Merge branch 'eugenp:master' into JAVA-26280

aws-modules/aws-miscellaneous/README.md

@@ -5,6 +5,5 @@ This module contains articles about various Amazon Web Services (AWS) such as EC
 ### Relevant articles
 
 - [Managing EC2 Instances in Java](https://www.baeldung.com/ec2-java)
-- [Integration Testing with a Local DynamoDB Instance](https://www.baeldung.com/dynamodb-local-integration-tests)
 - [Managing Amazon SQS Queues in Java](https://www.baeldung.com/aws-queues-java)
 - [Guide to AWS Aurora RDS with Java](https://www.baeldung.com/aws-aurora-rds-java)

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

@@ -11,5 +11,5 @@ This module contains articles about Java 8 core features
 - [Finding Min/Max in an Array with Java](https://www.baeldung.com/java-array-min-max)
 - [Internationalization and Localization in Java 8](https://www.baeldung.com/java-8-localization)
 - [Generalized Target-Type Inference in Java](https://www.baeldung.com/java-generalized-target-type-inference)
-- [Monads in Java](https://www.baeldung.com/java-monads)
+- [Monads in Java – Optional](https://www.baeldung.com/java-monads)
 - [[More -->]](/core-java-modules/core-java-8-2)

core-java-modules/core-java-8/src/main/java/com/baeldung/spliterator/CustomSpliterator.java

@@ -0,0 +1,48 @@
+package com.baeldung.spliterator;
+
+import java.util.List;
+import java.util.Spliterator;
+import java.util.function.Consumer;
+
+public class CustomSpliterator implements Spliterator<Integer> {
+    private final List<Integer> elements;
+    private int currentIndex;
+    
+    public CustomSpliterator(List<Integer> elements) {
+        this.elements = elements;
+        this.currentIndex = 0;
+    }
+    
+    @Override
+    public boolean tryAdvance(Consumer<? super Integer> action) {
+        if (currentIndex < elements.size()) {
+            action.accept(elements.get(currentIndex));
+            currentIndex++;
+            return true;
+        }
+        return false;
+    }
+    
+    @Override
+    public Spliterator<Integer> trySplit() {
+        int currentSize = elements.size() - currentIndex;
+        if (currentSize < 2) {
+            return null;
+        }
+        
+        int splitIndex = currentIndex + currentSize / 2;
+        CustomSpliterator newSpliterator = new CustomSpliterator(elements.subList(currentIndex, splitIndex));
+        currentIndex = splitIndex;
+        return newSpliterator;
+    }
+    
+    @Override
+    public long estimateSize() {
+        return elements.size() - currentIndex;
+    }
+    
+    @Override
+    public int characteristics() {
+        return ORDERED | SIZED | SUBSIZED | NONNULL;
+    }
+} 

core-java-modules/core-java-8/src/main/java/com/baeldung/spliterator/Executor.java

@@ -1,12 +0,0 @@
-package com.baeldung.spliterator;
-
-import java.util.stream.Stream;
-
-public class Executor {
-
-	public static int countAutors(Stream<Author> stream) {
-		RelatedAuthorCounter wordCounter = stream.reduce(new RelatedAuthorCounter(0, true),
-				RelatedAuthorCounter::accumulate, RelatedAuthorCounter::combine);
-		return wordCounter.getCounter();
-	}
-}

core-java-modules/core-java-8/src/main/java/com/baeldung/spliterator/RelatedAuthorCounter.java

@@ -1,27 +0,0 @@
-package com.baeldung.spliterator;
-
-public class RelatedAuthorCounter {
-    private final int counter;
-    private final boolean isRelated;
-
-    public RelatedAuthorCounter(int counter, boolean isRelated) {
-        this.counter = counter;
-        this.isRelated = isRelated;
-    }
-
-    public RelatedAuthorCounter accumulate(Author author) {
-        if (author.getRelatedArticleId() == 0) {
-            return isRelated ? this : new RelatedAuthorCounter(counter, true);
-        } else {
-            return isRelated ? new RelatedAuthorCounter(counter + 1, false) : this;
-        }
-    }
-
-    public RelatedAuthorCounter combine(RelatedAuthorCounter RelatedAuthorCounter) {
-        return new RelatedAuthorCounter(counter + RelatedAuthorCounter.counter, RelatedAuthorCounter.isRelated);
-    }
-
-    public int getCounter() {
-        return counter;
-    }
-}

core-java-modules/core-java-8/src/main/java/com/baeldung/spliterator/RelatedAuthorSpliterator.java

@@ -1,49 +0,0 @@
-package com.baeldung.spliterator;
-
-import java.util.List;
-import java.util.Spliterator;
-import java.util.concurrent.atomic.AtomicInteger;
-import java.util.function.Consumer;
-
-public class RelatedAuthorSpliterator implements Spliterator<Author> {
-	private final List<Author> list;
-	AtomicInteger current = new AtomicInteger();
-
-	public RelatedAuthorSpliterator(List<Author> list) {
-		this.list = list;
-	}
-
-	@Override
-	public boolean tryAdvance(Consumer<? super Author> action) {
-
-		action.accept(list.get(current.getAndIncrement()));
-		return current.get() < list.size();
-	}
-
-	@Override
-	public Spliterator<Author> trySplit() {
-		int currentSize = list.size() - current.get();
-		if (currentSize < 10) {
-			return null;
-		}
-		for (int splitPos = currentSize / 2 + current.intValue(); splitPos < list.size(); splitPos++) {
-			if (list.get(splitPos).getRelatedArticleId() == 0) {
-				Spliterator<Author> spliterator = new RelatedAuthorSpliterator(list.subList(current.get(), splitPos));
-				current.set(splitPos);
-				return spliterator;
-			}
-		}
-		return null;
-	}
-
-	@Override
-	public long estimateSize() {
-		return list.size() - current.get();
-	}
-
-	@Override
-	public int characteristics() {
-		return CONCURRENT;
-	}
-
-}

core-java-modules/core-java-8/src/test/java/com/baeldung/spliterator/ExecutorUnitTest.java

@@ -6,10 +6,10 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Spliterator;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import java.util.stream.StreamSupport;
-
 import org.junit.Before;
 import org.junit.Test;
 
@@ -18,22 +18,50 @@ import lombok.extern.slf4j.Slf4j;
 @Slf4j
 public class ExecutorUnitTest {
     Article article;
-    Stream<Author> stream;
-    Spliterator<Author> spliterator;
 
     @Before
     public void init() {
         article = new Article(Arrays.asList(new Author("Ahmad", 0), new Author("Eugen", 0), new Author("Alice", 1), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0),
             new Author("Alice", 1), new Author("Mike", 0), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1),
             new Author("Mike", 0), new Author("Michał", 0), new Author("Loredana", 1)), 0);
-
-        spliterator = new RelatedAuthorSpliterator(article.getListOfAuthors());
     }
 
     @Test
-    public void givenAstreamOfAuthors_whenProcessedInParallelWithCustomSpliterator_coubtProducessRightOutput() {
-        Stream<Author> stream2 = StreamSupport.stream(spliterator, true);
-        assertThat(Executor.countAutors(stream2.parallel())).isEqualTo(9);
+    public void givenAStreamOfIntegers_whenProcessedSequentialCustomSpliterator_countProducesRightOutput() {
+        List<Integer> numbers = new ArrayList<>();
+        numbers.add(1);
+        numbers.add(2);
+        numbers.add(3);
+        numbers.add(4);
+        numbers.add(5);
+
+        CustomSpliterator customSpliterator = new CustomSpliterator(numbers);
+
+        AtomicInteger sum = new AtomicInteger();
+
+        customSpliterator.forEachRemaining(sum::addAndGet);
+        assertThat(sum.get()).isEqualTo(15);
+    }
+
+    @Test
+    public void givenAStreamOfIntegers_whenProcessedInParallelWithCustomSpliterator_countProducesRightOutput() {
+        List<Integer> numbers = new ArrayList<>();
+        numbers.add(1);
+        numbers.add(2);
+        numbers.add(3);
+        numbers.add(4);
+        numbers.add(5);
+
+        CustomSpliterator customSpliterator = new CustomSpliterator(numbers);
+
+        // Create a ForkJoinPool for parallel processing
+        ForkJoinPool forkJoinPool = ForkJoinPool.commonPool();
+
+        AtomicInteger sum = new AtomicInteger(0);
+
+        // Process elements in parallel using parallelStream
+        forkJoinPool.submit(() -> customSpliterator.forEachRemaining(sum::addAndGet)).join();
+        assertThat(sum.get()).isEqualTo(15);
     }
 
     @Test
@@ -43,9 +71,7 @@ public class ExecutorUnitTest {
             .collect(Collectors.toList());
 
         Spliterator<Article> spliterator = articles.spliterator();
-        while (spliterator.tryAdvance(article -> article.setName(article.getName()
-            .concat("- published by Baeldung"))))
-            ;
+        while(spliterator.tryAdvance(article -> article.setName(article.getName().concat("- published by Baeldung"))));
 
         articles.forEach(article -> assertThat(article.getName()).isEqualTo("Java- published by Baeldung"));
     }

core-java-modules/core-java-arrays-operations-advanced/pom.xml

@@ -57,5 +57,9 @@
             </plugin>
         </plugins>
     </build>
+    
+    <properties>
+        <maven.compiler.release>11</maven.compiler.release>
+    </properties>
 
 </project>

core-java-modules/core-java-arrays-operations-advanced/src/test/java/com/baeldung/arraycompare/ArraysCompareUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.arraycompare;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+
+import org.junit.jupiter.api.Test;
+
+class ArraysCompareUnitTest {
+
+    @Test
+    void givenSameContents_whenCompare_thenCorrect() {
+        String[] array1 = new String[] { "A", "B", "C" };
+        String[] array2 = new String[] { "A", "B", "C" };
+
+        assertThat(Arrays.compare(array1, array2)).isEqualTo(0);
+    }
+
+    @Test
+    void givenDifferentContents_whenCompare_thenDifferent() {
+        String[] array1 = new String[] { "A", "B", "C" };
+        String[] array2 = new String[] { "A", "C", "B", "D" };
+
+        assertThat(Arrays.compare(array1, array2)).isLessThan(0);
+        assertThat(Arrays.compare(array2, array1)).isGreaterThan(0);
+        assertThat(Arrays.compare(array1, null)).isGreaterThan(0);
+    }
+
+}

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

@@ -3,3 +3,4 @@
 This module contains articles about Java array fundamentals. They assume no previous background knowledge on working with arrays.
 
 ### Relevant Articles: 
+- [Arrays mismatch() Method in Java](https://www.baeldung.com/java-arrays-mismatch)

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

@@ -7,4 +7,5 @@
 - [Creating Custom Iterator in Java](https://www.baeldung.com/java-creating-custom-iterator)
 - [Difference Between Arrays.sort() and Collections.sort()](https://www.baeldung.com/java-arrays-collections-sort-methods)
 - [Skipping the First Iteration in Java](https://www.baeldung.com/java-skip-first-iteration)
+- [Remove Elements From a Queue Using Loop](https://www.baeldung.com/java-remove-elements-queue)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-4)

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

@@ -1,2 +1,3 @@
 ## Relevant Articles
 - [Difference Between putIfAbsent() and computeIfAbsent() in Java’s Map](https://www.baeldung.com/java-map-putifabsent-computeifabsent)
+- [How to Write Hashmap to CSV File](https://www.baeldung.com/java-write-hashmap-csv)

core-java-modules/core-java-concurrency-advanced-5/README.md

@@ -0,0 +1,3 @@
+
+### Relevant Articles:
+- [Why wait() Requires Synchronization?](https://www.baeldung.com/java-wait-necessary-synchronization)

core-java-modules/core-java-concurrency-basic-3/README.md

@@ -10,4 +10,5 @@ This module contains articles about basic Java concurrency.
 - [Returning a Value After Finishing Thread’s Job in Java](https://www.baeldung.com/java-return-value-after-thread-finish)
 - [CompletableFuture and ThreadPool in Java](https://www.baeldung.com/java-completablefuture-threadpool)
 - [CompletableFuture allOf().join() vs. CompletableFuture.join()](https://www.baeldung.com/java-completablefuture-allof-join)
+- [Retry Logic with CompletableFuture](https://www.baeldung.com/java-completablefuture-retry-logic)
 - [[<-- Prev]](../core-java-concurrency-basic-2)

core-java-modules/core-java-concurrency-basic-3/src/main/java/com/baeldung/concurrent/completablefuturelist/Application.java

