Merge branch 'eugenp:master' into master

apache-kafka-2/README.md

@@ -7,3 +7,4 @@ You can build the project from the command line using: *mvn clean install*, or i
 
 ### Relevant Articles:
 - [Guide to Check if Apache Kafka Server Is Running](https://www.baeldung.com/apache-kafka-check-server-is-running)
+- [Add Custom Headers to a Kafka Message](https://www.baeldung.com/java-kafka-custom-headers)

apache-poi/pom.xml

@@ -30,6 +30,16 @@
                 </exclusion>
             </exclusions>
         </dependency>
+        <dependency>
+            <groupId>org.dhatim</groupId>
+            <artifactId>fastexcel</artifactId>
+            <version>${fastexcel.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.dhatim</groupId>
+            <artifactId>fastexcel-reader</artifactId>
+            <version>${fastexcel.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -52,6 +62,7 @@
     <properties>
         <poi.version>5.2.0</poi.version>
         <jexcel.version>1.0.6</jexcel.version>
+        <fastexcel.version>0.15.3</fastexcel.version>
         <maven.resources.plugin.version>3.2.0</maven.resources.plugin.version>
     </properties>
 

apache-poi/src/main/java/com/baeldung/fastexcel/FastexcelHelper.java

@@ -0,0 +1,63 @@
+package com.baeldung.fastexcel;
+
+import org.dhatim.fastexcel.Workbook;
+import org.dhatim.fastexcel.Worksheet;
+import org.dhatim.fastexcel.reader.Cell;
+import org.dhatim.fastexcel.reader.ReadableWorkbook;
+import org.dhatim.fastexcel.reader.Row;
+import org.dhatim.fastexcel.reader.Sheet;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Stream;
+
+public class FastexcelHelper {
+
+    public Map<Integer, List<String>> readExcel(String fileLocation) throws IOException {
+        Map<Integer, List<String>> data = new HashMap<>();
+
+        try (FileInputStream file = new FileInputStream(fileLocation); ReadableWorkbook wb = new ReadableWorkbook(file)) {
+            Sheet sheet = wb.getFirstSheet();
+            try (Stream<Row> rows = sheet.openStream()) {
+                rows.forEach(r -> {
+                    data.put(r.getRowNum(), new ArrayList<>());
+
+                    for (Cell cell : r) {
+                        data.get(r.getRowNum()).add(cell.getRawValue());
+                    }
+                });
+            }
+        }
+
+        return data;
+    }
+
+    public void writeExcel() throws IOException {
+        File currDir = new File(".");
+        String path = currDir.getAbsolutePath();
+        String fileLocation = path.substring(0, path.length() - 1) + "fastexcel.xlsx";
+
+        try (OutputStream os = Files.newOutputStream(Paths.get(fileLocation)); Workbook wb = new Workbook(os, "MyApplication", "1.0")) {
+            Worksheet ws = wb.newWorksheet("Sheet 1");
+
+            ws.width(0, 25);
+            ws.width(1, 15);
+
+            ws.range(0, 0, 0, 1).style().fontName("Arial").fontSize(16).bold().fillColor("3366FF").set();
+            ws.value(0, 0, "Name");
+            ws.value(0, 1, "Age");
+
+            ws.range(2, 0, 2, 1).style().wrapText(true).set();
+            ws.value(2, 0, "John Smith");
+            ws.value(2, 1, 20L);
+        }
+    }
+}

apache-poi/src/test/java/com/baeldung/fastexcel/FastexcelIntegrationTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.fastexcel;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+
+public class FastexcelIntegrationTest {
+
+    private FastexcelHelper fastexcelHelper;
+    private static String FILE_NAME = "fastexcel.xlsx";
+    private String fileLocation;
+
+    @Before
+    public void generateExcelFile() throws IOException {
+
+        File currDir = new File(".");
+        String path = currDir.getAbsolutePath();
+        fileLocation = path.substring(0, path.length() - 1) + FILE_NAME;
+
+        fastexcelHelper = new FastexcelHelper();
+        fastexcelHelper.writeExcel();
+    }
+
+    @Test
+    public void whenParsingExcelFile_thenCorrect() throws IOException {
+        Map<Integer, List<String>> data = fastexcelHelper.readExcel(fileLocation);
+
+        assertEquals("Name", data.get(1).get(0));
+        assertEquals("Age", data.get(1).get(1));
+
+        assertEquals("John Smith", data.get(3).get(0));
+        assertEquals("20", data.get(3).get(1));
+    }
+
+    @After
+    public void cleanup() {
+        File testFile = new File(fileLocation);
+        if (testFile.exists()) {
+            testFile.delete();
+        }
+    }
+}

aws-modules/aws-s3/src/main/java/com/baeldung/s3/AWSS3ObjectUtils.java

@@ -0,0 +1,42 @@
+package com.baeldung.s3;
+
+import org.apache.http.HttpStatus;
+
+import com.amazonaws.AmazonServiceException;
+import com.amazonaws.services.s3.AmazonS3;
+
+public class AWSS3ObjectUtils {
+
+    private AmazonS3 s3Client;
+
+    public AWSS3ObjectUtils(AmazonS3 s3client) {
+        this.s3Client = s3client;
+    }
+
+    public boolean doesObjectExistByDefaultMethod(String bucket, String key) {
+        return s3Client.doesObjectExist(bucket, key);
+    }
+
+    public boolean doesObjectExistByListObjects(String bucket, String key) {
+        return s3Client.listObjects(bucket)
+            .getObjectSummaries()
+            .stream()
+            .filter(s3ObjectSummary -> s3ObjectSummary.getKey()
+                .equals(key))
+            .findFirst()
+            .isPresent();
+    }
+
+    public boolean doesObjectExistByMetaData(String bucket, String key) {
+        try {
+            s3Client.getObjectMetadata(bucket, key);
+            return true;
+        } catch (AmazonServiceException e) {
+            if (e.getStatusCode() == HttpStatus.SC_NOT_FOUND) {
+                return false;
+            } else {
+                throw e;
+            }
+        }
+    }
+}

