Merge branch 'eugenp:master' into master

algorithms-modules/algorithms-miscellaneous-8/src/main/java/com/baeldung/algorithms/mergeintervals/MergeOverlappingIntervals.java

@@ -1,23 +1,22 @@
 package com.baeldung.algorithms.mergeintervals;
 
+import static java.lang.Integer.max;
+
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
 
 public class MergeOverlappingIntervals {
 
     public List<Interval> doMerge(List<Interval> intervals) {
-        // Sort the intervals based on start time
-        intervals.sort((one, two) -> one.start - two.start);
-
-        // Create somewhere to put the merged list, start it off with the earliest starting interval
+        intervals.sort(Comparator.comparingInt(interval -> interval.start));
         ArrayList<Interval> merged = new ArrayList<>();
         merged.add(intervals.get(0));
 
-        // Loop over each interval and merge if start time is before the end time of the
-        // previous interval
         intervals.forEach(interval -> {
-            if (merged.get(merged.size() - 1).end > interval.start) {
-                merged.get(merged.size() - 1).setEnd(interval.end);
+            Interval lastMerged = merged.get(merged.size() - 1);
+            if (interval.start <= lastMerged.end){
+                lastMerged.setEnd(max(interval.end, lastMerged.end));
             } else {
                 merged.add(interval);
             }
@@ -25,5 +24,4 @@ public class MergeOverlappingIntervals {
 
         return merged;
     }
-
-}
+}

algorithms-modules/algorithms-miscellaneous-8/src/test/java/com/baeldung/algorithms/mergeintervals/MergeIntervalsUnitTest.java

@@ -1,30 +1,38 @@
 package com.baeldung.algorithms.mergeintervals;
 
-import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 
 import org.junit.jupiter.api.Test;
 
 class MergeIntervalsUnitTest {
 
-    private ArrayList<Interval> intervals = new ArrayList<>(Arrays.asList(
-      new Interval(2, 5),
-      new Interval(13, 20),
-      new Interval(11, 15),
-      new Interval(1, 3)
+    private List<Interval> intervals = new ArrayList<>(Arrays.asList(
+        // @formatter:off
+        new Interval(3, 5),
+        new Interval(13, 20),
+        new Interval(11, 15),
+        new Interval(15, 16),
+        new Interval(1, 3),
+        new Interval(4, 5),
+        new Interval(16, 17)
+        // @formatter:on
     ));
-    private ArrayList<Interval> intervalsMerged = new ArrayList<>(Arrays.asList(
-      new Interval(1, 5),
-      new Interval(11, 20)
+    private List<Interval> intervalsMerged = new ArrayList<>(Arrays.asList(
+        // @formatter:off
+        new Interval(1, 5),
+        new Interval(11, 20)
+        // @formatter:on
     ));
 
     @Test
     void givenIntervals_whenMerging_thenReturnMergedIntervals() {
         MergeOverlappingIntervals merger = new MergeOverlappingIntervals();
-        ArrayList<Interval> result = (ArrayList<Interval>) merger.doMerge(intervals);
-        assertArrayEquals(intervalsMerged.toArray(), result.toArray());
+        List<Interval> result = merger.doMerge(intervals);
+        assertEquals(intervalsMerged, result);
     }
 
-}
+}

core-java-modules/core-java-arrays-operations-advanced-2/README.md

@@ -3,3 +3,4 @@
 - [Find the Equilibrium Indexes of an Array in Java](https://www.baeldung.com/java-equilibrium-index-array)
 - [Moves Zeros to the End of an Array in Java](https://www.baeldung.com/java-array-sort-move-zeros-end)
 - [Finding the Majority Element of an Array in Java](https://www.baeldung.com/java-array-find-majority-element)
+- [Set Matrix Elements to Zero in Java](https://www.baeldung.com/java-set-matrix-elements-to-zero)

core-java-modules/core-java-arrays-operations-advanced-2/src/main/java/com/baeldung/matrixtozero/SetMatrixToZero.java