@@ -0,0 +1,100 @@
+package com.baeldung.concurrent.completablefuturelist;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.stream.Collectors;
+
+public class Application {
+
+    ScheduledExecutorService asyncOperationEmulation;
+
+    Application initialize() {
+        asyncOperationEmulation = Executors.newScheduledThreadPool(10);
+        return this;
+    }
+
+    CompletableFuture<String> asyncOperation(String operationId) {
+        CompletableFuture<String> cf = new CompletableFuture<>();
+        asyncOperationEmulation.submit(() -> {
+            // The following lines simulate an exception happening on the 567th operation
+            //  if (operationId.endsWith("567")) {
+            //      cf.completeExceptionally(new Exception("Error on operation " + operationId));
+            //      return;
+            //  }
+            try {
+                Thread.sleep(100);
+                cf.complete(operationId);
+            } catch (InterruptedException e) {
+                System.err.println("Thread interrupted error");
+                cf.completeExceptionally(e);
+            }
+        });
+        return cf;
+    }
+
+    void startNaive() {
+        List<CompletableFuture<String>> futures = new ArrayList<>();
+        for (int i = 1; i <= 1000; i++) {
+            String operationId = "Naive-Operation-" + i;
+            futures.add(asyncOperation(operationId));
+        }
+
+        CompletableFuture<List<String>> aggregate = CompletableFuture.completedFuture(new ArrayList<>());
+        for (CompletableFuture<String> future : futures) {
+            aggregate = aggregate.thenCompose(list -> {
+                try {
+                    list.add(future.get());
+                    return CompletableFuture.completedFuture(list);
+                } catch (Exception e) {
+                    final CompletableFuture<List<String>> excFuture = new CompletableFuture<>();
+                    excFuture.completeExceptionally(e);
+                    return excFuture;
+                }
+            });
+        }
+
+        try {
+            final List<String> results = aggregate.join();
+            System.out.println("Printing first 10 results");
+            for (int i = 0; i < 10; i++) {
+                System.out.println("Finished " + results.get(i));
+            }
+        } finally {
+            close();
+        }
+    }
+
+    void start() {
+        List<CompletableFuture<String>> futures = new ArrayList<>();
+        for (int i = 1; i <= 1000; i++) {
+            String operationId = "Operation-" + i;
+            futures.add(asyncOperation(operationId));
+        }
+        CompletableFuture<?>[] futuresArray = futures.toArray(new CompletableFuture<?>[0]);
+        CompletableFuture<List<String>> listFuture = CompletableFuture.allOf(futuresArray).thenApply(v -> futures.stream().map(CompletableFuture::join).collect(Collectors.toList()));
+        try {
+            final List<String> results = listFuture.join();
+            System.out.println("Printing first 10 results");
+            for (int i = 0; i < 10; i++) {
+                System.out.println("Finished " + results.get(i));
+            }
+        } finally {
+            close();
+        }
+    }
+
+    void close() {
+        asyncOperationEmulation.shutdownNow();
+    }
+
+    public static void main(String[] args) {
+        new Application().initialize()
+        // Switch between .startNaive() and .start() to test both implementations
+        //  .startNaive();
+          .start();
+    }
+
+}

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

@@ -12,6 +12,7 @@ This module contains articles about Java Concurrency that are also part of an Eb
 - [Guide to the Volatile Keyword in Java](https://www.baeldung.com/java-volatile)
 - [A Guide to the Java ExecutorService](https://www.baeldung.com/java-executor-service-tutorial)
 - [Guide To CompletableFuture](https://www.baeldung.com/java-completablefuture)
+- [How To Manage Timeout for CompletableFuture](https://www.baeldung.com/java-completablefuture-timeout)
 
 ### NOTE:
 

core-java-modules/core-java-concurrency-simple/pom.xml

@@ -12,6 +12,15 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>org.wiremock</groupId>
+            <artifactId>wiremock</artifactId>
+            <version>3.1.0</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
     <build>
         <finalName>core-java-concurrency-simple</finalName>
         <resources>

core-java-modules/core-java-concurrency-simple/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureTimeoutUnitTest.java

@@ -0,0 +1,182 @@
+package com.baeldung.concurrent.completablefuture;
+
+import com.github.tomakehurst.wiremock.WireMockServer;
+import com.github.tomakehurst.wiremock.client.WireMock;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.concurrent.*;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+class CompletableFutureTimeoutUnitTest {
+    private WireMockServer wireMockServer;
+    private ScheduledExecutorService executorService;
+    private static final int DEFAULT_TIMEOUT = 1000; //1 seconds
+    private static final String DEFAULT_PRODUCT = """
+            {
+              "products": [
+                {
+                  "id": 2,
+                  "title": "iPhone X",
+                  "description": "SIM-Free, Model A19211 6.5-inch Super Retina HD display with OLED technology A12 Bionic chip with ...",
+                  "price": 899,
+                  "discountPercentage": 0.0,
+                  "rating": 4.44,
+                  "stock": 34,
+                  "brand": "Apple",
+                  "category": "smartphones"
+                },
+                {
+                  "id": 3,
+                  "title": "Samsung Universe 9",
+                  "description": "Samsung's new variant which goes beyond Galaxy to the Universe",
+                  "price": 1249,
+                  "discountPercentage": 0.0,
+                  "rating": 4.09,
+                  "stock": 36,
+                  "brand": "Samsung",
+                  "category": "smartphones"
+                }
+              ],
+              "total": 2
+            }""";
+    private static final String PRODUCT_OFFERS = """
+            {
+              "products": [
+                {
+                  "id": 1,
+                  "title": "iPhone 9",
+                  "description": "An apple mobile which is nothing like apple",
+                  "price": 549,
+                  "discountPercentage": 12.96,
+                  "rating": 4.69,
+                  "stock": 94,
+                  "brand": "Apple",
+                  "category": "smartphones"
+                },
+                {
+                  "id": 2,
+                  "title": "iPhone X",
+                  "description": "SIM-Free, Model A19211 6.5-inch Super Retina HD display with OLED technology A12 Bionic chip with ...",
+                  "price": 899,
+                  "discountPercentage": 17.94,
+                  "rating": 4.44,
+                  "stock": 34,
+                  "brand": "Apple",
+                  "category": "smartphones"
+                },
+                {
+                  "id": 3,
+                  "title": "Samsung Universe 9",
+                  "description": "Samsung's new variant which goes beyond Galaxy to the Universe",
+                  "price": 1249,
+                  "discountPercentage": 15.46,
+                  "rating": 4.09,
+                  "stock": 36,
+                  "brand": "Samsung",
+                  "category": "smartphones"
+                },
+                {
+                  "id": 4,
+                  "title": "OPPOF19",
+                  "description": "OPPO F19 is officially announced on April 2021.",
+                  "price": 280,
+                  "discountPercentage": 17.91,
+                  "rating": 4.3,
+                  "stock": 123,
+                  "brand": "OPPO",
+                  "category": "smartphones"
+                },
+                {
+                  "id": 5,
+                  "title": "Huawei P30",
+                  "description": "Huawei’s re-badged P30 Pro New Edition was officially unveiled yesterday in Germany and now the device has made its way to the UK.",
+                  "price": 499,
+                  "discountPercentage": 10.58,
+                  "rating": 4.09,
+                  "stock": 32,
+                  "brand": "Huawei",
+                  "category": "smartphones"
+                }
+              ],
+              "total": 5
+            }""";
+
+    @BeforeAll
+    void setUp() {
+        wireMockServer = new WireMockServer(8080);
+        wireMockServer.start();
+        WireMock.configureFor("localhost", 8080);
+
+        stubFor(get(urlEqualTo("/api/dummy"))
+                .willReturn(aResponse()
+                        .withFixedDelay(5000) // must be > DEFAULT_TIMEOUT for a timeout to occur.
+                        .withBody(PRODUCT_OFFERS)));
+
+        executorService = Executors.newScheduledThreadPool(1);
+    }
+
+    @AfterAll
+    void tearDown() {
+        executorService.shutdown();
+        wireMockServer.stop();
+    }
+
+    private CompletableFuture<String> fetchProductData() {
+        return CompletableFuture.supplyAsync(() -> {
+            try {
+                URL url = new URL("http://localhost:8080/api/dummy");
+                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+
+                try (BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()))) {
+                    String inputLine;
+                    StringBuffer response = new StringBuffer();
+
+                    while ((inputLine = in.readLine()) != null) {
+                        response.append(inputLine);
+                    }
+
+                    return response.toString();
+                } finally {
+                    connection.disconnect();
+                }
+            } catch (IOException e) {
+                return "";
+            }
+        });
+    }
+
+
+    @Test
+    void whenorTimeout_thenGetThrow() {
+        CompletableFuture<String> productDataFuture = fetchProductData();
+        productDataFuture.orTimeout(DEFAULT_TIMEOUT, TimeUnit.MILLISECONDS);
+        assertThrows(ExecutionException.class, productDataFuture::get);
+    }
+
+    @Test
+    void whencompleteOnTimeout_thenReturnValue() throws ExecutionException, InterruptedException {
+        CompletableFuture<String> productDataFuture = fetchProductData();
+        productDataFuture.completeOnTimeout(DEFAULT_PRODUCT, DEFAULT_TIMEOUT, TimeUnit.MILLISECONDS);
+        assertEquals(DEFAULT_PRODUCT, productDataFuture.get());
+    }
+
+    @Test
+    void whencompleteExceptionally_thenGetThrow() {
+        CompletableFuture<String> productDataFuture = fetchProductData();
+        executorService.schedule(() -> productDataFuture
+                .completeExceptionally(new TimeoutException("Timeout occurred")), DEFAULT_TIMEOUT, TimeUnit.MILLISECONDS);
+        assertThrows(ExecutionException.class, productDataFuture::get);
+    }
+}

core-java-modules/core-java-date-operations-3/src/test/java/com/baeldung/firstdaymonth/FirstDayOfMonthUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.firstdaymonth;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.time.LocalDate;
+import java.time.YearMonth;
+import java.time.temporal.TemporalAdjusters;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
+
+import org.junit.jupiter.api.Test;
+
+public class FirstDayOfMonthUnitTest {
+
+    @Test
+    void givenMonth_whenUsingCalendar_thenReturnFirstDay() {
+        Date currentDate = new GregorianCalendar(2023, Calendar.NOVEMBER, 23).getTime();
+        Date expectedDate = new GregorianCalendar(2023, Calendar.NOVEMBER, 1).getTime();
+
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(currentDate);
+        cal.set(Calendar.DAY_OF_MONTH, 1);
+
+        assertEquals(expectedDate, cal.getTime());
+    }
+
+    @Test
+    void givenMonth_whenUsingLocalDate_thenReturnFirstDay() {
+        LocalDate currentDate = LocalDate.of(2023, 9, 6);
+        LocalDate expectedDate = LocalDate.of(2023, 9, 1);
+
+        assertEquals(expectedDate, currentDate.withDayOfMonth(1));
+    }
+
+    @Test
+    void givenMonth_whenUsingTemporalAdjusters_thenReturnFirstDay() {
+        LocalDate currentDate = LocalDate.of(2023, 7, 19);
+        LocalDate expectedDate = LocalDate.of(2023, 7, 1);
+
+        assertEquals(expectedDate, currentDate.with(TemporalAdjusters.firstDayOfMonth()));
+    }
+
+    @Test
+    void givenMonth_whenUsingYearMonth_thenReturnFirstDay() {
+        YearMonth currentDate = YearMonth.of(2023, 4);
+        LocalDate expectedDate = LocalDate.of(2023, 4, 1);
+
+        assertEquals(expectedDate, currentDate.atDay(1));
+    }
+
+    @Test
+    void givenMonth_whenUsingJodaTime_thenReturnFirstDay() {
+        org.joda.time.LocalDate currentDate = org.joda.time.LocalDate.parse("2023-5-10");
+        org.joda.time.LocalDate expectedDate = org.joda.time.LocalDate.parse("2023-5-1");
+
+        assertEquals(expectedDate, currentDate.dayOfMonth()
+          .withMinimumValue());
+    }
+
+}

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

@@ -35,6 +35,21 @@
             <artifactId>simplemagic</artifactId>
             <version>${simplemagic.version}</version>
         </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -62,5 +77,6 @@
         <jmime-magic.version>0.1.5</jmime-magic.version>
         <jodd-util.version>6.2.1</jodd-util.version>
         <simplemagic.version>1.17</simplemagic.version>
+        <jmh.version>1.37</jmh.version>
     </properties>
 </project>

core-java-modules/core-java-io-5/src/main/java/com/baeldung/zip/ZipBenchmark.java