aws-modules/aws-s3/src/test/java/com/baeldung/s3/AWSS3ObjectIntegrationTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.s3;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.amazonaws.auth.EnvironmentVariableCredentialsProvider;
+import com.amazonaws.regions.Regions;
+import com.amazonaws.services.s3.AmazonS3;
+import com.amazonaws.services.s3.AmazonS3ClientBuilder;
+
+public class AWSS3ObjectIntegrationTest {
+
+    private static final String BUCKET = "your-bucket";
+    private static final String KEY_THAT_EXIST = "your-key-that-exist";
+    private AWSS3ObjectUtils s3ObjectUtils;
+
+    @Before
+    public void setUp() {
+        AmazonS3 client = AmazonS3ClientBuilder.standard()
+            .withRegion(Regions.DEFAULT_REGION)
+            .withCredentials(new EnvironmentVariableCredentialsProvider())
+            .build();
+
+        s3ObjectUtils = new AWSS3ObjectUtils(client);
+    }
+
+    @Test
+    public void whenVerifyIfObjectExistByDefaultMethod_thenCorrect() {
+        assertTrue(s3ObjectUtils.doesObjectExistByDefaultMethod(BUCKET, KEY_THAT_EXIST), "Key: " + KEY_THAT_EXIST + " doesn't exist");
+
+    }
+
+    @Test
+    public void whenVerifyIfObjectExistByListObjects_thenCorrect() {
+        assertTrue(s3ObjectUtils.doesObjectExistByListObjects(BUCKET, KEY_THAT_EXIST), "Key: " + KEY_THAT_EXIST + " doesn't exist");
+    }
+
+    @Test
+    public void whenVerifyIfObjectExistByMetaData_thenCorrect() {
+        assertTrue(s3ObjectUtils.doesObjectExistByMetaData(BUCKET, KEY_THAT_EXIST), "Key: " + KEY_THAT_EXIST + " doesn't exist");
+    }
+}

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

@@ -12,3 +12,4 @@ This module contains articles about Java array fundamentals. They assume no prev
 - [Extending an Array’s Length](https://www.baeldung.com/java-array-add-element-at-the-end)
 - [Initializing a Boolean Array in Java](https://www.baeldung.com/java-initializing-boolean-array)
 - [Find the Index of an Element in a Java Array](https://www.baeldung.com/java-array-find-index)
+- [Comparing Two Byte Arrays in Java](https://www.baeldung.com/java-comparing-byte-arrays)

core-java-modules/core-java-concurrency-advanced-4/src/main/java/com/baeldung/producerconsumer/Consumer.java

@@ -1,6 +1,9 @@
 package com.baeldung.producerconsumer;
 
+import java.util.logging.Logger;
+
 public class Consumer implements Runnable {
+    private static final Logger log = Logger.getLogger(Consumer.class.getCanonicalName());
     private final DataQueue dataQueue;
 
     public Consumer(DataQueue dataQueue) {
@@ -14,7 +17,7 @@ public class Consumer implements Runnable {
 
     public void consume() {
         while (dataQueue.runFlag) {
-            synchronized (this) {
+            synchronized (dataQueue) {
                 while (dataQueue.isEmpty() && dataQueue.runFlag) {
                     try {
                         dataQueue.waitOnEmpty();
@@ -31,12 +34,13 @@ public class Consumer implements Runnable {
                 useMessage(message);
             }
         }
-        System.out.println("Consumer Stopped");
+        log.info("Consumer Stopped");
     }
 
     private void useMessage(Message message) {
         if (message != null) {
-            System.out.printf("[%s] Consuming Message. Id: %d, Data: %f\n", Thread.currentThread().getName(), message.getId(), message.getData());
+            log.info(String.format("[%s] Consuming Message. Id: %d, Data: %f%n",
+                Thread.currentThread().getName(), message.getId(), message.getData()));
 
             //Sleeping on random time to make it realistic
             ThreadUtil.sleep((long) (message.getData() * 100));

core-java-modules/core-java-concurrency-advanced-4/src/main/java/com/baeldung/producerconsumer/Producer.java

@@ -1,6 +1,9 @@
 package com.baeldung.producerconsumer;
 
+import java.util.logging.Logger;
+
 public class Producer implements Runnable {
+    private static final Logger log = Logger.getLogger(Producer.class.getCanonicalName());
     private final DataQueue dataQueue;
 
     private static int idSequence = 0;
@@ -16,7 +19,7 @@ public class Producer implements Runnable {
 
     public void produce() {
         while (dataQueue.runFlag) {
-            synchronized (this) {
+            synchronized (dataQueue) {
                 while (dataQueue.isFull() && dataQueue.runFlag) {
                     try {
                         dataQueue.waitOnFull();
@@ -33,12 +36,13 @@ public class Producer implements Runnable {
                 dataQueue.notifyAllForEmpty();
             }
         }
-        System.out.println("Producer Stopped");
+        log.info("Producer Stopped");
     }
 
     private Message generateMessage() {
-        Message message = new Message(++idSequence, Math.random());
-        System.out.printf("[%s] Generated Message. Id: %d, Data: %f\n", Thread.currentThread().getName(), message.getId(), message.getData());
+        Message message = new Message(incrementAndGetId(), Math.random());
+        log.info(String.format("[%s] Generated Message. Id: %d, Data: %f%n",
+            Thread.currentThread().getName(), message.getId(), message.getData()));
 
         //Sleeping on random time to make it realistic
         ThreadUtil.sleep((long) (message.getData() * 100));
@@ -46,6 +50,10 @@ public class Producer implements Runnable {
         return message;
     }
 
+    private static int incrementAndGetId() {
+        return ++idSequence;
+    }
+
     public void stop() {
         dataQueue.runFlag = false;
         dataQueue.notifyAllForFull();

core-java-modules/core-java-concurrency-advanced-4/src/main/java/com/baeldung/producerconsumer/SimpleProducerConsumerDemonstrator.java

