Merge pull request #9 from eugenp/master

update with origin

.travis.yml

@@ -1,24 +0,0 @@
-language: java
-
-before_install: 
-  - echo "MAVEN_OPTS='-Xmx2048M -Xss128M -XX:+CMSClassUnloadingEnabled -XX:+UseG1GC -XX:-UseGCOverheadLimit'" > ~/.mavenrc
-
-install: skip
-script: travis_wait 60 mvn -q install -Pdefault-first,default-second -Dgib.enabled=true
-
-sudo: required
-
-jdk:
-  - oraclejdk8
-
-addons:
-  apt:
-    packages:
-      - oracle-java8-installer
-
-cache:
-  directories:
-  - .autoconf
-  - $HOME/.m2
-  
-

algorithms-miscellaneous-3/README.md

@@ -7,3 +7,4 @@
 - [Checking If a List Is Sorted in Java](https://www.baeldung.com/java-check-if-list-sorted)
 - [Checking if a Java Graph has a Cycle](https://www.baeldung.com/java-graph-has-a-cycle)
 - [A Guide to the Folding Technique in Java](https://www.baeldung.com/folding-hashing-technique)
+- [Creating a Triangle with for Loops in Java](https://www.baeldung.com/java-print-triangle)

algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/bucketsort/IntegerBucketSorter.java

@@ -0,0 +1,70 @@
+package com.baeldung.bucketsort;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+public class IntegerBucketSorter implements Sorter<Integer> {
+
+    private final Comparator<Integer> comparator;
+
+    public IntegerBucketSorter(Comparator<Integer> comparator) {
+        this.comparator = comparator;
+    }
+
+    public IntegerBucketSorter() {
+        comparator = Comparator.naturalOrder();
+    }
+
+    public List<Integer> sort(List<Integer> arrayToSort) {
+
+        List<List<Integer>> buckets = splitIntoUnsortedBuckets(arrayToSort);
+
+        for(List<Integer> bucket  : buckets){
+            bucket.sort(comparator);
+        }
+
+        return concatenateSortedBuckets(buckets);
+    }
+
+    private List<Integer> concatenateSortedBuckets(List<List<Integer>> buckets){
+        List<Integer> sortedArray = new ArrayList<>();
+        int index = 0;
+        for(List<Integer> bucket : buckets){
+            for(int number : bucket){
+                sortedArray.add(index++, number);
+            }
+        }
+        return sortedArray;
+    }
+
+    private List<List<Integer>> splitIntoUnsortedBuckets(List<Integer> initialList){
+
+        final int[] codes = createHashes(initialList);
+
+        List<List<Integer>> buckets = new ArrayList<>(codes[1]);
+        for(int i = 0; i < codes[1]; i++) buckets.add(new ArrayList<>());
+
+        //distribute the data
+        for (int i : initialList) {
+            buckets.get(hash(i, codes)).add(i);
+        }
+        return buckets;
+
+    }
+
+    private int[] createHashes(List<Integer> input){
+        int m = input.get(0);
+        for (int i = 1; i < input.size(); i++) {
+            if (m < input.get(i)) {
+                m = input.get(i);
+            }
+        }
+        return new int[]{m, (int) Math.sqrt(input.size())};
+    }
+
+    private static int hash(int i, int[] code) {
+        return (int) ((double) i / code[0] * (code[1] - 1));
+    }
+
+}

algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/bucketsort/Sorter.java

@@ -0,0 +1,8 @@
+package com.baeldung.bucketsort;
+
+import java.util.List;
+
+public interface Sorter<T> {
+
+    List<T> sort(List<T> arrayToSort);
+}

algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/printtriangles/PrintTriangleExamples.java

@@ -4,7 +4,7 @@ import org.apache.commons.lang3.StringUtils;
 
 public class PrintTriangleExamples {
 
-    public static String printARightAngledTriangle(int N) {
+    public static String printARightTriangle(int N) {
         StringBuilder result = new StringBuilder();
         for (int r = 1; r <= N; r++) {
             for (int j = 1; j <= r; j++) {
@@ -29,6 +29,17 @@ public class PrintTriangleExamples {
         return result.toString();
     }
 
+    public static String printAnIsoscelesTriangleUsingStringUtils(int N) {
+        StringBuilder result = new StringBuilder();
+
+        for (int r = 1; r <= N; r++) {
+            result.append(StringUtils.repeat(' ', N - r));
+            result.append(StringUtils.repeat('*', 2 * r - 1));
+            result.append(System.lineSeparator());
+        }
+        return result.toString();
+    }
+
     public static String printAnIsoscelesTriangleUsingSubstring(int N) {
         StringBuilder result = new StringBuilder();
         String helperString = StringUtils.repeat(' ', N - 1) + StringUtils.repeat('*', N * 2 - 1);
@@ -41,8 +52,9 @@ public class PrintTriangleExamples {
     }
 
     public static void main(String[] args) {
-        System.out.println(printARightAngledTriangle(5));
+        System.out.println(printARightTriangle(5));
         System.out.println(printAnIsoscelesTriangle(5));
+        System.out.println(printAnIsoscelesTriangleUsingStringUtils(5));
         System.out.println(printAnIsoscelesTriangleUsingSubstring(5));
     }
 

algorithms-miscellaneous-3/src/test/java/com/baeldung/algorithms/bucketsort/IntegerBucketSorterUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.bucketsort;
+
+import com.baeldung.bucketsort.IntegerBucketSorter;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+public class IntegerBucketSorterUnitTest {
+
+    private IntegerBucketSorter sorter;
+
+    @Before
+    public void setUp() throws Exception {
+        sorter = new IntegerBucketSorter();
+    }
+
+    @Test
+    public void givenUnsortedList_whenSortedUsingBucketSorter_checkSortingCorrect() {
+
+        List<Integer> unsorted = Arrays.asList(80,50,60,30,20,10,70,0,40,500,600,602,200,15);
+        List<Integer> expected = Arrays.asList(0,10,15,20,30,40,50,60,70,80,200,500,600,602);
+
+        List<Integer> actual = sorter.sort(unsorted);
+
+        assertEquals(expected, actual);
+
+
+    }
+}

algorithms-miscellaneous-3/src/test/java/com/baeldung/algorithms/printtriangles/PrintTriangleExamplesUnitTest.java

@@ -10,7 +10,7 @@ import static org.junit.Assert.assertEquals;
 @RunWith(JUnitParamsRunner.class)
 public class PrintTriangleExamplesUnitTest {
 
-    private static Object[][] rightAngledTriangles() {
+    private static Object[][] rightTriangles() {
         String expected0 = "";
         
         String expected2 = "*" + System.lineSeparator() 
@@ -39,9 +39,9 @@ public class PrintTriangleExamplesUnitTest {
     }
 
     @Test
-    @Parameters(method = "rightAngledTriangles")
+    @Parameters(method = "rightTriangles")
-    public void whenPrintARightAngledTriangleIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
+    public void whenPrintARightTriangleIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
-        String actual = PrintTriangleExamples.printARightAngledTriangle(nrOfRows);
+        String actual = PrintTriangleExamples.printARightTriangle(nrOfRows);
 
         assertEquals(expected, actual);
     }
@@ -82,6 +82,14 @@ public class PrintTriangleExamplesUnitTest {
         assertEquals(expected, actual);
     }
 