@@ -0,0 +1,147 @@
+package com.baeldung.matrixtozero;
+
+import java.util.*;
+
+public class SetMatrixToZero{
+    static void setZeroesByNaiveApproach(int[][] matrix) {
+        int row = matrix.length;
+        int col = matrix[0].length;
+        int [][] result = new int[row][col];
+
+        for(int i = 0; i<row; i++){
+            for(int j = 0; j < col; j++){
+                result[i][j] = matrix[i][j];
+            }
+        }
+        
+        for(int i = 0; i < row; i++){
+            for(int j = 0; j < col; j++){
+                if(matrix[i][j] == 0){
+                    for(int k = 0; k < col; k++){
+                        result[i][k] = 0;
+                    }
+                    for(int k = 0; k < row; k++){
+                        result[k][j] = 0;
+                    }
+                }
+            }
+        }
+
+        for(int i = 0; i < row; i++){
+            for(int j = 0; j < col; j++){
+                matrix[i][j] = result[i][j];
+            }
+        }
+    }
+    
+    static void setZeroesByTimeOptimizedApproach(int[][] matrix) {
+        int rows = matrix.length;
+        int cols = matrix[0].length;
+
+        Set<Integer> rowSet = new HashSet<>();
+        Set<Integer> colSet = new HashSet<>();
+
+        for(int i = 0; i < rows; i++){
+            for(int j = 0; j < cols; j++){
+                if (matrix[i][j] == 0){
+                    rowSet.add(i);
+                    colSet.add(j);
+                }
+            }
+        }
+        
+        for(int row: rowSet){
+            for(int j = 0; j < cols; j++){
+                matrix[row][j] = 0;
+            }
+        }
+        
+        for(int col: colSet) {
+            for(int i = 0; i < rows; i++){
+                matrix[i][col] = 0;
+            }
+        }
+    } 
+
+    static boolean hasZeroInFirstRow(int[][] matrix, int cols) {
+        for (int j = 0; j < cols; j++) {
+            if (matrix[0][j] == 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    static boolean hasZeroInFirstCol(int[][] matrix, int rows) {
+        for (int i = 0; i < rows; i++) {
+            if (matrix[i][0] == 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    static void markZeroesInMatrix(int[][] matrix, int rows, int cols) {
+        for (int i = 1; i < rows; i++) {
+            for (int j = 1; j < cols; j++) {
+                if (matrix[i][j] == 0) {
+                    matrix[i][0] = 0;
+                    matrix[0][j] = 0;
+                }
+            }
+        }
+    }
+
+    static void setZeroesInRows(int[][] matrix, int rows, int cols) {
+        for (int i = 1; i < rows; i++) {
+            if (matrix[i][0] == 0) {
+                for (int j = 1; j < cols; j++) {
+                    matrix[i][j] = 0;
+                }
+            }
+        }
+    }
+
+    static void setZeroesInCols(int[][] matrix, int rows, int cols) {
+        for (int j = 1; j < cols; j++) {
+            if (matrix[0][j] == 0) {
+                for (int i = 1; i < rows; i++) {
+                    matrix[i][j] = 0;
+                }
+            }
+        }
+    }
+
+    static void setZeroesInFirstRow(int[][] matrix, int cols) {
+        for (int j = 0; j < cols; j++) {
+            matrix[0][j] = 0;
+        }
+    }
+
+    static void setZeroesInFirstCol(int[][] matrix, int rows) {
+        for (int i = 0; i < rows; i++) {
+            matrix[i][0] = 0;
+        }
+    }
+
+    static void setZeroesByOptimalApproach(int[][] matrix) {
+        int rows = matrix.length;
+        int cols = matrix[0].length;
+        
+        boolean firstRowZero = hasZeroInFirstRow(matrix, cols);
+        boolean firstColZero = hasZeroInFirstCol(matrix, rows);
+        
+        markZeroesInMatrix(matrix, rows, cols);
+        
+        setZeroesInRows(matrix, rows, cols);
+        setZeroesInCols(matrix, rows, cols);
+        
+        if (firstRowZero) {
+            setZeroesInFirstRow(matrix, cols);
+        }
+        if (firstColZero) {
+            setZeroesInFirstCol(matrix, rows);
+        }
+    }
+
+}

