Merge remote-tracking branch 'upstream/master'

2021-02-13 08:50:10 +01:00
parent caf864b8e7 89eb93a46c
commit 2d2f29b524
2486 changed files with 19128 additions and 22288 deletions
@@ -1,5 +1,3 @@
-**UPDATE**: The price of "Learn Spring Security OAuth" will permanently change on the 11th of December, along with the upcoming OAuth2 material: http://bit.ly/github-lss
-
 The Courses
 ==============================

@@ -5,6 +5,6 @@ This module contains articles about genetic algorithms.
 ### Relevant articles:

 - [Introduction to Jenetics Library](https://www.baeldung.com/jenetics)
- [Ant Colony Optimization](https://www.baeldung.com/java-ant-colony-optimization)
+- [Ant Colony Optimization with a Java Example](https://www.baeldung.com/java-ant-colony-optimization)
 - [Design a Genetic Algorithm in Java](https://www.baeldung.com/java-genetic-algorithm)
 - [The Traveling Salesman Problem in Java](https://www.baeldung.com/java-simulated-annealing-for-traveling-salesman)
@@ -6,8 +6,8 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 ### Relevant articles:

 - [Validating Input With Finite Automata in Java](https://www.baeldung.com/java-finite-automata)
- [Example of Hill Climbing Algorithm](https://www.baeldung.com/java-hill-climbing-algorithm)
- [Introduction to Minimax Algorithm](https://www.baeldung.com/java-minimax-algorithm)
+- [Example of Hill Climbing Algorithm in Java](https://www.baeldung.com/java-hill-climbing-algorithm)
+- [Introduction to Minimax Algorithm with a Java Implementation](https://www.baeldung.com/java-minimax-algorithm)
 - [How to Calculate Levenshtein Distance in Java?](https://www.baeldung.com/java-levenshtein-distance)
 - [How to Find the Kth Largest Element in Java](https://www.baeldung.com/java-kth-largest-element)
 - More articles: [[next -->]](/algorithms-miscellaneous-2)
@@ -5,8 +5,8 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 ### Relevant articles:

 - [Multi-Swarm Optimization Algorithm in Java](https://www.baeldung.com/java-multi-swarm-algorithm)
- [Check If a String Contains All The Letters of The Alphabet](https://www.baeldung.com/java-string-contains-all-letters)
- [Find the Middle Element of a Linked List](https://www.baeldung.com/java-linked-list-middle-element)
+- [Check If a String Contains All The Letters of The Alphabet with Java](https://www.baeldung.com/java-string-contains-all-letters)
+- [Find the Middle Element of a Linked List in Java](https://www.baeldung.com/java-linked-list-middle-element)
 - [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)
 - [Find the Longest Substring without Repeating Characters](https://www.baeldung.com/java-longest-substring-without-repeated-characters)
 - [Permutations of an Array in Java](https://www.baeldung.com/java-array-permutations)
@@ -9,11 +9,11 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Reversing a Binary Tree in Java](https://www.baeldung.com/java-reversing-a-binary-tree)
 - [Find If Two Numbers Are Relatively Prime in Java](https://www.baeldung.com/java-two-relatively-prime-numbers)
 - [Knapsack Problem Implementation in Java](https://www.baeldung.com/java-knapsack)
- [How to Determine if a Binary Tree is Balanced](https://www.baeldung.com/java-balanced-binary-tree)
+- [How to Determine if a Binary Tree is Balanced in Java](https://www.baeldung.com/java-balanced-binary-tree)
 - [Overview of Combinatorial Problems in Java](https://www.baeldung.com/java-combinatorial-algorithms)
- [Prim’s Algorithm](https://www.baeldung.com/java-prim-algorithm)
- [Maximum Subarray Problem](https://www.baeldung.com/java-maximum-subarray)
- [How to Merge Two Sorted Arrays](https://www.baeldung.com/java-merge-sorted-arrays)
- [Median of Stream of Integers using Heap](https://www.baeldung.com/java-stream-integers-median-using-heap)
+- [Prim’s Algorithm with a Java Implementation](https://www.baeldung.com/java-prim-algorithm)
+- [Maximum Subarray Problem in Java](https://www.baeldung.com/java-maximum-subarray)
+- [How to Merge Two Sorted Arrays in Java](https://www.baeldung.com/java-merge-sorted-arrays)
+- [Median of Stream of Integers using Heap in Java](https://www.baeldung.com/java-stream-integers-median-using-heap)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-4) [[next -->]](/algorithms-miscellaneous-6)