+    @Test
+    @Parameters(method = "isoscelesTriangles")
+    public void whenPrintAnIsoscelesTriangleUsingStringUtilsIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
+        String actual = PrintTriangleExamples.printAnIsoscelesTriangleUsingStringUtils(nrOfRows);
+
+        assertEquals(expected, actual);
+    }
+    
     @Test
     @Parameters(method = "isoscelesTriangles")
     public void whenPrintAnIsoscelesTriangleUsingSubstringIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {

algorithms-sorting/README.md

@@ -6,3 +6,4 @@
 - [Insertion Sort in Java](https://www.baeldung.com/java-insertion-sort)
 - [Heap Sort in Java](https://www.baeldung.com/java-heap-sort)
 - [Shell Sort in Java](https://www.baeldung.com/java-shell-sort)
+- [Counting Sort in Java](https://www.baeldung.com/java-counting-sort)

algorithms-sorting/src/main/java/com/baeldung/algorithms/counting/CountingSort.java

@@ -0,0 +1,48 @@
+package com.baeldung.algorithms.counting;
+
+import java.util.Arrays;
+import java.util.stream.IntStream;
+
+public class CountingSort {
+
+    public static int[] sort(int[] input, int k) {
+        verifyPreconditions(input, k);
+        if (input.length == 0) return input;
+
+        int[] c = countElements(input, k);
+        int[] sorted = new int[input.length];
+        for (int i = input.length - 1; i >= 0; i--) {
+            int current = input[i];
+            sorted[c[current] - 1] = current;
+            c[current] -= 1;
+        }
+
+        return sorted;
+    }
+
+    static int[] countElements(int[] input, int k) {
+        int[] c = new int[k + 1];
+        Arrays.fill(c, 0);
+        for (int i : input) {
+            c[i] += 1;
+        }
+
+        for (int i = 1; i < c.length; i++) {
+            c[i] += c[i - 1];
+        }
+        return c;
+    }
+
+    private static void verifyPreconditions(int[] input, int k) {
+        if (input == null) {
+            throw new IllegalArgumentException("Input is required");
+        }
+
+        int min = IntStream.of(input).min().getAsInt();
+        int max = IntStream.of(input).max().getAsInt();
+
+        if (min < 0 || max > k) {
+            throw new IllegalArgumentException("The input numbers should be between zero and " + k);
+        }
+    }
+}

algorithms-sorting/src/main/java/com/baeldung/algorithms/radixsort/RadixSort.java

@@ -0,0 +1,53 @@
+package com.baeldung.algorithms.radixsort;
+
+import java.util.Arrays;
+
+public class RadixSort {
+
+    public static void sort(int numbers[]) {
+        int maximumNumber = findMaximumNumberIn(numbers);
+
+        int numberOfDigits = calculateNumberOfDigitsIn(maximumNumber);
+
+        int placeValue = 1;
+
+        while (numberOfDigits-- > 0) {
+            applyCountingSortOn(numbers, placeValue);
+            placeValue *= 10;
+        }
+    }
+
+    private static void applyCountingSortOn(int[] numbers, int placeValue) {
+        int range = 10; // radix or the base
+
+        int length = numbers.length;
+        int[] frequency = new int[range];
+        int[] sortedValues = new int[length];
+
+        for (int i = 0; i < length; i++) {
+            int digit = (numbers[i] / placeValue) % range;
+            frequency[digit]++;
+        }
+
+        for (int i = 1; i < 10; i++) {
+            frequency[i] += frequency[i - 1];
+        }
+
+        for (int i = length - 1; i >= 0; i--) {
+            int digit = (numbers[i] / placeValue) % range;
+            sortedValues[frequency[digit] - 1] = numbers[i];
+            frequency[digit]--;
+        }
+
+        System.arraycopy(sortedValues, 0, numbers, 0, length);
+    }
+
+    private static int calculateNumberOfDigitsIn(int number) {
+        return (int) Math.log10(number) + 1; // valid only if number > 0
+    }
+
+    private static int findMaximumNumberIn(int[] arr) {
+        return Arrays.stream(arr).max().getAsInt();
+    }
+
+}

algorithms-sorting/src/main/java/com/baeldung/algorithms/sort/bynumber/NaturalOrderComparators.java

@@ -1,4 +1,4 @@
-package com.baeldung.algorithms.stringsortingbynumber;
+package com.baeldung.algorithms.sort.bynumber;
 
 import java.util.Comparator;
 

algorithms-sorting/src/test/java/com/baeldung/algorithms/counting/CountingSortUnitTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.algorithms.counting;
+
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+class CountingSortUnitTest {
+
+    @Test
+    void countElements_GivenAnArray_ShouldCalculateTheFrequencyArrayAsExpected() {
+        int k = 5;
+        int[] input = { 4, 3, 2, 5, 4, 3, 5, 1, 0, 2, 5 };
+
+        int[] c = CountingSort.countElements(input, k);
+        int[] expected = { 1, 2, 4, 6, 8, 11 };
+        assertArrayEquals(expected, c);
+    }
+
+    @Test
+    void sort_GivenAnArray_ShouldSortTheInputAsExpected() {
+        int k = 5;
+        int[] input = { 4, 3, 2, 5, 4, 3, 5, 1, 0, 2, 5 };
+
+        int[] sorted = CountingSort.sort(input, k);
+
+        // Our sorting algorithm and Java's should return the same result
+        Arrays.sort(input);
+        assertArrayEquals(input, sorted);
+    }
+}

algorithms-sorting/src/test/java/com/baeldung/algorithms/radixsort/RadixSortUnitTest.java

@@ -0,0 +1,16 @@
+package com.baeldung.algorithms.radixsort;
+
+import static org.junit.Assert.assertArrayEquals;
+
+import org.junit.Test;
+
+public class RadixSortUnitTest {
+
+    @Test
+    public void givenUnsortedArrayWhenRadixSortThenArraySorted() {
+        int[] numbers = { 387, 468, 134, 123, 68, 221, 769, 37, 7 };
+        RadixSort.sort(numbers);
+        int[] numbersSorted = { 7, 37, 68, 123, 134, 221, 387, 468, 769 };
+        assertArrayEquals(numbersSorted, numbers);
+    }
+}

algorithms-sorting/src/test/java/com/baeldung/algorithms/sort/bynumber/NaturalOrderComparatorsUnitTest.java

@@ -1,6 +1,6 @@
-package com.baeldung.algorithms.stringsortingbynumber;
+package com.baeldung.algorithms.sort.bynumber;
 
-import com.baeldung.algorithms.stringsortingbynumber.NaturalOrderComparators;
+import com.baeldung.algorithms.sort.bynumber.NaturalOrderComparators;
 import org.junit.Test;
 
 import java.util.ArrayList;

apache-olingo/olingo2/pom.xml

@@ -4,9 +4,9 @@
 	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.baeldung.examples.olingo2</groupId>
-	<artifactId>olingo2-sample</artifactId>
+	<artifactId>olingo2</artifactId>
 	<version>0.0.1-SNAPSHOT</version>
-	<name>olingo2-sample</name>
+	<name>olingo2</name>
 	<description>Sample Olingo 2 Project</description>
 