core-java-modules/core-java-arrays-operations-advanced-2/src/test/java/com/baeldung/matrixtozero/SetMatrixToZeroUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.matrixtozero;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import org.junit.jupiter.api.Test;
+
+public class SetMatrixToZeroUnitTest{
+    @Test 
+    void givenMatrix_whenUsingSetZeroesByNaiveApproach_thenSetZeroes() {
+        int[][] matrix = {
+                {1, 2, 3},
+                {4, 0, 6},
+                {7, 8, 9}
+        };
+        int[][] expected = {
+                {1, 0, 3},
+                {0, 0, 0},
+                {7, 0, 9}
+        };
+        SetMatrixToZero.setZeroesByNaiveApproach(matrix);
+        assertArrayEquals(expected, matrix);
+    }
+
+    @Test
+    void givenMatrix_whenUsingSetZeroesByTimeOptimizedApproach_thenSetZeroes() {
+        int[][] matrix = {
+                {1, 2, 3},
+                {4, 0, 6},
+                {7, 8, 9}
+        };
+        int[][] expected = {
+                {1, 0, 3},
+                {0, 0, 0},
+                {7, 0, 9}
+        };
+        SetMatrixToZero.setZeroesByTimeOptimizedApproach(matrix);
+        assertArrayEquals(expected, matrix);
+    }
+
+    @Test
+    void givenMatrix_whenUsingSetZeroesByOptimalApproach_thenSetZeroes() {
+        int[][] matrix = {
+                {1, 2, 3},
+                {4, 0, 6},
+                {7, 8, 9}
+        };
+        int[][] expected = {
+                {1, 0, 3},
+                {0, 0, 0},
+                {7, 0, 9}
+        };
+        SetMatrixToZero.setZeroesByOptimalApproach(matrix);
+        assertArrayEquals(expected, matrix);
+    }
+}

core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/printnullvalues/Employee.java

@@ -0,0 +1,44 @@
+package com.baeldung.printnullvalues;
+
+import java.util.Objects;
+import java.util.Optional;
+
+public class Employee {
+    private String name;
+    private int age;
+    private String department;
+
+    public Employee(String name, int age, String department) {
+        this.name = name;
+        this.age = age;
+        this.department = department;
+    }
+
+    public String toStringUsingNullCheck() {
+        return "Name: " + (name != null ? name : "Unknown") +
+                ", Age: " + age +
+                ", Department: " + (department != null ? department : "Unknown");
+    }
+
+    public String toStringUsingOptional() {
+        return "Name: " + Optional.ofNullable(name).orElse("Unknown") +
+                ", Age: " + age +
+                ", Department: " + Optional.ofNullable(department).orElse("Unknown");
+    }
+
+    private String getDefaultIfNull(String value, String defaultValue) {
+        return value != null ? value : defaultValue;
+    }
+
+    public String toStringUsingCustomHelper() {
+        return "Name: " + getDefaultIfNull(name, "Unknown") +
+                ", Age: " + age +
+                ", Department: " + getDefaultIfNull(department, "Unknown");
+    }
+
+    public String toStringUsingObjects() {
+        return "Name: " + Objects.toString(name, "Unknown") +
+                ", Age: " + age +
+                ", Department: " + Objects.toString(department, "Unknown");
+    }
+}

core-java-modules/core-java-lang-oop-others/src/test/java/com/baeldung/printnullvalues/PrintingNullValuesUnitTest.java

@@ -0,0 +1,30 @@
+package com.baeldung.printnullvalues;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class PrintingNullValuesUnitTest {
+    Employee employee = new Employee(null, 30, null);
+    String expected = "Name: Unknown, Age: 30, Department: Unknown";
+
+    @Test
+    public void givenNullValues_whenToStringUsingNullCheck_thenCorrectStringReturned() {
+        assertEquals(expected, employee.toStringUsingNullCheck());
+    }
+
+    @Test
+    public void givenNullValues_whenToStringUsingOptional_thenCorrectStringReturned() {
+        assertEquals(expected, employee.toStringUsingOptional());
+    }
+
+    @Test
+    public void givenNullValues_whenToStringUsingCustomHelper_thenCorrectStringReturned() {
+        assertEquals(expected, employee.toStringUsingCustomHelper());
+    }
+
+    @Test
+    public void givenNullValues_whenToStringUsingObjects_thenCorrectStringReturned() {
+        assertEquals(expected, employee.toStringUsingObjects());
+    }
+}