@@ -0,0 +1,112 @@
+package com.baeldung.zip;
+
+import java.io.*;
+import java.util.concurrent.TimeUnit;
+import java.util.*;
+import java.util.zip.*;
+
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.infra.Blackhole;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+@State(Scope.Benchmark)
+@BenchmarkMode(Mode.AverageTime)
+@Warmup(iterations = 1, time = 2, timeUnit = TimeUnit.SECONDS)
+@Measurement(iterations = 3, time = 1, timeUnit = TimeUnit.SECONDS)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Fork(value = 1)
+public class ZipBenchmark {
+
+    public static final int NUM_OF_FILES = 10;
+    public static final int DATA_SIZE = 204800;
+
+    @State(Scope.Thread)
+    public static class SourceState {
+
+        public File compressedFile;
+
+        @Setup(Level.Trial)
+        public void setup() throws IOException {
+            ZipSampleFileStore sampleFileStore = new ZipSampleFileStore(NUM_OF_FILES, DATA_SIZE);
+            compressedFile = sampleFileStore.getFile();
+        }
+
+        @TearDown(Level.Trial)
+        public void cleanup() {
+            if (compressedFile.exists()) {
+                compressedFile.delete();
+            }
+        }
+    }
+
+    @Benchmark
+    public static void readAllEntriesByZipFile(SourceState sourceState, Blackhole blackhole) throws IOException {
+
+        try (ZipFile zipFile = new ZipFile(sourceState.compressedFile)) {
+            Enumeration<? extends ZipEntry> zipEntries = zipFile.entries();
+            while (zipEntries.hasMoreElements())  {
+                ZipEntry zipEntry = zipEntries.nextElement();
+                try (InputStream inputStream = new BufferedInputStream(zipFile.getInputStream(zipEntry))) {
+                    blackhole.consume(ZipSampleFileStore.getString(inputStream));
+                }
+            }
+        }
+    }
+
+    @Benchmark
+    public static void readAllEntriesByZipInputStream(SourceState sourceState, Blackhole blackhole) throws IOException {
+
+        try (
+            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(sourceState.compressedFile));
+            ZipInputStream zipInputStream = new ZipInputStream(bis)
+        ) {
+            ZipEntry entry;
+            while ((entry = zipInputStream.getNextEntry()) != null) {
+                blackhole.consume(ZipSampleFileStore.getString(zipInputStream));
+            }
+        }
+    }
+
+    @Benchmark
+    public static void readLastEntryByZipFile(SourceState sourceState, Blackhole blackhole) throws IOException {
+
+        try (ZipFile zipFile = new ZipFile(sourceState.compressedFile)) {
+           ZipEntry zipEntry = zipFile.getEntry(getLastEntryName());
+            try (InputStream inputStream = new BufferedInputStream(zipFile.getInputStream(zipEntry))) {
+                blackhole.consume(ZipSampleFileStore.getString(inputStream));
+            }
+        }
+    }
+
+    @Benchmark
+    public static void readLastEntryByZipInputStream(SourceState sourceState, Blackhole blackhole) throws IOException {
+
+        try (
+            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(sourceState.compressedFile));
+            ZipInputStream zipInputStream = new ZipInputStream(bis)
+        ) {
+            ZipEntry entry;
+            while ((entry = zipInputStream.getNextEntry()) != null) {
+                if (Objects.equals(entry.getName(), getLastEntryName())){
+                    blackhole.consume(ZipSampleFileStore.getString(zipInputStream));
+                }
+            }
+        }
+    }
+
+    private static String getLastEntryName() {
+        return String.format(ZipSampleFileStore.ENTRY_NAME_PATTERN, NUM_OF_FILES);
+    }
+
+    public static void main(String[] args) throws Exception {
+        Options options = new OptionsBuilder()
+          .include(ZipBenchmark.class.getSimpleName()).threads(1)
+          .shouldFailOnError(true)
+          .shouldDoGC(true)
+          .jvmArgs("-server").build();
+        new Runner(options).run();
+    }
+
+}

core-java-modules/core-java-io-5/src/main/java/com/baeldung/zip/ZipSampleFileStore.java

@@ -0,0 +1,70 @@
+package com.baeldung.zip;
+
+import java.io.*;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+import java.util.*;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
+
+import org.apache.commons.io.IOUtils;
+
+public class ZipSampleFileStore {
+
+    public static final String ENTRY_NAME_PATTERN = "str-data-%s.txt";
+    private static final Charset DEFAULT_ENCODING = StandardCharsets.UTF_8;
+
+    private final File file;
+    private final List<String> dataList;
+
+    public ZipSampleFileStore(int numOfFiles, int fileSize) throws IOException {
+
+        dataList = new ArrayList<>(numOfFiles);
+        file = File.createTempFile("zip-sample", "");
+
+        try (ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(file))) {
+
+            for (int idx=0; idx<=numOfFiles; idx++) {
+
+                byte[] data = createRandomStringInByte(fileSize);
+                dataList.add(new String(data, DEFAULT_ENCODING));
+
+                ZipEntry entry = new ZipEntry(String.format(ENTRY_NAME_PATTERN, idx));
+                zos.putNextEntry(entry);
+                zos.write(data);
+                zos.closeEntry();
+            }
+        }
+    }
+
+    public static byte[] createRandomStringInByte(int size) {
+        Random random = new Random();
+        byte[] data = new byte[size];
+        for (int n = 0; n < data.length; n++) {
+            char randomChar;
+            int choice = random.nextInt(2); // 0 for uppercase, 1 for lowercase
+            if (choice == 0) {
+                randomChar = (char) ('A' + random.nextInt(26)); // 'A' to 'Z'
+            } else {
+                randomChar = (char) ('a' + random.nextInt(26)); // 'a' to 'z'
+            }
+            data[n] = (byte) randomChar;
+        }
+        return data;
+    }
+
+    public File getFile() {
+        return file;
+    }
+
+    public List<String> getDataList() {
+        return dataList;
+    }
+
+    public static String getString(InputStream inputStream) throws IOException {
+        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        IOUtils.copy(inputStream, byteArrayOutputStream);
+        return byteArrayOutputStream.toString(DEFAULT_ENCODING);
+    }
+
+}

core-java-modules/core-java-io-5/src/test/java/com/baeldung/zip/ZipUnitTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.zip;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.*;
+import java.util.*;
+import java.util.zip.*;
+
+import org.junit.*;
+
+public class ZipUnitTest {
+
+    private static File compressedFile;
+    private static List<String> dataList = new ArrayList<>();
+
+    @BeforeClass
+    public static void prepareData() throws IOException {
+        ZipSampleFileStore sampleFileStore = new ZipSampleFileStore(ZipBenchmark.NUM_OF_FILES, ZipBenchmark.DATA_SIZE);
+        compressedFile = sampleFileStore.getFile();
+        dataList = sampleFileStore.getDataList();
+    }
+
+    @Test
+    public void whenCreateZipFile_thenCompressedSizeShouldBeLessThanOriginal() throws IOException {
+        byte[] data = ZipSampleFileStore.createRandomStringInByte(10240);
+        File file = File.createTempFile("zip-temp", "");
+
+        try (
+            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
+            ZipOutputStream zos = new ZipOutputStream(bos)
+        ) {
+            ZipEntry zipEntry = new ZipEntry("zip-entry.txt");
+            zos.putNextEntry(zipEntry);
+            zos.write(data);
+            zos.closeEntry();
+
+            assertThat(file.length()).isLessThan(data.length);
+        }
+        finally {
+            file.delete();
+        }
+    }
+
+    @Test
+    public void whenReadAllEntriesViaZipFile_thenDataIsEqualtoTheSource() throws IOException {
+
+        try (ZipFile zipFile = new ZipFile(compressedFile)) {
+            Enumeration<? extends ZipEntry> entries = zipFile.entries();
+            List<? extends ZipEntry> entryList = Collections.list(entries);
+
+            for (int idx=0; idx<entryList.size(); idx++) {
+                ZipEntry zipEntry = entryList.get(idx);
+                try (InputStream inputStream = zipFile.getInputStream(zipEntry)) {
+                    String actual = ZipSampleFileStore.getString(inputStream);
+                    assertThat(actual).as("Data for ZIP entry: " + zipEntry.getName()).isEqualTo(dataList.get(idx));
+                }
+            }
+        }
+    }
+
+    @Test
+    public void whenReadAllEntriesViaZipInputStream_thenDataIsEqualtoTheSource() throws IOException {
+        int idx = 0;
+        try (
+            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(compressedFile));
+            ZipInputStream zipInputStream = new ZipInputStream(bis)
+        ) {
+            ZipEntry zipEntry;
+            while ((zipEntry = zipInputStream.getNextEntry()) != null) {
+                String actual = ZipSampleFileStore.getString(zipInputStream);
+                assertThat(actual).as("Data for ZIP entry: " + zipEntry.getName()).isEqualTo(dataList.get(idx++));
+            }
+        }
+    }
+
+    @AfterClass
+    public static void cleanup() {
+        if (compressedFile.exists()) {
+            compressedFile.delete();
+        }
+    }
+
+}

core-java-modules/core-java-io-apis-2/alabama.txt

@@ -0,0 +1,2 @@
+I'm going to Alabama
+Alabama is a state in the US

core-java-modules/core-java-io-apis-2/dream.txt

@@ -0,0 +1 @@
+Dreams from My Father by Barack Obama

core-java-modules/core-java-io-apis-2/potter.txt

@@ -0,0 +1 @@
+Harry Potter and the Chamber of Secrets

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/printwritervsfilewriter/PrintWriterVsFilePrinterUnitTest.java

@@ -0,0 +1,64 @@
+package com.baeldung.printwritervsfilewriter;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+public class PrintWriterVsFilePrinterUnitTest {
+
+    @Test
+    public void whenWritingToTextFileUsingFileWriter_thenTextMatches() throws IOException {
+        String result = "Harry Potter and the Chamber of Secrets";
+
+        File file = new File("potter.txt");
+        try (FileWriter fw = new FileWriter(file);) {
+            fw.write("Harry Potter and the Chamber of Secrets");
+        }
+
+        try (BufferedReader reader = new BufferedReader(new FileReader(file));) {
+            String actualData = reader.readLine();
+            assertEquals(result, actualData);
+        }
+    }
+
+    @Test
+    public void whenWritingToTextFileUsingPrintWriterPrintf_thenTextMatches() throws IOException {
+        String result = "Dreams from My Father by Barack Obama";
+        File file = new File("dream.txt");
+        try (PrintWriter pw = new PrintWriter(file);) {
+            String author = "Barack Obama";
+            pw.printf("Dreams from My Father by %s", author);
+            assertTrue(!pw.checkError());
+        }
+
+        try (BufferedReader reader = new BufferedReader(new FileReader(file));) {
+            String actualData = reader.readLine();
+            assertEquals(result, actualData);
+        }
+    }
+
+    @Test
+    public void whenWritingToTextFileUsingPrintWriterPrintln_thenTextMatches() throws IOException {
+        String result = "I'm going to Alabama\nAlabama is a state in the US\n";
+        try (PrintWriter pw = new PrintWriter("alabama.txt");) {
+            pw.println("I'm going to Alabama");
+            pw.println("Alabama is a state in the US");
+        }
+        Path path = Paths.get("alabama.txt");
+        String actualData = new String(Files.readAllBytes(path));
+        assertEquals(result, actualData);
+    }
+
+}

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

@@ -4,3 +4,4 @@
 - [Aggregate Runtime Exceptions in Java Streams](https://www.baeldung.com/java-streams-aggregate-exceptions)
 - [Streams vs. Loops in Java](https://www.baeldung.com/java-streams-vs-loops)
 - [Partition a Stream in Java](https://www.baeldung.com/java-partition-stream)
+- [Taking Every N-th Element from Finite and Infinite Streams in Java](https://www.baeldung.com/java-nth-element-finite-infinite-streams)

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

@@ -13,3 +13,4 @@ This module contains articles about string-related algorithms.
 - [Find the Most Frequent Characters in a String](https://www.baeldung.com/java-string-find-most-frequent-characters)
 - [Checking If a String Is a Repeated Substring](https://www.baeldung.com/java-repeated-substring)
 - [Check if Letter Is Emoji With Java](https://www.baeldung.com/java-check-letter-emoji)
+- [Wrapping a String After a Number of Characters Word-Wise](https://www.baeldung.com/java-wrap-string-number-characters-word-wise)

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

@@ -3,3 +3,5 @@
 - [Convert String to Int Using Encapsulation](https://www.baeldung.com/java-encapsulation-convert-string-to-int)
 - [HashMap with Multiple Values for the Same Key](https://www.baeldung.com/java-hashmap-multiple-values-per-key)
 - [Split Java String Into Key-Value Pairs](https://www.baeldung.com/java-split-string-map)
+- [How to Center Text Output in Java](https://www.baeldung.com/java-center-text-output)
+- [How to Convert an Object to String](https://www.baeldung.com/java-object-string-representation)

core-java-modules/core-java-string-operations-2/pom.xml

@@ -54,6 +54,11 @@
             <artifactId>commons-codec</artifactId>
             <version>${commons-codec.version}</version>
         </dependency>
+        <dependency> 
+            <groupId>org.springframework</groupId> 
+            <artifactId>spring-core</artifactId> 
+            <version>${spring-core.version}</version> 
+        </dependency>
     </dependencies>
 
