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

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-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-3/pom.xml

@@ -16,6 +16,11 @@
     </parent>
 
     <dependencies>
+        <dependency>
+            <groupId>org.openjdk.jol</groupId>
+            <artifactId>jol-core</artifactId>
+            <version>${jol-core.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.openjdk.jmh</groupId>
             <artifactId>jmh-core</artifactId>
@@ -37,6 +42,7 @@
     <properties>
         <openjdk.jmh.version>1.19</openjdk.jmh.version>
         <assertj.version>3.11.1</assertj.version>
+        <jol-core.version>0.10</jol-core.version>
     </properties>
 
 </project>

core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/bitset/BitSetUnitTest.java

@@ -0,0 +1,178 @@
+package com.baeldung.collections.bitset;
+
+import org.junit.Test;
+import org.openjdk.jol.info.ClassLayout;
+import org.openjdk.jol.info.GraphLayout;
+
+import java.util.BitSet;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class BitSetUnitTest {
+
+    @Test
+    public void givenBoolArray_whenMemoryLayout_thenConsumeMoreThanOneBit() {
+        boolean[] bits = new boolean[1024 * 1024];
+
+        System.out.println(ClassLayout.parseInstance(bits).toPrintable());
+    }
+
+    @Test
+    public void givenBitSet_whenMemoryLayout_thenConsumeOneBitPerFlag() {
+        BitSet bitSet = new BitSet(1024 * 1024);
+
+        System.out.println(GraphLayout.parseInstance(bitSet).toPrintable());
+    }
+
+    @Test
+    public void givenBitSet_whenSetting_thenShouldBeTrue() {
+        BitSet bitSet = new BitSet();
+
+        bitSet.set(10);
+        assertThat(bitSet.get(10)).isTrue();
+
+        bitSet.set(20, 30);
+        for (int i = 20; i <= 29; i++) {
+            assertThat(bitSet.get(i)).isTrue();
+        }
+        assertThat(bitSet.get(30)).isFalse();
+
+        bitSet.set(10, false);
+        assertThat(bitSet.get(10)).isFalse();
+
+        bitSet.set(20, 30, false);
+        for (int i = 20; i <= 30; i++) {
+            assertThat(bitSet.get(i)).isFalse();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenClearing_thenShouldBeFalse() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(42);
+        assertThat(bitSet.get(42)).isTrue();
+
+        bitSet.clear(42);
+        assertThat(bitSet.get(42)).isFalse();
+
+        bitSet.set(10, 20);
+        for (int i = 10; i < 20; i++) {
+            assertThat(bitSet.get(i)).isTrue();
+        }
+
+        bitSet.clear(10, 20);
+        for (int i = 10; i < 20; i++) {
+            assertThat(bitSet.get(i)).isFalse();
+        }
+
+        bitSet.set(10, 20);
+        bitSet.clear();
+        for (int i = 0; i < 100; i++) {
+            assertThat(bitSet.get(i)).isFalse();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenGettingElements_thenShouldReturnRequestedBits() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(42);
+
+        assertThat(bitSet.get(42)).isTrue();
+        assertThat(bitSet.get(43)).isFalse();
+
+        bitSet.set(10, 20);
+        BitSet newBitSet = bitSet.get(10, 20);
+        for (int i = 0; i < 10; i++) {
+            assertThat(newBitSet.get(i)).isTrue();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenFlip_thenTogglesTrueToFalseAndViceVersa() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(42);
+        bitSet.flip(42);
+        assertThat(bitSet.get(42)).isFalse();
+
+        bitSet.flip(12);
+        assertThat(bitSet.get(12)).isTrue();
+
+        bitSet.flip(30, 40);
+        for (int i = 30; i < 40; i++) {
+            assertThat(bitSet.get(i)).isTrue();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenGettingTheSize_thenReturnsTheSize() {
+        BitSet defaultBitSet = new BitSet();
+        assertThat(defaultBitSet.size()).isEqualTo(64);
+
+        BitSet bitSet = new BitSet(1024);
+        assertThat(bitSet.size()).isEqualTo(1024);
+
+        assertThat(bitSet.cardinality()).isEqualTo(0);
+        bitSet.set(10, 30);
+        assertThat(bitSet.cardinality()).isEqualTo(30 - 10);
+
+        assertThat(bitSet.length()).isEqualTo(30);
+        bitSet.set(100);
+        assertThat(bitSet.length()).isEqualTo(101);
+
+        assertThat(bitSet.isEmpty()).isFalse();
+        bitSet.clear();
+        assertThat(bitSet.isEmpty()).isTrue();
+    }
+
+    @Test
+    public void givenBitSet_whenSetOperations_thenShouldReturnAnotherBitSet() {
+        BitSet first = new BitSet();
+        first.set(5, 10);
+
+        BitSet second = new BitSet();
+        second.set(7, 15);
+
+        assertThat(first.intersects(second)).isTrue();
+
+        first.and(second);
+        assertThat(first.get(7)).isTrue();
+        assertThat(first.get(8)).isTrue();
+        assertThat(first.get(9)).isTrue();
+        assertThat(first.get(10)).isFalse();
+
+        first.clear();
+        first.set(5, 10);
+
+        first.xor(second);
+        for (int i = 5; i < 7; i++) {
+            assertThat(first.get(i)).isTrue();
+        }
+        for (int i = 10; i < 15; i++) {
+            assertThat(first.get(i)).isTrue();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenStream_thenStreamsAllSetBits() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(15, 25);
+
+        bitSet.stream().forEach(System.out::println);
+        assertThat(bitSet.stream().count()).isEqualTo(10);
+    }
+
+    @Test
+    public void givenBitSet_whenNextOrPrev_thenReturnsTheNextOrPrevClearOrSetBit() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(15, 25);
+
+        assertThat(bitSet.nextSetBit(13)).isEqualTo(15);
+        assertThat(bitSet.nextSetBit(25)).isEqualTo(-1);
+
+        assertThat(bitSet.nextClearBit(23)).isEqualTo(25);
+
+        assertThat(bitSet.previousClearBit(24)).isEqualTo(14);
+        assertThat(bitSet.previousSetBit(29)).isEqualTo(24);
+        assertThat(bitSet.previousSetBit(14)).isEqualTo(-1);
+    }
+}