@@ -2,10 +2,12 @@ package com.baeldung.producerconsumer;
 
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingDeque;
+import java.util.logging.Logger;
 
 import static com.baeldung.producerconsumer.ThreadUtil.sleep;
 
 public class SimpleProducerConsumerDemonstrator {
+    private static final Logger log = Logger.getLogger(SimpleProducerConsumerDemonstrator.class.getCanonicalName());
     BlockingQueue<Double> blockingQueue = new LinkedBlockingDeque<>(5);
 
     private void produce() {
@@ -17,7 +19,7 @@ public class SimpleProducerConsumerDemonstrator {
                 e.printStackTrace();
                 break;
             }
-            System.out.printf("[%s] Value produced: %f\n", Thread.currentThread().getName(), value);
+            log.info(String.format("[%s] Value produced: %f%n", Thread.currentThread().getName(), value));
         }
     }
 
@@ -31,7 +33,7 @@ public class SimpleProducerConsumerDemonstrator {
                 break;
             }
             // Consume value
-            System.out.printf("[%s] Value consumed: %f\n", Thread.currentThread().getName(), value);
+            log.info(String.format("[%s] Value consumed: %f%n", Thread.currentThread().getName(), value));
         }
     }
 

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

@@ -6,4 +6,5 @@ This module contains articles about basic Java concurrency.
 
 - [How to Handle InterruptedException in Java](https://www.baeldung.com/java-interrupted-exception)
 - [Thread.sleep() vs Awaitility.await()](https://www.baeldung.com/java-thread-sleep-vs-awaitility-await)
+- [Is CompletableFuture Non-blocking?](https://www.baeldung.com/java-completablefuture-non-blocking)
 - [[<-- Prev]](../core-java-concurrency-basic-2)

core-java-modules/core-java-concurrency-basic-3/src/test/java/com/baeldung/concurrent/RequestProcessorUnitTest.java

@@ -20,7 +20,8 @@ public class RequestProcessorUnitTest {
     void whenWaitingWithThreadSleep_thenStatusIsDone() throws InterruptedException {
         String requestId = requestProcessor.processRequest();
 
-        Thread.sleep(2000);
+        //The sleep value should be greater than the maximum time the request takes to complete
+        Thread.sleep(2010);
 
         assertEquals("DONE", requestProcessor.getStatus(requestId));
     }
@@ -31,7 +32,8 @@ public class RequestProcessorUnitTest {
         String requestId = requestProcessor.processRequest();
 
         Awaitility.await()
-          .atMost(2, TimeUnit.SECONDS)
+           //The timeout value should exceed the maximum time the request takes to complete, for the time amount of a poll (500 ms)
+          .atMost(2501, TimeUnit.MILLISECONDS)
           .pollDelay(500, TimeUnit.MILLISECONDS)
           .until(() -> requestProcessor.getStatus(requestId), not(equalTo("PROCESSING")));
 

core-java-modules/core-java-concurrency-collections-2/src/test/java/com/baeldung/concurrent/queue/BlockingQueueUnitTest.java

@@ -0,0 +1,26 @@
+package com.baeldung.concurrent.queue;
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+
+public class BlockingQueueUnitTest {
+
+    @Test
+    public void givenArrayBlockingQueue_whenAddedElements_thenReturnQueueRemainingCapacity() {
+        BlockingQueue<String> arrayBlockingQueue = new ArrayBlockingQueue<>(10);
+        arrayBlockingQueue.add("TestString1");
+        arrayBlockingQueue.add("TestString2");
+        assertEquals(8, arrayBlockingQueue.remainingCapacity());
+    }
+
+    @Test
+    public void givenLinkedBlockingQueue_whenAddedElements_thenReturnQueueRemainingCapacity() {
+        BlockingQueue<String> linkedBlockingQueue = new LinkedBlockingQueue<>(10);
+        linkedBlockingQueue.add("TestString1");
+        assertEquals(9, linkedBlockingQueue.remainingCapacity());
+    }
+}

core-java-modules/core-java-io-apis-2/README.md

@@ -7,3 +7,4 @@ This module contains articles about core Java input/output(IO) APIs.
 - [Java Scanner Taking a Character Input](https://www.baeldung.com/java-scanner-character-input)
 - [Get the Desktop Path in Java](https://www.baeldung.com/java-desktop-path)
 - [Integer.parseInt(scanner.nextLine()) and scanner.nextInt() in Java](https://www.baeldung.com/java-scanner-integer)
+- [Difference Between FileReader and BufferedReader in Java](https://www.baeldung.com/java-filereader-vs-bufferedreader)

core-java-modules/core-java-io-apis-2/pom.xml

@@ -1,46 +1,115 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-    <modelVersion>4.0.0</modelVersion>
-    <artifactId>core-java-io-apis-2</artifactId>
-    <name>core-java-io-apis-2</name>
-    <packaging>jar</packaging>
-
-    <parent>
-        <groupId>com.baeldung.core-java-modules</groupId>
-        <artifactId>core-java-modules</artifactId>
-        <version>0.0.1-SNAPSHOT</version>
-    </parent>
-
-    <dependencies>
-        <!-- logging -->
-        <dependency>
-            <groupId>log4j</groupId>
-            <artifactId>log4j</artifactId>
-            <version>${log4j.version}</version>
-        </dependency>
-        <dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
-            <groupId>org.slf4j</groupId>
-            <artifactId>log4j-over-slf4j</artifactId>
-            <version>${org.slf4j.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.projectlombok</groupId>
-            <artifactId>lombok</artifactId>
-            <version>${lombok.version}</version>
-            <scope>provided</scope>
-        </dependency>
-    </dependencies>
-
-    <build>
-        <finalName>core-java-io-apis-2</finalName>
-        <resources>
-            <resource>
-                <directory>src/main/resources</directory>
-                <filtering>true</filtering>
-            </resource>
-        </resources>
-    </build>
-
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-io-apis-2</artifactId>
+    <name>core-java-io-apis-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <!-- logging -->
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
+            <groupId>org.slf4j</groupId>
+            <artifactId>log4j-over-slf4j</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.7.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+        </dependency>
+        <!-- this is all you need to write tests with JUnit Jupiter -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit-jupiter-version}</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- this dependency is needed to create parameterized tests -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <version>${junit-jupiter-version}</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- contains the engine that actually runs the Jupiter-tests -->
+        <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</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.testng</groupId>
+            <artifactId>testng</artifactId>
+            <version>7.1.0</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testng</groupId>
+            <artifactId>testng</artifactId>
+            <version>7.5</version>
+            <scope>compile</scope>
+        </dependency>
+    </dependencies>
+    <properties>
+        <junit-jupiter-version>5.2.0</junit-jupiter-version>
+    </properties>
+    <build>
+        <finalName>core-java-io-apis-2</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
 </project>