@@ -1,13 +1,13 @@
 ### Relevant Articles:

- [Boruvka’s Algorithm for Minimum Spanning Trees](https://www.baeldung.com/java-boruvka-algorithm)
+- [Boruvka’s Algorithm for Minimum Spanning Trees in Java](https://www.baeldung.com/java-boruvka-algorithm)
 - [Gradient Descent in Java](https://www.baeldung.com/java-gradient-descent)
- [Kruskal’s Algorithm for Spanning Trees](https://www.baeldung.com/java-spanning-trees-kruskal)
+- [Kruskal’s Algorithm for Spanning Trees with a Java Implementation](https://www.baeldung.com/java-spanning-trees-kruskal)
 - [Balanced Brackets Algorithm in Java](https://www.baeldung.com/java-balanced-brackets-algorithm)
 - [Efficiently Merge Sorted Java Sequences](https://www.baeldung.com/java-merge-sorted-sequences)
 - [Introduction to Greedy Algorithms with Java](https://www.baeldung.com/java-greedy-algorithms)
 - [The Caesar Cipher in Java](https://www.baeldung.com/java-caesar-cipher)
 - [Implementing a 2048 Solver in Java](https://www.baeldung.com/2048-java-solver)
- [Finding Top K Elements in an Array](https://www.baeldung.com/java-array-top-elements)
+- [Finding Top K Elements in a Java Array](https://www.baeldung.com/java-array-top-elements)
 - [Reversing a Linked List in Java](https://www.baeldung.com/java-reverse-linked-list)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-5)
@@ -8,8 +8,8 @@ This module contains articles about searching algorithms.
 - [Depth First Search in Java](https://www.baeldung.com/java-depth-first-search)
 - [Interpolation Search in Java](https://www.baeldung.com/java-interpolation-search)
 - [Breadth-First Search Algorithm in Java](https://www.baeldung.com/java-breadth-first-search)
- [String Search Algorithms for Large Texts](https://www.baeldung.com/java-full-text-search-algorithms)
- [Monte Carlo Tree Search for Tic-Tac-Toe Game](https://www.baeldung.com/java-monte-carlo-tree-search)
+- [String Search Algorithms for Large Texts with Java](https://www.baeldung.com/java-full-text-search-algorithms)
+- [Monte Carlo Tree Search for Tic-Tac-Toe Game in Java](https://www.baeldung.com/java-monte-carlo-tree-search)
 - [Range Search Algorithm in Java](https://www.baeldung.com/java-range-search)
- [Fast Pattern Matching of Strings Using Suffix Tree](https://www.baeldung.com/java-pattern-matching-suffix-tree)
- [Find the Kth Smallest Element in Two Sorted Arrays](https://www.baeldung.com/java-kth-smallest-element-in-sorted-arrays)
+- [Fast Pattern Matching of Strings Using Suffix Tree in Java](https://www.baeldung.com/java-pattern-matching-suffix-tree)
+- [Find the Kth Smallest Element in Two Sorted Arrays in Java](https://www.baeldung.com/java-kth-smallest-element-in-sorted-arrays)
@@ -2,6 +2,6 @@

 - [Sorting a String Alphabetically in Java](https://www.baeldung.com/java-sort-string-alphabetically)
 - [Sorting Strings by Contained Numbers in Java](https://www.baeldung.com/java-sort-strings-contained-numbers)
- [How an In-Place Sorting Algorithm Works](https://www.baeldung.com/java-in-place-sorting)
- [Partitioning and Sorting Arrays with Many Repeated Entries](https://www.baeldung.com/java-sorting-arrays-with-repeated-entries)
+- [Guide to In-Place Sorting Algorithm Works with a Java Implementation](https://www.baeldung.com/java-in-place-sorting)
+- [Partitioning and Sorting Arrays with Many Repeated Entries with Java Examples](https://www.baeldung.com/java-sorting-arrays-with-repeated-entries)
 - More articles: [[<-- prev]](/algorithms-sorting)
@@ -51,7 +51,7 @@
 		</dependency>
 		<dependency>
 			<groupId>org.hibernate</groupId>
-			<artifactId>hibernate-entitymanager</artifactId>
+			<artifactId>hibernate-core</artifactId>
 			<version>${hibernate.version}</version>
 			<scope>provided</scope>
 			<exclusions>
@@ -89,7 +89,6 @@