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-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/sourceDirectory";
+    private final String subDirectoryName = "/childDirectory";
+    private final String fileName = "/file.txt";
+    private final String destinationDirectoryLocation = "src/test/resources/destinationDirectory";
+
+    @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/sourceDirectory";
+    private final String subDirectoryName = "/childDirectory";
+    private final String fileName = "/file.txt";
+    private final String destinationDirectoryLocation = "src/test/resources/destinationDirectory";
+
+    @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/sourceDirectory";
+    private final String subDirectoryName = "/childDirectory";
+    private final String fileName = "/file.txt";
+    private final String destinationDirectoryLocation = "src/test/resources/destinationDirectory";
+
+    @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-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()));
+    }
+}

core-java-modules/core-java-os/src/test/java/com/baeldung/screenshot/ScreenshotUnitTest.java

@@ -0,0 +1,51 @@
+import javax.imageio.ImageIO;
+import java.awt.Component;
+import java.awt.GraphicsDevice;
+import java.awt.GraphicsEnvironment;
+import java.awt.Rectangle;
+import java.awt.Robot;
+import java.awt.Toolkit;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+
+public class ScreenshotUnitTest {
+
+    @Test
+    public void givenMainScreen_whenTakeScreenshot_thenSaveToFile() throws Exception {
+        Rectangle screenRect = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
+        BufferedImage capture = new Robot().createScreenCapture(screenRect);
+        File imageFile = File.createTempFile("single-screen", "bmp");
+        ImageIO.write(capture, "bmp", imageFile);
+        assertTrue(imageFile.exists());
+    }
+
+    @Test
+    public void givenMultipleScreens_whenTakeScreenshot_thenSaveToFile() throws Exception {
+        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
+        GraphicsDevice[] screens = ge.getScreenDevices();
+        Rectangle allScreenBounds = new Rectangle();
+        for (GraphicsDevice screen : screens) {
+            Rectangle screenBounds = screen.getDefaultConfiguration().getBounds();
+            allScreenBounds.width += screenBounds.width;
+            allScreenBounds.height = Math.max(allScreenBounds.height, screenBounds.height);
+        }
+        BufferedImage capture = new Robot().createScreenCapture(allScreenBounds);
+        File imageFile = File.createTempFile("all-screens", "bmp");
+        ImageIO.write(capture, "bmp", imageFile);
+        assertTrue(imageFile.exists());
+    }
+
+    @Test
+    public void givenComponent_whenTakeScreenshot_thenSaveToFile(Component component) throws Exception {
+        Rectangle componentRect = component.getBounds();
+        BufferedImage bufferedImage = new BufferedImage(componentRect.width, componentRect.height, BufferedImage.TYPE_INT_ARGB);
+        component.paint(bufferedImage.getGraphics());
+        File imageFile = File.createTempFile("component-screenshot", "bmp");
+        ImageIO.write(bufferedImage, "bmp", imageFile);
+        assertTrue(imageFile.exists());
+    }
+
+}

core-java-modules/core-java-reflection-2/src/test/java/com/baeldung/reflection/set/fields/SetFieldsUsingReflectionUnitTest.java