     <parent>

apache-spark/data/iris.data

@@ -0,0 +1,150 @@
+5.1,3.5,1.4,0.2,Iris-setosa
+4.9,3.0,1.4,0.2,Iris-setosa
+4.7,3.2,1.3,0.2,Iris-setosa
+4.6,3.1,1.5,0.2,Iris-setosa
+5.0,3.6,1.4,0.2,Iris-setosa
+5.4,3.9,1.7,0.4,Iris-setosa
+4.6,3.4,1.4,0.3,Iris-setosa
+5.0,3.4,1.5,0.2,Iris-setosa
+4.4,2.9,1.4,0.2,Iris-setosa
+4.9,3.1,1.5,0.1,Iris-setosa
+5.4,3.7,1.5,0.2,Iris-setosa
+4.8,3.4,1.6,0.2,Iris-setosa
+4.8,3.0,1.4,0.1,Iris-setosa
+4.3,3.0,1.1,0.1,Iris-setosa
+5.8,4.0,1.2,0.2,Iris-setosa
+5.7,4.4,1.5,0.4,Iris-setosa
+5.4,3.9,1.3,0.4,Iris-setosa
+5.1,3.5,1.4,0.3,Iris-setosa
+5.7,3.8,1.7,0.3,Iris-setosa
+5.1,3.8,1.5,0.3,Iris-setosa
+5.4,3.4,1.7,0.2,Iris-setosa
+5.1,3.7,1.5,0.4,Iris-setosa
+4.6,3.6,1.0,0.2,Iris-setosa
+5.1,3.3,1.7,0.5,Iris-setosa
+4.8,3.4,1.9,0.2,Iris-setosa
+5.0,3.0,1.6,0.2,Iris-setosa
+5.0,3.4,1.6,0.4,Iris-setosa
+5.2,3.5,1.5,0.2,Iris-setosa
+5.2,3.4,1.4,0.2,Iris-setosa
+4.7,3.2,1.6,0.2,Iris-setosa
+4.8,3.1,1.6,0.2,Iris-setosa
+5.4,3.4,1.5,0.4,Iris-setosa
+5.2,4.1,1.5,0.1,Iris-setosa
+5.5,4.2,1.4,0.2,Iris-setosa
+4.9,3.1,1.5,0.1,Iris-setosa
+5.0,3.2,1.2,0.2,Iris-setosa
+5.5,3.5,1.3,0.2,Iris-setosa
+4.9,3.1,1.5,0.1,Iris-setosa
+4.4,3.0,1.3,0.2,Iris-setosa
+5.1,3.4,1.5,0.2,Iris-setosa
+5.0,3.5,1.3,0.3,Iris-setosa
+4.5,2.3,1.3,0.3,Iris-setosa
+4.4,3.2,1.3,0.2,Iris-setosa
+5.0,3.5,1.6,0.6,Iris-setosa
+5.1,3.8,1.9,0.4,Iris-setosa
+4.8,3.0,1.4,0.3,Iris-setosa
+5.1,3.8,1.6,0.2,Iris-setosa
+4.6,3.2,1.4,0.2,Iris-setosa
+5.3,3.7,1.5,0.2,Iris-setosa
+5.0,3.3,1.4,0.2,Iris-setosa
+7.0,3.2,4.7,1.4,Iris-versicolor
+6.4,3.2,4.5,1.5,Iris-versicolor
+6.9,3.1,4.9,1.5,Iris-versicolor
+5.5,2.3,4.0,1.3,Iris-versicolor
+6.5,2.8,4.6,1.5,Iris-versicolor
+5.7,2.8,4.5,1.3,Iris-versicolor
+6.3,3.3,4.7,1.6,Iris-versicolor
+4.9,2.4,3.3,1.0,Iris-versicolor
+6.6,2.9,4.6,1.3,Iris-versicolor
+5.2,2.7,3.9,1.4,Iris-versicolor
+5.0,2.0,3.5,1.0,Iris-versicolor
+5.9,3.0,4.2,1.5,Iris-versicolor
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+5.6,2.9,3.6,1.3,Iris-versicolor
+6.7,3.1,4.4,1.4,Iris-versicolor
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+5.6,2.5,3.9,1.1,Iris-versicolor
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+6.1,2.8,4.0,1.3,Iris-versicolor
+6.3,2.5,4.9,1.5,Iris-versicolor
+6.1,2.8,4.7,1.2,Iris-versicolor
+6.4,2.9,4.3,1.3,Iris-versicolor
+6.6,3.0,4.4,1.4,Iris-versicolor
+6.8,2.8,4.8,1.4,Iris-versicolor
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+6.0,2.9,4.5,1.5,Iris-versicolor
+5.7,2.6,3.5,1.0,Iris-versicolor
+5.5,2.4,3.8,1.1,Iris-versicolor
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+6.0,2.7,5.1,1.6,Iris-versicolor
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+6.0,3.4,4.5,1.6,Iris-versicolor
+6.7,3.1,4.7,1.5,Iris-versicolor
+6.3,2.3,4.4,1.3,Iris-versicolor
+5.6,3.0,4.1,1.3,Iris-versicolor
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+5.5,2.6,4.4,1.2,Iris-versicolor
+6.1,3.0,4.6,1.4,Iris-versicolor
+5.8,2.6,4.0,1.2,Iris-versicolor
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+5.6,2.7,4.2,1.3,Iris-versicolor
+5.7,3.0,4.2,1.2,Iris-versicolor
+5.7,2.9,4.2,1.3,Iris-versicolor
+6.2,2.9,4.3,1.3,Iris-versicolor
+5.1,2.5,3.0,1.1,Iris-versicolor
+5.7,2.8,4.1,1.3,Iris-versicolor
+6.3,3.3,6.0,2.5,Iris-virginica
+5.8,2.7,5.1,1.9,Iris-virginica
+7.1,3.0,5.9,2.1,Iris-virginica
+6.3,2.9,5.6,1.8,Iris-virginica
+6.5,3.0,5.8,2.2,Iris-virginica
+7.6,3.0,6.6,2.1,Iris-virginica
+4.9,2.5,4.5,1.7,Iris-virginica
+7.3,2.9,6.3,1.8,Iris-virginica
+6.7,2.5,5.8,1.8,Iris-virginica
+7.2,3.6,6.1,2.5,Iris-virginica
+6.5,3.2,5.1,2.0,Iris-virginica
+6.4,2.7,5.3,1.9,Iris-virginica
+6.8,3.0,5.5,2.1,Iris-virginica
+5.7,2.5,5.0,2.0,Iris-virginica
+5.8,2.8,5.1,2.4,Iris-virginica
+6.4,3.2,5.3,2.3,Iris-virginica
+6.5,3.0,5.5,1.8,Iris-virginica
+7.7,3.8,6.7,2.2,Iris-virginica
+7.7,2.6,6.9,2.3,Iris-virginica
+6.0,2.2,5.0,1.5,Iris-virginica
+6.9,3.2,5.7,2.3,Iris-virginica
+5.6,2.8,4.9,2.0,Iris-virginica
+7.7,2.8,6.7,2.0,Iris-virginica
+6.3,2.7,4.9,1.8,Iris-virginica
+6.7,3.3,5.7,2.1,Iris-virginica
+7.2,3.2,6.0,1.8,Iris-virginica
+6.2,2.8,4.8,1.8,Iris-virginica
+6.1,3.0,4.9,1.8,Iris-virginica
+6.4,2.8,5.6,2.1,Iris-virginica
+7.2,3.0,5.8,1.6,Iris-virginica
+7.4,2.8,6.1,1.9,Iris-virginica
+7.9,3.8,6.4,2.0,Iris-virginica
+6.4,2.8,5.6,2.2,Iris-virginica
+6.3,2.8,5.1,1.5,Iris-virginica
+6.1,2.6,5.6,1.4,Iris-virginica
+7.7,3.0,6.1,2.3,Iris-virginica
+6.3,3.4,5.6,2.4,Iris-virginica
+6.4,3.1,5.5,1.8,Iris-virginica
+6.0,3.0,4.8,1.8,Iris-virginica
+6.9,3.1,5.4,2.1,Iris-virginica
+6.7,3.1,5.6,2.4,Iris-virginica
+6.9,3.1,5.1,2.3,Iris-virginica
+5.8,2.7,5.1,1.9,Iris-virginica
+6.8,3.2,5.9,2.3,Iris-virginica
+6.7,3.3,5.7,2.5,Iris-virginica
+6.7,3.0,5.2,2.3,Iris-virginica
+6.3,2.5,5.0,1.9,Iris-virginica
+6.5,3.0,5.2,2.0,Iris-virginica
+6.2,3.4,5.4,2.3,Iris-virginica
+5.9,3.0,5.1,1.8,Iris-virginica

apache-spark/model/logistic-regression/metadata/part-00000

@@ -0,0 +1 @@
+{"class":"org.apache.spark.mllib.classification.LogisticRegressionModel","version":"1.0","numFeatures":4,"numClasses":3}

apache-spark/pom.xml

@@ -1,31 +1,32 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    <modelVersion>4.0.0</modelVersion>
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-    <groupId>com.baeldung</groupId>
+	<modelVersion>4.0.0</modelVersion>
-    <artifactId>apache-spark</artifactId>
+	<groupId>com.baeldung</groupId>
-    <version>1.0-SNAPSHOT</version>
+	<artifactId>apache-spark</artifactId>
-    <name>apache-spark</name>
+	<version>1.0-SNAPSHOT</version>
-    <packaging>jar</packaging>
+	<name>apache-spark</name>
-    <url>http://maven.apache.org</url>
+	<packaging>jar</packaging>
+	<url>http://maven.apache.org</url>
 