    <properties>
        <json-simple.version>1.1.1</json-simple.version>
-        <commons-io.version>2.5</commons-io.version>
        <aws-lambda-java-events.version>1.3.0</aws-lambda-java-events.version>
        <aws-lambda-java-core.version>1.2.0</aws-lambda-java-core.version>
        <gson.version>2.8.2</gson.version>
@@ -6,10 +6,12 @@ import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.zaxxer.hikari.HikariDataSource;
 import org.hibernate.SessionFactory;
 import org.hibernate.boot.MetadataSources;
 import org.hibernate.boot.registry.StandardServiceRegistry;
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;

 import java.util.HashMap;
 import java.util.Map;
@@ -22,11 +24,14 @@ import static org.hibernate.cfg.AvailableSettings.PASS;
 */
 public class App implements RequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
 private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
+    private SessionFactory sessionFactory = createSessionFactory();

    public APIGatewayProxyResponseEvent handleRequest(APIGatewayProxyRequestEvent input, Context context) {
-        try (SessionFactory sessionFactory = createSessionFactory()) {
+        try {
            ShippingService service = new ShippingService(sessionFactory, new ShippingDao());
            return routeRequest(input, service);
+        } finally {
+            flushConnectionPool();
        }
    }

@@ -105,4 +110,12 @@ private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
          .buildMetadata()
          .buildSessionFactory();
    }
+
+    private void flushConnectionPool() {
+        ConnectionProvider connectionProvider = sessionFactory.getSessionFactoryOptions()
+          .getServiceRegistry()
+          .getService(ConnectionProvider.class);
+        HikariDataSource hikariDataSource = connectionProvider.unwrap(HikariDataSource.class);
+        hikariDataSource.getHikariPoolMXBean().softEvictConnections();
+    }
 }
@@ -154,7 +154,6 @@
    <properties>
        <blade-mvc.version>2.0.14.RELEASE</blade-mvc.version>
        <bootstrap.version>4.2.1</bootstrap.version>
-        <commons-lang3.version>3.8.1</commons-lang3.version>
        <lombok.version>1.18.4</lombok.version>
        <httpclient.version>4.5.6</httpclient.version>
        <httpmime.version>4.5.6</httpmime.version>
@@ -5,8 +5,9 @@ This module contains articles about Java 10 core features
 ### Relevant Articles: 

 - [Java 10 LocalVariable Type-Inference](http://www.baeldung.com/java-10-local-variable-type-inference)
- [Guide to Java 10](http://www.baeldung.com/java-10-overview)
+- [New Features in Java 10](https://www.baeldung.com/java-10-overview)
 - [Copy a List to Another List in Java](http://www.baeldung.com/java-copy-list-to-another)
 - [Deep Dive Into the New Java JIT Compiler – Graal](https://www.baeldung.com/graal-java-jit-compiler)
 - [Copying Sets in Java](https://www.baeldung.com/java-copy-sets)
 - [Converting between a List and a Set in Java](https://www.baeldung.com/convert-list-to-set-and-set-to-list)
+- [Java IndexOutOfBoundsException “Source Does Not Fit in Dest”](https://www.baeldung.com/java-indexoutofboundsexception)
@@ -6,3 +6,4 @@ This module contains articles about Java 11 core features
 - [Guide to Java 8 Optional](https://www.baeldung.com/java-optional)
 - [Guide to Java Reflection](http://www.baeldung.com/java-reflection)
 - [Guide to Java 8’s Collectors](https://www.baeldung.com/java-8-collectors)
+- [New Features in Java 11](https://www.baeldung.com/java-11-new-features)
@@ -28,6 +28,29 @@
            <version>${assertj.version}</version>
            <scope>test</scope>
        </dependency>
+        <dependency>
+            <groupId>org.mock-server</groupId>
+            <artifactId>mockserver-junit-jupiter</artifactId>
+            <version>${mockserver.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
    </dependencies>

