Merge branch 'master' of https://github.com/eugenp/tutorials

.gitignore

@@ -85,5 +85,6 @@ transaction.log
 *-shell.log
 
 apache-cxf/cxf-aegis/baeldung.xml
+testing-modules/report-*.json
 
 libraries-2/*.db

algorithms-searching/README.md

@@ -11,3 +11,4 @@ This module contains articles about searching algorithms.
 - [Monte Carlo Tree Search for Tic-Tac-Toe Game](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)
+- [Topological Sort of Directed Acyclic Graph](https://www.baeldung.com/cs/dag-topological-sort)

apache-cxf/README.md

@@ -7,4 +7,3 @@ This module contains articles about Apache CXF
 - [Apache CXF Support for RESTful Web Services](https://www.baeldung.com/apache-cxf-rest-api)
 - [A Guide to Apache CXF with Spring](https://www.baeldung.com/apache-cxf-with-spring)
 - [Introduction to Apache CXF](https://www.baeldung.com/introduction-to-apache-cxf)
-- [Server-Sent Events (SSE) In JAX-RS](https://www.baeldung.com/java-ee-jax-rs-sse)

apache-cxf/sse-jaxrs/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Server-Sent Events (SSE) In JAX-RS](https://www.baeldung.com/java-ee-jax-rs-sse)

apache-poi/src/main/java/com/baeldung/poi/excel/setformula/ExcelFormula.java

@@ -0,0 +1,26 @@
+package com.baeldung.poi.excel.setformula;
+
+import org.apache.poi.xssf.usermodel.XSSFCell;
+import org.apache.poi.xssf.usermodel.XSSFFormulaEvaluator;
+import org.apache.poi.xssf.usermodel.XSSFSheet;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+public class ExcelFormula {
+    public double setFormula(String fileLocation, XSSFWorkbook wb, String formula) throws IOException {
+        XSSFSheet sheet = wb.getSheetAt(0);
+        int lastCellNum = sheet.getRow(0).getLastCellNum();
+        XSSFCell formulaCell = sheet.getRow(0).createCell(lastCellNum);
+        formulaCell.setCellFormula(formula);
+        XSSFFormulaEvaluator formulaEvaluator = wb.getCreationHelper().createFormulaEvaluator();
+        formulaEvaluator.evaluateFormulaCell(formulaCell);
+        FileOutputStream fileOut = new FileOutputStream(new File(fileLocation));
+        wb.write(fileOut);
+        wb.close();
+        fileOut.close();
+        return formulaCell.getNumericCellValue();
+    }
+}

apache-poi/src/test/java/com/baeldung/poi/excel/setformula/ExcelFormulaUnitTest.java

@@ -0,0 +1,51 @@
+package com.baeldung.poi.excel.setformula;
+
+import org.apache.poi.ss.util.CellReference;
+import org.apache.poi.xssf.usermodel.XSSFSheet;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.Assert;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+
+class ExcelFormulaUnitTest {
+    private static String FILE_NAME = "com/baeldung/poi/excel/setformula/SetFormulaTest.xlsx";
+    private String fileLocation;
+    private ExcelFormula excelFormula;
+
+    @BeforeEach
+    public void setup() throws URISyntaxException {
+        fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME).toURI()).toString();
+        excelFormula = new ExcelFormula();
+    }
+
+    @Test
+    void givenExcelData_whenSetFormula_thenSuccess() throws IOException {
+        FileInputStream inputStream = new FileInputStream(new File(fileLocation));
+        XSSFWorkbook wb = new XSSFWorkbook(inputStream);
+        XSSFSheet sheet = wb.getSheetAt(0);
+        double resultColumnA = 0;
+        double resultColumnB = 0;
+        for (int row = 0; row <= sheet.getLastRowNum(); row++) {
+            resultColumnA += sheet.getRow(row).getCell(0).getNumericCellValue();
+            resultColumnB += sheet.getRow(row).getCell(1).getNumericCellValue();
+        }
+        String colNameA = CellReference.convertNumToColString(0);
+        String colNameB = CellReference.convertNumToColString(1);
+        String startCellA = colNameA + 1;
+        String stopCellA = colNameA + (sheet.getLastRowNum() + 1);
+        String sumFormulaForColumnA = String.format("SUM(%s:%s)", startCellA, stopCellA);
+        String startCellB = colNameB + 1;
+        String stopCellB = colNameB + (sheet.getLastRowNum() + 1);
+        String sumFormulaForColumnB = String.format("SUM(%s:%s)", startCellB, stopCellB);
+
+        double resultValue = excelFormula.setFormula(fileLocation, wb, sumFormulaForColumnA + "-" + sumFormulaForColumnB);
+
+        Assert.assertEquals(resultColumnA - resultColumnB, resultValue, 0d);
+    }
+}