core-java-modules/core-java-networking-5/README.md

@@ -0,0 +1,2 @@
+## Relevant Articles:
+- [[<-- Prev]](/core-java-modules/core-java-networking-4)

core-java-modules/core-java-networking-5/pom.xml

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-networking-5</artifactId>
+    <packaging>jar</packaging>
+    <name>core-java-networking-5</name>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>commons-validator</groupId>
+            <artifactId>commons-validator</artifactId>
+            <version>${commons-validator.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jsoup</groupId>
+            <artifactId>jsoup</artifactId>
+            <version>${jsoup.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpclient</artifactId>
+            <version>${httpclient.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.ws.rs</groupId>
+            <artifactId>javax.ws.rs-api</artifactId>
+            <version>${javax.ws.rs-api.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.glassfish.jersey.core</groupId>
+            <artifactId>jersey-common</artifactId>
+            <version>${jersey-common.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-web</artifactId>
+            <version>${spring-web.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <commons-validator.version>1.7</commons-validator.version>
+        <jsoup.version>1.17.2</jsoup.version>
+        <httpclient.version>4.5.2</httpclient.version>
+        <javax.ws.rs-api.version>2.1.1</javax.ws.rs-api.version>
+        <jersey-common.version>2.22.2</jersey-common.version>
+        <spring-web.version>6.0.6</spring-web.version>
+    </properties>
+
+</project>

core-java-modules/core-java-networking-5/src/test/java/com/baeldung/redirectedurl/RedirectedUrlUnitTest.java

@@ -0,0 +1,57 @@
+package com.baeldung.redirectedurl;
+
+import org.apache.http.client.config.RequestConfig;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClients;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+import static org.junit.Assert.assertEquals;
+
+public class RedirectedUrlUnitTest {
+    String canonicalUrl = "http://www.baeldung.com/";
+    String expectedRedirectedUrl = "https://www.baeldung.com/";
+
+    @Test
+    public void givenOriginalUrl_whenFindRedirectUrlUsingHttpURLConnection_thenCorrectRedirectedUrlReturned() throws IOException {
+        URL url = new URL(canonicalUrl);
+        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+        connection.setInstanceFollowRedirects(true);
+        int status = connection.getResponseCode();
+        String redirectedUrl = null;
+        if (status == HttpURLConnection.HTTP_MOVED_PERM || status == HttpURLConnection.HTTP_MOVED_TEMP) {
+            redirectedUrl = connection.getHeaderField("Location");
+        }
+        connection.disconnect();
+        assertEquals(expectedRedirectedUrl, redirectedUrl);
+    }
+
+    @Test
+    public void givenOriginalUrl_whenFindRedirectUrlUsingHttpClient_thenCorrectRedirectedUrlReturned() throws IOException {
+        RequestConfig config = RequestConfig.custom()
+                .setRedirectsEnabled(false)
+                .build();
+        try (CloseableHttpClient httpClient = HttpClients.custom()
+                .setDefaultRequestConfig(config)
+                .build()) {
+            HttpGet httpGet = new HttpGet(canonicalUrl);
+            try (CloseableHttpResponse response = httpClient.execute(httpGet)) {
+                int statusCode = response.getStatusLine().getStatusCode();
+                String redirectedUrl = null;
+                if (statusCode == HttpURLConnection.HTTP_MOVED_PERM || statusCode == HttpURLConnection.HTTP_MOVED_TEMP) {
+                    org.apache.http.Header[] headers = response.getHeaders("Location");
+                    if (headers.length > 0) {
+                        redirectedUrl = headers[0].getValue();
+                    }
+                }
+                assertEquals(expectedRedirectedUrl, redirectedUrl);
+            }
+        }
+    }
+
+}

core-java-modules/pom.xml

@@ -165,6 +165,7 @@
         <module>core-java-networking</module>
         <module>core-java-networking-2</module>
         <module>core-java-networking-4</module>
+        <module>core-java-networking-5</module>
         <module>core-java-nio</module>
         <module>core-java-nio-2</module>
         <module>core-java-numbers</module>