@@ -0,0 +1,183 @@
+package com.baeldung.reflection.set.fields;
+
+import java.lang.reflect.Field;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.reflection.access.privatefields.Person;
+
+public class SetFieldsUsingReflectionUnitTest {
+
+    @Test
+    public void whenSetIntegerFields_thenSuccess() throws Exception {
+        Person person = new Person();
+
+        Field ageField = person.getClass()
+            .getDeclaredField("age");
+        ageField.setAccessible(true);
+
+        byte age = 26;
+        ageField.setByte(person, age);
+        Assertions.assertEquals(age, person.getAge());
+
+        Field uidNumberField = person.getClass()
+            .getDeclaredField("uidNumber");
+        uidNumberField.setAccessible(true);
+
+        short uidNumber = 5555;
+        uidNumberField.setShort(person, uidNumber);
+        Assertions.assertEquals(uidNumber, person.getUidNumber());
+
+        Field pinCodeField = person.getClass()
+            .getDeclaredField("pinCode");
+        pinCodeField.setAccessible(true);
+
+        int pinCode = 411057;
+        pinCodeField.setInt(person, pinCode);
+        Assertions.assertEquals(pinCode, person.getPinCode());
+
+        Field contactNumberField = person.getClass()
+            .getDeclaredField("contactNumber");
+        contactNumberField.setAccessible(true);
+
+        long contactNumber = 123456789L;
+        contactNumberField.setLong(person, contactNumber);
+        Assertions.assertEquals(contactNumber, person.getContactNumber());
+
+    }
+
+    @Test
+    public void whenDoUnboxing_thenSuccess() throws Exception {
+        Person person = new Person();
+
+        Field pinCodeField = person.getClass()
+            .getDeclaredField("pinCode");
+        pinCodeField.setAccessible(true);
+
+        Integer pinCode = 411057;
+        pinCodeField.setInt(person, pinCode);
+        Assertions.assertEquals(pinCode, person.getPinCode());
+    }
+
+    @Test
+    public void whenDoNarrowing_thenSuccess() throws Exception {
+        Person person = new Person();
+
+        Field pinCodeField = person.getClass()
+            .getDeclaredField("pinCode");
+        pinCodeField.setAccessible(true);
+
+        short pinCode = 4110;
+        pinCodeField.setInt(person, pinCode);
+        Assertions.assertEquals(pinCode, person.getPinCode());
+    }
+
+    @Test
+    public void whenSetFloatingTypeFields_thenSuccess() throws Exception {
+        Person person = new Person();
+
+        Field heightField = person.getClass()
+            .getDeclaredField("height");
+        heightField.setAccessible(true);
+
+        float height = 6.1242f;
+        heightField.setFloat(person, height);
+        Assertions.assertEquals(height, person.getHeight());
+
+        Field weightField = person.getClass()
+            .getDeclaredField("weight");
+        weightField.setAccessible(true);
+
+        double weight = 75.2564;
+        weightField.setDouble(person, weight);
+        Assertions.assertEquals(weight, person.getWeight());
+    }
+
+    @Test
+    public void whenSetCharacterFields_thenSuccess() throws Exception {
+        Person person = new Person();
+
+        Field genderField = person.getClass()
+            .getDeclaredField("gender");
+        genderField.setAccessible(true);
+
+        char gender = 'M';
+        genderField.setChar(person, gender);
+        Assertions.assertEquals(gender, person.getGender());
+    }
+
+    @Test
+    public void whenSetBooleanFields_thenSuccess() throws Exception {
+        Person person = new Person();
+
+        Field activeField = person.getClass()
+            .getDeclaredField("active");
+        activeField.setAccessible(true);
+
+        activeField.setBoolean(person, true);
+        Assertions.assertTrue(person.isActive());
+    }
+
+    @Test
+    public void whenSetObjectFields_thenSuccess() throws Exception {
+        Person person = new Person();
+
+        Field nameField = person.getClass()
+            .getDeclaredField("name");
+        nameField.setAccessible(true);
+
+        String name = "Umang Budhwar";
+        nameField.set(person, name);
+        Assertions.assertEquals(name, person.getName());
+    }
+
+    @Test
+    public void givenInt_whenSetStringField_thenIllegalArgumentException() throws Exception {
+        Person person = new Person();
+        Field nameField = person.getClass()
+            .getDeclaredField("name");
+        nameField.setAccessible(true);
+
+        Assertions.assertThrows(IllegalArgumentException.class, () -> nameField.setInt(person, 26));
+    }
+
+    @Test
+    public void givenInt_whenSetLongField_thenIllegalArgumentException() throws Exception {
+        Person person = new Person();
+
+        Field pinCodeField = person.getClass()
+            .getDeclaredField("pinCode");
+        pinCodeField.setAccessible(true);
+
+        long pinCode = 411057L;
+
+        Assertions.assertThrows(IllegalArgumentException.class, () -> pinCodeField.setLong(person, pinCode));
+    }
+
+    @Test
+    public void whenFieldNotSetAccessible_thenIllegalAccessException() throws Exception {
+        Person person = new Person();
+        Field nameField = person.getClass()
+            .getDeclaredField("name");
+
+        Assertions.assertThrows(IllegalAccessException.class, () -> nameField.set(person, "Umang Budhwar"));
+    }
+
+    @Test
+    public void whenAccessingWrongProperty_thenNoSuchFieldException() throws Exception {
+        Person person = new Person();
+
+        Assertions.assertThrows(NoSuchFieldException.class, () -> person.getClass()
+            .getDeclaredField("firstName"));
+    }
+
+    @Test
+    public void whenAccessingNullProperty_thenNullPointerException() throws Exception {
+        Person person = new Person();
+
+        Assertions.assertThrows(NullPointerException.class, () -> person.getClass()
+            .getDeclaredField(null));
+    }
+
+}