core-java-modules/core-java-9-new-features/README.md

@@ -14,3 +14,4 @@ This module contains articles about core Java features that have been introduced
 - [Java 9 Reactive Streams](https://www.baeldung.com/java-9-reactive-streams)
 - [Multi-Release JAR Files with Maven](https://www.baeldung.com/maven-multi-release-jars)
 - [The Difference between RxJava API and the Java 9 Flow API](https://www.baeldung.com/rxjava-vs-java-flow-api)
+- [How to Get a Name of a Method Being Executed?](https://www.baeldung.com/java-name-of-executing-method)

core-java-modules/core-java-arrays-operations-advanced/src/main/java/com/baeldung/arraycompare/Plane.java

@@ -0,0 +1,39 @@
+package com.baeldung.arraycompare;
+
+import java.util.Objects;
+
+public class Plane {
+
+    private final String name;
+
+    private final String model;
+
+    public Plane(String name, String model) {
+
+        this.name = name;
+        this.model = model;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Plane plane = (Plane) o;
+        return Objects.equals(name, plane.name) && Objects.equals(model, plane.model);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, model);
+    }
+}

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

@@ -0,0 +1,30 @@
+package com.baeldung.arraycompare;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class DeepEqualsCompareUnitTest {
+
+    @Test
+    public void givenSameContents_whenDeepEquals_thenTrue() {
+        final Plane[][] planes1 = new Plane[][] { new Plane[] { new Plane("Plane 1", "A320") },
+            new Plane[] { new Plane("Plane 2", "B738") } };
+        final Plane[][] planes2 = new Plane[][] { new Plane[] { new Plane("Plane 1", "A320") },
+            new Plane[] { new Plane("Plane 2", "B738") } };
+
+        assertThat(Arrays.deepEquals(planes1, planes2)).isTrue();
+    }
+
+    @Test
+    public void givenSameContentsWithDifferentOrder_whenDeepEquals_thenFalse() {
+        final Plane[][] planes1 = new Plane[][] { new Plane[] { new Plane("Plane 1", "A320") },
+            new Plane[] { new Plane("Plane 2", "B738") } };
+        final Plane[][] planes2 = new Plane[][] { new Plane[] { new Plane("Plane 2", "B738") },
+            new Plane[] { new Plane("Plane 1", "A320") } };
+
+        assertThat(Arrays.deepEquals(planes1, planes2)).isFalse();
+    }
+}

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

@@ -0,0 +1,26 @@
+package com.baeldung.arraycompare;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class EqualsCompareUnitTest {
+
+    @Test
+    public void givenSameContents_whenEquals_thenTrue() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final String[] planes2 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+
+        assertThat(Arrays.equals(planes1, planes2)).isTrue();
+    }
+
+    @Test
+    public void givenSameContentsDifferentOrder_whenEquals_thenFalse() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final String[] planes2 = new String[] { "B738", "A320", "A321", "A319", "B77W", "B737", "A333", "A332" };
+
+        assertThat(Arrays.equals(planes1, planes2)).isFalse();
+    }
+}

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

@@ -0,0 +1,18 @@
+package com.baeldung.arraycompare;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class LengthsCompareUnitTest {
+
+    @Test
+    public void givenSameContent_whenSizeCompare_thenTrue() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final Integer[] quantities = new Integer[] { 10, 12, 34, 45, 12, 43, 5, 2 };
+
+        assertThat(planes1).hasSize(8);
+        assertThat(quantities).hasSize(8);
+    }
+}
+

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

@@ -0,0 +1,33 @@
+package com.baeldung.arraycompare;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertTrue;
+
+public class OrderCompareUnitTest {
+    @Test
+    public void givenSameContentDifferentOrder_whenSortedAndDeepEquals_thenTrue() {
+        final Plane[][] planes1 = new Plane[][] {
+            new Plane[] { new Plane("Plane 1", "A320"), new Plane("Plane 2", "B738") } };
+        final Plane[][] planes2 = new Plane[][] {
+            new Plane[] { new Plane("Plane 2", "B738"), new Plane("Plane 1", "A320") } };
+
+        Comparator<Plane> planeComparator = (o1, o2) -> {
+            if (o1.getName()
+                .equals(o2.getName())) {
+                return o2.getModel()
+                    .compareTo(o1.getModel());
+            }
+            return o2.getName()
+                .compareTo(o1.getName());
+        };
+        Arrays.sort(planes1[0], planeComparator);
+        Arrays.sort(planes2[0], planeComparator);
+
+        assertThat(Arrays.deepEquals(planes1, planes2)).isTrue();
+    }
+}