-    <parent>
+	<parent>
-        <groupId>com.baeldung</groupId>
+		<groupId>com.baeldung</groupId>
-        <artifactId>parent-modules</artifactId>
+		<artifactId>parent-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
+		<version>1.0.0-SNAPSHOT</version>
-    </parent>
+	</parent>
 
-    <dependencies>
+	<dependencies>
-        <dependency>
-            <groupId>org.apache.spark</groupId>
-            <artifactId>spark-core_2.11</artifactId>
-            <version>${org.apache.spark.spark-core.version}</version>
-            <scope>provided</scope>
-        </dependency>
 		<dependency>
-    		<groupId>org.apache.spark</groupId>
+			<groupId>org.apache.spark</groupId>
-    		<artifactId>spark-sql_2.11</artifactId>
+			<artifactId>spark-core_2.11</artifactId>
-    		<version>${org.apache.spark.spark-sql.version}</version>
+			<version>${org.apache.spark.spark-core.version}</version>
-    		<scope>provided</scope>
+			<scope>provided</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.apache.spark</groupId>
+			<artifactId>spark-sql_2.11</artifactId>
+			<version>${org.apache.spark.spark-sql.version}</version>
+			<scope>provided</scope>
 		</dependency>
 		<dependency>
 			<groupId>org.apache.spark</groupId>
@@ -33,6 +34,12 @@
 			<version>${org.apache.spark.spark-streaming.version}</version>
 			<scope>provided</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.apache.spark</groupId>
+			<artifactId>spark-mllib_2.11</artifactId>
+			<version>${org.apache.spark.spark-mllib.version}</version>
+			<scope>provided</scope>
+		</dependency>
 		<dependency>
 			<groupId>org.apache.spark</groupId>
 			<artifactId>spark-streaming-kafka-0-10_2.11</artifactId>
@@ -48,46 +55,47 @@
 			<artifactId>spark-cassandra-connector-java_2.11</artifactId>
 			<version>${com.datastax.spark.spark-cassandra-connector-java.version}</version>
 		</dependency>
-    </dependencies>
+	</dependencies>
 
 	<build>
-    	<plugins>
+		<plugins>
-    	  	<plugin>
+			<plugin>
-    			<groupId>org.apache.maven.plugins</groupId>
+				<groupId>org.apache.maven.plugins</groupId>
-    			<artifactId>maven-compiler-plugin</artifactId>
+				<artifactId>maven-compiler-plugin</artifactId>
-    			<version>${maven-compiler-plugin.version}</version>
+				<version>${maven-compiler-plugin.version}</version>
-    			<configuration>
+				<configuration>
-      				<source>${java.version}</source>
+					<source>${java.version}</source>
-      				<target>${java.version}</target>
+					<target>${java.version}</target>
-    			</configuration>
+				</configuration>
-  			</plugin>
+			</plugin>
-      		<plugin>
+			<plugin>
-        		<artifactId>maven-assembly-plugin</artifactId>
+				<artifactId>maven-assembly-plugin</artifactId>
-        		<executions>
+				<executions>
-          			<execution>
+					<execution>
-            			<phase>package</phase>
+						<phase>package</phase>
-            			<goals>
+						<goals>
-              				<goal>single</goal>
+							<goal>single</goal>
-            			</goals>
+						</goals>
-          			</execution>
+					</execution>
-        		</executions>
+				</executions>
-        		<configuration>
+				<configuration>
-          			<descriptorRefs>
+					<descriptorRefs>
-            			<descriptorRef>jar-with-dependencies</descriptorRef>
+						<descriptorRef>jar-with-dependencies</descriptorRef>
-          			</descriptorRefs>
+					</descriptorRefs>
-        		</configuration>
+				</configuration>
-      		</plugin>
+			</plugin>
-   		</plugins>
+		</plugins>
-  	</build>
+	</build>
 
-    <properties>
+	<properties>
-        <org.apache.spark.spark-core.version>2.3.0</org.apache.spark.spark-core.version>
+		<org.apache.spark.spark-core.version>2.3.0</org.apache.spark.spark-core.version>
-        <org.apache.spark.spark-sql.version>2.3.0</org.apache.spark.spark-sql.version>
+		<org.apache.spark.spark-sql.version>2.3.0</org.apache.spark.spark-sql.version>
-        <org.apache.spark.spark-streaming.version>2.3.0</org.apache.spark.spark-streaming.version>
+		<org.apache.spark.spark-streaming.version>2.3.0</org.apache.spark.spark-streaming.version>
-        <org.apache.spark.spark-streaming-kafka.version>2.3.0</org.apache.spark.spark-streaming-kafka.version>
+		<org.apache.spark.spark-mllib.version>2.3.0</org.apache.spark.spark-mllib.version>
-        <com.datastax.spark.spark-cassandra-connector.version>2.3.0</com.datastax.spark.spark-cassandra-connector.version>
+		<org.apache.spark.spark-streaming-kafka.version>2.3.0</org.apache.spark.spark-streaming-kafka.version>
-        <com.datastax.spark.spark-cassandra-connector-java.version>1.5.2</com.datastax.spark.spark-cassandra-connector-java.version>
+		<com.datastax.spark.spark-cassandra-connector.version>2.3.0</com.datastax.spark.spark-cassandra-connector.version>
+		<com.datastax.spark.spark-cassandra-connector-java.version>1.5.2</com.datastax.spark.spark-cassandra-connector-java.version>
 		<maven-compiler-plugin.version>3.2</maven-compiler-plugin.version>
-    </properties>
+	</properties>
 