core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/countmatches/CountMatchesUnitTest.java

@@ -1,12 +1,11 @@
 package com.baeldung.regex.countmatches;
 
-import static org.junit.Assert.assertNotEquals;
+import org.junit.Test;
-import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 /**
  * Unit Test intended to count number of matches of a RegEx using Java 8 and 9.
@@ -65,7 +64,7 @@ public class CountMatchesUnitTest {
             count++;
         }
 
-        assertNotEquals(3, count);
+        assertEquals(2, count);
     }
 
     @Test

core-kotlin-modules/core-kotlin/src/main/kotlin/com/baeldung/exceptionhandling/ExceptionHandling.kt

@@ -0,0 +1,88 @@
+package com.baeldung.exceptionhandling
+
+import java.io.IOException
+
+class ExceptionHandling {
+
+    fun tryCatchBlock(): Int? {
+        try {
+            val message = "Welcome to Kotlin Tutorials"
+            return message.toInt()
+        } catch (exception: NumberFormatException) {
+            println("NumberFormatException in the code")
+            return null
+        }
+    }
+
+    fun tryCatchExpression(): Int? {
+        val number = try {
+            val message = "Welcome to Kotlin Tutorials"
+            message.toInt()
+        } catch (exception: NumberFormatException) {
+            println("NumberFormatException in the code")
+            null
+        }
+        return number
+    }
+
+    fun multipleCatchBlock(): Int? {
+        return try {
+            val result = 25 / 0
+            result
+        } catch (exception: NumberFormatException) {
+            println("NumberFormatException in the code")
+            null
+        } catch (exception: ArithmeticException) {
+            println("ArithmeticException in the code")
+            null
+        } catch (exception: Exception) {
+            println("Exception in the code")
+            null
+        }
+    }
+
+    fun nestedTryCatchBlock(): Int? {
+        return try {
+            val firstNumber = 50 / 2 * 0
+            try {
+                val secondNumber = 100 / firstNumber
+                secondNumber
+            } catch (exception: ArithmeticException) {
+                println("ArithmeticException in the code")
+                null
+            }
+        } catch (exception: NumberFormatException) {
+            println("NumberFormatException in the code")
+            null
+        }
+    }
+
+    fun finallyBlock(): Int? {
+        return try {
+            val message = "Welcome to Kotlin Tutorials"
+            message.toInt()
+        } catch (exception: NumberFormatException) {
+            println("NumberFormatException in the code")
+            null
+        } finally {
+            println("In the Finally block")
+        }
+    }
+
+    fun throwKeyword(): Int {
+        val message = "Welcome to Kotlin Tutorials"
+        if (message.length > 10) throw IllegalArgumentException("String is invalid")
+        else return message.length
+    }
+
+    fun throwExpression(): Int? {
+        val message: String? = null
+        return message?.length ?: throw IllegalArgumentException("String is null")
+    }
+
+    @Throws(IOException::class)
+    fun throwsAnnotation(): String?{
+        val filePath = null
+        return filePath ?: throw IOException("File path is invalid")
+    }
+}

core-kotlin-modules/core-kotlin/src/test/kotlin/com/baeldung/exceptionhandling/ExceptionHandlingUnitTest.kt