core-java-modules/core-java-io-apis-2/src/main/java/com/baeldung/multinput/MultiInputs.java

@@ -0,0 +1,36 @@
+package com.baeldung.multinput;
+
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class MultiInputs {
+    public void UsingSpaceDelimiter(){
+        Scanner scanner = new Scanner(System.in);
+        System.out.print("Enter two numbers: ");
+        int num1 = scanner.nextInt();
+        int num2 = scanner.nextInt();
+        System.out.println("You entered " + num1 + " and " + num2);
+
+    }
+    public void UsingREDelimiter(){
+        Scanner scanner = new Scanner(System.in);
+        scanner.useDelimiter("[\\s,]+");
+        System.out.print("Enter two numbers separated by a space or a comma: ");
+        int num1 = scanner.nextInt();
+        int num2 = scanner.nextInt();
+        System.out.println("You entered " + num1 + " and " + num2);
+
+    }
+    public void UsingCustomDelimiter(){
+        Scanner scanner = new Scanner(System.in);
+        scanner.useDelimiter(";");
+        System.out.print("Enter two numbers separated by a semicolon: ");
+        try { int num1 = scanner.nextInt();
+            int num2 = scanner.nextInt();
+            System.out.println("You entered " + num1 + " and " + num2); }
+        catch (InputMismatchException e)
+        { System.out.println("Invalid input. Please enter two integers separated by a semicolon."); }
+
+    }
+}
+

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/absolutetorelative/AbsoluteToRelativeUnitTest.java

@@ -1,93 +1,92 @@
-package com.baeldung.absolutetorelative;
-
-import org.assertj.core.api.Assertions;
-import org.junit.jupiter.api.Test;
-
-import java.net.URI;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-
-public class AbsoluteToRelativeUnitTest {
-
-    // given - until using Paths, no need to create physical files
-    private final Path pathOne = Paths.get("/baeldung/bar/one.txt");
-    private final Path pathTwo = Paths.get("/baeldung/bar/two.txt");
-    private final Path pathThree = Paths.get("/baeldung/foo/three.txt");
-
-    private final URI uriOne = pathOne.toUri();
-    private final URI uriTwo = pathTwo.toUri();
-    private final URI uriThree = pathThree.toUri();
-
-    @Test
-    public void givenAbsolutePaths_whenRelativizePathOneToPathTwo_thenRelativeIsReturned() {
-        Path result = pathOne.relativize(pathTwo);
-
-        Assertions.assertThat(result)
-                .isRelative()
-                .isEqualTo(Paths.get("../two.txt"));
-    }
-
-    @Test
-    public void givenAbsolutePaths_whenRelativizePathTwoToPathOne_thenRelativeIsReturned() {
-        Path result = pathTwo.relativize(pathOne);
-
-        Assertions.assertThat(result)
-                .isRelative()
-                .isEqualTo(Paths.get("../one.txt"));
-    }
-
-    @Test
-    public void givenAbsolutePaths_whenRelativizePathOneParentToPathTwo_thenRelativeIsReturned() {
-        Path result = pathOne.getParent().relativize(pathTwo);
-
-        Assertions.assertThat(result)
-                .isRelative()
-                .isEqualTo(Paths.get("two.txt"));
-    }
-
-    @Test
-    public void givenAbsolutePaths_whenRelativizePathOneToPathThree_thenRelativeIsReturned() {
-        Path result = pathOne.relativize(pathThree);
-
-        Assertions.assertThat(result)
-                .isRelative()
-                .isEqualTo(Paths.get("../../foo/three.txt"));
-    }
-
-    @Test
-    public void givenAbsolutePaths_whenRelativizePathThreeToPathOne_thenRelativeIsReturned() {
-        Path result = pathThree.relativize(pathOne);
-
-        Assertions.assertThat(result)
-                .isRelative()
-                .isEqualTo(Paths.get("../../bar/one.txt"));
-    }
-
-    @Test
-    public void givenAbsoluteURIs_whenRelativizeUriOneToUriTwo_thenAbsoluteIsReturned() {
-        URI result = uriOne.relativize(uriTwo);
-
-        Assertions.assertThat(result)
-                .asString()
-                .contains("/baeldung/bar/two.txt");
-    }
-
-    @Test
-    public void givenAbsoluteURIs_whenRelativizeUriOneParentToUriTwo_thenRelativeIsReturned() {
-        URI result = pathOne.getParent().toUri().relativize(uriTwo);
-
-        Assertions.assertThat(result)
-                .asString()
-                .contains("two.txt");
-    }
-
-    @Test
-    public void givenAbsoluteURIs_whenRelativizeUriOneParentToUriThree_thenAbsoluteIsReturned() {
-        URI result = pathOne.getParent().toUri().relativize(uriThree);
-
-        Assertions.assertThat(result)
-                .asString()
-                .contains("/baeldung/foo/three.txt");
-    }
-
-}
+package com.baeldung.absolutetorelative;
+
+import java.net.URI;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class AbsoluteToRelativeUnitTest {
+
+    // given - until using Paths, no need to create physical files
+    private final Path pathOne = Paths.get("/baeldung/bar/one.txt");
+    private final Path pathTwo = Paths.get("/baeldung/bar/two.txt");
+    private final Path pathThree = Paths.get("/baeldung/foo/three.txt");
+
+    private final URI uriOne = pathOne.toUri();
+    private final URI uriTwo = pathTwo.toUri();
+    private final URI uriThree = pathThree.toUri();
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathOneToPathTwo_thenRelativeIsReturned() {
+        Path result = pathOne.relativize(pathTwo);
+
+        org.assertj.core.api.Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("../two.txt"));
+    }
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathTwoToPathOne_thenRelativeIsReturned() {
+        Path result = pathTwo.relativize(pathOne);
+
+        org.assertj.core.api.Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("../one.txt"));
+    }
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathOneParentToPathTwo_thenRelativeIsReturned() {
+        Path result = pathOne.getParent().relativize(pathTwo);
+
+        org.assertj.core.api.Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("two.txt"));
+    }
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathOneToPathThree_thenRelativeIsReturned() {
+        Path result = pathOne.relativize(pathThree);
+
+        org.assertj.core.api.Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("../../foo/three.txt"));
+    }
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathThreeToPathOne_thenRelativeIsReturned() {
+        Path result = pathThree.relativize(pathOne);
+
+        org.assertj.core.api.Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("../../bar/one.txt"));
+    }
+
+    @Test
+    public void givenAbsoluteURIs_whenRelativizeUriOneToUriTwo_thenAbsoluteIsReturned() {
+        URI result = uriOne.relativize(uriTwo);
+
+        org.assertj.core.api.Assertions.assertThat(result)
+                .asString()
+                .contains("/baeldung/bar/two.txt");
+    }
+
+    @Test
+    public void givenAbsoluteURIs_whenRelativizeUriOneParentToUriTwo_thenRelativeIsReturned() {
+        URI result = pathOne.getParent().toUri().relativize(uriTwo);
+
+        org.assertj.core.api.Assertions.assertThat(result)
+                .asString()
+                .contains("two.txt");
+    }
+
+    @Test
+    public void givenAbsoluteURIs_whenRelativizeUriOneParentToUriThree_thenAbsoluteIsReturned() {
+        URI result = pathOne.getParent().toUri().relativize(uriThree);
+
+        org.assertj.core.api.Assertions.assertThat(result)
+                .asString()
+                .contains("/baeldung/foo/three.txt");
+    }
+
+}