     <build>
@@ -95,6 +100,7 @@
         <javax.el-api.version>3.0.0</javax.el-api.version>
         <javax.el.version>2.2.6</javax.el.version>
         <commons-codec.version>1.14</commons-codec.version>
+        <spring-core.version>5.3.0</spring-core.version>
     </properties>
 
 </project>

core-java-modules/core-java-string-operations-2/src/test/java/com/baeldung/emptystrings/EmptyStringsUnitTest.java

@@ -3,6 +3,7 @@ package com.baeldung.emptystrings;
 import com.google.common.base.Strings;
 import org.apache.commons.lang3.StringUtils;
 import org.junit.Test;
+import org.springframework.util.ObjectUtils;
 
 import javax.validation.ConstraintViolation;
 import javax.validation.Validation;
@@ -109,6 +110,24 @@ public class EmptyStringsUnitTest {
         assertFalse(Strings.isNullOrEmpty(blankString));
     }
 
+    /*
+     * Spring Core ObjectUtils
+     */
+    @Test
+    public void givenSomeEmptyString_thenObjectUtilsIsEmptyReturnsTrue() {
+        assertTrue(ObjectUtils.isEmpty(emptyString));
+    }
+
+    @Test
+    public void givenSomeNonEmptyString_thenObjectUtilsIsEmptyReturnsFalse() {
+        assertFalse(ObjectUtils.isEmpty(nonEmptyString));
+    }
+
+    @Test
+    public void givenSomeBlankString_thenObjectUtilsIsEmptyReturnsFalse() {
+        assertFalse(ObjectUtils.isEmpty(blankString));
+    }
+
     /*
      * Bean Validation
      */

core-java-modules/core-java-string-operations-6/README.md

@@ -11,4 +11,4 @@
 - [Check if a String Has All Unique Characters in Java](https://www.baeldung.com/java-check-string-all-unique-chars)
 - [Performance Comparison Between Different Java String Concatenation Methods](https://www.baeldung.com/java-string-concatenation-methods)
 - [Replacing Single Quote with \’ in Java String](https://www.baeldung.com/java-replacing-single-quote-string)
-
+- [Check if a String Contains a Number Value in Java](https://www.baeldung.com/java-string-number-presence)

core-java-modules/core-java-string-operations-7/README.md

@@ -1,2 +1,4 @@
 
 ### Relevant Articles:
+- [How to Center Text Output in Java](https://www.baeldung.com/java-center-text-output)
+- [Capitalize the First Letter of Each Word in a String](https://www.baeldung.com/java-string-initial-capital-letter-every-word)

core-java-modules/core-java-string-operations-7/src/main/java/com/baeldung/unicode/UnicodeLetterChecker.java

@@ -0,0 +1,30 @@
+package com.baeldung.unicode;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import org.apache.commons.lang3.StringUtils;
+
+public class UnicodeLetterChecker {
+    public boolean characterClassCheck(String input) {
+        for (char c : input.toCharArray()) {
+            if (!Character.isLetter(c)) {
+                return false;
+            }
+        }
+        return true;
+    }
+    
+    public boolean regexCheck(String input) {
+        Pattern pattern = Pattern.compile("^\\p{L}+$");
+        Matcher matcher = pattern.matcher(input);
+        return matcher.matches();
+    }
+    
+    public boolean isAlphaCheck(String input) {
+        return StringUtils.isAlpha(input);
+    }
+    
+    public boolean StreamsCheck(String input) {
+        return input.codePoints().allMatch(Character::isLetter);
+    }
+}

core-java-modules/core-java-string-operations-7/src/test/java/com/baeldung/unicode/UnicodeLetterCheckerUnitTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.unicode;
+
+import org.junit.Test;
+import static org.junit.Assert.assertTrue;
+
+public class UnicodeLetterCheckerUnitTest {
+    @Test
+    public void givenString_whenUsingIsLetter_thenReturnTrue() {
+        UnicodeLetterChecker checker = new UnicodeLetterChecker();
+
+        boolean isUnicodeLetter = checker.characterClassCheck("HelloWorld");
+        assertTrue(isUnicodeLetter);
+    }
+
+    @Test
+    public void givenString_whenUsingRegex_thenReturnTrue() {
+        UnicodeLetterChecker checker = new UnicodeLetterChecker();
+
+        boolean isUnicodeLetter = checker.regexCheck("HelloWorld");
+        assertTrue(isUnicodeLetter);
+    }
+
+    @Test
+    public void givenString_whenUsingIsAlpha_thenReturnTrue() {
+        UnicodeLetterChecker checker = new UnicodeLetterChecker();
+
+        boolean isUnicodeLetter = checker.isAlphaCheck("HelloWorld");
+        assertTrue(isUnicodeLetter);
+    }
+
+    @Test
+    public void givenString_whenUsingStreams_thenReturnTrue() {
+        UnicodeLetterChecker checker = new UnicodeLetterChecker();
+
+        boolean isUnicodeLetter = checker.StreamsCheck("HelloWorld");
+        assertTrue(isUnicodeLetter);
+    }
+}

core-java-modules/core-java-strings/src/test/java/com/baeldung/passstringbyreference/Dummy.java

@@ -0,0 +1,14 @@
+package com.baeldung.passstringbyreference;
+
+public class Dummy {
+
+    String dummyString;
+
+    public String getDummyString() {
+        return dummyString;
+    }
+
+    public void setDummyString(String dummyString) {
+        this.dummyString = dummyString;
+    }
+}

core-java-modules/core-java-strings/src/test/java/com/baeldung/passstringbyreference/PassStringUnitTest.java

@@ -0,0 +1,85 @@
+package com.baeldung.passstringbyreference;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import org.junit.jupiter.api.Test;
+
+class PassStringUnitTest {
+
+    @Test
+    void givenAString_whenPassedToVoidMethod_thenStringIsNotModified() {
+        String s = "hello";
+        concatStringWithNoReturn(s);
+        assertEquals("hello", s);
+    }
+
+    void concatStringWithNoReturn(String input) {
+        input += " world";
+        assertEquals("hello world", input);
+    }
+
+    @Test
+    void givenAString_whenPassedToMethodAndReturnNewString_thenStringIsModified() {
+        String s = "hello";
+        assertEquals("hello world", concatStringWithReturn(s));
+    }
+
+    String concatStringWithReturn(String input) {
+        return input + " world";
+    }
+
+    @Test
+    void givenAString_whenPassStringBuilderToVoidMethod_thenConcatNewStringOk() {
+        StringBuilder builder = new StringBuilder("hello");
+        concatWithStringBuilder(builder);
+
+        assertEquals("hello world", builder.toString());
+    }
+
+    void concatWithStringBuilder(StringBuilder input) {
+        input.append(" world");
+    }
+
+    @Test
+    void givenAString_whenPassStringBufferToVoidMethod_thenConcatNewStringOk() {
+        StringBuffer builder = new StringBuffer("hello");
+        concatWithStringBuffer(builder);
+
+        assertEquals("hello world", builder.toString());
+    }
+
+    void concatWithStringBuffer(StringBuffer input) {
+        input.append(" world");
+    }
+
+    @Test
+    void givenObjectWithStringField_whenSetDifferentValue_thenObjectIsModified() {
+        Dummy dummy = new Dummy();
+        assertNull(dummy.getDummyString());
+        modifyStringValueInInputObject(dummy, "hello world");
+        assertEquals("hello world", dummy.getDummyString());
+    }
+
+    void modifyStringValueInInputObject(Dummy dummy, String dummyString) {
+        dummy.setDummyString(dummyString);
+    }
+
+    @Test
+    void givenObjectWithStringField_whenSetDifferentValueWithStringBuilder_thenSetStringInNewObject() {
+        assertEquals("hello world", getDummy("hello", "world").getDummyString());
+    }
+
+    Dummy getDummy(String hello, String world) {
+        StringBuilder builder = new StringBuilder();
+
+        builder.append(hello)
+          .append(" ")
+          .append(world);
+
+        Dummy dummy = new Dummy();
+        dummy.setDummyString(builder.toString());
+
+        return dummy;
+    }
+}

data-structures/src/main/java/com/baeldung/avltree/AVLTree.java

@@ -42,17 +42,17 @@ public class AVLTree {
         return root == null ? -1 : root.height;
     }
 
-    private Node insert(Node node, int key) {
-        if (node == null) {
+    private Node insert(Node root, int key) {
+        if (root == null) {
             return new Node(key);
-        } else if (node.key > key) {
-            node.left = insert(node.left, key);
-        } else if (node.key < key) {
-            node.right = insert(node.right, key);
+        } else if (root.key > key) {
+            root.left = insert(root.left, key);
+        } else if (root.key < key) {
+            root.right = insert(root.right, key);
         } else {
             throw new RuntimeException("duplicate Key!");
         }
-        return rebalance(node);
+        return rebalance(root);
     }
 
     private Node delete(Node node, int key) {

libraries-io/README.md

@@ -3,4 +3,4 @@
 
 - [Transferring a File Through SFTP in Java](https://www.baeldung.com/java-file-sftp)
 - [How to Create Password-Protected Zip Files and Unzip Them in Java](https://www.baeldung.com/java-password-protected-zip-unzip)
-
+- [How to Create CSV File from POJO with Custom Column Headers and Positions](https://www.baeldung.com/java-create-csv-pojo-customize-columns)

libraries-llms/pom.xml

@@ -0,0 +1,43 @@
+<?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>libraries-llms</artifactId>
+    <name>libraries-llms</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <!-- dependencies for langchain4j -->
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j</artifactId>
+            <version>${langchain4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-embeddings</artifactId>
+            <version>${langchain4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-open-ai</artifactId>
+            <version>${langchain4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-embeddings-all-minilm-l6-v2</artifactId>
+            <version>${langchain4j.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <langchain4j.version>0.23.0</langchain4j.version>
+    </properties>
+
+</project>

libraries-llms/src/test/java/com/baeldung/langchain/ChainWithDocumentLiveTest.java

@@ -0,0 +1,65 @@
+package com.baeldung.langchain;
+
+import static dev.langchain4j.data.document.FileSystemDocumentLoader.loadDocument;
+import static java.time.Duration.ofSeconds;
+import static org.junit.Assert.assertNotNull;
+
+import java.nio.file.Paths;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import dev.langchain4j.chain.ConversationalRetrievalChain;
+import dev.langchain4j.data.document.Document;
+import dev.langchain4j.data.document.splitter.DocumentSplitters;
+import dev.langchain4j.data.segment.TextSegment;
+import dev.langchain4j.memory.chat.MessageWindowChatMemory;
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.embedding.AllMiniLmL6V2EmbeddingModel;
+import dev.langchain4j.model.embedding.EmbeddingModel;
+import dev.langchain4j.model.input.PromptTemplate;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.retriever.EmbeddingStoreRetriever;
+import dev.langchain4j.store.embedding.EmbeddingStore;
+import dev.langchain4j.store.embedding.EmbeddingStoreIngestor;
+import dev.langchain4j.store.embedding.inmemory.InMemoryEmbeddingStore;
+
+public class ChainWithDocumentLiveTest {
+
+    private static final Logger logger = LoggerFactory.getLogger(ChainWithDocumentLiveTest.class);
+
+    @Test
+    public void givenChainWithDocument_whenPrompted_thenValidResponse() {
+        EmbeddingModel embeddingModel = new AllMiniLmL6V2EmbeddingModel();
+
+        EmbeddingStore<TextSegment> embeddingStore = new InMemoryEmbeddingStore<>();
+
+        EmbeddingStoreIngestor ingestor = EmbeddingStoreIngestor.builder()
+            .documentSplitter(DocumentSplitters.recursive(500, 0))
+            .embeddingModel(embeddingModel)
+            .embeddingStore(embeddingStore)
+            .build();
+
+        Document document = loadDocument(Paths.get("src/test/resources/example-files/simpson's_adventures.txt"));
+        ingestor.ingest(document);
+
+        ChatLanguageModel chatModel = OpenAiChatModel.builder()
+            .apiKey(Constants.OPENAI_API_KEY)
+            .timeout(ofSeconds(60))
+            .build();
+
+        ConversationalRetrievalChain chain = ConversationalRetrievalChain.builder()
+            .chatLanguageModel(chatModel)
+            .retriever(EmbeddingStoreRetriever.from(embeddingStore, embeddingModel))
+            .chatMemory(MessageWindowChatMemory.withMaxMessages(10))
+            .promptTemplate(PromptTemplate.from("Answer the following question to the best of your ability: {{question}}\n\nBase your answer on the following information:\n{{information}}"))
+            .build();
+
+        String answer = chain.execute("Who is Simpson?");
+
+        logger.info(answer);
+        assertNotNull(answer);
+    }
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/ChatWithDocumentLiveTest.java