 </project>

apache-spark/src/main/java/com/baeldung/ml/MachineLearningApp.java

@@ -0,0 +1,111 @@
+package com.baeldung.ml;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.log4j.Level;
+import org.apache.log4j.Logger;
+import org.apache.spark.SparkConf;
+import org.apache.spark.api.java.JavaPairRDD;
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.JavaSparkContext;
+import org.apache.spark.mllib.classification.LogisticRegressionModel;
+import org.apache.spark.mllib.classification.LogisticRegressionWithLBFGS;
+import org.apache.spark.mllib.evaluation.MulticlassMetrics;
+import org.apache.spark.mllib.linalg.Matrix;
+import org.apache.spark.mllib.linalg.Vector;
+import org.apache.spark.mllib.linalg.Vectors;
+import org.apache.spark.mllib.regression.LabeledPoint;
+import org.apache.spark.mllib.stat.MultivariateStatisticalSummary;
+import org.apache.spark.mllib.stat.Statistics;
+
+import scala.Tuple2;
+
+public class MachineLearningApp {
+
+    public static void main(String[] args) {
+
+        // 1. Setting the Spark Context
+        SparkConf conf = new SparkConf().setAppName("Main")
+            .setMaster("local[2]")
+            .set("spark.executor.memory", "3g")
+            .set("spark.driver.memory", "3g");
+        JavaSparkContext sc = new JavaSparkContext(conf);
+        Logger.getLogger("org")
+            .setLevel(Level.OFF);
+        Logger.getLogger("akka")
+            .setLevel(Level.OFF);
+
+        // 2. Loading the Data-set
+        String dataFile = "data\\iris.data";
+        JavaRDD<String> data = sc.textFile(dataFile);
+
+        // 3. Exploratory Data Analysis
+        // 3.1. Creating Vector of Input Data
+        JavaRDD<Vector> inputData = data.map(line -> {
+            String[] parts = line.split(",");
+            double[] v = new double[parts.length - 1];
+            for (int i = 0; i < parts.length - 1; i++) {
+                v[i] = Double.parseDouble(parts[i]);
+            }
+            return Vectors.dense(v);
+        });
+        // 3.2. Performing Statistical Analysis
+        MultivariateStatisticalSummary summary = Statistics.colStats(inputData.rdd());
+        System.out.println("Summary Mean:");
+        System.out.println(summary.mean());
+        System.out.println("Summary Variance:");
+        System.out.println(summary.variance());
+        System.out.println("Summary Non-zero:");
+        System.out.println(summary.numNonzeros());
+        // 3.3. Performing Correlation Analysis
+        Matrix correlMatrix = Statistics.corr(inputData.rdd(), "pearson");
+        System.out.println("Correlation Matrix:");
+        System.out.println(correlMatrix.toString());
+
+        // 4. Data Preparation
+        // 4.1. Creating Map for Textual Output Labels
+        Map<String, Integer> map = new HashMap<String, Integer>();
+        map.put("Iris-setosa", 0);
+        map.put("Iris-versicolor", 1);
+        map.put("Iris-virginica", 2);
+        // 4.2. Creating LabeledPoint of Input and Output Data
+        JavaRDD<LabeledPoint> parsedData = data.map(line -> {
+            String[] parts = line.split(",");
+            double[] v = new double[parts.length - 1];
+            for (int i = 0; i < parts.length - 1; i++) {
+                v[i] = Double.parseDouble(parts[i]);
+            }
+            return new LabeledPoint(map.get(parts[parts.length - 1]), Vectors.dense(v));
+        });
+
+        // 5. Data Splitting into 80% Training and 20% Test Sets
+        JavaRDD<LabeledPoint>[] splits = parsedData.randomSplit(new double[] { 0.8, 0.2 }, 11L);
+        JavaRDD<LabeledPoint> trainingData = splits[0].cache();
+        JavaRDD<LabeledPoint> testData = splits[1];
+
+        // 6. Modeling
+        // 6.1. Model Training
+        LogisticRegressionModel model = new LogisticRegressionWithLBFGS().setNumClasses(3)
+            .run(trainingData.rdd());
+        // 6.2. Model Evaluation
+        JavaPairRDD<Object, Object> predictionAndLabels = testData.mapToPair(p -> new Tuple2<>(model.predict(p.features()), p.label()));
+        MulticlassMetrics metrics = new MulticlassMetrics(predictionAndLabels.rdd());
+        double accuracy = metrics.accuracy();
+        System.out.println("Model Accuracy on Test Data: " + accuracy);
+
+        // 7. Model Saving and Loading
+        // 7.1. Model Saving
+        model.save(sc.sc(), "model\\logistic-regression");
+        // 7.2. Model Loading
+        LogisticRegressionModel sameModel = LogisticRegressionModel.load(sc.sc(), "model\\logistic-regression");
+        // 7.3. Prediction on New Data
+        Vector newData = Vectors.dense(new double[] { 1, 1, 1, 1 });
+        double prediction = sameModel.predict(newData);
+        System.out.println("Model Prediction on New Data = " + prediction);
+
+        // 8. Clean-up
+        sc.close();
+    }
+
+}

bazel/README.md

@@ -0,0 +1,3 @@
+## Relevant Articles:
+
+- [Building Java Applications with Bazel](https://www.baeldung.com/bazel-build-tool)

bazel/WORKSPACE

@@ -0,0 +1,31 @@
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_jar")
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+
+RULES_JVM_EXTERNAL_TAG = "2.0.1"
+RULES_JVM_EXTERNAL_SHA = "55e8d3951647ae3dffde22b4f7f8dee11b3f70f3f89424713debd7076197eaca"
+
+http_archive(
+    name = "rules_jvm_external",
+    strip_prefix = "rules_jvm_external-%s" % RULES_JVM_EXTERNAL_TAG,
+    sha256 = RULES_JVM_EXTERNAL_SHA,
+    url = "https://github.com/bazelbuild/rules_jvm_external/archive/%s.zip" % RULES_JVM_EXTERNAL_TAG,
+)
+
+load("@rules_jvm_external//:defs.bzl", "maven_install")
+
+maven_install(
+    artifacts = [
+        "org.apache.commons:commons-lang3:3.9"
+    ],
+    repositories = [
+        "https://repo1.maven.org/maven2",
+    ]
+)
+
+http_jar (
+    name = "apache-commons-lang",
+    url = "https://repo1.maven.org/maven2/org/apache/commons/commons-lang3/3.9/commons-lang3-3.9.jar"
+)
+

bazel/bazelapp/BUILD

@@ -0,0 +1,7 @@
+
+java_binary (
+    name = "BazelApp",
+    srcs = glob(["src/main/java/com/baeldung/*.java"]),
+    main_class = "com.baeldung.BazelApp",
+    deps = ["//bazelgreeting:greeter", "@maven//:org_apache_commons_commons_lang3"]
+)

bazel/bazelapp/pom.xml

@@ -0,0 +1,29 @@
+<?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>bazelapp</artifactId>
+    <name>bazelapp</name>
+	
+    <parent>
+        <artifactId>bazel</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.baeldung</groupId>
+            <artifactId>bazelgreeting</artifactId>
+            <version>1.0.0-SNAPSHOT</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>3.9</version>
+        </dependency>
+    </dependencies>
+
+
+</project>

bazel/bazelapp/src/main/java/com/baeldung/BazelApp.java

@@ -0,0 +1,15 @@
+package com.baeldung;
+
+import com.baeldung.Greetings;
+import org.apache.commons.lang3.StringUtils;
+
+public class BazelApp {
+
+    public static void main(String ... args) {
+        Greetings greetings = new Greetings();
+
+        System.out.println(greetings.greet("Bazel"));
+
+        System.out.println(StringUtils.lowerCase("Bazel"));
+    }
+}

bazel/bazelgreeting/BUILD

@@ -0,0 +1,6 @@
+
+java_library (
+    name = "greeter",
+    srcs = glob(["src/main/java/com/baeldung/*.java"]),
+    visibility = ["//bazelapp:__pkg__"]
+)

bazel/bazelgreeting/pom.xml

@@ -0,0 +1,16 @@
+<?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>bazelgreeting</artifactId>
+    <name>bazelgreeting</name>
+	
+    <parent>
+        <artifactId>bazel</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+
+</project>

bazel/bazelgreeting/src/main/java/com/baeldung/Greetings.java

@@ -0,0 +1,8 @@
+package com.baeldung;
+
+public class Greetings {
+
+    public String greet(String name) {
+        return "Hello ".concat(name);
+    }
+}

bazel/pom.xml

@@ -0,0 +1,22 @@
+<?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>bazel</artifactId>
+    <packaging>pom</packaging>
+    <name>bazel</name>
+	
+    <parent>
+        <artifactId>parent-modules</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+	
+    <modules>
+        <module>bazelgreeting</module>
+        <module>bazelapp</module>
+    </modules>
+
+
+</project>