    <build>
@@ -48,7 +71,9 @@
        <maven.compiler.source.version>11</maven.compiler.source.version>
        <maven.compiler.target.version>11</maven.compiler.target.version>
        <guava.version>29.0-jre</guava.version>
+        <junit.jupiter.version>5.7.0</junit.jupiter.version>
        <assertj.version>3.17.2</assertj.version>
+        <mockserver.version>5.11.1</mockserver.version>
    </properties>

 </project>
@@ -0,0 +1,17 @@
+package com.baeldung.features;
+
+public class MainClass {
+
+    private static boolean mainPrivateMethod() {
+        return true;
+    }
+
+    public static class NestedClass {
+
+        boolean nestedPublicMethod() {
+            return mainPrivateMethod();
+        }
+
+    }
+
+}
@@ -0,0 +1,54 @@
+package com.baeldung.features;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.mockserver.integration.ClientAndServer;
+import org.mockserver.model.HttpStatusCode;
+import org.mockserver.socket.PortFactory;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.time.Duration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockserver.integration.ClientAndServer.startClientAndServer;
+
+class HttpClientIntegrationTest {
+
+    private static ClientAndServer mockServer;
+    private static int port;
+
+    @BeforeAll
+    static void startServer() {
+        port = PortFactory.findFreePort();
+        mockServer = startClientAndServer(port);
+        mockServer.when(new org.mockserver.model.HttpRequest().withMethod("GET"))
+          .respond(new org.mockserver.model.HttpResponse()
+            .withStatusCode(HttpStatusCode.OK_200.code())
+            .withBody("Hello from the server!"));
+    }
+
+    @AfterAll
+    static void stopServer() {
+        mockServer.stop();
+    }
+
+    @Test
+    void givenSampleHttpRequest_whenRequestIsSent_thenServerResponseIsReceived() throws IOException, InterruptedException {
+        HttpClient httpClient = HttpClient.newBuilder()
+          .version(HttpClient.Version.HTTP_2)
+          .connectTimeout(Duration.ofSeconds(20))
+          .build();
+        HttpRequest httpRequest = HttpRequest.newBuilder()
+          .GET()
+          .uri(URI.create("http://localhost:" + port))
+          .build();
+        HttpResponse<String> httpResponse = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofString());
+        assertThat(httpResponse.body()).isEqualTo("Hello from the server!");
+    }
+
+}
@@ -0,0 +1,61 @@
+package com.baeldung.features;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import javax.annotation.Nonnull;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class JavaElevenFeaturesUnitTest {
+
+    @Test
+    void givenMultilineString_whenExtractingNonBlankStrippedLines_thenLinesAreReturned() {
+        String multilineString = "Baeldung helps \n \n developers \n explore Java.";
+        List<String> lines = multilineString.lines()
+          .filter(line -> !line.isBlank())
+          .map(String::strip)
+          .collect(Collectors.toList());
+        assertThat(lines).containsExactly("Baeldung helps", "developers", "explore Java.");
+    }
+
+    @Test
+    void givenTemporaryFile_whenReadingStringContent_thenContentIsReturned(@TempDir Path tempDir) throws IOException {
+        Path filePath = Files.writeString(Files.createTempFile(tempDir, "demo", ".txt"), "Sample text");
+        String fileContent = Files.readString(filePath);
+        assertThat(fileContent).isEqualTo("Sample text");
+    }
+
+    @Test
+    void givenSampleList_whenConvertingToArray_thenItemsRemainUnchanged() {
+        List<String> sampleList = Arrays.asList("Java", "Kotlin");
+        String[] sampleArray = sampleList.toArray(String[]::new);
+        assertThat(sampleArray).containsExactly("Java", "Kotlin");
+    }
+
+    @Test
+    void givenSampleList_whenConvertingToUppercaseString_thenUppercaseIsReturned() {
+        List<String> sampleList = Arrays.asList("Java", "Kotlin");
+        String resultString = sampleList.stream()
+          .map((@Nonnull var x) -> x.toUpperCase())
+          .collect(Collectors.joining(", "));
+        assertThat(resultString).isEqualTo("JAVA, KOTLIN");
+    }
+
+    @Test
+    void givenSampleList_whenExtractingNonBlankValues_thenOnlyNonBlanksAreReturned() {
+        List<String> sampleList = Arrays.asList("Java", "\n \n", "Kotlin", " ");
+        List<String> withoutBlanks = sampleList.stream()
+          .filter(Predicate.not(String::isBlank))
+          .collect(Collectors.toList());
+        assertThat(withoutBlanks).containsExactly("Java", "Kotlin");
+    }
+
+}
@@ -0,0 +1,37 @@
+package com.baeldung.features;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class NestedClassesUnitTest {
+
+    @Test
+    public void giveNestedClass_whenCallingMainClassPrivateMethod_thenNoExceptionIsThrown() {
+        MainClass.NestedClass nestedInstance = new MainClass.NestedClass();
+        assertThat(nestedInstance.nestedPublicMethod()).isTrue();
+    }
+
+    @Test
+    public void giveNestedClass_whenCheckingNestmate_thenNestedClassIsReturned() {
+        assertThat(MainClass.class.isNestmateOf(MainClass.NestedClass.class)).isTrue();
+    }
+
+    @Test
+    public void giveNestedClass_whenCheckingNestHost_thenMainClassIsReturned() {
+        assertThat(MainClass.NestedClass.class.getNestHost()).isEqualTo(MainClass.class);
+    }
+
+    @Test
+    public void giveNestedClass_whenCheckingNestMembers_thenNestMembersAreReturned() {
+        Set<String> nestedMembers = Arrays.stream(MainClass.NestedClass.class.getNestMembers())
+          .map(Class::getName)
+          .collect(Collectors.toSet());
+        assertThat(nestedMembers).contains(MainClass.class.getName(), MainClass.NestedClass.class.getName());
+    }
+
+}
@@ -64,7 +64,7 @@ public class HttpClientUnitTest {
            .send(request, HttpResponse.BodyHandlers.ofString());