@@ -0,0 +1,51 @@
+package com.baeldung.exceptionhandling
+
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import java.io.IOException
+import kotlin.test.assertNull
+
+class ExceptionHandlingUnitTest {
+
+    private val classUnderTest: ExceptionHandling = ExceptionHandling()
+
+    @Test
+    fun givenInvalidConversion_whenTryCatchUsed_thenReturnsCatchBlockValue(){
+        assertNull(classUnderTest.tryCatchBlock())
+    }
+
+    @Test
+    fun givenInvalidConversion_whenTryCatchExpressionUsed_thenReturnsCatchBlockValue(){
+        assertNull(classUnderTest.tryCatchExpression())
+    }
+
+    @Test
+    fun givenDivisionByZero_whenMultipleCatchUsed_thenReturnsCatchBlockValue(){
+        assertNull(classUnderTest.multipleCatchBlock())
+    }
+
+    @Test
+    fun givenDivisionByZero_whenNestedTryCatchUsed_thenReturnsNestedCatchBlockValue(){
+        assertNull(classUnderTest.nestedTryCatchBlock())
+    }
+
+    @Test
+    fun givenInvalidConversion_whenTryCatchFinallyUsed_thenReturnsCatchAndFinallyBlock(){
+        assertNull(classUnderTest.finallyBlock())
+    }
+
+    @Test
+    fun givenIllegalArgument_whenThrowKeywordUsed_thenThrowsException(){
+        assertThrows<IllegalArgumentException> { classUnderTest.throwKeyword() }
+    }
+
+    @Test
+    fun givenIllegalArgument_whenElvisExpressionUsed_thenThrowsException(){
+        assertThrows<IllegalArgumentException> { classUnderTest.throwExpression() }
+    }
+
+    @Test
+    fun whenAnnotationUsed_thenThrowsException(){
+        assertThrows<IOException> { classUnderTest.throwsAnnotation() }
+    }
+}

deeplearning4j/pom.xml

@@ -37,6 +37,16 @@
             <artifactId>deeplearning4j-nn</artifactId>
             <version>${dl4j.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>${slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-log4j12</artifactId>
+            <version>${slf4j.version}</version>
+        </dependency>
         <!-- https://mvnrepository.com/artifact/org.datavec/datavec-api -->
         <dependency>
             <groupId>org.datavec</groupId>
@@ -53,6 +63,7 @@
     <properties>
         <dl4j.version>0.9.1</dl4j.version> <!-- Latest non beta version -->
         <httpclient.version>4.3.5</httpclient.version>
+        <slf4j.version>1.7.5</slf4j.version>
     </properties>
 
 </project>

deeplearning4j/src/main/java/com/baeldung/deeplearning4j/cnn/CifarDataSetService.java

@@ -0,0 +1,47 @@
+package com.baeldung.deeplearning4j.cnn;
+
+import lombok.Getter;
+import org.deeplearning4j.datasets.iterator.impl.CifarDataSetIterator;
+import org.deeplearning4j.nn.conf.inputs.InputType;
+import org.nd4j.linalg.dataset.api.iterator.DataSetIterator;
+
+import java.util.List;
+
+@Getter
+class CifarDataSetService implements IDataSetService {
+
+    private final InputType inputType = InputType.convolutional(32, 32, 3);
+    private final int trainImagesNum = 512;
+    private final int testImagesNum = 128;
+    private final int trainBatch = 16;
+    private final int testBatch = 8;
+
+    private final CifarDataSetIterator trainIterator;
+
+    private final CifarDataSetIterator testIterator;
+
+    CifarDataSetService() {
+        trainIterator = new CifarDataSetIterator(trainBatch, trainImagesNum, true);
+        testIterator = new CifarDataSetIterator(testBatch, testImagesNum, false);
+    }
+
+    @Override
+    public DataSetIterator trainIterator() {
+        return trainIterator;
+    }
+
+    @Override
+    public DataSetIterator testIterator() {
+        return testIterator;
+    }
+
+    @Override
+    public InputType inputType() {
+        return inputType;
+    }
+
+    @Override
+    public List<String> labels() {
+        return trainIterator.getLabels();
+    }
+}