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

@@ -0,0 +1,30 @@
+package com.baeldung.arraycompare;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ReferenceCompareUnitTest {
+
+    @Test
+    public void givenSameReferences_whenSame_thenTrue() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final String[] planes2 = planes1;
+
+        assertThat(planes1).isSameAs(planes2);
+
+        planes2[0] = "747";
+
+        assertThat(planes1).isSameAs(planes2);
+        assertThat(planes2[0]).isEqualTo("747");
+        assertThat(planes1[0]).isEqualTo("747");
+    }
+
+    @Test
+    public void givenSameContentDifferentReferences_whenSame_thenFalse() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final String[] planes2 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+
+        assertThat(planes1).isNotSameAs(planes2);
+    }
+}

core-java-modules/core-java-collections-list-3/pom.xml

@@ -21,6 +21,12 @@
             <artifactId>commons-collections4</artifactId>
             <version>${commons-collections4.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+            <scope>compile</scope>
+        </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>

core-java-modules/core-java-collections-list-3/src/test/java/com/baeldung/list/difference/FindDifferencesBetweenListsUnitTest.java

@@ -0,0 +1,96 @@
+package com.baeldung.list.difference;
+
+import com.google.common.collect.Sets;
+import org.apache.commons.collections4.CollectionUtils;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.assertj.core.api.Assertions.*;
+
+public class FindDifferencesBetweenListsUnitTest {
+
+    private static final List<String> listOne = Arrays.asList("Jack", "Tom", "Sam", "John", "James", "Jack");
+    private static final List<String> listTwo = Arrays.asList("Jack", "Daniel", "Sam", "Alan", "James", "George");
+
+    @Test
+    public void givenLists_whenUsingPlainJavaImpl_thenDifferencesAreFound() {
+        List<String> differences = new ArrayList<>(listOne);
+        differences.removeAll(listTwo);
+        assertEquals(2, differences.size());
+        assertThat(differences).containsExactly("Tom", "John");
+    }
+
+    @Test
+    public void givenReverseLists_whenUsingPlainJavaImpl_thenDifferencesAreFound() {
+        List<String> differences = new ArrayList<>(listTwo);
+        differences.removeAll(listOne);
+        assertEquals(3, differences.size());
+        assertThat(differences).containsExactly("Daniel", "Alan", "George");
+    }
+
+    @Test
+    public void givenLists_whenUsingJavaStreams_thenDifferencesAreFound() {
+        List<String> differences = listOne.stream()
+                .filter(element -> !listTwo.contains(element))
+                .collect(Collectors.toList());
+        assertEquals(2, differences.size());
+        assertThat(differences).containsExactly("Tom", "John");
+    }
+
+    @Test
+    public void givenReverseLists_whenUsingJavaStreams_thenDifferencesAreFound() {
+        List<String> differences = listTwo.stream()
+                .filter(element -> !listOne.contains(element))
+                .collect(Collectors.toList());
+        assertEquals(3, differences.size());
+        assertThat(differences).containsExactly("Daniel", "Alan", "George");
+    }
+
+    @Test
+    public void givenLists_whenUsingGoogleGuava_thenDifferencesAreFound() {
+        List<String> differences = new ArrayList<>(Sets.difference(Sets.newHashSet(listOne), Sets.newHashSet(listTwo)));
+        assertEquals(2, differences.size());
+        assertThat(differences).containsExactlyInAnyOrder("Tom", "John");
+    }
+
+    @Test
+    public void givenReverseLists_whenUsingGoogleGuava_thenDifferencesAreFound() {
+        List<String> differences = new ArrayList<>(Sets.difference(Sets.newHashSet(listTwo), Sets.newHashSet(listOne)));
+        assertEquals(3, differences.size());
+        assertThat(differences).containsExactlyInAnyOrder("Daniel", "Alan", "George");
+    }
+
+    @Test
+    public void givenLists_whenUsingApacheCommons_thenDifferencesAreFound() {
+        List<String> differences = new ArrayList<>((CollectionUtils.removeAll(listOne, listTwo)));
+        assertEquals(2, differences.size());
+        assertThat(differences).containsExactly("Tom", "John");
+    }
+
+    @Test
+    public void givenReverseLists_whenUsingApacheCommons_thenDifferencesAreFound() {
+        List<String> differences = new ArrayList<>((CollectionUtils.removeAll(listTwo, listOne)));
+        assertEquals(3, differences.size());
+        assertThat(differences).containsExactly("Daniel", "Alan", "George");
+    }
+
+    @Test
+    public void givenLists_whenUsingPlainJavaImpl_thenDifferencesWithDuplicatesAreFound() {
+        List<String> differences = new ArrayList<>(listOne);
+        listTwo.forEach(differences::remove);
+        assertThat(differences).containsExactly("Tom", "John", "Jack");
+    }
+
+    @Test
+    public void givenLists_whenUsingApacheCommons_thenDifferencesWithDuplicatesAreFound() {
+        List<String> differences = new ArrayList<>(CollectionUtils.subtract(listOne, listTwo));
+        assertEquals(3, differences.size());
+        assertThat(differences).containsExactly("Tom", "John", "Jack");
+    }
+
+}