        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_MOVED_PERM));
-        assertThat(response.body(), containsString("https://stackoverflow.com/"));
+        assertTrue(response.headers().map().get("location").stream().anyMatch("https://stackoverflow.com/"::equals));
    }

    @Test
@@ -18,6 +18,7 @@ import java.security.NoSuchAlgorithmException;
 import java.time.Duration;

 import org.junit.Test;
+import org.junit.jupiter.api.Disabled;

 public class HttpRequestUnitTest {

@@ -48,7 +49,12 @@ public class HttpRequestUnitTest {
        assertThat(response.version(), equalTo(HttpClient.Version.HTTP_2));
    }

-    @Test
+    /*
+    * This test will fail as soon as the given URL returns a HTTP 2 response.
+    * Therefore, let's leave it commented out.
+    * */
+   @Test
+   @Disabled
    public void shouldFallbackToHttp1_1WhenWebsiteDoesNotUseHttp2() throws IOException, InterruptedException, URISyntaxException, NoSuchAlgorithmException {
        HttpRequest request = HttpRequest.newBuilder()
            .uri(new URI("https://postman-echo.com/get"))
@@ -1,4 +1,4 @@
 ## Relevant Articles:

-
 - [String API Updates in Java 12](https://www.baeldung.com/java12-string-api)
+- [New Features in Java 12](https://www.baeldung.com/java-12-new-features)
@@ -0,0 +1,21 @@
+package java.com.baeldung.newfeatures;
+
+import org.junit.Test;
+
+import java.text.NumberFormat;
+import java.util.Locale;
+
+import static org.junit.Assert.assertEquals;
+
+public class CompactNumbersUnitTest {
+
+    @Test
+    public void givenNumber_thenCompactValues() {
+        NumberFormat likesShort = NumberFormat.getCompactNumberInstance(new Locale("en", "US"), NumberFormat.Style.SHORT);
+        likesShort.setMaximumFractionDigits(2);
+        assertEquals("2.59K", likesShort.format(2592));
+        NumberFormat likesLong = NumberFormat.getCompactNumberInstance(new Locale("en", "US"), NumberFormat.Style.LONG);
+        likesLong.setMaximumFractionDigits(2);
+        assertEquals("2.59 thousand", likesShort.format(2592));
+    }
+}
@@ -0,0 +1,32 @@
+package java.com.baeldung.newfeatures;
+
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.Assert.assertEquals;
+
+public class FileMismatchUnitTest {
+
+    @Test
+    public void givenIdenticalFiles_thenShouldNotFindMismatch() throws IOException {
+        Path filePath1 = Files.createTempFile("file1", ".txt");
+        Path filePath2 = Files.createTempFile("file2", ".txt");
+        Files.writeString(filePath1, "Java 12 Article");
+        Files.writeString(filePath2, "Java 12 Article");
+        long mismatch = Files.mismatch(filePath1, filePath2);
+        assertEquals(-1, mismatch);
+    }
+
+    @Test
+    public void givenDifferentFiles_thenShouldFindMismatch() throws IOException {
+        Path filePath3 = Files.createTempFile("file3", ".txt");
+        Path filePath4 = Files.createTempFile("file4", ".txt");