libraries-stream/pom.xml

@@ -49,11 +49,23 @@
 
     <properties>
         <jool.version>0.9.12</jool.version>
-        <parallel-collectors.version>2.6.0</parallel-collectors.version>
+        <parallel-collectors.version>3.0.0</parallel-collectors.version>
         <vavr.version>0.9.0</vavr.version>
         <eclipse-collections.version>8.2.0</eclipse-collections.version>
         <streamex.version>0.8.1</streamex.version>
         <protonpack.version>1.15</protonpack.version>
     </properties>
 
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>21</source>
+                    <target>21</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
 </project>

libraries-stream/src/test/java/com/baeldung/parallel_collectors/ParallelCollectorsVirtualThreadsManualTest.java

@@ -0,0 +1,73 @@
+package com.baeldung.parallel_collectors;
+
+import com.pivovarit.collectors.ParallelCollectors;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.concurrent.Executors;
+import java.util.function.Supplier;
+import java.util.stream.Stream;
+
+import static java.util.stream.Collectors.toList;
+
+public class ParallelCollectorsVirtualThreadsManualTest {
+
+    private static final Logger log = LoggerFactory.getLogger(ParallelCollectorsVirtualThreadsManualTest.class);
+
+    // increase the number of parallel processes to find the max number of threads on your machine
+    @Test
+    public void givenParallelism_whenUsingOSThreads_thenShouldRunOutOfThreads() {
+        int parallelProcesses = 50_000;
+
+        var e = Executors.newFixedThreadPool(parallelProcesses);
+
+        var result = timed(() -> Stream.iterate(0, i -> i + 1).limit(parallelProcesses)
+          .collect(ParallelCollectors.parallel(i -> fetchById(i), toList(), e, parallelProcesses))
+          .join());
+
+        log.info("{}", result);
+    }
+
+    @Test
+    public void givenParallelism_whenUsingVThreads_thenShouldProcessInParallel() {
+        int parallelProcesses = 1000_000;
+
+        var result = timed(() -> Stream.iterate(0, i -> i + 1).limit(parallelProcesses)
+          .collect(ParallelCollectors.parallel(i -> fetchById(i), toList()))
+          .join());
+
+        log.info("{}", result);
+    }
+
+    @Test
+    public void givenParallelismAndPCollectors2_whenUsingVThreads_thenShouldProcessInParallel() {
+        int parallelProcesses = 1000_000;
+
+        var result = timed(() -> Stream.iterate(0, i -> i + 1).limit(parallelProcesses)
+          .collect(ParallelCollectors.parallel(i -> fetchById(i), toList(), Executors.newVirtualThreadPerTaskExecutor(), Integer.MAX_VALUE))
+          .join());
+
+        log.info("{}", result);
+    }
+
+    private static String fetchById(int id) {
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            // ignore shamelessly
+        }
+
+        return "user-" + id;
+    }
+
+    private static <T> T timed(Supplier<T> supplier) {
+        var before = Instant.now();
+        T result = supplier.get();
+        var after = Instant.now();
+        log.info("Execution time: {} ms", Duration.between(before, after).toMillis());
+        return result;
+    }
+}

microservices-modules/event-driven-microservice/pom.xml

@@ -34,7 +34,7 @@
         <dependency>
             <groupId>org.springdoc</groupId>
             <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
-            <version>${spring.webmvc.version}</version>
+            <version>${springdoc-openapi-webmvc-ui.version}</version>
         </dependency>
 
         <dependency>
@@ -71,6 +71,7 @@
         <java.version>17</java.version>
         <conductor.client.version>2.0.8</conductor.client.version>
         <spring.webmvc.version>2.1.0</spring.webmvc.version>
+        <springdoc-openapi-webmvc-ui.version>2.5.0</springdoc-openapi-webmvc-ui.version>
     </properties>
 
 </project>

patterns-modules/design-patterns-creational-2/pom.xml

@@ -19,10 +19,15 @@
             <version>${mockito-inline.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.32</version>
+        </dependency>
     </dependencies>
 