deeplearning4j/src/main/java/com/baeldung/deeplearning4j/cnn/CnnExample.java

@@ -0,0 +1,18 @@
+package com.baeldung.deeplearning4j.cnn;
+
+
+import lombok.extern.slf4j.Slf4j;
+import org.deeplearning4j.eval.Evaluation;
+
+@Slf4j
+class CnnExample {
+
+    public static void main(String... args) {
+        CnnModel network = new CnnModel(new CifarDataSetService(), new CnnModelProperties());
+
+        network.train();
+        Evaluation evaluation = network.evaluate();
+
+        log.info(evaluation.stats());
+    }
+}

deeplearning4j/src/main/java/com/baeldung/deeplearning4j/cnn/CnnModel.java

@@ -0,0 +1,119 @@
+package com.baeldung.deeplearning4j.cnn;
+
+import lombok.extern.slf4j.Slf4j;
+import org.deeplearning4j.eval.Evaluation;
+import org.deeplearning4j.nn.api.OptimizationAlgorithm;
+import org.deeplearning4j.nn.conf.MultiLayerConfiguration;
+import org.deeplearning4j.nn.conf.NeuralNetConfiguration;
+import org.deeplearning4j.nn.conf.layers.ConvolutionLayer;
+import org.deeplearning4j.nn.conf.layers.OutputLayer;
+import org.deeplearning4j.nn.conf.layers.SubsamplingLayer;
+import org.deeplearning4j.nn.multilayer.MultiLayerNetwork;
+import org.deeplearning4j.nn.weights.WeightInit;
+import org.nd4j.linalg.activations.Activation;
+import org.nd4j.linalg.lossfunctions.LossFunctions;
+
+import java.util.stream.IntStream;
+
+@Slf4j
+class CnnModel {
+
+    private final IDataSetService dataSetService;
+
+    private final MultiLayerNetwork network;
+
+    private final CnnModelProperties properties;
+
+    CnnModel(IDataSetService dataSetService, CnnModelProperties properties) {
+
+        this.dataSetService = dataSetService;
+        this.properties = properties;
+
+        MultiLayerConfiguration configuration = new NeuralNetConfiguration.Builder()
+          .seed(1611)
+          .optimizationAlgo(OptimizationAlgorithm.STOCHASTIC_GRADIENT_DESCENT)
+          .learningRate(properties.getLearningRate())
+          .regularization(true)
+          .updater(properties.getOptimizer())
+          .list()
+          .layer(0, conv5x5())
+          .layer(1, pooling2x2Stride2())
+          .layer(2, conv3x3Stride1Padding2())
+          .layer(3, pooling2x2Stride1())
+          .layer(4, conv3x3Stride1Padding1())
+          .layer(5, pooling2x2Stride1())
+          .layer(6, dense())
+          .pretrain(false)
+          .backprop(true)
+          .setInputType(dataSetService.inputType())
+          .build();
+
+        network = new MultiLayerNetwork(configuration);
+    }
+
+    void train() {
+        network.init();
+        int epochsNum = properties.getEpochsNum();
+        IntStream.range(1, epochsNum + 1).forEach(epoch -> {
+            log.info("Epoch {} / {}", epoch, epochsNum);
+            network.fit(dataSetService.trainIterator());
+        });
+    }
+
+    Evaluation evaluate() {
+        return network.evaluate(dataSetService.testIterator());
+    }
+
+    private ConvolutionLayer conv5x5() {
+        return new ConvolutionLayer.Builder(5, 5)
+                .nIn(3)
+                .nOut(16)
+                .stride(1, 1)
+                .padding(1, 1)
+                .weightInit(WeightInit.XAVIER_UNIFORM)
+                .activation(Activation.RELU)
+                .build();
+    }
+
+    private SubsamplingLayer pooling2x2Stride2() {
+        return new SubsamplingLayer.Builder(SubsamplingLayer.PoolingType.MAX)
+                .kernelSize(2, 2)
+                .stride(2, 2)
+                .build();
+    }
+
+    private ConvolutionLayer conv3x3Stride1Padding2() {
+        return new ConvolutionLayer.Builder(3, 3)
+                .nOut(32)
+                .stride(1, 1)
+                .padding(2, 2)
+                .weightInit(WeightInit.XAVIER_UNIFORM)
+                .activation(Activation.RELU)
+                .build();
+    }
+
+    private SubsamplingLayer pooling2x2Stride1() {
+        return new SubsamplingLayer.Builder(SubsamplingLayer.PoolingType.MAX)
+                .kernelSize(2, 2)
+                .stride(1, 1)
+                .build();
+    }
+
+    private ConvolutionLayer conv3x3Stride1Padding1() {
+        return new ConvolutionLayer.Builder(3, 3)
+                .nOut(64)
+                .stride(1, 1)
+                .padding(1, 1)
+                .weightInit(WeightInit.XAVIER_UNIFORM)
+                .activation(Activation.RELU)
+                .build();
+    }
+
+    private OutputLayer dense() {
+        return new OutputLayer.Builder(LossFunctions.LossFunction.MEAN_SQUARED_LOGARITHMIC_ERROR)
+                .activation(Activation.SOFTMAX)
+                .weightInit(WeightInit.XAVIER_UNIFORM)
+                .nOut(dataSetService.labels().size() - 1)
+                .build();
+    }
+}