core-java-modules/core-java-concurrency-advanced-3/src/test/java/com/baeldung/workstealing/PrimeNumbersManualTest.java

@@ -15,7 +15,15 @@ import java.util.logging.Logger;
 
 import static org.junit.Assert.fail;
 
-public class PrimeNumbersUnitManualTest {
+/**
+ * This test expects the file target/test-classes/META-INF/BenchmarkList to be present.
+ *
+ * Before running the test ensure that the file is present. 
+ * If not, please run mvn install on the module.
+ * 
+ */
+
+public class PrimeNumbersManualTest {
 
     private static Logger logger = Logger.getAnonymousLogger();
 

core-java-modules/core-java-concurrency-advanced/src/main/java/com/baeldung/threadlocal/ThreadLocalAwareThreadPool.java

@@ -0,0 +1,25 @@
+package com.baeldung.threadlocal;
+
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.RejectedExecutionHandler;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+public class ThreadLocalAwareThreadPool extends ThreadPoolExecutor {
+
+    public ThreadLocalAwareThreadPool(int corePoolSize,
+      int maximumPoolSize,
+      long keepAliveTime,
+      TimeUnit unit,
+      BlockingQueue<Runnable> workQueue,
+      ThreadFactory threadFactory,
+      RejectedExecutionHandler handler) {
+        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
+    }
+
+    @Override
+    protected void afterExecute(Runnable r, Throwable t) {
+        // Call remove on each ThreadLocal
+    }
+}

core-java-modules/core-java-io-3/.gitignore

@@ -0,0 +1,2 @@
+test-link*
+0.*

core-java-modules/core-java-io-3/src/main/java/com/baeldung/copydirectory/ApacheCommons.java

@@ -0,0 +1,15 @@
+package com.baeldung.copydirectory;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.apache.commons.io.FileUtils;
+
+public class ApacheCommons {
+
+    public static void copyDirectory(String sourceDirectoryLocation, String destinationDirectoryLocation) throws IOException {
+        File sourceDirectory = new File(sourceDirectoryLocation);
+        File destinationDirectory = new File(destinationDirectoryLocation);
+        FileUtils.copyDirectory(sourceDirectory, destinationDirectory);
+    }
+}

core-java-modules/core-java-io-3/src/main/java/com/baeldung/copydirectory/CoreOld.java

@@ -0,0 +1,38 @@
+package com.baeldung.copydirectory;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+public class CoreOld {
+
+    public static void copyDirectoryJavaUnder7(File source, File destination) throws IOException {
+        if (source.isDirectory()) {
+            copyDirectory(source, destination);
+        } else {
+            copyFile(source, destination);
+        }
+    }
+
+    private static void copyDirectory(File sourceDirectory, File destinationDirectory) throws IOException {
+        if (!destinationDirectory.exists()) {
+            destinationDirectory.mkdir();
+        }
+        for (String f : sourceDirectory.list()) {
+            copyDirectoryJavaUnder7(new File(sourceDirectory, f), new File(destinationDirectory, f));
+        }
+    }
+
+    private static void copyFile(File sourceFile, File destinationFile) throws IOException {
+        try (InputStream in = new FileInputStream(sourceFile); OutputStream out = new FileOutputStream(destinationFile)) {
+            byte[] buf = new byte[1024];
+            int length;
+            while ((length = in.read(buf)) > 0) {
+                out.write(buf, 0, length);
+            }
+        }
+    }
+}

core-java-modules/core-java-io-3/src/main/java/com/baeldung/copydirectory/JavaNio.java