     <properties>
         <mockito-inline.version>5.2.0</mockito-inline.version>
     </properties>
 
-</project>
+</project>

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/implementation/GenericBuilder.java

@@ -0,0 +1,29 @@
+package com.baeldung.builder.implementation;
+
+import java.util.function.BiConsumer;
+import java.util.function.Supplier;
+
+public class GenericBuilder<T> {
+
+    private final Supplier<T> supplier;
+
+    private GenericBuilder(Supplier<T> supplier) {
+        this.supplier = supplier;
+    }
+
+    public static <T> GenericBuilder<T> of(Supplier<T> supplier) {
+        return new GenericBuilder<>(supplier);
+    }
+
+    public <P> GenericBuilder<T> with(BiConsumer<T, P> consumer, P value) {
+        return new GenericBuilder<>(() -> {
+            T object = supplier.get();
+            consumer.accept(object, value);
+            return object;
+        });
+    }
+
+    public T build() {
+        return supplier.get();
+    }
+}

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/implementation/LombokPost.java

@@ -0,0 +1,18 @@
+package com.baeldung.builder.implementation;
+
+import lombok.Builder;
+import lombok.Getter;
+import lombok.Setter;
+
+@Builder
+@Getter
+@Setter
+public class LombokPost {
+
+    private String title;
+
+    private String text;
+
+    private String category;
+
+}

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/implementation/Post.java

@@ -0,0 +1,74 @@
+package com.baeldung.builder.implementation;
+
+public class Post {
+
+    private String title;
+
+    private String text;
+
+    private String category;
+
+    Post(Builder builder) {
+        this.title = builder.title;
+        this.text = builder.text;
+        this.category = builder.category;
+    }
+
+    Post() {}
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public String getCategory() {
+        return category;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public void setCategory(String category) {
+        this.category = category;
+    }
+
+    @Override
+    public String toString() {
+        return "Post{" + "title='" + title + '\'' + ", text='" + text + '\'' + ", category='" + category + '\'' + '}';
+    }
+
+    public static class Builder {
+        private String title;
+        private String text;
+        private String category;
+
+        public Builder() {}
+
+        public Builder title(String title) {
+            this.title = title;
+            return this;
+        }
+
+        public Builder text(String text) {
+            this.text = text;
+            return this;
+        }
+
+        public Builder category(String category) {
+            this.category = category;
+            return this;
+        }
+
+        public Post build() {
+            return new Post(this);
+        }
+    }
+}

patterns-modules/design-patterns-creational-2/src/test/java/com/baeldung/builder/implementation/BuilderImplementationUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.builder.implementation;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class BuilderImplementationUnitTest {
+
+    @Test
+    void givenClassicBuilder_whenBuild_thenReturnObject() {
+
+        Post post = new Post.Builder()
+          .title("Java Builder Pattern")
+          .text("Explaining how to implement the Builder Pattern in Java")
+          .category("Programming")
+          .build();
+
+        assertEquals("Java Builder Pattern", post.getTitle());
+        assertEquals("Explaining how to implement the Builder Pattern in Java", post.getText());
+        assertEquals("Programming", post.getCategory());
+    }
+
+    @Test
+    void givenGenericBuilder_whenBuild_thenReturnObject() {
+
+        Post post = GenericBuilder.of(Post::new)
+          .with(Post::setTitle, "Java Builder Pattern")
+          .with(Post::setText, "Explaining how to implement the Builder Pattern in Java")
+          .with(Post::setCategory, "Programming")
+          .build();
+
+        assertEquals("Java Builder Pattern", post.getTitle());
+        assertEquals("Explaining how to implement the Builder Pattern in Java", post.getText());
+        assertEquals("Programming", post.getCategory());
+    }
+
+    @Test
+    void givenLombokBuilder_whenBuild_thenReturnObject() {
+
+        LombokPost post = LombokPost.builder()
+          .title("Java Builder Pattern")
+          .text("Explaining how to implement the Builder Pattern in Java")
+          .category("Programming")
+          .build();
+
+        assertEquals("Java Builder Pattern", post.getTitle());
+        assertEquals("Explaining how to implement the Builder Pattern in Java", post.getText());
+        assertEquals("Programming", post.getCategory());
+    }
+}