@@ -0,0 +1,81 @@
+package com.baeldung.langchain;
+
+import static dev.langchain4j.data.document.FileSystemDocumentLoader.loadDocument;
+import static dev.langchain4j.model.openai.OpenAiModelName.GPT_3_5_TURBO;
+import static java.time.Duration.ofSeconds;
+import static java.util.stream.Collectors.joining;
+import static org.junit.Assert.assertNotNull;
+
+import java.nio.file.Paths;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import dev.langchain4j.data.document.Document;
+import dev.langchain4j.data.document.DocumentSplitter;
+import dev.langchain4j.data.document.splitter.DocumentSplitters;
+import dev.langchain4j.data.embedding.Embedding;
+import dev.langchain4j.data.message.AiMessage;
+import dev.langchain4j.data.segment.TextSegment;
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.embedding.AllMiniLmL6V2EmbeddingModel;
+import dev.langchain4j.model.embedding.EmbeddingModel;
+import dev.langchain4j.model.input.Prompt;
+import dev.langchain4j.model.input.PromptTemplate;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.model.openai.OpenAiTokenizer;
+import dev.langchain4j.store.embedding.EmbeddingMatch;
+import dev.langchain4j.store.embedding.EmbeddingStore;
+import dev.langchain4j.store.embedding.inmemory.InMemoryEmbeddingStore;
+
+public class ChatWithDocumentLiveTest {
+
+    private static final Logger logger = LoggerFactory.getLogger(ChatWithDocumentLiveTest.class);
+
+    @Test
+    public void givenDocument_whenPrompted_thenValidResponse() {
+        Document document = loadDocument(Paths.get("src/test/resources/example-files/simpson's_adventures.txt"));
+        DocumentSplitter splitter = DocumentSplitters.recursive(100, 0, new OpenAiTokenizer(GPT_3_5_TURBO));
+        List<TextSegment> segments = splitter.split(document);
+
+        EmbeddingModel embeddingModel = new AllMiniLmL6V2EmbeddingModel();
+        List<Embedding> embeddings = embeddingModel.embedAll(segments)
+            .content();
+        EmbeddingStore<TextSegment> embeddingStore = new InMemoryEmbeddingStore<>();
+        embeddingStore.addAll(embeddings, segments);
+
+        String question = "Who is Simpson?";
+        Embedding questionEmbedding = embeddingModel.embed(question)
+            .content();
+        int maxResults = 3;
+        double minScore = 0.7;
+        List<EmbeddingMatch<TextSegment>> relevantEmbeddings = embeddingStore.findRelevant(questionEmbedding, maxResults, minScore);
+
+        PromptTemplate promptTemplate = PromptTemplate.from("Answer the following question to the best of your ability:\n" + "\n" + "Question:\n" + "{{question}}\n" + "\n" + "Base your answer on the following information:\n" + "{{information}}");
+
+        String information = relevantEmbeddings.stream()
+            .map(match -> match.embedded()
+                .text())
+            .collect(joining("\n\n"));
+
+        Map<String, Object> variables = new HashMap<>();
+        variables.put("question", question);
+        variables.put("information", information);
+
+        Prompt prompt = promptTemplate.apply(variables);
+        ChatLanguageModel chatModel = OpenAiChatModel.builder()
+            .apiKey(Constants.OPENAI_API_KEY)
+            .timeout(ofSeconds(60))
+            .build();
+        AiMessage aiMessage = chatModel.generate(prompt.toUserMessage())
+            .content();
+
+        logger.info(aiMessage.text());
+        assertNotNull(aiMessage.text());
+    }
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/ChatWithMemoryLiveTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.langchain;
+
+import static dev.langchain4j.data.message.UserMessage.userMessage;
+import static dev.langchain4j.model.openai.OpenAiModelName.GPT_3_5_TURBO;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertNotNull;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import dev.langchain4j.data.message.AiMessage;
+import dev.langchain4j.memory.ChatMemory;
+import dev.langchain4j.memory.chat.TokenWindowChatMemory;
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.model.openai.OpenAiTokenizer;
+
+public class ChatWithMemoryLiveTest {
+
+    private static final Logger logger = LoggerFactory.getLogger(ChatWithMemoryLiveTest.class);
+
+    @Test
+    public void givenMemory_whenPrompted_thenValidResponse() {
+        ChatLanguageModel model = OpenAiChatModel.withApiKey(Constants.OPENAI_API_KEY);
+        ChatMemory chatMemory = TokenWindowChatMemory.withMaxTokens(300, new OpenAiTokenizer(GPT_3_5_TURBO));
+
+        chatMemory.add(userMessage("Hello, my name is Kumar"));
+        AiMessage answer = model.generate(chatMemory.messages())
+            .content();
+        logger.info(answer.text());
+        chatMemory.add(answer);
+        assertNotNull(answer.text());
+
+        chatMemory.add(userMessage("What is my name?"));
+        AiMessage answerWithName = model.generate(chatMemory.messages())
+            .content();
+        logger.info(answerWithName.text());
+        chatMemory.add(answerWithName);
+        assertThat(answerWithName.text()).contains("Kumar");
+    }
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/Constants.java

@@ -0,0 +1,12 @@
+package com.baeldung.langchain;
+
+public class Constants {
+    
+    /**
+     * A limited access key for access to OpenAI language models can be generated by first
+     * registering for free at (https://platform.openai.com/signup) and then by navigating
+     * to "Create new secret key" page at (https://platform.openai.com/account/api-keys).
+     */
+    public static String OPENAI_API_KEY = "<OPENAI_API_KEY>";
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/PromptTemplatesLiveTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.langchain;
+
+import static dev.langchain4j.model.openai.OpenAiModelName.GPT_3_5_TURBO;
+import static org.junit.Assert.assertNotNull;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.input.Prompt;
+import dev.langchain4j.model.input.PromptTemplate;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+
+public class PromptTemplatesLiveTest {
+    
+    private static final Logger logger = LoggerFactory.getLogger(PromptTemplatesLiveTest.class);
+
+    @Test
+    public void givenPromptTemplate_whenSuppliedInput_thenValidResponse() {
+        PromptTemplate promptTemplate = PromptTemplate.from("Tell me a {{adjective}} joke about {{content}}..");
+        Map<String, Object> variables = new HashMap<>();
+        variables.put("adjective", "funny");
+        variables.put("content", "humans");
+        Prompt prompt = promptTemplate.apply(variables);
+
+        ChatLanguageModel model = OpenAiChatModel.builder()
+            .apiKey(Constants.OPENAI_API_KEY)
+            .modelName(GPT_3_5_TURBO)
+            .temperature(0.3)
+            .build();
+
+        String response = model.generate(prompt.text());
+        logger.info(response);
+        assertNotNull(response);
+    }
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/ServiceWithToolsLiveTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.langchain;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import dev.langchain4j.agent.tool.Tool;
+import dev.langchain4j.memory.chat.MessageWindowChatMemory;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.service.AiServices;
+
+public class ServiceWithToolsLiveTest {
+    
+    private static final Logger logger = LoggerFactory.getLogger(ServiceWithToolsLiveTest.class);
+
+    static class Calculator {
+        @Tool("Calculates the length of a string")
+        int stringLength(String s) {
+            return s.length();
+        }
+
+        @Tool("Calculates the sum of two numbers")
+        int add(int a, int b) {
+            return a + b;
+        }
+    }
+
+    interface Assistant {
+        String chat(String userMessage);
+    }
+
+    @Test
+    public void givenServiceWithTools_whenPrompted_thenValidResponse() {
+        Assistant assistant = AiServices.builder(Assistant.class)
+            .chatLanguageModel(OpenAiChatModel.withApiKey(Constants.OPENAI_API_KEY))
+            .tools(new Calculator())
+            .chatMemory(MessageWindowChatMemory.withMaxMessages(10))
+            .build();
+
+        String question = "What is the sum of the numbers of letters in the words \"language\" and \"model\"?";
+        String answer = assistant.chat(question);
+
+        logger.info(answer);
+        assertThat(answer).contains("13");
+    }
+
+}

libraries-llms/src/test/resources/example-files/simpson's_adventures.txt

@@ -0,0 +1,28 @@
+Once upon a time in the town of VeggieVille, there lived a cheerful carrot named Simpson.
+Simpson was a radiant carrot, always beaming with joy and positivity.
+His vibrant orange skin and lush green top were a sight to behold, but it was his infectious laughter and warm personality that really set him apart.
+
+Simpson had a diverse group of friends, each a vegetable with their own unique characteristics.
+There was Bella the blushing beetroot, always ready with a riddle or two; Timmy the timid tomato, a gentle soul with a heart of gold; and Percy the prankster potato, whose jokes always brought a smile to everyone's faces.
+Despite their differences, they shared a close bond, their friendship as robust as their natural goodness.
+
+Their lives were filled with delightful adventures, from playing hide-and-seek amidst the leafy lettuce to swimming in the dewy droplets that pooled on the cabbage leaves.
+Their favorite place, though, was the sunlit corner of the vegetable patch, where they would bask in the warmth of the sun, share stories, and have hearty laughs.
+
+One day, a bunch of pesky caterpillars invaded VeggieVille.
+The vegetables were terrified, fearing they would be nibbled to nothingness.
+But Simpson, with his usual sunny disposition, had an idea.
+He proposed they host a grand feast for the caterpillars, with the juiciest leaves from the outskirts of the town.
+Simpson's optimism was contagious, and his friends eagerly joined in to prepare the feast.
+
+When the caterpillars arrived, they were pleasantly surprised.
+They enjoyed the feast and were so impressed with the vegetables' hospitality that they promised not to trouble VeggieVille again.
+In return, they agreed to help pollinate the flowers, contributing to a more lush and vibrant VeggieVille.
+
+Simpson's idea had saved the day, but he humbly attributed the success to their teamwork and friendship.
+They celebrated their victory with a grand party, filled with laughter, dance, and merry games.
+That night, under the twinkling stars, they made a pact to always stand by each other, come what may.
+
+From then on, the story of the happy carrot and his friends spread far and wide, a tale of friendship, unity, and positivity.
+Simpson, Bella, Timmy, and Percy continued to live their joyful lives, their laughter echoing through VeggieVille.
+And so, the tale of the happy carrot and his friends serves as a reminder that no matter the challenge, with optimism, teamwork, and a bit of creativity, anything is possible.

persistence-modules/hibernate-ogm/src/test/java/com/baeldung/hibernate/ogm/EditorUnitTest.java

@@ -22,6 +22,7 @@ public class EditorUnitTest {
         loadAndVerifyTestData(entityManagerFactory, editor);
     }
     */
+
     @Test
     public void givenNeo4j_WhenEntitiesCreated_thenCanBeRetrieved() throws Exception {
         EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("ogm-neo4j");

persistence-modules/pom.xml

@@ -106,6 +106,7 @@
         <module>spring-jpa</module>
         <module>spring-jpa-2</module>
         <module>spring-jdbc</module>
+	<module>spring-jdbc-2</module>
         <module>spring-jooq</module>
         <module>spring-mybatis</module>
         <module>spring-persistence-simple</module>

persistence-modules/spring-jdbc-2/pom.xml

@@ -0,0 +1,93 @@
+<?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>
+
+    <groupId>org.example</groupId>
+    <artifactId>spring-jdbc-2</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>spring-jdbc-2</name>
+    <description>Demo project for Spring Jdbc</description>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-3</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-3</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-jdbc</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+    <repositories>
+        <repository>
+            <id>spring-milestones</id>
+            <name>Spring Milestones</name>
+            <url>https://repo.spring.io/milestone</url>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
+        </repository>
+        <repository>
+            <id>spring-snapshots</id>
+            <name>Spring Snapshots</name>
+            <url>https://repo.spring.io/snapshot</url>
+            <releases>
+                <enabled>false</enabled>
+            </releases>
+        </repository>
+    </repositories>
+    <pluginRepositories>
+        <pluginRepository>
+            <id>spring-milestones</id>
+            <name>Spring Milestones</name>
+            <url>https://repo.spring.io/milestone</url>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
+        </pluginRepository>
+        <pluginRepository>
+            <id>spring-snapshots</id>
+            <name>Spring Snapshots</name>
+            <url>https://repo.spring.io/snapshot</url>
+            <releases>
+                <enabled>false</enabled>
+            </releases>
+        </pluginRepository>
+    </pluginRepositories>
+
+    <properties>
+        <spring-boot.version>3.2.0-SNAPSHOT</spring-boot.version>
+        <junit-jupiter.version>5.10.0</junit-jupiter.version>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+</project>

persistence-modules/spring-jdbc-2/src/main/java/com/baeldung/jdbcclient/JdbcClientDemoApplication.java

