Exception {
+    @Bean
+    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
         http
           .authorizeRequests()
           .antMatchers("/securityNone")
@@ -40,6 +40,8 @@ public class CustomWebSecurityConfigurerAdapter extends WebSecurityConfigurerAda
           .authenticationEntryPoint(authenticationEntryPoint);
 
         http.addFilterAfter(new CustomFilter(), BasicAuthenticationFilter.class);
+
+        return http.build();
     }
     
     @Bean

apache-httpclient4/src/test/java/com/baeldung/httpclient/advancedconfig/HttpClientAdvancedConfigurationIntegrationTest.java

@@ -102,7 +102,7 @@ class HttpClientAdvancedConfigurationIntegrationTest {
     void givenServerThatIsBehindProxy_whenClientIsConfiguredToSendRequestViaProxy_shouldReturn200() throws IOException {
         //given
         proxyMock.stubFor(get(urlMatching(".*"))
-          .willReturn(aResponse().proxiedFrom("http://localhost:8089/")));
+          .willReturn(aResponse().proxiedFrom("http://localhost:8089")));
 
         serviceMock.stubFor(get(urlEqualTo("/private"))
           .willReturn(aResponse().withStatus(200)));
@@ -128,7 +128,7 @@ class HttpClientAdvancedConfigurationIntegrationTest {
     void givenServerThatIsBehindAuthorizationProxy_whenClientSendRequest_shouldAuthorizeProperly() throws IOException {
         //given
         proxyMock.stubFor(get(urlMatching("/private"))
-          .willReturn(aResponse().proxiedFrom("http://localhost:8089/")));
+          .willReturn(aResponse().proxiedFrom("http://localhost:8089")));
         serviceMock.stubFor(get(urlEqualTo("/private"))
           .willReturn(aResponse().withStatus(200)));
 

apache-kafka-2/README.md

@@ -13,3 +13,5 @@ You can build the project from the command line using: *mvn clean install*, or i
 - [Read Data From the Beginning Using Kafka Consumer API](https://www.baeldung.com/java-kafka-consumer-api-read)
 - [Get Partition Count for a Topic in Kafka](https://www.baeldung.com/java-kafka-partition-count-topic)
 - [bootstrap-server in Kafka Configuration](https://www.baeldung.com/java-kafka-bootstrap-server)
+- [Introduction to Apache Kafka](https://www.baeldung.com/apache-kafka)
+- [Ensuring Message Ordering in Kafka: Strategies and Configurations](https://www.baeldung.com/kafka-message-ordering)

apache-kafka-2/log4j.properties

@@ -1 +0,0 @@
-log4j.rootLogger=INFO, stdout

apache-kafka-2/pom.xml

@@ -23,11 +23,6 @@
             <artifactId>slf4j-api</artifactId>
             <version>${org.slf4j.version}</version>
         </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-log4j12</artifactId>
-            <version>${org.slf4j.version}</version>
-        </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
@@ -57,13 +52,19 @@
             <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.databind.version}</version>
+        </dependency>
     </dependencies>
 
     <properties>
         <jna.version>5.7.0</jna.version>
         <kafka.version>2.8.0</kafka.version>
-        <testcontainers-kafka.version>1.15.3</testcontainers-kafka.version>
+        <testcontainers-kafka.version>1.19.3</testcontainers-kafka.version>
         <testcontainers-jupiter.version>1.15.3</testcontainers-jupiter.version>
+        <jackson.databind.version>2.15.2</jackson.databind.version>
     </properties>
 
 </project>

apache-kafka-2/src/main/java/com/baeldung/kafka/message/ordering/Config.java

@@ -0,0 +1,11 @@
+package com.baeldung.kafka.message.ordering;
+
+public class Config {
+    public static final String CONSUMER_VALUE_DESERIALIZER_SERIALIZED_CLASS = "value.deserializer.serializedClass";
+    public static final String MULTI_PARTITION_TOPIC = "multi_partition_topic";
+    public static final String SINGLE_PARTITION_TOPIC = "single_partition_topic";
+
+    public static final int MULTIPLE_PARTITIONS = 5;
+    public static final int SINGLE_PARTITION = 1;
+    public static final short REPLICATION_FACTOR = 1;
+}

apache-kafka-2/src/main/java/com/baeldung/kafka/message/ordering/payload/UserEvent.java