core-groovy-2/pom.xml

@@ -48,6 +48,11 @@
             <version>${spock-core.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.github.groovy-wslite</groupId>
+            <artifactId>groovy-wslite</artifactId>
+            <version>${groovy-wslite.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -175,6 +180,7 @@
         <junit.platform.version>1.0.0</junit.platform.version>
         <hsqldb.version>2.4.0</hsqldb.version>
         <spock-core.version>1.1-groovy-2.4</spock-core.version>
+        <groovy-wslite.version>1.1.3</groovy-wslite.version>        
         <maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
         <logback.version>1.2.3</logback.version>
         <groovy.version>2.5.7</groovy.version>

core-groovy-2/src/test/groovy/com/baeldung/webservice/WebserviceUnitTest.groovy

@@ -0,0 +1,152 @@
+package com.baeldung.webservice
+
+import groovy.json.JsonSlurper
+import wslite.rest.ContentType
+import wslite.rest.RESTClient
+import wslite.rest.RESTClientException
+import wslite.soap.SOAPClient
+import wslite.soap.SOAPMessageBuilder
+import wslite.http.auth.HTTPBasicAuthorization
+import org.junit.Test
+
+class WebserviceUnitTest extends GroovyTestCase {
+
+    JsonSlurper jsonSlurper = new JsonSlurper()
+
+    static RESTClient client = new RESTClient("https://postman-echo.com")
+    
+    static {
+        client.defaultAcceptHeader = ContentType.JSON
+        client.httpClient.sslTrustAllCerts = true
+    }
+
+    void test_whenSendingGet_thenRespose200() {
+        def postmanGet = new URL('https://postman-echo.com/get')
+        def getConnection = postmanGet.openConnection()
+        getConnection.requestMethod = 'GET'
+        assert getConnection.responseCode == 200
+        if (getConnection.responseCode == 200) {
+            assert jsonSlurper.parseText(getConnection.content.text)?.headers?.host == "postman-echo.com"
+        }
+    }
+
+    void test_whenSendingPost_thenRespose200() {
+        def postmanPost = new URL('https://postman-echo.com/post')
+        def query = "q=This is post request form parameter."
+        def postConnection = postmanPost.openConnection()
+        postConnection.requestMethod = 'POST'
+        assert postConnection.responseCode == 200
+    }
+    
+    void test_whenSendingPostWithParams_thenRespose200() {
+        def postmanPost = new URL('https://postman-echo.com/post')
+        def form = "param1=This is request parameter."
+        def postConnection = postmanPost.openConnection()
+        postConnection.requestMethod = 'POST'
+        postConnection.doOutput = true
+        def text
+        postConnection.with {
+            outputStream.withWriter { outputStreamWriter ->
+                outputStreamWriter << form
+            }
+            text = content.text
+        }
+        assert postConnection.responseCode == 200
+        assert jsonSlurper.parseText(text)?.json.param1 == "This is request parameter."
+    }
+    
+    void test_whenReadingRSS_thenReceiveFeed() {
+        def rssFeed = new XmlParser().parse("https://news.google.com/rss?hl=en-US&gl=US&ceid=US:en")
+        def stories = []
+        (0..4).each {
+            def item = rssFeed.channel.item.get(it)
+            stories << item.title.text()
+        }
+        assert stories.size() == 5
+    }
+
+    void test_whenReadingAtom_thenReceiveFeed() {
+        def atomFeed = new XmlParser().parse("https://news.google.com/atom?hl=en-US&gl=US&ceid=US:en")
+        def stories = []
+        (0..4).each {
+            def entry = atomFeed.entry.get(it)
+            stories << entry.title.text()
+        }
+        assert stories.size() == 5
+    }
+    
+    void test_whenConsumingSoap_thenReceiveResponse() {
+        def url = "http://www.dataaccess.com/webservicesserver/numberconversion.wso"
+        def soapClient = new SOAPClient(url)
+        def message = new SOAPMessageBuilder().build({
+            body {
+                NumberToWords(xmlns: "http://www.dataaccess.com/webservicesserver/") {
+                    ubiNum(1234)
+                }
+            }
+        })
+        def response = soapClient.send(message.toString());
+        def words = response.NumberToWordsResponse
+        assert words == "one thousand two hundred and thirty four "
+    }
+
+    void test_whenConsumingRestGet_thenReceiveResponse() {
+        def path = "/get"
+        def response
+        try {
+            response = client.get(path: path)
+            assert response.statusCode == 200
+            assert response.json?.headers?.host == "postman-echo.com"
+        } catch (RESTClientException e) {
+            assert e?.response?.statusCode != 200
+        }
+    }
+
+    void test_whenConsumingRestPost_thenReceiveResponse() {
+        def path = "/post"
+        def params = ["foo":1,"bar":2]
+        def response
+        try {
+            response = client.post(path: path) {
+                type ContentType.JSON
+                json params
+            }
+            assert response.json?.data == params
+        } catch (RESTClientException e) {
+            e.printStackTrace()
+            assert e?.response?.statusCode != 200
+        }
+    }
+
+    void test_whenBasicAuthentication_thenReceive200() {
+        def path = "/basic-auth"
+        def response
+        try {
+            client.authorization = new HTTPBasicAuthorization("postman", "password")
+            response = client.get(path: path)
+            assert response.statusCode == 200
+            assert response.json?.authenticated == true
+        } catch (RESTClientException e) {
+            e.printStackTrace()
+            assert e?.response?.statusCode != 200
+        }
+    }
+
+    void test_whenOAuth_thenReceive200() {
+        RESTClient oAuthClient = new RESTClient("https://postman-echo.com")
+        oAuthClient.defaultAcceptHeader = ContentType.JSON
+        oAuthClient.httpClient.sslTrustAllCerts = true
+
+        def path = "/oauth1"
+        def params = [oauth_consumer_key: "RKCGzna7bv9YD57c", oauth_signature_method: "HMAC-SHA1", oauth_timestamp:1567089944, oauth_nonce: "URT7v4", oauth_version: 1.0, oauth_signature: 'RGgR/ktDmclkM0ISWaFzebtlO0A=']
+        def response
+        try {
+            response = oAuthClient.get(path: path, query: params)
+            assert response.statusCode == 200
+            assert response.statusMessage == "OK"
+            assert response.json.status == "pass"
+        } catch (RESTClientException e) {
+            assert e?.response?.statusCode != 200
+        }
+    }
+}

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

@@ -20,7 +20,6 @@
 - [Finding Min/Max in an Array with Java](http://www.baeldung.com/java-array-min-max)
 - [Internationalization and Localization in Java 8](http://www.baeldung.com/java-8-localization)
 - [Java Optional – orElse() vs orElseGet()](http://www.baeldung.com/java-optional-or-else-vs-or-else-get)
-- [Method Parameter Reflection in Java](http://www.baeldung.com/java-parameter-reflection)
 - [Java 8 Unsigned Arithmetic Support](http://www.baeldung.com/java-unsigned-arithmetic)
 - [Generalized Target-Type Inference in Java](http://www.baeldung.com/java-generalized-target-type-inference)
 - [Overriding System Time for Testing in Java](http://www.baeldung.com/java-override-system-time)

core-java-modules/core-java-8/pom.xml

@@ -134,16 +134,6 @@
         </resources>
 
         <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-                <version>${maven-compiler-plugin.version}</version>
-                <configuration>
-                    <source>1.8</source>
-                    <target>1.8</target>
-                    <compilerArgument>-parameters</compilerArgument>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
@@ -192,7 +182,6 @@
         <jmh-generator.version>1.19</jmh-generator.version>
         <spring-boot-maven-plugin.version>2.0.4.RELEASE</spring-boot-maven-plugin.version>
         <!-- plugins -->
-        <maven-compiler-plugin.version>3.8.0</maven-compiler-plugin.version>
         <maven-surefire-plugin.version>2.22.1</maven-surefire-plugin.version>
     </properties>
 </project>

core-java-modules/core-java-8/src/test/java/com/baeldung/java_8_features/groupingby/Java8GroupingByCollectorUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.java8;
+package com.baeldung.java_8_features.groupingby;
 
 import com.baeldung.java_8_features.groupingby.BlogPost;
 import com.baeldung.java_8_features.groupingby.BlogPostType;

core-java-modules/core-java-collections-array-list/src/main/java/com/baeldung/java/list/RemoveFromList.java