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/bufferedreadervsfilereader/BufferedReaderUnitTest.java

@@ -1,31 +1,31 @@
-package com.baeldung.bufferedreadervsfilereader;
-
-import org.junit.Test;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-import java.io.BufferedReader;
-import java.io.FileReader;
-import java.io.IOException;
-
-public class BufferedReaderUnitTest {
-
-    @Test
-    public void whenReadingAFile_thenReadsLineByLine() {
-        StringBuilder result = new StringBuilder();
-
-        try (BufferedReader br = new BufferedReader(new FileReader("src/test/resources/sampleText1.txt"))) {
-            String line;
-
-            while((line = br.readLine()) != null) {
-                result.append(line);
-                result.append('\n');
-            }
-        } catch (IOException e) {
-            e.printStackTrace();
-        }
-
-        assertEquals("first line\nsecond line\nthird line\n", result.toString());
-    }
-
-}
+package com.baeldung.bufferedreadervsfilereader;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+
+import org.junit.jupiter.api.Assertions;
+import org.testng.annotations.Test;
+public class BufferedReaderUnitTest {
+
+    @Test
+    public void whenReadingAFile_thenReadsLineByLine() {
+        StringBuilder result = new StringBuilder();
+
+        try (BufferedReader br = new BufferedReader(new FileReader("src/test/resources/sampleText1.txt"))) {
+            String line;
+
+            while((line = br.readLine()) != null) {
+                result.append(line);
+                result.append('\n');
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        assertEquals("first line\nsecond line\nthird line\n", result.toString());
+    }
+
+}

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/bufferedreadervsfilereader/FileReaderUnitTest.java

@@ -1,30 +1,30 @@
-package com.baeldung.bufferedreadervsfilereader;
-
-import org.junit.jupiter.api.Test;
-
-import java.io.FileReader;
-import java.io.IOException;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-public class FileReaderUnitTest {
-
-    @Test
-    public void whenReadingAFile_thenReadsCharByChar() {
-        StringBuilder result = new StringBuilder();
-
-        try (FileReader fr = new FileReader("src/test/resources/sampleText2.txt")) {
-            int i = fr.read();
-
-            while(i != -1) {
-                result.append((char)i);
-
-                i = fr.read();
-            }
-        } catch (IOException e) {
-            e.printStackTrace();
-        }
-
-        assertEquals("qwerty", result.toString());
-    }
-}
+package com.baeldung.bufferedreadervsfilereader;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.FileReader;
+import java.io.IOException;
+
+import org.junit.jupiter.api.Test;
+
+public class FileReaderUnitTest {
+
+    @Test
+    public void whenReadingAFile_thenReadsCharByChar() {
+        StringBuilder result = new StringBuilder();
+
+        try (FileReader fr = new FileReader("src/test/resources/sampleText2.txt")) {
+            int i = fr.read();
+
+            while(i != -1) {
+                result.append((char)i);
+
+                i = fr.read();
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        assertEquals("qwerty", result.toString());
+    }
+}

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/multinput/TestMultipleInputsUnitTest.java