@@ -0,0 +1,61 @@
+package com.baeldung.kafka.message.ordering.payload;
+
+import java.util.Objects;
+
+public class UserEvent implements Comparable<UserEvent> {
+    private String userEventId;
+    private long eventNanoTime;
+    private long globalSequenceNumber;
+
+    @SuppressWarnings("unused")
+    public UserEvent() {
+        // Required for Jackson Serialization and Deserialization
+    }
+
+    public UserEvent(String userEventId) {
+        this.userEventId = userEventId;
+    }
+
+    public String getUserEventId() {
+        return userEventId;
+    }
+
+    public long getEventNanoTime() {
+        return eventNanoTime;
+    }
+
+    public void setEventNanoTime(long eventNanoTime) {
+        this.eventNanoTime = eventNanoTime;
+    }
+
+    public long getGlobalSequenceNumber() {
+        return globalSequenceNumber;
+    }
+
+    public void setGlobalSequenceNumber(long globalSequenceNumber) {
+        this.globalSequenceNumber = globalSequenceNumber;
+    }
+
+    @Override
+    public int compareTo(UserEvent other) {
+        return Long.compare(this.globalSequenceNumber, other.globalSequenceNumber);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (!(obj instanceof UserEvent)) {
+            return false;
+        }
+        UserEvent userEvent = (UserEvent) obj;
+        return this.globalSequenceNumber == userEvent.globalSequenceNumber;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(globalSequenceNumber);
+    }
+}
+

apache-kafka-2/src/main/java/com/baeldung/kafka/message/ordering/serialization/JacksonDeserializer.java

@@ -0,0 +1,34 @@
+package com.baeldung.kafka.message.ordering.serialization;
+
+import com.baeldung.kafka.message.ordering.Config;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import org.apache.kafka.common.serialization.Deserializer;
+
+import java.util.Map;
+
+/**
+ * Configured via {@link org.apache.kafka.clients.consumer.ConsumerConfig#VALUE_DESERIALIZER_CLASS_CONFIG}
+ */
+public class JacksonDeserializer<T> implements Deserializer<T> {
+    private final ObjectMapper objectMapper = new ObjectMapper();
+    private Class<T> type;
+
+    @Override
+    public void configure(Map<String, ?> configs, boolean isKey) {
+        this.type = (Class<T>) configs.get(Config.CONSUMER_VALUE_DESERIALIZER_SERIALIZED_CLASS);
+    }
+
+    @Override
+    public T deserialize(String topic, byte[] bytes) {
+        if (bytes == null) {
+            return null;
+        }
+        try {
+            return objectMapper.readValue(bytes, type);
+        } catch (Exception e) {
+            throw new RuntimeException("Error deserializing value", e);
+        }
+    }
+}
+

apache-kafka-2/src/main/java/com/baeldung/kafka/message/ordering/serialization/JacksonSerializer.java

@@ -0,0 +1,24 @@
+package com.baeldung.kafka.message.ordering.serialization;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import org.apache.kafka.common.serialization.Serializer;
+
+/**
+ * Configured via {@link org.apache.kafka.clients.producer.ProducerConfig#VALUE_SERIALIZER_CLASS_CONFIG}
+ */
+public class JacksonSerializer<T> implements Serializer<T> {
+    private final ObjectMapper objectMapper = new ObjectMapper();
+
+    @Override
+    public byte[] serialize(String topic, T data) {
+        if (data == null) {
+            return null;
+        }
+        try {
+            return objectMapper.writeValueAsBytes(data);
+        } catch (Exception e) {
+            throw new RuntimeException("Error serializing value", e);
+        }
+    }
+}

apache-kafka-2/src/test/java/com/baeldung/kafka/message/ordering/ExternalSequenceWithTimeWindowLiveTest.java