+        Files.writeString(filePath3, "Java 12 Article");
+        Files.writeString(filePath4, "Java 12 Tutorial");
+        long mismatch = Files.mismatch(filePath3, filePath4);
+        assertEquals(8, mismatch);
+    }
+}
@@ -0,0 +1,15 @@
+package java.com.baeldung.newfeatures;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class StringUnitTest {
+
+    @Test
+    public void givenString_thenRevertValue() {
+        String text = "Baeldung";
+        String transformed = text.transform(value -> new StringBuilder(value).reverse().toString());
+        assertEquals("gnudleaB", transformed);
+    }
+}
@@ -0,0 +1,18 @@
+package java.com.baeldung.newfeatures;
+
+import org.junit.Test;
+
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.assertEquals;
+
+public class TeeingCollectorUnitTest {
+
+    @Test
+    public void givenSetOfNumbers_thenCalculateAverage() {
+        double mean = Stream.of(1, 2, 3, 4, 5)
+          .collect(Collectors.teeing(Collectors.summingDouble(i -> i), Collectors.counting(), (sum, count) -> sum / count));
+        assertEquals(3.0, mean);
+    }
+}
@@ -1,4 +1,4 @@
 ### Relevant articles:

 - [Java Switch Statement](https://www.baeldung.com/java-switch)
- [New Java 13 Features](https://www.baeldung.com/java-13-new-features)
+- [New Features in Java 13](https://www.baeldung.com/java-13-new-features)
@@ -10,3 +10,4 @@ This module contains articles about Java 14.
 - [Helpful NullPointerExceptions in Java 14](https://www.baeldung.com/java-14-nullpointerexception)
 - [Foreign Memory Access API in Java 14](https://www.baeldung.com/java-foreign-memory-access)
 - [Java 14 Record Keyword](https://www.baeldung.com/java-record-keyword)
+- [New Features in Java 14](https://www.baeldung.com/java-14-new-features)
@@ -44,6 +44,8 @@
                <configuration>
                    <release>${maven.compiler.release}</release>
                    <compilerArgs>--enable-preview</compilerArgs>
+                    <source>14</source>
+                    <target>14</target>
                </configuration>
            </plugin>
            <plugin>
@@ -0,0 +1,30 @@
+package com.baeldung.java14.character;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
+
+public class IsLetterOrAlphabetUnitTest {
+
+    @Test
+    public void givenACharacter_whenLetter_thenAssertIsLetterTrue() {
+        assertTrue(Character.isLetter(65));
+    }
+
+    @Test
+    public void givenACharacter_whenLetter_thenAssertIsAlphabeticTrue() {
+        assertTrue(Character.isAlphabetic(65));
+    }
+
+    @Test
+    public void givenACharacter_whenAlphabeticAndNotLetter_thenAssertIsLetterFalse() {
+        assertFalse(Character.isLetter(837));
+    }
+
+    @Test
+    public void givenACharacter_whenAlphabeticAndNotLetter_thenAssertIsAlphabeticTrue() {
+        assertTrue(Character.isAlphabetic(837));
+    }
+
+}
--- a/Show More
+++ b/Show More