@@ -0,0 +1,14 @@
+package com.baeldung.jdbcclient;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.ComponentScan;
+
+@SpringBootApplication
+@ComponentScan(basePackages = "com.baledung.jdbcclient")
+public class JdbcClientDemoApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(JdbcClientDemoApplication.class, args);
+    }
+}

persistence-modules/spring-jdbc-2/src/main/java/com/baeldung/jdbcclient/dao/StudentDao.java

@@ -0,0 +1,95 @@
+package com.baeldung.jdbcclient.dao;
+
+import com.baeldung.jdbcclient.model.Student;
+import com.baeldung.jdbcclient.model.StudentResultExtractor;
+import com.baeldung.jdbcclient.model.StudentRowMapper;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.jdbc.core.RowCountCallbackHandler;
+import org.springframework.jdbc.core.simple.JdbcClient;
+import org.springframework.stereotype.Repository;
+
+import java.sql.Types;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+@Repository
+public class StudentDao {
+
+    private static final Logger logger = LoggerFactory.getLogger(StudentDao.class);
+    @Autowired
+    private JdbcClient jdbcClient;
+
+    public Integer insertWithSetParamWithNamedParamAndSqlType(Student student) {
+        String sql = "INSERT INTO student (student_name, age, grade, gender, state)"
+          + "VALUES (:name, :age, :grade, :gender, :state)";
+        Integer noOfrowsAffected = this.jdbcClient.sql(sql)
+          .param("name", student.getStudentName(), Types.VARCHAR)
+          .param("age", student.getAge(), Types.INTEGER)
+          .param("grade", student.getGrade(), Types.INTEGER)
+          .param("gender", student.getStudentGender(), Types.VARCHAR)
+          .param("state", student.getState(), Types.VARCHAR)
+          .update();
+        logger.info("No. of rows affected: " + noOfrowsAffected);
+        return noOfrowsAffected;
+    }
+
+    public List<Student> getStudentsOfGradeStateAndGenderWithPositionalParams(int grade, String state, String gender) {
+        String sql = "select student_id, student_name, age, grade, gender, state from student"
+          + " where grade = ? and state = ? and gender = ?";
+        return jdbcClient.sql(sql)
+          .param(grade)
+          .param(state)
+          .param(gender)
+          .query(new StudentRowMapper()).list();
+    }
+
+    public List<Student> getStudentsOfGradeStateAndGenderWithParamIndex(int grade, String state, String gender) {
+        String sql = "select student_id, student_name, age, grade, gender, state from student"
+          + " where grade = ? and state = ? and gender = ?";
+        return jdbcClient.sql(sql)
+          .param(1,grade)
+          .param(2, state)
+          .param(3, gender)
+          .query(new StudentResultExtractor());
+    }
+
+    public Student getStudentsOfGradeStateAndGenderWithParamsInVarargs(int grade, String state, String gender) {
+        String sql = "select student_id, student_name, age, grade, gender, state from student"
+          + " where grade = ? and state = ? and gender = ? limit 1";
+        return jdbcClient.sql(sql)
+          .params(grade, state, gender)
+          .query(new StudentRowMapper()).single();
+    }
+
+    public Optional<Student> getStudentsOfGradeStateAndGenderWithParamsInList(List params) {
+        String sql = "select student_id, student_name, age, grade, gender, state from student"
+          + " where grade = ? and state = ? and gender = ? limit 1";
+        return jdbcClient.sql(sql)
+          .params(params)
+          .query(new StudentRowMapper()).optional();
+    }
+
+
+    public int getCountOfStudentsOfGradeStateAndGenderWithNamedParam(int grade, String state, String gender) {
+        String sql = "select student_id, student_name, age, grade, gender, state from student"
+          + " where grade = :grade and state = :state and gender = :gender";
+        RowCountCallbackHandler countCallbackHandler = new RowCountCallbackHandler();
+        jdbcClient.sql(sql)
+          .param("grade", grade)
+          .param("state", state)
+          .param("gender", gender)
+          .query(countCallbackHandler);
+        return countCallbackHandler.getRowCount();
+    }
+
+    public List<Student> getStudentsOfGradeStateAndGenderWithParamMap(Map<String, ?> paramMap) {
+        String sql = "select student_id, student_name, age, grade, gender, state from student"
+          + " where grade = :grade and state = :state and gender = :gender";
+        return jdbcClient.sql(sql)
+          .params(paramMap)
+          .query(new StudentRowMapper()).list();
+    }
+}

persistence-modules/spring-jdbc-2/src/main/java/com/baeldung/jdbcclient/model/Student.java

@@ -0,0 +1,60 @@
+package com.baeldung.jdbcclient.model;
+
+public class Student {
+    private Integer studentId;
+    private String studentName;
+    private String studentGender;
+    private Integer age;
+    private Integer grade;
+
+    public Integer getStudentId() {
+        return studentId;
+    }
+
+    public void setStudentId(Integer studentId) {
+        this.studentId = studentId;
+    }
+
+    public String getStudentName() {
+        return studentName;
+    }
+
+    public void setStudentName(String studentName) {
+        this.studentName = studentName;
+    }
+
+    public String getStudentGender() {
+        return studentGender;
+    }
+
+    public void setStudentGender(String studentGender) {
+        this.studentGender = studentGender;
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+
+    public void setAge(Integer age) {
+        this.age = age;
+    }
+
+    public Integer getGrade() {
+        return grade;
+    }
+
+    public void setGrade(Integer grade) {
+        this.grade = grade;
+    }
+
+    public String getState() {
+        return state;
+    }
+
+    public void setState(String state) {
+        this.state = state;
+    }
+
+    private String state;
+
+}

persistence-modules/spring-jdbc-2/src/main/java/com/baeldung/jdbcclient/model/StudentResultExtractor.java

@@ -0,0 +1,26 @@
+package com.baeldung.jdbcclient.model;
+
+import org.springframework.jdbc.core.ResultSetExtractor;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+
+public class StudentResultExtractor implements ResultSetExtractor<List<Student>> {
+    @Override
+    public List<Student> extractData(ResultSet rs) throws SQLException {
+        List<Student> students = new ArrayList<Student>();
+        while(rs.next()) {
+            Student student = new Student();
+            student.setStudentId(rs.getInt("student_id"));
+            student.setStudentName(rs.getString("student_name"));
+            student.setAge(rs.getInt("age"));
+            student.setStudentGender(rs.getString("gender"));
+            student.setGrade(rs.getInt("grade"));
+            student.setState(rs.getString("state"));
+            students.add(student);
+        }
+        return students;
+    }
+}

persistence-modules/spring-jdbc-2/src/main/java/com/baeldung/jdbcclient/model/StudentRowMapper.java

@@ -0,0 +1,20 @@
+package com.baeldung.jdbcclient.model;
+
+import org.springframework.jdbc.core.RowMapper;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+public class StudentRowMapper  implements RowMapper<Student> {
+    @Override
+    public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
+        Student student = new Student();
+        student.setStudentId(rs.getInt("student_id"));
+        student.setStudentName(rs.getString("student_name"));
+        student.setAge(rs.getInt("age"));
+        student.setStudentGender(rs.getString("gender"));
+        student.setGrade(rs.getInt("grade"));
+        student.setState(rs.getString("state"));
+        return student;
+    }
+}

persistence-modules/spring-jdbc-2/src/main/resources/jdbcclient/application.properties

@@ -0,0 +1,5 @@
+# DataSource Configuration
+spring.datasource.url=jdbc:h2:mem:testdb
+spring.datasource.driverClassName=org.h2.Driver
+spring.datasource.username=user
+spring.datasource.password=  # Leave this empty

persistence-modules/spring-jdbc-2/src/main/resources/jdbcclient/drop_student.sql

@@ -0,0 +1 @@
+DROP TABLE student;

persistence-modules/spring-jdbc-2/src/main/resources/jdbcclient/student.sql

@@ -0,0 +1,98 @@
+
+CREATE TABLE student (
+    student_id INT AUTO_INCREMENT PRIMARY KEY,
+    student_name VARCHAR(255) NOT NULL,
+    age INT,
+    grade INT NOT NULL,
+    gender VARCHAR(10) NOT NULL,
+    state VARCHAR(100) NOT NULL
+);
+-- Student 1
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('John Smith', 18, 3, 'Male', 'California');
+
+-- Student 2
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Emily Johnson', 17, 2, 'Female', 'New York');
+
+-- Student 3
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Michael Davis', 4, 1, 'Male', 'Texas');
+
+-- Student 4
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Sophia Martinez', 2, 1, 'Female', 'Florida');
+
+-- Student 5
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('William Brown', 5, 5, 'Male', 'California');
+
+-- Student 6
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Olivia Garcia', 4, 2, 'Female', 'Texas');
+
+-- Student 7
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Ethan Rodriguez', 3, 1, 'Male', 'New York');
+
+-- Student 8
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Ava Hernandez', 2, 1, 'Female', 'Florida');
+
+-- Student 9
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('James Wilson', 5, 4, 'Male', 'Texas');
+
+-- Student 10
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Emma Miller', 3, 1, 'Female', 'California');
+
+-- Student 11
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Benjamin Brown', 4, 1, 'Male', 'New York');
+
+-- Student 12
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Mia Smith', 2, 1, 'Female', 'Florida');
+
+-- Student 13
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Daniel Johnson', 5, 4, 'Male', 'California');
+
+-- Student 14
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Ava Davis', 4, 2, 'Female', 'Texas');
+
+-- Student 15
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Matthew Martinez', 3, 1, 'Male', 'New York');
+
+-- Student 16
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Sophia Taylor', 2, 1, 'Female', 'Florida');
+
+-- Student 17
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Alexander White', 5, 4, 'Male', 'California');
+
+-- Student 18
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Olivia Johnson', 4, 2, 'Female', 'Texas');
+
+-- Student 19
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Christopher Lee', 3, 1, 'Male', 'New York');
+
+-- Student 20
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Emma Wilson', 2, 1, 'Female', 'Florida');
+
+-- Student 21
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Elijah Smith', 5, 3, 'Male', 'Texas');
+
+-- Student 22
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Isabella Davis', 4, 2, 'Female', 'California');
+
+-- Student 23
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Liam Johnson', 3, 1, 'Male', 'New York');
+
+-- Student 24
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Olivia Garcia', 2, 1, 'Female', 'Florida');
+
+-- Student 25
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Noah Rodriguez', 5, 3, 'Male', 'Texas');
+
+-- Student 26
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Sophia Hernandez', 4, 2, 'Female', 'California');
+
+-- Student 27
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Mason Smith', 3, 1, 'Male', 'New York');
+
+-- Student 28
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Ava Taylor', 2, 1, 'Female', 'Florida');
+
+-- Student 29
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('William Brown', 5, 5, 'Male', 'Texas');
+
+-- Student 30
+INSERT INTO student (student_name, age, grade, gender, state) VALUES ('Olivia Martinez', 4, 4, 'Female', 'California');

persistence-modules/spring-jdbc-2/src/test/java/com/baeldung/jdbcclient/JdbcClientUnitTest.java