@@ -0,0 +1,126 @@
+package com.baeldung.kafka.message.ordering;
+
+import com.baeldung.kafka.message.ordering.payload.UserEvent;
+import com.baeldung.kafka.message.ordering.serialization.JacksonDeserializer;
+import com.baeldung.kafka.message.ordering.serialization.JacksonSerializer;
+
+import org.apache.kafka.clients.admin.*;
+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.apache.kafka.clients.producer.RecordMetadata;
+import org.apache.kafka.common.serialization.LongDeserializer;
+import org.apache.kafka.common.serialization.LongSerializer;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+import java.time.Duration;
+import java.util.*;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+import com.google.common.collect.ImmutableList;
+
+import static org.assertj.core.api.AssertionsForInterfaceTypes.assertThat;
+
+@Testcontainers
+public class ExternalSequenceWithTimeWindowLiveTest {
+
+    private static Admin admin;
+    private static KafkaProducer<Long, UserEvent> producer;
+    private static KafkaConsumer<Long, UserEvent> consumer;
+    private static final Duration TIMEOUT_WAIT_FOR_MESSAGES = Duration.ofSeconds(5);
+    private static final long BUFFER_PERIOD_NS = Duration.ofSeconds(5)
+        .toNanos();
+    private static Logger logger = LoggerFactory.getLogger(ExternalSequenceWithTimeWindowLiveTest.class);
+
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+
+    @BeforeAll
+    static void setup() throws ExecutionException, InterruptedException {
+        KAFKA_CONTAINER.addExposedPort(9092);
+
+        Properties adminProperties = new Properties();
+        adminProperties.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+
+        Properties producerProperties = new Properties();
+        producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, LongSerializer.class.getName());
+        producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JacksonSerializer.class.getName());
+
+        Properties consumerProperties = new Properties();
+        consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, LongDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JacksonDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        consumerProperties.put(Config.CONSUMER_VALUE_DESERIALIZER_SERIALIZED_CLASS, UserEvent.class);
+        consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, "test-group");
+        admin = Admin.create(adminProperties);
+        producer = new KafkaProducer<>(producerProperties);
+        consumer = new KafkaConsumer<>(consumerProperties);
+        admin.createTopics(ImmutableList.of(new NewTopic(Config.MULTI_PARTITION_TOPIC, Config.MULTIPLE_PARTITIONS, Config.REPLICATION_FACTOR)))
+            .all()
+            .get();
+    }
+
+    @AfterAll
+    static void destroy() {
+        KAFKA_CONTAINER.stop();
+    }
+
+    @Test
+    void givenMultiplePartitions_whenPublishedToKafkaAndConsumedWithExtSeqNumberAndTimeWindow_thenCheckForMessageOrder() throws ExecutionException, InterruptedException {
+        List<UserEvent> sentUserEventList = new ArrayList<>();
+        List<UserEvent> receivedUserEventList = new ArrayList<>();
+        for (long sequenceNumber = 1; sequenceNumber <= 10; sequenceNumber++) {
+            UserEvent userEvent = new UserEvent(UUID.randomUUID()
+                .toString());
+            userEvent.setEventNanoTime(System.nanoTime());
+            userEvent.setGlobalSequenceNumber(sequenceNumber);
+            Future<RecordMetadata> future = producer.send(new ProducerRecord<>(Config.MULTI_PARTITION_TOPIC, sequenceNumber, userEvent));
+            sentUserEventList.add(userEvent);
+            RecordMetadata metadata = future.get();
+            logger.info("User Event ID: " + userEvent.getUserEventId() + ", Partition : " + metadata.partition());
+        }
+
+        consumer.subscribe(Collections.singletonList(Config.MULTI_PARTITION_TOPIC));
+        List<UserEvent> buffer = new ArrayList<>();
+        long lastProcessedTime = System.nanoTime();
+        ConsumerRecords<Long, UserEvent> records = consumer.poll(TIMEOUT_WAIT_FOR_MESSAGES);
+        records.forEach(record -> {
+            buffer.add(record.value());
+        });
+        while (!buffer.isEmpty()) {
+            if (System.nanoTime() - lastProcessedTime > BUFFER_PERIOD_NS) {
+                processBuffer(buffer, receivedUserEventList);
+                lastProcessedTime = System.nanoTime();
+            }
+            records = consumer.poll(TIMEOUT_WAIT_FOR_MESSAGES);
+            records.forEach(record -> {
+                buffer.add(record.value());
+            });
+        }
+        assertThat(receivedUserEventList).isEqualTo(sentUserEventList)
+            .containsExactlyElementsOf(sentUserEventList);
+    }
+
+    private static void processBuffer(List<UserEvent> buffer, List<UserEvent> receivedUserEventList) {
+        Collections.sort(buffer);
+        buffer.forEach(userEvent -> {
+            receivedUserEventList.add(userEvent);
+            logger.info("Processing message with Global Sequence number: " + userEvent.getGlobalSequenceNumber() + ", User Event Id: " + userEvent.getUserEventId());
+        });
+        buffer.clear();
+    }
+}

apache-kafka-2/src/test/java/com/baeldung/kafka/message/ordering/MultiplePartitionLiveTest.java