@@ -0,0 +1,22 @@
+package com.baeldung.copydirectory;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public class JavaNio {
+
+    public static void copyDirectory(String sourceDirectoryLocation, String destinationDirectoryLocation) throws IOException {
+        Files.walk(Paths.get(sourceDirectoryLocation))
+          .forEach(source -> {
+              Path destination = Paths.get(destinationDirectoryLocation, source.toString()
+                .substring(sourceDirectoryLocation.length()));
+              try {
+                  Files.copy(source, destination);
+              } catch (IOException e) {
+                  e.printStackTrace();
+              }
+          });
+    }
+}

core-java-modules/core-java-io-3/src/test/java/com/baeldung/copydirectory/ApacheCommonsUnitTest.java

@@ -0,0 +1,59 @@
+package com.baeldung.copydirectory;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Comparator;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class ApacheCommonsUnitTest {
+
+    private final String sourceDirectoryLocation = "src/test/resources/sourceDirectory3";
+    private final String subDirectoryName = "/childDirectory";
+    private final String fileName = "/file.txt";
+    private final String destinationDirectoryLocation = "src/test/resources/destinationDirectory3";
+
+    @BeforeEach
+    public void createDirectoryWithSubdirectoryAndFile() throws IOException {
+        Files.createDirectories(Paths.get(sourceDirectoryLocation));
+        Files.createDirectories(Paths.get(sourceDirectoryLocation + subDirectoryName));
+        Files.createFile(Paths.get(sourceDirectoryLocation + subDirectoryName + fileName));
+    }
+
+    @Test
+    public void whenSourceDirectoryExists_thenDirectoryIsFullyCopied() throws IOException {
+        ApacheCommons.copyDirectory(sourceDirectoryLocation, destinationDirectoryLocation);
+
+        assertTrue(new File(destinationDirectoryLocation).exists());
+        assertTrue(new File(destinationDirectoryLocation + subDirectoryName).exists());
+        assertTrue(new File(destinationDirectoryLocation + subDirectoryName + fileName).exists());
+    }
+
+    @Test
+    public void whenSourceDirectoryDoesNotExist_thenExceptionIsThrown() {
+        assertThrows(Exception.class, () -> ApacheCommons.copyDirectory("nonExistingDirectory", destinationDirectoryLocation));
+    }
+
+    @AfterEach
+    public void cleanUp() throws IOException {
+        Files.walk(Paths.get(sourceDirectoryLocation))
+            .sorted(Comparator.reverseOrder())
+            .map(Path::toFile)
+            .forEach(File::delete);
+        if (new File(destinationDirectoryLocation).exists()) {
+            Files.walk(Paths.get(destinationDirectoryLocation))
+                .sorted(Comparator.reverseOrder())
+                .map(Path::toFile)
+                .forEach(File::delete);
+        }
+    }
+
+}

core-java-modules/core-java-io-3/src/test/java/com/baeldung/copydirectory/CoreOldUnitTest.java

@@ -0,0 +1,63 @@
+package com.baeldung.copydirectory;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Comparator;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class CoreOldUnitTest {
+
+    private final String sourceDirectoryLocation = "src/test/resources/sourceDirectory1";
+    private final String subDirectoryName = "/childDirectory";
+    private final String fileName = "/file.txt";
+    private final String destinationDirectoryLocation = "src/test/resources/destinationDirectory1";
+
+    @BeforeEach
+    public void createDirectoryWithSubdirectoryAndFile() throws IOException {
+        Files.createDirectories(Paths.get(sourceDirectoryLocation));
+        Files.createDirectories(Paths.get(sourceDirectoryLocation + subDirectoryName));
+        Files.createFile(Paths.get(sourceDirectoryLocation + subDirectoryName + fileName));
+    }
+
+    @Test
+    public void whenSourceDirectoryExists_thenDirectoryIsFullyCopied() throws IOException {
+        File sourceDirectory = new File(sourceDirectoryLocation);
+        File destinationDirectory = new File(destinationDirectoryLocation);
+        CoreOld.copyDirectoryJavaUnder7(sourceDirectory, destinationDirectory);
+
+        assertTrue(new File(destinationDirectoryLocation).exists());
+        assertTrue(new File(destinationDirectoryLocation + subDirectoryName).exists());
+        assertTrue(new File(destinationDirectoryLocation + subDirectoryName + fileName).exists());
+    }
+
+    @Test
+    public void whenSourceDirectoryDoesNotExist_thenExceptionIsThrown() throws IOException {
+        File sourceDirectory = new File("nonExistingDirectory");
+        File destinationDirectory = new File(destinationDirectoryLocation);
+        assertThrows(IOException.class, () -> CoreOld.copyDirectoryJavaUnder7(sourceDirectory, destinationDirectory));
+    }
+
+    @AfterEach
+    public void cleanUp() throws IOException {
+        Files.walk(Paths.get(sourceDirectoryLocation))
+            .sorted(Comparator.reverseOrder())
+            .map(Path::toFile)
+            .forEach(File::delete);
+        if (new File(destinationDirectoryLocation).exists()) {
+            Files.walk(Paths.get(destinationDirectoryLocation))
+                .sorted(Comparator.reverseOrder())
+                .map(Path::toFile)
+                .forEach(File::delete);
+        }
+    }
+
+}