persistence-modules/pom.xml

@@ -69,6 +69,7 @@
         <module>spring-boot-persistence-mongodb</module>
         <module>spring-boot-persistence-mongodb-2</module>
         <module>spring-boot-persistence-mongodb-3</module>
+        <module>spring-boot-persistence-mongodb-4</module>
         <module>spring-data-arangodb</module>
         <!--<module>spring-data-cassandra</module>-->   <!-- failing after upgrading to jdk17. JDK 17 compatibility in progress CASSANDRA-16895 -->
         <module>spring-data-cassandra-test</module>

persistence-modules/spring-boot-persistence-mongodb-4/README.md

@@ -0,0 +1,5 @@
+# Relevant Articles
+
+- [ZonedDateTime with Spring Data MongoDB](https://www.baeldung.com/spring-data-mongodb-zoneddatetime)
+- [A Guide to @DBRef in MongoDB](https://www.baeldung.com/spring-mongodb-dbref-annotation)
+- More articles: [[<--prev]](../spring-boot-persistence-mongodb-3) 

persistence-modules/spring-boot-persistence-mongodb-4/pom.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>spring-boot-persistence-mongodb-4</artifactId>
+    <name>spring-boot-persistence-mongodb-4</name>
+    <description>This is simple boot application for Spring boot persistence mongodb test</description>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-2</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-2</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <!-- MongoDB -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-mongodb</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>de.flapdoodle.embed</groupId>
+            <artifactId>de.flapdoodle.embed.mongo</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

persistence-modules/spring-boot-persistence-mongodb-4/src/main/java/com/baeldung/mongodb/dbref/DbRefTester.java

@@ -1,5 +1,6 @@
 package com.baeldung.mongodb.dbref;
 
+import com.baeldung.mongodb.dbref.repository.PersonRepository;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -7,8 +8,6 @@ import org.springframework.boot.ApplicationArguments;
 import org.springframework.boot.ApplicationRunner;
 import org.springframework.stereotype.Component;
 
-import com.baeldung.mongodb.dbref.repository.PersonRepository;
-
 @Component
 public class DbRefTester implements ApplicationRunner {
 

persistence-modules/spring-boot-persistence-mongodb-4/src/main/java/com/baeldung/mongodb/dbref/model/Person.java

@@ -1,11 +1,11 @@
 package com.baeldung.mongodb.dbref.model;
 
-import java.util.List;
-
 import org.springframework.data.annotation.Id;
 import org.springframework.data.mongodb.core.mapping.DBRef;
 import org.springframework.data.mongodb.core.mapping.Document;
 
+import java.util.List;
+
 @Document(collection = "Person")
 public class Person {
 

persistence-modules/spring-boot-persistence-mongodb-4/src/main/java/com/baeldung/mongodb/dbref/repository/PersonRepository.java

@@ -1,8 +1,7 @@
 package com.baeldung.mongodb.dbref.repository;
 
-import org.springframework.data.mongodb.repository.MongoRepository;
-
 import com.baeldung.mongodb.dbref.model.Person;
+import org.springframework.data.mongodb.repository.MongoRepository;
 
 public interface PersonRepository extends MongoRepository<Person, String> {
 

persistence-modules/spring-boot-persistence-mongodb-4/src/main/java/com/baeldung/zoneddatetime/config/MongoConfig.java

@@ -1,15 +1,14 @@
 package com.baeldung.zoneddatetime.config;
 
-import java.util.ArrayList;
-import java.util.List;
-
+import com.baeldung.zoneddatetime.converter.ZonedDateTimeReadConverter;
+import com.baeldung.zoneddatetime.converter.ZonedDateTimeWriteConverter;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.mongodb.config.AbstractMongoClientConfiguration;
 import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
 import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
 
-import com.baeldung.zoneddatetime.converter.ZonedDateTimeReadConverter;
-import com.baeldung.zoneddatetime.converter.ZonedDateTimeWriteConverter;
+import java.util.ArrayList;
+import java.util.List;
 
 @EnableMongoRepositories(basePackages = { "com.baeldung" })
 public class MongoConfig extends AbstractMongoClientConfiguration {