@@ -0,0 +1,47 @@
+package com.baeldung.multinput;
+    import java.io.ByteArrayInputStream;
+    import java.io.InputStream;
+    import java.util.InputMismatchException;
+    import org.junit.jupiter.api.Assertions;
+    import org.testng.annotations.Test;
+import com.baeldung.multinput.MultiInputs;
+public class TestMultipleInputsUnitTest {
+    @Test
+    public void givenMultipleInputs_whenUsingSpaceDelimiter_thenExpectPrintingOutputs() {
+        String input = "10 20\n";
+        InputStream in = new ByteArrayInputStream(input.getBytes());
+        System.setIn(in);
+        MultiInputs mi = new MultiInputs();
+        mi.UsingSpaceDelimiter();
+        // You can add assertions here to verify the behavior of the method
+    }
+
+    @Test
+    public void givenMultipleInputs_whenUsingREDelimiter_thenExpectPrintingOutputs() {
+        String input = "30, 40\n";
+        InputStream in = new ByteArrayInputStream(input.getBytes());
+        System.setIn(in);
+        MultiInputs mi = new MultiInputs();
+        mi.UsingREDelimiter();
+        // You can add assertions here to verify the behavior of the method
+    }
+
+    @Test
+    public void givenMultipleInputs_whenUsingCustomDelimiter_thenExpectPrintingOutputs() {
+        String input = "50; 60\n";
+        InputStream in = new ByteArrayInputStream(input.getBytes());
+        System.setIn(in);
+        MultiInputs mi = new MultiInputs();
+        mi.UsingCustomDelimiter();
+        // You can add assertions here to verify the behavior of the method
+    }
+
+    @Test
+    public void givenInvalidInput_whenUsingSpaceDelimiter_thenExpectInputMismatchException() {
+        String input = "abc\n";
+        InputStream in = new ByteArrayInputStream(input.getBytes());
+        System.setIn(in);
+        MultiInputs mi = new MultiInputs();
+        Assertions.assertThrows(InputMismatchException.class, mi::UsingSpaceDelimiter);
+    }
+}

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/path/DesktopPathUnitTest.java

@@ -1,29 +1,27 @@
-package com.baeldung.path;
-
-import org.junit.jupiter.api.Test;
-
-import java.io.File;
-
-import static org.junit.Assert.assertEquals;
-
-import javax.swing.filechooser.FileSystemView;
-
-public class DesktopPathUnitTest {
-    // Adapt DESKTOP_PATH variable to your own system path
-    // private static final String DESKTOP_PATH = "C:\\Users\\HRAF\\Desktop";
-
-    @Test
-    public void whenUsingGetUserHomeProperty_thenShouldEqualDesktopPath() {
-        String desktopPath = System.getProperty("user.home") + File.separator + "Desktop";
-        // assertEquals(DESKTOP_PATH, desktopPath);
-    }
-
-    @Test
-    public void whenUsingFileSystemViewGetHomeDirectory_thenShouldEqualDesktopPath() {
-        FileSystemView view = FileSystemView.getFileSystemView();
-        File file = view.getHomeDirectory();
-        String path = file.getPath();
-        // assertEquals(DESKTOP_PATH, path);
-    }
-
-}
+package com.baeldung.path;
+
+import java.io.File;
+
+import javax.swing.filechooser.FileSystemView;
+
+import org.junit.jupiter.api.Test;
+
+public class DesktopPathUnitTest {
+    // Adapt DESKTOP_PATH variable to your own system path
+    // private static final String DESKTOP_PATH = "C:\\Users\\HRAF\\Desktop";
+
+    @Test
+    public void whenUsingGetUserHomeProperty_thenShouldEqualDesktopPath() {
+        String desktopPath = System.getProperty("user.home") + File.separator + "Desktop";
+        // assertEquals(DESKTOP_PATH, desktopPath);
+    }
+
+    @Test
+    public void whenUsingFileSystemViewGetHomeDirectory_thenShouldEqualDesktopPath() {
+        FileSystemView view = FileSystemView.getFileSystemView();
+        File file = view.getHomeDirectory();
+        String path = file.getPath();
+        // assertEquals(DESKTOP_PATH, path);
+    }
+
+}

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/scanner/NextLineVsNextIntUnitTest.java