core-java-modules/core-java-io-3/src/test/java/com/baeldung/copydirectory/JavaNioUnitTest.java

@@ -0,0 +1,59 @@
+package com.baeldung.copydirectory;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Comparator;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class JavaNioUnitTest {
+
+    private final String sourceDirectoryLocation = "src/test/resources/sourceDirectory2";
+    private final String subDirectoryName = "/childDirectory";
+    private final String fileName = "/file.txt";
+    private final String destinationDirectoryLocation = "src/test/resources/destinationDirectory2";
+
+    @BeforeEach
+    public void createDirectoryWithSubdirectoryAndFile() throws IOException {
+        Files.createDirectories(Paths.get(sourceDirectoryLocation));
+        Files.createDirectories(Paths.get(sourceDirectoryLocation + subDirectoryName));
+        Files.createFile(Paths.get(sourceDirectoryLocation + subDirectoryName + fileName));
+    }
+
+    @Test
+    public void whenSourceDirectoryExists_thenDirectoryIsFullyCopied() throws IOException {
+        JavaNio.copyDirectory(sourceDirectoryLocation, destinationDirectoryLocation);
+
+        assertTrue(new File(destinationDirectoryLocation).exists());
+        assertTrue(new File(destinationDirectoryLocation + subDirectoryName).exists());
+        assertTrue(new File(destinationDirectoryLocation + subDirectoryName + fileName).exists());
+    }
+
+    @Test
+    public void whenSourceDirectoryDoesNotExist_thenExceptionIsThrown() {
+        assertThrows(IOException.class, () -> JavaNio.copyDirectory("nonExistingDirectory", destinationDirectoryLocation));
+    }
+
+    @AfterEach
+    public void cleanUp() throws IOException {
+        Files.walk(Paths.get(sourceDirectoryLocation))
+            .sorted(Comparator.reverseOrder())
+            .map(Path::toFile)
+            .forEach(File::delete);
+        if (new File(destinationDirectoryLocation).exists()) {
+            Files.walk(Paths.get(destinationDirectoryLocation))
+                .sorted(Comparator.reverseOrder())
+                .map(Path::toFile)
+                .forEach(File::delete);
+        }
+    }
+
+}

core-java-modules/core-java-io-3/src/test/java/com/baeldung/existence/ExistenceUnitTest.java