deeplearning4j/src/main/java/com/baeldung/deeplearning4j/cnn/CnnModelProperties.java

@@ -0,0 +1,13 @@
+package com.baeldung.deeplearning4j.cnn;
+
+import lombok.Value;
+import org.deeplearning4j.nn.conf.Updater;
+
+@Value
+class CnnModelProperties {
+    private final int epochsNum = 512;
+
+    private final double learningRate = 0.001;
+
+    private final Updater optimizer = Updater.ADAM;
+}

deeplearning4j/src/main/java/com/baeldung/deeplearning4j/cnn/IDataSetService.java

@@ -0,0 +1,16 @@
+package com.baeldung.deeplearning4j.cnn;
+
+import org.deeplearning4j.nn.conf.inputs.InputType;
+import org.nd4j.linalg.dataset.api.iterator.DataSetIterator;
+
+import java.util.List;
+
+interface IDataSetService {
+    DataSetIterator trainIterator();
+
+    DataSetIterator testIterator();
+
+    InputType inputType();
+
+    List<String> labels();
+}

excelformula/README.md

@@ -0,0 +1,8 @@
+## Apache POI
+
+This module contains articles about Apache POI
+
+### Relevant Articles:
+- [Working with Microsoft Excel in Java](https://www.baeldung.com/java-microsoft-excel)
+- [Read Excel Cell Value Rather Than Formula With Apache POI](https://www.baeldung.com/apache-poi-read-cell-value-formula)
+- [Upload and Display Excel Files with Spring MVC](https://www.baeldung.com/spring-mvc-excel-files)

guava-2/README.md

@@ -1,7 +0,0 @@
-## Guava
-
-This module contains articles a Google Guava
-
-### Relevant Articles: 
-
-- [Guava CharMatcher](https://www.baeldung.com/guava-string-charmatcher)

guava-modules/guava-18/README.md

@@ -1,8 +1,5 @@
-=========
+## Guava 18
-
-## Guava and Hamcrest Cookbooks and Examples
 
 
 ### Relevant Articles: 
-- [Guava Functional Cookbook](http://www.baeldung.com/guava-functions-predicates)
 - [Guava 18: What’s New?](http://www.baeldung.com/whats-new-in-guava-18)

guava-modules/guava-19/README.md

@@ -1,5 +1,3 @@
-=========
-
 ## Guava 19
 
 

guava-modules/guava-21/README.md

@@ -1,4 +1,6 @@
+## Guava 21
+
 ### Relevant articles:
+
 - [New Stream, Comparator and Collector in Guava 21](http://www.baeldung.com/guava-21-new)
 - [New in Guava 21 common.util.concurrent](http://www.baeldung.com/guava-21-util-concurrent)
-- [Zipping Collections in Java](http://www.baeldung.com/java-collections-zip)

guava-modules/guava-21/pom.xml

@@ -13,17 +13,8 @@
         <relativePath>../</relativePath>
     </parent>
 
-    <dependencies>
-        <dependency>
-            <groupId>org.jooq</groupId>
-            <artifactId>jool</artifactId>
-            <version>${jool.version}</version>
-        </dependency>
-    </dependencies>
-
     <properties>
         <guava.version>21.0</guava.version>
-        <jool.version>0.9.12</jool.version>
     </properties>
 