@@ -1,85 +1,85 @@
-package com.baeldung.scanner;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-
-import java.util.InputMismatchException;
-import java.util.Scanner;
-
-import org.junit.jupiter.api.Test;
-
-public class NextLineVsNextIntUnitTest {
-
-    @Test
-    void whenInputLineIsNumber_thenNextLineAndNextIntBothWork() {
-        String input = "42\n";
-
-        //nextLine()
-        Scanner sc1 = new Scanner(input);
-        int num1 = Integer.parseInt(sc1.nextLine());
-        assertEquals(42, num1);
-
-        //nextInt()
-        Scanner sc2 = new Scanner(input);
-        int num2 = sc2.nextInt();
-        assertEquals(42, num2);
-
-    }
-
-    @Test
-    void whenInputIsNotValidNumber_thenNextLineAndNextIntThrowDifferentException() {
-        String input = "Nan\n";
-
-        //nextLine() -> NumberFormatException
-        Scanner sc1 = new Scanner(input);
-        assertThrows(NumberFormatException.class, () -> Integer.parseInt(sc1.nextLine()));
-
-        //nextInt() -> InputMismatchException
-        Scanner sc2 = new Scanner(input);
-        assertThrows(InputMismatchException.class, sc2::nextInt);
-    }
-
-    @Test
-    void whenUsingNextInt_thenTheNextTokenAfterItFailsToParseIsNotConsumed() {
-        String input = "42 is a magic number\n";
-
-        //nextInt() to read '42'
-        Scanner sc2 = new Scanner(input);
-        int num2 = sc2.nextInt();
-        assertEquals(42, num2);
-
-        // call nextInt() again on "is"
-        assertThrows(InputMismatchException.class, sc2::nextInt);
-
-        String theNextToken = sc2.next();
-        assertEquals("is", theNextToken);
-
-        theNextToken = sc2.next();
-        assertEquals("a", theNextToken);
-    }
-
-    @Test
-    void whenReadingTwoInputLines_thenNextLineAndNextIntBehaveDifferently() {
-
-        String input = new StringBuilder().append("42\n")
-          .append("It is a magic number.\n")
-          .toString();
-
-        //nextLine()
-        Scanner sc1 = new Scanner(input);
-        int num1 = Integer.parseInt(sc1.nextLine());
-        String nextLineText1 = sc1.nextLine();
-        assertEquals(42, num1);
-        assertEquals("It is a magic number.", nextLineText1);
-
-        //nextInt()
-        Scanner sc2 = new Scanner(input);
-        int num2 = sc2.nextInt();
-        assertEquals(42, num2);
-
-        // nextInt() leaves the newline character (\n) behind
-        String nextLineText2 = sc2.nextLine();
-        assertEquals("", nextLineText2);
-    }
-
+package com.baeldung.scanner;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+import org.junit.jupiter.api.Test;
+
+public class NextLineVsNextIntUnitTest {
+
+    @Test
+    void whenInputLineIsNumber_thenNextLineAndNextIntBothWork() {
+        String input = "42\n";
+
+        //nextLine()
+        Scanner sc1 = new Scanner(input);
+        int num1 = Integer.parseInt(sc1.nextLine());
+        assertEquals(42, num1);
+
+        //nextInt()
+        Scanner sc2 = new Scanner(input);
+        int num2 = sc2.nextInt();
+        assertEquals(42, num2);
+
+    }
+
+    @Test
+    void whenInputIsNotValidNumber_thenNextLineAndNextIntThrowDifferentException() {
+        String input = "Nan\n";
+
+        //nextLine() -> NumberFormatException
+        Scanner sc1 = new Scanner(input);
+        assertThrows(NumberFormatException.class, () -> Integer.parseInt(sc1.nextLine()));
+
+        //nextInt() -> InputMismatchException
+        Scanner sc2 = new Scanner(input);
+        assertThrows(InputMismatchException.class, sc2::nextInt);
+    }
+
+    @Test
+    void whenUsingNextInt_thenTheNextTokenAfterItFailsToParseIsNotConsumed() {
+        String input = "42 is a magic number\n";
+
+        //nextInt() to read '42'
+        Scanner sc2 = new Scanner(input);
+        int num2 = sc2.nextInt();
+        assertEquals(42, num2);
+
+        // call nextInt() again on "is"
+        assertThrows(InputMismatchException.class, sc2::nextInt);
+
+        String theNextToken = sc2.next();
+        assertEquals("is", theNextToken);
+
+        theNextToken = sc2.next();
+        assertEquals("a", theNextToken);
+    }
+
+    @Test
+    void whenReadingTwoInputLines_thenNextLineAndNextIntBehaveDifferently() {
+
+        String input = new StringBuilder().append("42\n")
+          .append("It is a magic number.\n")
+          .toString();
+
+        //nextLine()
+        Scanner sc1 = new Scanner(input);
+        int num1 = Integer.parseInt(sc1.nextLine());
+        String nextLineText1 = sc1.nextLine();
+        assertEquals(42, num1);
+        assertEquals("It is a magic number.", nextLineText1);
+
+        //nextInt()
+        Scanner sc2 = new Scanner(input);
+        int num2 = sc2.nextInt();
+        assertEquals(42, num2);
+
+        // nextInt() leaves the newline character (\n) behind
+        String nextLineText2 = sc2.nextLine();
+        assertEquals("", nextLineText2);
+    }
+
 }

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/scanner/ScanACharacterUnitTest.java

@@ -1,38 +1,38 @@
-package com.baeldung.scanner;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-import java.util.Scanner;
-
-import org.junit.jupiter.api.Test;
-
-public class ScanACharacterUnitTest {
-
-    // given - input scanner source, no need to scan from console
-    String input = new StringBuilder().append("abc\n")
-      .append("mno\n")
-      .append("xyz\n")
-      .toString();
-
-    @Test
-    public void givenInputSource_whenScanCharUsingNext_thenOneCharIsRead() {
-        Scanner sc = new Scanner(input);
-        char c = sc.next().charAt(0);
-        assertEquals('a', c);
-    }
-
-    @Test
-    public void givenInputSource_whenScanCharUsingFindInLine_thenOneCharIsRead() {
-        Scanner sc = new Scanner(input);
-        char c = sc.findInLine(".").charAt(0);
-        assertEquals('a', c);
-    }
-
-    @Test
-    public void givenInputSource_whenScanCharUsingUseDelimiter_thenOneCharIsRead() {
-        Scanner sc = new Scanner(input);
-        char c = sc.useDelimiter("").next().charAt(0);
-        assertEquals('a', c);
-    }
-
-}
+package com.baeldung.scanner;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Scanner;
+
+import org.junit.jupiter.api.Test;
+
+public class ScanACharacterUnitTest {
+
+    // given - input scanner source, no need to scan from console
+    String input = new StringBuilder().append("abc\n")
+      .append("mno\n")
+      .append("xyz\n")
+      .toString();
+
+    @Test
+    public void givenInputSource_whenScanCharUsingNext_thenOneCharIsRead() {
+        Scanner sc = new Scanner(input);
+        char c = sc.next().charAt(0);
+        assertEquals('a', c);
+    }
+
+    @Test
+    public void givenInputSource_whenScanCharUsingFindInLine_thenOneCharIsRead() {
+        Scanner sc = new Scanner(input);
+        char c = sc.findInLine(".").charAt(0);
+        assertEquals('a', c);
+    }
+
+    @Test
+    public void givenInputSource_whenScanCharUsingUseDelimiter_thenOneCharIsRead() {
+        Scanner sc = new Scanner(input);
+        char c = sc.useDelimiter("").next().charAt(0);
+        assertEquals('a', c);
+    }
+
+}

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/scanner/ScannerToArrayUnitTest.java