@@ -0,0 +1,91 @@
+package com.baeldung.existence;
+
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.LinkOption;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.concurrent.ThreadLocalRandom;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class ExistenceUnitTest {
+
+    @Test
+    public void givenFile_whenDoesNotExist_thenFilesReturnsFalse() {
+        Path path = Paths.get("does-not-exist.txt");
+
+        assertFalse(Files.exists(path));
+        assertTrue(Files.notExists(path));
+    }
+
+    @Test
+    public void givenFile_whenExists_thenFilesShouldReturnTrue() throws IOException {
+        Path tempFile = Files.createTempFile("baeldung", "exist-nio");
+        assertTrue(Files.exists(tempFile));
+        assertFalse(Files.notExists(tempFile));
+
+        Path tempDirectory = Files.createTempDirectory("baeldung-exists");
+        assertTrue(Files.exists(tempDirectory));
+        assertFalse(Files.notExists(tempDirectory));
+
+        assertTrue(Files.isDirectory(tempDirectory));
+        assertFalse(Files.isDirectory(tempFile));
+        assertTrue(Files.isRegularFile(tempFile));
+
+        assertTrue(Files.isReadable(tempFile));
+
+        Files.deleteIfExists(tempFile);
+        Files.deleteIfExists(tempDirectory);
+    }
+
+    @Test
+    public void givenSymbolicLink_whenTargetDoesNotExists_thenFollowOrNotBasedOnTheOptions() throws IOException {
+        Path target = Files.createTempFile("baeldung", "target");
+        Path symbol = Paths.get("test-link-" + ThreadLocalRandom.current().nextInt());
+
+        Path symbolicLink = Files.createSymbolicLink(symbol, target);
+        assertTrue(Files.exists(symbolicLink));
+        assertTrue(Files.isSymbolicLink(symbolicLink));
+        assertFalse(Files.isSymbolicLink(target));
+
+        Files.deleteIfExists(target);
+        assertFalse(Files.exists(symbolicLink));
+        assertTrue(Files.exists(symbolicLink, LinkOption.NOFOLLOW_LINKS));
+
+        Files.deleteIfExists(symbolicLink);
+    }
+
+    @Test
+    public void givenFile_whenDoesNotExist_thenFileReturnsFalse() {
+        assertFalse(new File("invalid").exists());
+        assertFalse(new File("invalid").isFile());
+    }
+
+    @Test
+    public void givenFile_whenExist_thenShouldReturnTrue() throws IOException {
+        Path tempFilePath = Files.createTempFile("baeldung", "exist-io");
+        Path tempDirectoryPath = Files.createTempDirectory("baeldung-exists-io");
+
+        File tempFile = new File(tempFilePath.toString());
+        File tempDirectory = new File(tempDirectoryPath.toString());
+
+        assertTrue(tempFile.exists());
+        assertTrue(tempDirectory.exists());
+
+        assertTrue(tempFile.isFile());
+        assertFalse(tempDirectory.isFile());
+
+        assertTrue(tempDirectory.isDirectory());
+        assertFalse(tempFile.isDirectory());
+
+        assertTrue(tempFile.canRead());
+
+        Files.deleteIfExists(tempFilePath);
+        Files.deleteIfExists(tempDirectoryPath);
+    }
+}

core-java-modules/core-java-io-3/src/test/java/com/baeldung/openoptions/OpenOptionsUnitTest.java

@@ -0,0 +1,96 @@
+package com.baeldung.openoptions;
+
+import org.hamcrest.CoreMatchers;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.*;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+
+import static org.junit.Assert.*;
+
+public class OpenOptionsUnitTest {
+
+    private static final String HOME = System.getProperty("user.home");
+    private static final String DUMMY_FILE_NAME = "sample.txt";
+    private static final String EXISTING_FILE_NAME = "existingFile.txt";
+
+    private static final String DUMMY_TEXT = "This is a sample text.";
+    private static final String ANOTHER_DUMMY_TEXT = "This is a another text.";
+
+    @BeforeClass
+    public static void beforeAll() throws IOException {
+        Path path = Paths.get(HOME, DUMMY_FILE_NAME);
+
+        try (OutputStream out = Files.newOutputStream(path)) {
+            out.write(DUMMY_TEXT.getBytes());
+        }
+
+        Files.createFile(Paths.get(HOME, EXISTING_FILE_NAME));
+    }
+
+    @AfterClass
+    public static void afterAll() throws IOException {
+        Files.delete(Paths.get(HOME, "newfile.txt"));
+        Files.delete(Paths.get(HOME, "sparse.txt"));
+        Files.delete(Paths.get(HOME, DUMMY_FILE_NAME));
+    }
+
+    @Test
+    public void givenExistingPath_whenCreateNewFile_thenCorrect() throws IOException {
+        Path path = Paths.get(HOME, "newfile.txt");
+        assertFalse(Files.exists(path));
+
+        Files.write(path, DUMMY_TEXT.getBytes(), StandardOpenOption.CREATE);
+        assertTrue(Files.exists(path));
+    }
+
+    @Test
+    public void givenExistingPath_whenReadExistingFile_thenCorrect() throws IOException {
+        Path path = Paths.get(HOME, DUMMY_FILE_NAME);
+
+        try (InputStream in = Files.newInputStream(path); BufferedReader reader = new BufferedReader(new InputStreamReader(in))) {
+            String line;
+            while ((line = reader.readLine()) != null) {
+                assertThat(line, CoreMatchers.containsString(DUMMY_TEXT));
+            }
+        }
+    }
+
+    @Test
+    public void givenExistingPath_whenWriteToExistingFile_thenCorrect() throws IOException {
+        Path path = Paths.get(HOME, DUMMY_FILE_NAME);
+
+        try (OutputStream out = Files.newOutputStream(path, StandardOpenOption.APPEND, StandardOpenOption.WRITE)) {
+            out.write(ANOTHER_DUMMY_TEXT.getBytes());
+        }
+    }
+
+    @Test
+    public void givenExistingPath_whenCreateSparseFile_thenCorrect() throws IOException {
+        Path path = Paths.get(HOME, "sparse.txt");
+        Files.write(path, DUMMY_TEXT.getBytes(), StandardOpenOption.CREATE_NEW, StandardOpenOption.SPARSE);
+    }
+
+    @Test
+    public void givenExistingPath_whenDeleteOnClose_thenCorrect() throws IOException {
+        Path path = Paths.get(HOME, EXISTING_FILE_NAME);
+        assertTrue(Files.exists(path)); // file was already created and exists
+
+        try (OutputStream out = Files.newOutputStream(path, StandardOpenOption.APPEND, StandardOpenOption.WRITE, StandardOpenOption.DELETE_ON_CLOSE)) {
+            out.write(ANOTHER_DUMMY_TEXT.getBytes());
+        }
+
+        assertFalse(Files.exists(path)); // file is deleted
+    }
+
+    @Test
+    public void givenExistingPath_whenWriteAndSync_thenCorrect() throws IOException {
+        Path path = Paths.get(HOME, DUMMY_FILE_NAME);
+        Files.write(path, ANOTHER_DUMMY_TEXT.getBytes(), StandardOpenOption.APPEND, StandardOpenOption.WRITE, StandardOpenOption.SYNC);
+    }
+}