@@ -0,0 +1,104 @@
+package com.baeldung.jdbcclient;
+
+import com.baeldung.jdbcclient.dao.StudentDao;
+import com.baeldung.jdbcclient.model.Student;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.TestPropertySource;
+import org.springframework.test.context.jdbc.Sql;
+
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@Sql(value = "/jdbcclient/student.sql", executionPhase = Sql.ExecutionPhase.BEFORE_TEST_METHOD)
+@Sql(value = "/jdbcclient/drop_student.sql", executionPhase = Sql.ExecutionPhase.AFTER_TEST_METHOD)
+@SpringBootTest(classes = JdbcClientDemoApplication.class)
+@TestPropertySource(locations = {"classpath:jdbcclient/application.properties"})
+
+public class JdbcClientUnitTest {
+    private static final Logger logger = LoggerFactory.getLogger(JdbcClientUnitTest.class);
+
+    @Autowired
+    private StudentDao studentDao;
+
+    @Test
+    void givenJdbcClient_whenInsertWithNamedParamAndSqlType_thenSuccess() {
+        logger.info("testing invoked successfully");
+        Student student = getSampleStudent("Johny Dep", 8, 4, "Male", "New York");
+        assertEquals(1, studentDao.insertWithSetParamWithNamedParamAndSqlType(student));
+    }
+
+    @Test
+    void givenJdbcClient_whenQueryWithPositionalParams_thenSuccess() {
+        logger.info("testing invoked successfully");
+        List<Student> students = studentDao.getStudentsOfGradeStateAndGenderWithPositionalParams(
+          1, "New York", "Male");
+        logger.info("number of students fetched " + students.size());
+        assertEquals(6, students.size());
+    }
+
+    @Test
+    void givenJdbcClient_whenQueryWithParamsInVarargs_thenSuccess() {
+        logger.info("testing invoked successfully");
+        Student student = studentDao.getStudentsOfGradeStateAndGenderWithParamsInVarargs(
+          1, "New York", "Male");
+        assertNotNull(student);
+    }
+
+    @Test
+    void givenJdbcClient_whenQueryWithParamsInList_thenSuccess() {
+        logger.info("testing invoked successfully");
+        List params = List.of(1, "New York", "Male");
+        Optional<Student> optional = studentDao.getStudentsOfGradeStateAndGenderWithParamsInList(params);
+        if(optional.isPresent()) {
+            assertNotNull(optional.get());
+        } else {
+            assertThrows(NoSuchElementException.class, () -> optional.get());
+        }
+    }
+
+    @Test
+    void givenJdbcClient_whenQueryWithParamsIndex_thenSuccess() {
+        logger.info("testing invoked successfully");
+        List<Student> students = studentDao.getStudentsOfGradeStateAndGenderWithParamIndex(
+          1, "New York", "Male");
+        assertEquals(6, students.size());
+    }
+    @Test
+    void givenJdbcClient_whenQueryWithNamedParam_thenSuccess() {
+        logger.info("testing invoked successfully");
+        Integer count = studentDao.getCountOfStudentsOfGradeStateAndGenderWithNamedParam(
+          1, "New York", "Male");
+        logger.info("number of students fetched " + count);
+        assertEquals(6, count);
+    }
+    @Test
+    void givenJdbcClient_whenQueryWithParamMap_thenSuccess() {
+        logger.info("testing invoked successfully");
+        Map<String, ?> paramMap = Map.of(
+          "grade", 1,
+          "gender", "Male",
+          "state", "New York"
+        );
+        List<Student> students = studentDao.getStudentsOfGradeStateAndGenderWithParamMap(paramMap);
+        logger.info("number of students fetched " + students.size());
+        assertEquals(6, students.size());
+    }
+
+    private Student getSampleStudent(String name, int age, int grade, String gender, String state) {
+        Student student = new Student();
+        student.setStudentName(name);
+        student.setStudentGender(gender);
+        student.setAge(age);
+        student.setGrade(grade);
+        student.setState(state);
+        return student;
+    }
+}

persistence-modules/spring-jdbc-2/src/test/resources/logback-test.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration scan="true" scanPeriod="15 seconds" debug="false">
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>[%d{ISO8601}]-[%thread] %-5level %logger - %msg%n</pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

pom.xml

@@ -349,7 +349,6 @@
 
                 <!-- <module>ethereum</module> --> <!-- JAVA-6001 -->
                 <!-- <module>gradle-modules</module> --> <!-- Not a maven project -->
-                <!-- <module>grails</module> --> <!-- Not a maven project -->
                 <!-- <module>guest</module> --> <!-- not to be built as its for guest articles  -->
 
                 <!-- <module>lagom</module> --> <!-- Not a maven project -->
@@ -362,7 +361,7 @@
                 <module>muleesb</module>
                 <module>web-modules/java-lite</module>
                 <module>persistence-modules/deltaspike</module> <!-- delta spike it doesn't support yet the jakarta API-->
-                <module>persistence-modules/hibernate-ogm</module> <!-- hibernate-ogm wasn't updated because it doesn't support jakarta API -->
+                <module>persistence-modules/hibernate-ogm</module> <!-- hibernate-ogm wasn't updated because a workaround for jakarta namespace wasn't found JAVA-20557 -->
                 <module>persistence-modules/spring-data-cassandra-reactive</module> <!--JAVA-21844-->
                 <module>java-nashorn</module>
                 <module>jeromq</module>
@@ -523,7 +522,6 @@
 
                 <!-- <module>ethereum</module> --> <!-- JAVA-6001 -->
                 <!-- <module>gradle-modules</module> --> <!-- Not a maven project -->
-                <!-- <module>grails</module> --> <!-- Not a maven project -->
                 <!-- <module>guest</module> --> <!-- not to be built as its for guest articles  -->
 
                 <!-- <module>lagom</module> --> <!-- Not a maven project -->
@@ -534,7 +532,7 @@
                 <module>muleesb</module>
                 <module>web-modules/java-lite</module>
                 <module>persistence-modules/deltaspike</module> <!-- delta spike it doesn't support yet the jakarta API-->
-                <module>persistence-modules/hibernate-ogm</module> <!-- hibernate-ogm wasn't updated because it doesn't support jakarta API -->
+                <module>persistence-modules/hibernate-ogm</module> <!-- hibernate-ogm wasn't updated because a workaround for jakarta namespace wasn't found JAVA-20557 -->
                 <module>persistence-modules/spring-data-cassandra-reactive</module> <!--JAVA-21844-->
                 <module>java-nashorn</module>
                 <module>jeromq</module>
@@ -932,6 +930,7 @@
                 <module>spring-di-4</module>
                 <module>spring-kafka-2</module>
                 <!--<module>java-panama</module> Java-19 module-->
+                <module>libraries-llms</module>
             </modules>
 
             <properties>
@@ -1211,10 +1210,10 @@
                 <module>gradle-modules/gradle/maven-to-gradle</module>
                 <module>persistence-modules/spring-data-neo4j</module>
                 <module>spring-actuator</module>
-                <module>gcp-firebase</module>
                 <module>spring-di-4</module>
                 <module>spring-kafka-2</module>
                 <!--<module>java-panama</module> Java-19 module-->
+                <module>libraries-llms</module>
             </modules>
 
             <properties>

spring-activiti/src/test/java/com/baeldung/activitiwithspring/ActivitiWithSpringApplicationIntegrationTest.java

@@ -1,18 +0,0 @@
-package com.baeldung.activitiwithspring;
-
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
-import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.test.context.junit4.SpringRunner;
-
-@RunWith(SpringRunner.class)
-@SpringBootTest(classes = ActivitiWithSpringApplication.class)
-@AutoConfigureTestDatabase
-public class ActivitiWithSpringApplicationIntegrationTest {
-
-    @Test
-    public void contextLoads() {
-    }
-
-}

spring-boot-modules/spring-boot-3-2/README.md

@@ -0,0 +1,2 @@
+## Relevant Articles
+- [Spring Boot 3.1’s ConnectionDetails Abstraction](https://www.baeldung.com/spring-boot-3-1-connectiondetails-abstraction)

spring-boot-modules/spring-boot-3-2/pom.xml

@@ -15,6 +15,14 @@
         <relativePath>../../parent-boot-3</relativePath>
     </parent>
 
+    <repositories>
+        <repository>
+            <id>repository.spring.release</id>
+            <name>Spring GA Repository</name>
+            <url>https://repo.spring.io/milestone</url>
+        </repository>
+    </repositories>
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -94,6 +102,17 @@
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
+            <version>3.2.0-M2</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.10.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.10.0</version>
         </dependency>
         <dependency>
             <groupId>org.postgresql</groupId>
@@ -175,6 +194,18 @@
         </dependency>
     </dependencies>
 
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-dependencies</artifactId>
+                <version>3.2.0-M2</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <profiles>
 
         <profile>
@@ -244,9 +275,6 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <configuration>
-                    <compilerArgs>--enable-preview</compilerArgs>
-                </configuration>
             </plugin>
         </plugins>
     </build>

spring-boot-modules/spring-boot-3-2/src/test/java/com/baeldung/conditionalonthreading/ConditionalOnThreadingUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.conditionalonthreading;
+
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnThreading;
+import org.springframework.boot.autoconfigure.thread.Threading;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+public class ConditionalOnThreadingUnitTest {
+
+    ApplicationContextRunner applicationContextRunner = new ApplicationContextRunner()
+      .withUserConfiguration(CurrentConfig.class);
+
+    @Configuration
+    static class CurrentConfig {
+
+        @Bean
+        @ConditionalOnThreading(Threading.PLATFORM)
+        ThreadingType platformBean() {
+            return ThreadingType.PLATFORM;
+        }
+
+        @Bean
+        @ConditionalOnThreading(Threading.VIRTUAL)
+        ThreadingType virtualBean() {
+            return ThreadingType.VIRTUAL;
+        }
+    }
+
+    enum ThreadingType {
+        PLATFORM, VIRTUAL
+    }
+
+    @Test
+    @EnabledForJreRange(max = JRE.JAVA_20)
+    public void whenJava20AndVirtualThreadsEnabled_thenThreadingIsPlatform() {
+        applicationContextRunner.withPropertyValues("spring.threads.virtual.enabled=true").run(context -> {
+            Assertions.assertThat(context.getBean(ThreadingType.class)).isEqualTo(ThreadingType.PLATFORM);
+        });
+    }
+
+    @Test
+    @EnabledForJreRange(max = JRE.JAVA_20)
+    public void whenJava20AndVirtualThreadsDisabled_thenThreadingIsPlatform() {
+        applicationContextRunner.withPropertyValues("spring.threads.virtual.enabled=false").run(context -> {
+            Assertions.assertThat(context.getBean(ThreadingType.class)).isEqualTo(ThreadingType.PLATFORM);
+        });
+    }
+
+    @Test
+    @EnabledForJreRange(min = JRE.JAVA_21)
+    public void whenJava21AndVirtualThreadsEnabled_thenThreadingIsVirtual() {
+        applicationContextRunner.withPropertyValues("spring.threads.virtual.enabled=true").run(context -> {
+            Assertions.assertThat(context.getBean(ThreadingType.class)).isEqualTo(ThreadingType.VIRTUAL);
+        });
+    }
+
+    @Test
+    @EnabledForJreRange(min = JRE.JAVA_21)
+    public void whenJava21AndVirtualThreadsDisabled_thenThreadingIsPlatform() {
+        applicationContextRunner.withPropertyValues("spring.threads.virtual.enabled=false").run(context -> {
+            Assertions.assertThat(context.getBean(ThreadingType.class)).isEqualTo(ThreadingType.PLATFORM);
+        });
+    }
+
+}

spring-boot-modules/spring-boot-3/README.md

@@ -8,3 +8,4 @@
 - [HTTP Interface in Spring 6](https://www.baeldung.com/spring-6-http-interface)
 - [Working with Virtual Threads in Spring 6](https://www.baeldung.com/spring-6-virtual-threads)
 - [Docker Compose Support in Spring Boot 3](https://www.baeldung.com/ops/docker-compose-support-spring-boot)
+- [A Guide to RestClient in Spring Boot](https://www.baeldung.com/spring-boot-restclient)

spring-boot-modules/spring-boot-data-2/README.md

@@ -1,7 +1,6 @@
 ### Relevant Articles:
 
 - [HttpMessageNotWritableException: No Converter for [class …] With Preset Content-Type](https://www.baeldung.com/spring-no-converter-with-preset)
-- [Spring Boot: Customize the Jackson ObjectMapper](https://www.baeldung.com/spring-boot-customize-jackson-objectmapper)
 - [“HttpMessageNotWritableException: No converter found for return value of type”](https://www.baeldung.com/spring-no-converter-found)
 - [Creating a Read-Only Repository with Spring Data](https://www.baeldung.com/spring-data-read-only-repository)
 - [Using JaVers for Data Model Auditing in Spring Data](https://www.baeldung.com/spring-data-javers-audit)

spring-boot-modules/spring-boot-data/README.md

@@ -11,4 +11,5 @@ This module contains articles about Spring Boot with Spring Data
 - [Spring Custom Property Editor](https://www.baeldung.com/spring-mvc-custom-property-editor)
 - [Using @JsonComponent in Spring Boot](https://www.baeldung.com/spring-boot-jsoncomponent)
 - [Guide To Running Logic on Startup in Spring](https://www.baeldung.com/running-setup-logic-on-startup-in-spring)
+- [Spring Boot: Customize the Jackson ObjectMapper](https://www.baeldung.com/spring-boot-customize-jackson-objectmapper)
 

spring-boot-modules/spring-boot-data/src/main/java/com/baeldung/boot/jackson/config/CoffeeConstants.java

@@ -1,10 +1,10 @@
 package com.baeldung.boot.jackson.config;
 
-import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
-
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
 
+import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
+
 public class CoffeeConstants {
 
     public static final String DATETIME_FORMAT = "dd-MM-yyyy HH:mm";

spring-boot-modules/spring-boot-data/src/main/java/com/baeldung/boot/jackson/config/CoffeeCustomizerConfig.java

@@ -1,11 +1,12 @@
 package com.baeldung.boot.jackson.config;
 
-import com.fasterxml.jackson.annotation.JsonInclude;
+import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+
 import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
-import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+import com.fasterxml.jackson.annotation.JsonInclude;
 
 @Configuration
 public class CoffeeCustomizerConfig {

spring-boot-modules/spring-boot-data/src/main/java/com/baeldung/boot/jackson/config/CoffeeHttpConverterConfiguration.java

@@ -1,12 +1,13 @@
 package com.baeldung.boot.jackson.config;
 
-import com.fasterxml.jackson.annotation.JsonInclude;
+import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
 
-import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+import com.fasterxml.jackson.annotation.JsonInclude;
 