@@ -0,0 +1,40 @@
+package com.baeldung.java.list;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+public class RemoveFromList {
+
+        public static void main(String[] args) {
+                List<String> sports = new ArrayList<>();
+                sports.add("Football");
+                sports.add("Basketball");
+                sports.add("Baseball");
+                sports.add("Boxing");
+                sports.add("Cycling");
+
+                System.out.println("List before removing:  " + sports);
+
+                // Remove with index
+                sports.remove(1);
+
+                // Remove with an element
+                sports.remove("Baseball");
+
+                // Iterator remove method
+                Iterator<String> iterator = sports.iterator();
+                while (iterator.hasNext()) {
+                        if (iterator.next().equals("Boxing")) {
+                                iterator.remove();
+                                break;
+                        }
+                }
+
+                // ArrayList removeIf method (Java 8)
+                sports.removeIf(p -> p.equals("Cycling"));
+
+                System.out.println("List after removing:  " + sports);
+        }
+
+}

core-java-modules/core-java-collections-list-2/README.md

@@ -11,7 +11,3 @@
 - [Ways to Iterate Over a List in Java](https://www.baeldung.com/java-iterate-list)
 - [Flattening Nested Collections in Java](http://www.baeldung.com/java-flatten-nested-collections)
 - [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)
-- [Determine If All Elements Are the Same in a Java List](https://www.baeldung.com/java-list-all-equal)
-- [List of Primitive Integer Values in Java](https://www.baeldung.com/java-list-primitive-int)
-- [Performance Comparison of Primitive Lists in Java](https://www.baeldung.com/java-list-primitive-performance)
-- [Filtering a Java Collection by a List](https://www.baeldung.com/java-filter-collection-by-list)

core-java-modules/core-java-collections-list-2/pom.xml

@@ -36,41 +36,11 @@
             <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
-
-        <dependency>
-            <groupId>net.sf.trove4j</groupId>
-            <artifactId>trove4j</artifactId>
-            <version>${trove4j.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>it.unimi.dsi</groupId>
-            <artifactId>fastutil</artifactId>
-            <version>${fastutil.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>colt</groupId>
-            <artifactId>colt</artifactId>
-            <version>${colt.version}</version>
-        </dependency>
-
-        <dependency>
-            <groupId>org.openjdk.jmh</groupId>
-            <artifactId>jmh-core</artifactId>
-            <version>${jmh-core.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.openjdk.jmh</groupId>
-            <artifactId>jmh-generator-annprocess</artifactId>
-            <version>${jmh-core.version}</version>
-        </dependency>
     </dependencies>
 
     <properties>
         <commons-collections4.version>4.1</commons-collections4.version>
         <commons-lang3.version>3.8.1</commons-lang3.version>
         <assertj.version>3.11.1</assertj.version>
-		<trove4j.version>3.0.2</trove4j.version>
-		<fastutil.version>8.1.0</fastutil.version>
-		<colt.version>1.2.0</colt.version>
     </properties>
 </project>

core-java-modules/core-java-collections-list-3/README.md

@@ -0,0 +1,11 @@
+=========
+
+## Core Java Collections List Cookbooks and Examples
+
+### Relevant Articles: 
+- [Collections.emptyList() vs. New List Instance](https://www.baeldung.com/java-collections-emptylist-new-list)
+- [Copy a List to Another List in Java](http://www.baeldung.com/java-copy-list-to-another)
+- [Determine If All Elements Are the Same in a Java List](https://www.baeldung.com/java-list-all-equal)
+- [List of Primitive Integer Values in Java](https://www.baeldung.com/java-list-primitive-int)
+- [Performance Comparison of Primitive Lists in Java](https://www.baeldung.com/java-list-primitive-performance)
+- [Filtering a Java Collection by a List](https://www.baeldung.com/java-filter-collection-by-list)

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

@@ -0,0 +1,76 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-collections-list-3</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-collections-list-3</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <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.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>net.sf.trove4j</groupId>
+            <artifactId>trove4j</artifactId>
+            <version>${trove4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>it.unimi.dsi</groupId>
+            <artifactId>fastutil</artifactId>
+            <version>${fastutil.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>colt</groupId>
+            <artifactId>colt</artifactId>
+            <version>${colt.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <commons-lang3.version>3.8.1</commons-lang3.version>
+        <assertj.version>3.11.1</assertj.version>
+		<trove4j.version>3.0.2</trove4j.version>
+		<fastutil.version>8.1.0</fastutil.version>
+		<colt.version>1.2.0</colt.version>
+    </properties>
+</project>

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

@@ -10,7 +10,5 @@
 - [Iterating Backward Through a List](http://www.baeldung.com/java-list-iterate-backwards)
 - [Remove the First Element from a List](http://www.baeldung.com/java-remove-first-element-from-list)
 - [How to Find an Element in a List with Java](http://www.baeldung.com/find-list-element-java)
-- [Copy a List to Another List in Java](http://www.baeldung.com/java-copy-list-to-another)
 - [Finding Max/Min of a List or Collection](http://www.baeldung.com/java-collection-min-max)
-- [Collections.emptyList() vs. New List Instance](https://www.baeldung.com/java-collections-emptylist-new-list)
 - [Remove All Occurrences of a Specific Value from a List](https://www.baeldung.com/java-remove-value-from-list)

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGenerator.java

@@ -1,11 +1,12 @@
 package com.baeldung.concurrent.mutex;
 
 public class SequenceGenerator {
+
     private int currentValue = 0;
 
-    public int getNextSequence() throws InterruptedException {
+    public int getNextSequence() {
         currentValue = currentValue + 1;
-        Thread.sleep(500);
         return currentValue;
     }
+
 }

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingMonitor.java

@@ -4,15 +4,16 @@ import com.google.common.util.concurrent.Monitor;
 
 public class SequenceGeneratorUsingMonitor extends SequenceGenerator {
 
-    private Monitor monitor = new Monitor();
+    private Monitor mutex = new Monitor();
 
     @Override
-    public int getNextSequence() throws InterruptedException {
+    public int getNextSequence() {
-        monitor.enter();
+        mutex.enter();
         try {
             return super.getNextSequence();
         } finally {
-            monitor.leave();
+            mutex.leave();
         }
     }
+
 }

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingReentrantLock.java

@@ -7,7 +7,7 @@ public class SequenceGeneratorUsingReentrantLock extends SequenceGenerator {
     private ReentrantLock mutex = new ReentrantLock();
 
     @Override
-    public int getNextSequence() throws InterruptedException {
+    public int getNextSequence() {
         try {
             mutex.lock();
             return super.getNextSequence();
@@ -15,4 +15,5 @@ public class SequenceGeneratorUsingReentrantLock extends SequenceGenerator {
             mutex.unlock();
         }
     }
+
 }

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSemaphore.java

@@ -7,12 +7,15 @@ public class SequenceGeneratorUsingSemaphore extends SequenceGenerator {
     private Semaphore mutex = new Semaphore(1);
 
     @Override
-    public int getNextSequence() throws InterruptedException {
+    public int getNextSequence() {
         try {
             mutex.acquire();
             return super.getNextSequence();
+        } catch (InterruptedException e) {
+            throw new RuntimeException("Exception in critical section.", e);
         } finally {
             mutex.release();
         }
     }
+
 }