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

@@ -12,4 +12,12 @@
     <artifactId>core-java-lang-oop-types</artifactId>
     <name>core-java-lang-oop-types</name>
     <packaging>jar</packaging>
+    
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+    </dependencies>
 </project>

core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/primitivetype/PrimitiveTypeUtil.java

@@ -0,0 +1,26 @@
+package com.baeldung.primitivetype;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class PrimitiveTypeUtil {
+
+    private static final Map<Class<?>, Class<?>> WRAPPER_TYPE_MAP;
+    static {
+        WRAPPER_TYPE_MAP = new HashMap<Class<?>, Class<?>>(16);
+        WRAPPER_TYPE_MAP.put(Integer.class, int.class);
+        WRAPPER_TYPE_MAP.put(Byte.class, byte.class);
+        WRAPPER_TYPE_MAP.put(Character.class, char.class);
+        WRAPPER_TYPE_MAP.put(Boolean.class, boolean.class);
+        WRAPPER_TYPE_MAP.put(Double.class, double.class);
+        WRAPPER_TYPE_MAP.put(Float.class, float.class);
+        WRAPPER_TYPE_MAP.put(Long.class, long.class);
+        WRAPPER_TYPE_MAP.put(Short.class, short.class);
+        WRAPPER_TYPE_MAP.put(Void.class, void.class);
+    }
+
+    public static boolean isPrimitiveType(Object source) {
+        return WRAPPER_TYPE_MAP.containsKey(source.getClass());
+    }
+
+}

core-java-modules/core-java-lang-oop-types/src/test/java/com/baeldung/primitivetype/PrimitiveTypeUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.primitivetype;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.apache.commons.lang3.ClassUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.junit.Test;
+
+import com.google.common.primitives.Primitives;
+
+public class PrimitiveTypeUnitTest {
+
+    @Test
+    public void givenAClass_whenCheckWithPrimitiveTypeUtil_thenShouldValidate() {
+        assertTrue(PrimitiveTypeUtil.isPrimitiveType(false));
+        assertTrue(PrimitiveTypeUtil.isPrimitiveType(1L));
+        assertFalse(PrimitiveTypeUtil.isPrimitiveType(StringUtils.EMPTY));
+    }
+
+    @Test
+    public void givenAClass_whenCheckWithCommonsLang_thenShouldValidate() {
+        assertTrue(ClassUtils.isPrimitiveOrWrapper(Boolean.FALSE.getClass()));
+        assertTrue(ClassUtils.isPrimitiveOrWrapper(boolean.class));
+        assertFalse(ClassUtils.isPrimitiveOrWrapper(StringUtils.EMPTY.getClass()));
+    }
+
+    @Test
+    public void givenAClass_whenCheckWithGuava_thenShouldValidate() {
+        assertTrue(Primitives.isWrapperType(Boolean.FALSE.getClass()));
+        assertFalse(Primitives.isWrapperType(StringUtils.EMPTY.getClass()));
+        assertFalse(Primitives.isWrapperType(Boolean.TYPE.getClass()));
+    }
+}