@@ -0,0 +1,105 @@
+package com.baeldung.kafka.message.ordering;
+
+import com.baeldung.kafka.message.ordering.payload.UserEvent;
+import com.baeldung.kafka.message.ordering.serialization.JacksonDeserializer;
+import com.baeldung.kafka.message.ordering.serialization.JacksonSerializer;
+
+import org.apache.kafka.clients.admin.*;
+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.apache.kafka.clients.producer.RecordMetadata;
+import org.apache.kafka.common.serialization.LongDeserializer;
+import org.apache.kafka.common.serialization.LongSerializer;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+import java.time.Duration;
+import java.util.*;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+import com.google.common.collect.ImmutableList;
+
+import static org.assertj.core.api.AssertionsForInterfaceTypes.assertThat;
+
+@Testcontainers
+public class MultiplePartitionLiveTest {
+
+    private static Admin admin;
+    private static KafkaProducer<Long, UserEvent> producer;
+    private static KafkaConsumer<Long, UserEvent> consumer;
+    private static final Duration TIMEOUT_WAIT_FOR_MESSAGES = Duration.ofSeconds(5);
+
+    private static Logger logger = LoggerFactory.getLogger(MultiplePartitionLiveTest.class);
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+
+    @BeforeAll
+    static void setup() throws ExecutionException, InterruptedException {
+        KAFKA_CONTAINER.addExposedPort(9092);
+
+        Properties adminProperties = new Properties();
+        adminProperties.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+
+        Properties producerProperties = new Properties();
+        producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, LongSerializer.class.getName());
+        producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JacksonSerializer.class.getName());
+
+        Properties consumerProperties = new Properties();
+        consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, LongDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JacksonDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        consumerProperties.put(Config.CONSUMER_VALUE_DESERIALIZER_SERIALIZED_CLASS, UserEvent.class);
+        consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, "test-group");
+        admin = Admin.create(adminProperties);
+        producer = new KafkaProducer<>(producerProperties);
+        consumer = new KafkaConsumer<>(consumerProperties);
+        admin.createTopics(ImmutableList.of(new NewTopic(Config.MULTI_PARTITION_TOPIC, Config.MULTIPLE_PARTITIONS, Config.REPLICATION_FACTOR)))
+            .all()
+            .get();
+    }
+
+    @AfterAll
+    static void destroy() {
+        KAFKA_CONTAINER.stop();
+    }
+
+    @Test
+    void givenMultiplePartitions_whenPublishedToKafkaAndConsumed_thenCheckForMessageOrder() throws ExecutionException, InterruptedException {
+        List<UserEvent> sentUserEventList = new ArrayList<>();
+        List<UserEvent> receivedUserEventList = new ArrayList<>();
+        for (long sequenceNumber = 1; sequenceNumber <= 10; sequenceNumber++) {
+            UserEvent userEvent = new UserEvent(UUID.randomUUID()
+                .toString());
+            userEvent.setGlobalSequenceNumber(sequenceNumber);
+            userEvent.setEventNanoTime(System.nanoTime());
+            Future<RecordMetadata> future = producer.send(new ProducerRecord<>(Config.MULTI_PARTITION_TOPIC, sequenceNumber, userEvent));
+            sentUserEventList.add(userEvent);
+            RecordMetadata metadata = future.get();
+            logger.info("User Event ID: " + userEvent.getUserEventId() + ", Partition : " + metadata.partition());
+        }
+
+        consumer.subscribe(Collections.singletonList(Config.MULTI_PARTITION_TOPIC));
+        ConsumerRecords<Long, UserEvent> records = consumer.poll(TIMEOUT_WAIT_FOR_MESSAGES);
+        records.forEach(record -> {
+            UserEvent userEvent = record.value();
+            receivedUserEventList.add(userEvent);
+            logger.info("User Event ID: " + userEvent.getUserEventId());
+        });
+        assertThat(receivedUserEventList).isNotEqualTo(sentUserEventList)
+            .containsExactlyInAnyOrderElementsOf(sentUserEventList);
+    }
+}

apache-kafka-2/src/test/java/com/baeldung/kafka/message/ordering/SinglePartitionLiveTest.java