 </project>

guava-modules/guava-collections-list/README.md

@@ -0,0 +1,8 @@
+## Guava Collections List examples
+
+This module contains articles about list collections in Guava
+
+### Relevant Articles: 
+
+- [Partition a List in Java](https://www.baeldung.com/java-list-split)
+- [Guava – Lists](https://www.baeldung.com/guava-lists)

guava-modules/guava-collections-list/pom.xml

@@ -4,15 +4,15 @@
     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>guava-collections</artifactId>
+    <artifactId>guava-collections-list</artifactId>
     <version>0.1.0-SNAPSHOT</version>
-    <name>guava-collections</name>
+    <name>guava-collections-list</name>
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <artifactId>guava-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
+        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

guava-modules/guava-collections-map/pom.xml

@@ -9,9 +9,9 @@
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <artifactId>guava-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
+        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

guava-modules/guava-collections-set/pom.xml

@@ -8,9 +8,9 @@
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <artifactId>guava-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
+        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

guava-modules/guava-collections/README.md

@@ -8,9 +8,8 @@ This module contains articles about Google Guava collections
 - [Guava Ordering Cookbook](https://www.baeldung.com/guava-order)
 - [Guide to Guava’s Ordering](https://www.baeldung.com/guava-ordering)
 - [Hamcrest Collections Cookbook](https://www.baeldung.com/hamcrest-collections-arrays)
-- [Partition a List in Java](https://www.baeldung.com/java-list-split)
 - [Filtering and Transforming Collections in Guava](https://www.baeldung.com/guava-filter-and-transform-a-collection)
 - [Guava – Join and Split Collections](https://www.baeldung.com/guava-joiner-and-splitter-tutorial)
-- [Guava – Lists](https://www.baeldung.com/guava-lists)
 - [Guide to Guava MinMaxPriorityQueue and EvictingQueue](https://www.baeldung.com/guava-minmax-priority-queue-and-evicting-queue)
 - [Guide to Guava Table](https://www.baeldung.com/guava-table)
+- [Zipping Collections in Java](http://www.baeldung.com/java-collections-zip)

guava-modules/guava-collections/pom.xml

@@ -0,0 +1,95 @@
+<?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>guava-collections</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>guava-collections</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>guava-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../</relativePath>
+    </parent>
+
+    <dependencies>
+        <!-- utils -->
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jooq</groupId>
+            <artifactId>jool</artifactId>
+            <version>${jool.version}</version>
+        </dependency>
+
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${junit-jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.vintage</groupId>
+            <artifactId>junit-vintage-engine</artifactId>
+            <version>${junit-jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/org.hamcrest/java-hamcrest -->
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>java-hamcrest</artifactId>
+            <version>${java-hamcrest.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>guava-collections</finalName>
+
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>2.22.2</version>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <!-- util -->
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <jool.version>0.9.12</jool.version>
+
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <java-hamcrest.version>2.0.0.0</java-hamcrest.version>
+        <junit-jupiter.version>5.6.2</junit-jupiter.version>
+    </properties>
+
+</project>

guava-modules/guava-core/README.md

@@ -0,0 +1,10 @@
+## Guava Core
+
+This module contains articles about core or base functionality provided by Google Guava
+
+### Relevant Articles: 
+- [Introduction to Guava Throwables](https://www.baeldung.com/guava-throwables)
+- [Guava CharMatcher](https://www.baeldung.com/guava-string-charmatcher)
+- [Guide to Guava’s PreConditions](https://www.baeldung.com/guava-preconditions)
+- [Introduction to Guava Memoizer](https://www.baeldung.com/guava-memoizer)
+- [Guava Functional Cookbook](https://www.baeldung.com/guava-functions-predicates)

guava-modules/guava-core/pom.xml

@@ -4,15 +4,15 @@
     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>guava-2</artifactId>
+    <artifactId>guava-core</artifactId>
     <version>0.1.0-SNAPSHOT</version>
-    <name>guava-2</name>
+    <name>guava-core</name>
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <artifactId>guava-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
+        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

guava-modules/guava-core/src/test/java/com/baeldung/guava/functional/GuavaFunctionalExamplesUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.guava;
+package com.baeldung.guava.functional;
 
 import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.equalTo;

guava-modules/guava-core/src/test/java/com/baeldung/guava/memoizer/GuavaMemoizerUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.guava;
+package com.baeldung.guava.memoizer;
 
 import com.google.common.base.Suppliers;
 import com.baeldung.guava.memoizer.CostlySupplier;

guava-modules/guava-core/src/test/java/com/baeldung/guava/preconditions/GuavaPreConditionsUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.guava;
+package com.baeldung.guava.preconditions;
 
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import java.util.Arrays;