 @Configuration
 public class CoffeeHttpConverterConfiguration {

spring-boot-modules/spring-boot-data/src/main/java/com/baeldung/boot/jackson/config/CoffeeJacksonBuilderConfig.java

@@ -1,12 +1,13 @@
 package com.baeldung.boot.jackson.config;
 
-import com.fasterxml.jackson.annotation.JsonInclude;
+import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
 
-import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+import com.fasterxml.jackson.annotation.JsonInclude;
 
 @Configuration
 public class CoffeeJacksonBuilderConfig {

spring-boot-modules/spring-boot-data/src/main/java/com/baeldung/boot/jackson/config/CoffeeObjectMapperConfig.java

@@ -1,13 +1,14 @@
 package com.baeldung.boot.jackson.config;
 
-import com.fasterxml.jackson.annotation.JsonInclude;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 
-import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 
 @Configuration
 public class CoffeeObjectMapperConfig {

spring-boot-modules/spring-boot-data/src/main/java/com/baeldung/boot/jackson/config/CoffeeRegisterModuleConfig.java

@@ -1,19 +1,19 @@
 package com.baeldung.boot.jackson.config;
 
-import com.fasterxml.jackson.databind.Module;
-import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.PropertySource;
 
-import static com.baeldung.boot.jackson.config.CoffeeConstants.LOCAL_DATETIME_SERIALIZER;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 
 @Configuration
 @PropertySource("classpath:coffee.properties")
 public class CoffeeRegisterModuleConfig {
 
     @Bean
-    public Module javaTimeModule() {
+    public JavaTimeModule javaTimeModule() {
         JavaTimeModule module = new JavaTimeModule();
         module.addSerializer(LOCAL_DATETIME_SERIALIZER);
         return module;

spring-boot-modules/spring-boot-data/src/main/java/com/baeldung/boot/jackson/controller/CoffeeController.java

@@ -1,11 +1,12 @@
 package com.baeldung.boot.jackson.controller;
 
-import com.baeldung.boot.jackson.model.Coffee;
+import static com.baeldung.boot.jackson.config.CoffeeConstants.FIXED_DATE;
+
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
-import static com.baeldung.boot.jackson.config.CoffeeConstants.FIXED_DATE;
+import com.baeldung.boot.jackson.model.Coffee;
 
 @RestController
 public class CoffeeController {

spring-boot-modules/spring-boot-data/src/test/java/com/baeldung/boot/jackson/app/AbstractCoffeeIntegrationTest.java

@@ -1,15 +1,16 @@
 package com.baeldung.boot.jackson.app;
 
-import com.baeldung.boot.jackson.config.CoffeeConstants;
+import static com.baeldung.boot.jackson.config.CoffeeConstants.FIXED_DATE;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.format.DateTimeFormatter;
+
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.web.client.TestRestTemplate;
 
-import java.time.format.DateTimeFormatter;
-
-import static com.baeldung.boot.jackson.config.CoffeeConstants.FIXED_DATE;
-import static org.assertj.core.api.Assertions.assertThat;
+import com.baeldung.boot.jackson.config.CoffeeConstants;
 
 @SpringBootTest(classes = Application.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 public abstract class AbstractCoffeeIntegrationTest {

spring-boot-modules/spring-boot-data/src/test/java/com/baeldung/boot/jackson/app/CoffeeCustomizerIntegrationTest.java

@@ -1,8 +1,9 @@
 package com.baeldung.boot.jackson.app;
 
-import com.baeldung.boot.jackson.config.CoffeeCustomizerConfig;
 import org.springframework.context.annotation.Import;
 
+import com.baeldung.boot.jackson.config.CoffeeCustomizerConfig;
+
 @Import(CoffeeCustomizerConfig.class)
 public class CoffeeCustomizerIntegrationTest extends AbstractCoffeeIntegrationTest {
 }

spring-boot-modules/spring-boot-data/src/test/java/com/baeldung/boot/jackson/app/CoffeeHttpConverterIntegrationTest.java

@@ -1,8 +1,9 @@
 package com.baeldung.boot.jackson.app;
 
-import com.baeldung.boot.jackson.config.CoffeeHttpConverterConfiguration;
 import org.springframework.context.annotation.Import;
 
+import com.baeldung.boot.jackson.config.CoffeeHttpConverterConfiguration;
+
 @Import(CoffeeHttpConverterConfiguration.class)
 public class CoffeeHttpConverterIntegrationTest extends AbstractCoffeeIntegrationTest {
 }

spring-boot-modules/spring-boot-data/src/test/java/com/baeldung/boot/jackson/app/CoffeeJacksonBuilderIntegrationTest.java

@@ -1,8 +1,9 @@
 package com.baeldung.boot.jackson.app;
 
-import com.baeldung.boot.jackson.config.CoffeeJacksonBuilderConfig;
 import org.springframework.context.annotation.Import;
 
+import com.baeldung.boot.jackson.config.CoffeeJacksonBuilderConfig;
+
 @Import(CoffeeJacksonBuilderConfig.class)
 public class CoffeeJacksonBuilderIntegrationTest extends AbstractCoffeeIntegrationTest {
 }

spring-boot-modules/spring-boot-data/src/test/java/com/baeldung/boot/jackson/app/CoffeeObjectMapperIntegrationTest.java

@@ -1,8 +1,9 @@
 package com.baeldung.boot.jackson.app;
 
-import com.baeldung.boot.jackson.config.CoffeeObjectMapperConfig;
 import org.springframework.context.annotation.Import;
 
+import com.baeldung.boot.jackson.config.CoffeeObjectMapperConfig;
+
 @Import(CoffeeObjectMapperConfig.class)
 public class CoffeeObjectMapperIntegrationTest extends AbstractCoffeeIntegrationTest {
 }

spring-boot-modules/spring-boot-data/src/test/java/com/baeldung/boot/jackson/app/CoffeeRegisterModuleIntegrationTest.java

@@ -1,8 +1,9 @@
 package com.baeldung.boot.jackson.app;
 
-import com.baeldung.boot.jackson.config.CoffeeRegisterModuleConfig;
 import org.springframework.context.annotation.Import;
 
+import com.baeldung.boot.jackson.config.CoffeeRegisterModuleConfig;
+
 @Import(CoffeeRegisterModuleConfig.class)
 public class CoffeeRegisterModuleIntegrationTest extends AbstractCoffeeIntegrationTest {
 }

spring-cloud-modules/spring-cloud-contract/spring-cloud-contract-consumer/src/test/java/com/baeldung/spring/cloud/springcloudcontractconsumer/controller/BasicMathControllerIntegrationTest.java

@@ -1,5 +1,10 @@
 package com.baeldung.spring.cloud.springcloudcontractconsumer.controller;
 
+import com.github.tomakehurst.wiremock.WireMockServer;
+import com.github.tomakehurst.wiremock.core.WireMockConfiguration;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -13,6 +18,7 @@ import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
 
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
@@ -26,6 +32,36 @@ public class BasicMathControllerIntegrationTest {
 
     @Autowired
     private MockMvc mockMvc;
+    private static WireMockServer wireMockServer;
+
+
+    @BeforeClass
+    public static void setupClass() {
+        WireMockConfiguration wireMockConfiguration = WireMockConfiguration.options().port(8090); // Use the same port as in your code
+
+        wireMockServer = new WireMockServer(wireMockConfiguration);
+        wireMockServer.start();
+    }
+
+    @AfterClass
+    public static void teardownClass() {
+        wireMockServer.stop();
+    }
+
+    @Before
+    public void setup() {
+        wireMockServer.stubFor(get(urlEqualTo("/validate/prime-number?number=1"))
+                .willReturn(aResponse()
+                        .withStatus(200)
+                        .withHeader("Content-Type", "application/json")
+                        .withBody("Odd")));
+
+        wireMockServer.stubFor(get(urlEqualTo("/validate/prime-number?number=2"))
+                .willReturn(aResponse()
+                        .withStatus(200)
+                        .withHeader("Content-Type", "application/json")
+                        .withBody("Even")));
+    }
 
     @Test
     public void given_WhenPassEvenNumberInQueryParam_ThenReturnEven() throws Exception {

spring-cucumber/pom.xml

@@ -45,6 +45,12 @@
             <version>${cucumber.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.junit.vintage</groupId>
+            <artifactId>junit-vintage-engine</artifactId>
+            <version>${junit-vintage-engine.version}</version>
+            <scope>test</scope>
+        </dependency>
         <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-io -->
         <dependency>
             <groupId>org.apache.commons</groupId>
@@ -54,8 +60,9 @@
     </dependencies>
 
     <properties>
-        <cucumber.version>6.8.0</cucumber.version>
+        <cucumber.version>7.14.0</cucumber.version>
         <commons-io.version>1.3.2</commons-io.version>
+        <junit-vintage-engine.version>5.10.0</junit-vintage-engine.version>
     </properties>
 
 </project>

spring-cucumber/src/main/java/com/baeldung/cucumberoptions/CucumberOptionsApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.cucumberoptions;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class CucumberOptionsApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(CucumberOptionsApplication.class, args);
+    }
+
+}

spring-cucumber/src/main/java/com/baeldung/cucumberoptions/HealthCheckController.java

@@ -0,0 +1,22 @@
+package com.baeldung.cucumberoptions;
+
+import static org.springframework.http.MediaType.APPLICATION_JSON_VALUE;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class HealthCheckController {
+
+    @GetMapping(path = "/v1/status", produces = APPLICATION_JSON_VALUE)
+    public HttpStatus getV1Status() {
+        return ResponseEntity.ok().build().getStatusCode();
+    }
+
+    @GetMapping(path = "/v2/status", produces = APPLICATION_JSON_VALUE)
+    public HttpStatus getV2Status() {
+        return ResponseEntity.ok().build().getStatusCode();
+    }
+}

spring-cucumber/src/test/java/com/baeldung/cucumberoptions/HealthCheckStepDefsIntegrationTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.cucumberoptions;
+
+import io.cucumber.java.en.Then;
+import io.cucumber.java.en.When;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.client.RestTemplate;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+import com.baeldung.SpringIntegrationTest;
+
+public class HealthCheckStepDefsIntegrationTest extends SpringIntegrationTest {
+
+    private ResponseEntity<String> statusResponse;
+
+    private ResponseEntity<String> doGet(String url) {
+        return new RestTemplate().getForEntity(url, String.class);
+    }
+
+    @When("^the client calls /v1/status")
+    public void checkV1Status() throws Throwable {
+        statusResponse = doGet("http://localhost:8082/v1/status");
+    }
+
+    @When("^the client calls /v2/status")
+    public void checkV2Status() throws Throwable {
+        statusResponse = doGet("http://localhost:8082/v2/status");
+    }
+
+    @Then("^the client receives (\\d+) status code$")
+    public void verifyStatusCode(int statusCode) throws Throwable {
+        final HttpStatus currentStatusCode = statusResponse.getStatusCode();
+        assertThat(currentStatusCode.value(), is(statusCode));
+    }
+}

spring-cucumber/src/test/resources/com/baeldung/cucumberoptions/healthcheck.feature

@@ -0,0 +1,11 @@
+Feature: healthcheck endpoints can be verified
+
+  @v1
+  Scenario: v1 status is healthy
+    When the client calls /v1/status
+    Then the client receives 200 status code
+
+  @v2
+  Scenario: v2 status is healthy
+    When the client calls /v2/status
+    Then the client receives 200 status code

spring-cucumber/src/test/resources/cucumber.properties

@@ -0,0 +1 @@
+cucumber.filter.tags=not @v2

spring-security-modules/spring-security-core-2/README.md

@@ -8,7 +8,8 @@ This module contains articles about core Spring Security
 - [Prevent Cross-Site Scripting (XSS) in a Spring Application](https://www.baeldung.com/spring-prevent-xss)
 - [Guide to the AuthenticationManagerResolver in Spring Security](https://www.baeldung.com/spring-security-authenticationmanagerresolver)
 - [A Custom Spring SecurityConfigurer](https://www.baeldung.com/spring-security-custom-configurer)
-
+- [HttpSecurity vs. WebSecurity in Spring Security](https://www.baeldung.com/spring-security-httpsecurity-vs-websecurity)
+ 
 ### Build the Project
 
 `mvn clean install`

testing-modules/testing-libraries-2/README.md

@@ -7,3 +7,4 @@
 - [Gray Box Testing Using the OAT Technique](https://www.baeldung.com/java-gray-box-orthogonal-array-testing)
 - [Unit Testing of System.in With JUnit](https://www.baeldung.com/java-junit-testing-system-in)
 - [Fail Maven Build if JUnit Coverage Falls Below Certain Threshold](https://www.baeldung.com/maven-junit-fail-build-coverage-threshold)
+- [How to Mock Environment Variables in Unit Tests](https://www.baeldung.com/java-unit-testing-environment-variables)