@@ -0,0 +1,109 @@
+package com.baeldung.kafka.message.ordering;
+
+import com.baeldung.kafka.message.ordering.payload.UserEvent;
+import com.baeldung.kafka.message.ordering.serialization.JacksonDeserializer;
+import com.baeldung.kafka.message.ordering.serialization.JacksonSerializer;
+
+import org.apache.kafka.clients.admin.Admin;
+import org.apache.kafka.clients.admin.AdminClientConfig;
+import org.apache.kafka.clients.admin.NewTopic;
+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.apache.kafka.clients.producer.RecordMetadata;
+import org.apache.kafka.common.serialization.LongDeserializer;
+import org.apache.kafka.common.serialization.LongSerializer;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+import java.time.Duration;
+import java.util.*;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+import com.google.common.collect.ImmutableList;
+
+import static org.assertj.core.api.AssertionsForInterfaceTypes.assertThat;
+
+@Testcontainers
+public class SinglePartitionLiveTest {
+
+    private static Admin admin;
+    private static KafkaProducer<Long, UserEvent> producer;
+    private static KafkaConsumer<Long, UserEvent> consumer;
+
+    private static final Duration TIMEOUT_WAIT_FOR_MESSAGES = Duration.ofSeconds(5);
+
+    private static Logger logger = LoggerFactory.getLogger(SinglePartitionLiveTest.class);
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+
+    @BeforeAll
+    static void setup() throws ExecutionException, InterruptedException {
+        KAFKA_CONTAINER.addExposedPort(9092);
+
+        Properties adminProperties = new Properties();
+        adminProperties.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+
+        Properties producerProperties = new Properties();
+        producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, LongSerializer.class.getName());
+        producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JacksonSerializer.class.getName());
+
+        Properties consumerProperties = new Properties();
+        consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, LongDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JacksonDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        consumerProperties.put(Config.CONSUMER_VALUE_DESERIALIZER_SERIALIZED_CLASS, UserEvent.class);
+        consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, "test-group");
+        admin = Admin.create(adminProperties);
+        producer = new KafkaProducer<>(producerProperties);
+        consumer = new KafkaConsumer<>(consumerProperties);
+        admin.createTopics(ImmutableList.of(new NewTopic(Config.SINGLE_PARTITION_TOPIC, Config.SINGLE_PARTITION, Config.REPLICATION_FACTOR)))
+            .all()
+            .get();
+    }
+
+    @AfterAll
+    static void destroy() {
+        KAFKA_CONTAINER.stop();
+    }
+
+    @Test
+    void givenASinglePartition_whenPublishedToKafkaAndConsumed_thenCheckForMessageOrder() throws ExecutionException, InterruptedException {
+        List<UserEvent> sentUserEventList = new ArrayList<>();
+        List<UserEvent> receivedUserEventList = new ArrayList<>();
+        for (long sequenceNumber = 1; sequenceNumber <= 10; sequenceNumber++) {
+            UserEvent userEvent = new UserEvent(UUID.randomUUID()
+                .toString());
+            userEvent.setGlobalSequenceNumber(sequenceNumber);
+            userEvent.setEventNanoTime(System.nanoTime());
+            ProducerRecord<Long, UserEvent> producerRecord = new ProducerRecord<>(Config.SINGLE_PARTITION_TOPIC, userEvent);
+            Future<RecordMetadata> future = producer.send(producerRecord);
+            sentUserEventList.add(userEvent);
+            RecordMetadata metadata = future.get();
+            logger.info("User Event ID: " + userEvent.getUserEventId() + ", Partition : " + metadata.partition());
+        }
+
+        consumer.subscribe(Collections.singletonList(Config.SINGLE_PARTITION_TOPIC));
+        ConsumerRecords<Long, UserEvent> records = consumer.poll(TIMEOUT_WAIT_FOR_MESSAGES);
+        records.forEach(record -> {
+            UserEvent userEvent = record.value();
+            receivedUserEventList.add(userEvent);
+            logger.info("User Event ID: " + userEvent.getUserEventId());
+        });
+        assertThat(receivedUserEventList).isEqualTo(sentUserEventList)
+            .containsExactlyElementsOf(sentUserEventList);
+    }
+}

apache-kafka-2/src/test/java/com/baeldung/kafka/multipletopics/MultipleTopicsLiveTest.java