@@ -0,0 +1,107 @@
+package com.baeldung.scanner;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+import org.junit.jupiter.api.Test;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.ObjectArrays;
+
+public class ScannerToArrayUnitTest {
+
+    @Test
+    void whenMultipleElementsInOneLine_thenGetExpectedArray() {
+        String input = "Java Kotlin Ruby Python Go\n";
+        String[] expected = new String[] { "Java", "Kotlin", "Ruby", "Python", "Go" };
+
+        // scanner.next()
+        Scanner scanner1 = new Scanner(input);
+        String[] result1 = new String[5];
+        int i = 0;
+        while (i < result1.length) {
+            result1[i] = scanner1.next();
+            i++;
+        }
+        assertArrayEquals(expected, result1);
+
+        //split()
+        Scanner scanner2 = new Scanner(input);
+        String[] result2 = scanner2.nextLine()
+          .split("\\s+");
+        assertArrayEquals(expected, result2);
+    }
+
+    @Test
+    void whenOneElementPerLine_thenGetExpectedArray() {
+        String input = new StringBuilder().append("Baeldung Java\n")
+          .append("Baeldung Kotlin\n")
+          .append("Baeldung Linux\n")
+          .toString();
+
+        String[] expected = new String[] { "Baeldung Java", "Baeldung Kotlin", "Baeldung Linux" };
+
+        String[] result = new String[3];
+        Scanner scanner = new Scanner(input);
+        int i = 0;
+        while (i < result.length) {
+            result[i] = scanner.nextLine();
+            i++;
+        }
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    void whenOneElementPerLine_thenGetExpectedList() {
+        String input = new StringBuilder().append("Baeldung Java\n")
+          .append("Baeldung Kotlin\n")
+          .append("Baeldung Linux\n")
+          .toString();
+
+        List<String> expected = Lists.newArrayList("Baeldung Java", "Baeldung Kotlin", "Baeldung Linux");
+
+        List<String> result = new ArrayList<>();
+        Scanner scanner = new Scanner(input);
+        while (scanner.hasNextLine()) {
+            result.add(scanner.nextLine());
+        }
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void whenEveryTokenIsAnElement_thenGetExpectedList() {
+        String input = new StringBuilder().append("Linux Windows MacOS\n")
+          .append("Java Kotlin Python Go\n")
+          .toString();
+
+        List<String> expected = Lists.newArrayList("Linux", "Windows", "MacOS", "Java", "Kotlin", "Python", "Go");
+        List<String> result = new ArrayList<>();
+        Scanner scanner = new Scanner(input);
+        while (scanner.hasNext()) {
+            result.add(scanner.next());
+        }
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void whenEveryTokenIsAnElement_thenGetExpectedArray() {
+        String input = new StringBuilder().append("Linux Windows MacOS\n")
+          .append("Java Kotlin Python Go\n")
+          .toString();
+
+        String[] expected = new String[] { "Linux", "Windows", "MacOS", "Java", "Kotlin", "Python", "Go" };
+        String[] result = new String[] {};
+
+        Scanner scanner = new Scanner(input);
+        while (scanner.hasNextLine()) {
+            String[] lineInArray = scanner.nextLine()
+              .split("\\s+");
+            result = ObjectArrays.concat(result, lineInArray, String.class);
+        }
+        assertArrayEquals(expected, result);
+    }
+}

core-java-modules/core-java-io-apis-2/src/test/resources/sampleText1.txt

@@ -1,3 +1,3 @@
-first line
-second line
-third line
+first line
+second line
+third line

core-java-modules/core-java-io-conversions-2/src/test/java/com/baeldung/outputstreamtoinputstream/ConvertOutputStreamToInputStreamUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.outputstreamtoinputstream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.PipedInputStream;
+import java.io.PipedOutputStream;
+
+import org.junit.jupiter.api.Test;
+
+public class ConvertOutputStreamToInputStreamUnitTest {
+
+    @Test
+    void whenUsingByteArray_thenGetExpectedInputStream() throws IOException {
+        String content = "I'm an important message.";
+        try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
+            out.write(content.getBytes());
+            try (ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray())) {
+                String inContent = new String(in.readAllBytes());
+
+                assertEquals(content, inContent);
+            }
+        }
+    }
+
+    @Test
+    void whenUsingPipeStream_thenGetExpectedInputStream() throws IOException {
+        String content = "I'm going through the pipe.";
+
+        ByteArrayOutputStream originOut = new ByteArrayOutputStream();
+        originOut.write(content.getBytes());
+
+        //connect the pipe
+        PipedInputStream in = new PipedInputStream();
+        PipedOutputStream out = new PipedOutputStream(in);
+
+        try (in) {
+            new Thread(() -> {
+                try (out) {
+                    originOut.writeTo(out);
+                } catch (IOException iox) {
+                    // handle IOExceptions
+                }
+            }).start();
+
+            String inContent = new String(in.readAllBytes());
+            assertEquals(content, inContent);
+        }
+    }
+
+}

core-java-modules/core-java-lang-oop-modifiers/pom.xml

@@ -23,7 +23,7 @@
     </dependencies>
 
     <properties>
-        <h2.version>1.4.197</h2.version> <!-- needs to be specified as it fails with parent's 1.4.200 -->
+        <h2.version>2.1.214</h2.version>
     </properties>
 
 </project>

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interfacesingleimpl/Animal.java

@@ -0,0 +1,5 @@
+package com.baeldung.interfacesingleimpl;
+
+public interface Animal {
+    String makeSound();
+}

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interfacesingleimpl/AnimalCare.java

@@ -0,0 +1,13 @@
+package com.baeldung.interfacesingleimpl;
+
+public class AnimalCare {
+    private Animal animal;
+
+    public AnimalCare(Animal animal) {
+        this.animal = animal;
+    }
+
+    public String animalSound() {
+        return animal.makeSound();
+    }
+}

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interfacesingleimpl/Cat.java

@@ -0,0 +1,21 @@
+package com.baeldung.interfacesingleimpl;
+
+public class Cat {
+    private String name;
+
+    public Cat(String name) {
+        this.name = name;
+    }
+
+    public String makeSound() {
+        return "Meow! My name is " + name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}