@@ -0,0 +1,103 @@
+package com.baeldung.kafka.multipletopics;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Properties;
+import java.util.concurrent.ExecutionException;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+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.apache.kafka.common.serialization.StringDeserializer;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+// This live test needs a Docker Daemon running so that a kafka container can be created
+
+@Testcontainers
+public class MultipleTopicsLiveTest {
+
+    private final Logger log = LoggerFactory.getLogger(MultipleTopicsLiveTest.class);
+
+    private static final String CARD_PAYMENTS_TOPIC = "card-payments";
+    private static final String BANK_TRANSFERS_TOPIC = "bank-transfers";
+    private static KafkaProducer<String, String> producer;
+    private static KafkaConsumer<String, String> consumer;
+
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+
+    @BeforeAll
+    static void setup() {
+        KAFKA_CONTAINER.addExposedPort(9092);
+        producer = new KafkaProducer<>(getProducerProperties());
+        consumer = new KafkaConsumer<>(getConsumerProperties());
+    }
+
+    @AfterAll
+    static void destroy() {
+        KAFKA_CONTAINER.stop();
+    }
+
+    private static Properties getProducerProperties() {
+        Properties producerProperties = new Properties();
+        producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        return producerProperties;
+    }
+
+    private static Properties getConsumerProperties() {
+        Properties consumerProperties = new Properties();
+        consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, "payments");
+        return consumerProperties;
+    }
+
+    @Test
+    void whenSendingMessagesOnTwoTopics_thenConsumerReceivesMessages() throws Exception {
+        publishMessages();
+
+        consumer.subscribe(Arrays.asList(CARD_PAYMENTS_TOPIC, BANK_TRANSFERS_TOPIC));
+
+        int eventsProcessed = 0;
+        for (ConsumerRecord<String, String> record : consumer.poll(Duration.ofSeconds(10))) {
+            log.info("Event on topic={}, payload={}", record.topic(), record.value());
+            eventsProcessed++;
+        }
+
+        assertThat(eventsProcessed).isEqualTo(2);
+    }
+
+    private void publishMessages() throws ExecutionException, InterruptedException {
+        ProducerRecord<String, String> cardPayment = new ProducerRecord<>(CARD_PAYMENTS_TOPIC, createCardPayment());
+        producer.send(cardPayment).get();
+
+        ProducerRecord<String, String> bankTransfer = new ProducerRecord<>(BANK_TRANSFERS_TOPIC, createBankTransfer());
+        producer.send(bankTransfer).get();
+    }
+
+    private String createCardPayment() {
+        return "{\"paymentReference\":\"A184028KM0013790\", \"type\":\"card\", \"amount\":\"275\", \"currency\":\"GBP\"}";
+    }
+
+    private String createBankTransfer() {
+        return "{\"paymentReference\":\"19ae2-18mk73-009\", \"type\":\"bank\", \"amount\":\"150\", \"currency\":\"EUR\"}";
+    }
+}

apache-kafka-2/src/test/resources/logback.xml

@@ -0,0 +1,11 @@
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

apache-kafka/pom.xml

@@ -181,8 +181,9 @@
     </build>
 
     <properties>
+        <jackson.version>2.13.4</jackson.version>
         <kafka.version>3.4.0</kafka.version>
-        <testcontainers-kafka.version>1.15.3</testcontainers-kafka.version>
+        <testcontainers-kafka.version>1.19.3</testcontainers-kafka.version>
         <testcontainers-jupiter.version>1.15.3</testcontainers-jupiter.version>
         <flink.version>1.16.1</flink.version>
         <awaitility.version>3.0.0</awaitility.version>

apache-kafka/src/test/java/com/baeldung/flink/BackupCreatorUnitTest.java

@@ -29,7 +29,7 @@ import java.util.List;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 
-public class BackupCreatorIntegrationTest {
+public class BackupCreatorUnitTest {
     public static ObjectMapper mapper;
 
     @Before