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSynchronizedBlock.java

@@ -2,9 +2,11 @@ package com.baeldung.concurrent.mutex;
 
 public class SequenceGeneratorUsingSynchronizedBlock extends SequenceGenerator {
 
+    private Object mutex = new Object();
+
     @Override
-    public int getNextSequence() throws InterruptedException {
+    public int getNextSequence() {
-        synchronized (this) {
+        synchronized (mutex) {
             return super.getNextSequence();
         }
     }

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSynchronizedMethod.java

@@ -3,7 +3,7 @@ package com.baeldung.concurrent.mutex;
 public class SequenceGeneratorUsingSynchronizedMethod extends SequenceGenerator {
 
     @Override
-    public synchronized int getNextSequence() throws InterruptedException {
+    public synchronized int getNextSequence() {
         return super.getNextSequence();
     }
 

core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/concurrent/executorservice/Java8ExecutorServiceIntegrationTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.java8;
+package com.baeldung.concurrent.executorservice;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;

core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/concurrent/mutex/MutexUnitTest.java

@@ -1,7 +1,7 @@
 package com.baeldung.concurrent.mutex;
 
 import java.util.ArrayList;
-import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
@@ -12,59 +12,58 @@ import java.util.concurrent.TimeUnit;
 import org.junit.Assert;
 import org.junit.Test;
 
-import com.baeldung.concurrent.mutex.SequenceGenerator;
-import com.baeldung.concurrent.mutex.SequenceGeneratorUsingMonitor;
-import com.baeldung.concurrent.mutex.SequenceGeneratorUsingReentrantLock;
-import com.baeldung.concurrent.mutex.SequenceGeneratorUsingSemaphore;
-import com.baeldung.concurrent.mutex.SequenceGeneratorUsingSynchronizedBlock;
-import com.baeldung.concurrent.mutex.SequenceGeneratorUsingSynchronizedMethod;
-
 public class MutexUnitTest {
 
-    private final int RANGE = 30;
+    // @Test
-
+    // This test verifies the race condition use case, it may pass or fail based on execution environment
-    @Test
+    // Uncomment @Test to run it
     public void givenUnsafeSequenceGenerator_whenRaceCondition_thenUnexpectedBehavior() throws Exception {
-        Set<Integer> uniqueSequences = getASetOFUniqueSequences(new SequenceGenerator());
+        int count = 1000;
-        Assert.assertNotEquals(RANGE, uniqueSequences.size());
+        Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGenerator(), count);
+        Assert.assertNotEquals(count, uniqueSequences.size());
     }
 
     @Test
     public void givenSequenceGeneratorUsingSynchronizedMethod_whenRaceCondition_thenSuccess() throws Exception {
-        Set<Integer> uniqueSequences = getASetOFUniqueSequences(new SequenceGeneratorUsingSynchronizedMethod());
+        int count = 1000;
-        Assert.assertEquals(RANGE, uniqueSequences.size());
+        Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingSynchronizedMethod(), count);
+        Assert.assertEquals(count, uniqueSequences.size());
     }
 
     @Test
     public void givenSequenceGeneratorUsingSynchronizedBlock_whenRaceCondition_thenSuccess() throws Exception {
-        Set<Integer> uniqueSequences = getASetOFUniqueSequences(new SequenceGeneratorUsingSynchronizedBlock());
+        int count = 1000;
-        Assert.assertEquals(RANGE, uniqueSequences.size());
+        Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingSynchronizedBlock(), count);
+        Assert.assertEquals(count, uniqueSequences.size());
     }
 
     @Test
     public void givenSequenceGeneratorUsingReentrantLock_whenRaceCondition_thenSuccess() throws Exception {
-        Set<Integer> uniqueSequences = getASetOFUniqueSequences(new SequenceGeneratorUsingReentrantLock());
+        int count = 1000;
-        Assert.assertEquals(RANGE, uniqueSequences.size());
+        Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingReentrantLock(), count);
+        Assert.assertEquals(count, uniqueSequences.size());
     }
 
     @Test
     public void givenSequenceGeneratorUsingSemaphore_whenRaceCondition_thenSuccess() throws Exception {
-        Set<Integer> uniqueSequences = getASetOFUniqueSequences(new SequenceGeneratorUsingSemaphore());
+        int count = 1000;
-        Assert.assertEquals(RANGE, uniqueSequences.size());
+        Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingSemaphore(), count);
+        Assert.assertEquals(count, uniqueSequences.size());
     }
 
     @Test
     public void givenSequenceGeneratorUsingMonitor_whenRaceCondition_thenSuccess() throws Exception {
-        Set<Integer> uniqueSequences = getASetOFUniqueSequences(new SequenceGeneratorUsingMonitor());
+        int count = 1000;
-        Assert.assertEquals(RANGE, uniqueSequences.size());
+        Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingMonitor(), count);
+        Assert.assertEquals(count, uniqueSequences.size());
     }
 
-    private Set<Integer> getASetOFUniqueSequences(SequenceGenerator generator) throws Exception {
+    private Set<Integer> getUniqueSequences(SequenceGenerator generator, int count) throws Exception {
         ExecutorService executor = Executors.newFixedThreadPool(3);
-        Set<Integer> uniqueSequences = new HashSet<>();
+        Set<Integer> uniqueSequences = new LinkedHashSet<>();
         List<Future<Integer>> futures = new ArrayList<>();
 
-        for (int i = 0; i < RANGE; i++) {
+        for (int i = 0; i < count; i++) {
             futures.add(executor.submit(generator::getNextSequence));
         }
 
@@ -72,7 +71,7 @@ public class MutexUnitTest {
             uniqueSequences.add(future.get());
         }
 
-        executor.awaitTermination(15, TimeUnit.SECONDS);
+        executor.awaitTermination(1, TimeUnit.SECONDS);
         executor.shutdown();
 
         return uniqueSequences;

core-java-modules/core-java-exceptions/src/main/java/com/baeldung/exceptions/CheckedUncheckedExceptions.java

@@ -0,0 +1,43 @@
+package com.baeldung.exceptions;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+
+public class CheckedUncheckedExceptions {
+    public static void checkedExceptionWithThrows() throws FileNotFoundException {
+        File file = new File("not_existing_file.txt");
+        FileInputStream stream = new FileInputStream(file);
+    }
+
+    public static void checkedExceptionWithTryCatch() {
+        File file = new File("not_existing_file.txt");
+        try {
+            FileInputStream stream = new FileInputStream(file);
+        } catch (FileNotFoundException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static int divideByZero() {
+        int numerator = 1;
+        int denominator = 0;
+        return numerator / denominator;
+    }
+
+    public static void checkFile(String fileName) throws IncorrectFileNameException {
+        if (fileName == null || fileName.isEmpty()) {
+            throw new NullOrEmptyException("The filename is null.");
+        }
+        if (!isCorrectFileName(fileName)) {
+            throw new IncorrectFileNameException("Incorrect filename : " + fileName);
+        }
+    }
+
+    private static boolean isCorrectFileName(String fileName) {
+        if (fileName.equals("wrongFileName.txt"))
+            return false;
+        else
+            return true;
+    }
+}

core-java-modules/core-java-exceptions/src/main/java/com/baeldung/exceptions/IncorrectFileNameException.java

@@ -0,0 +1,13 @@
+package com.baeldung.exceptions;
+
+public class IncorrectFileNameException extends Exception {
+    private static final long serialVersionUID = 1L;
+
+    public IncorrectFileNameException(String errorMessage) {
+        super(errorMessage);
+    }
+
+    public IncorrectFileNameException(String errorMessage, Throwable thr) {
+        super(errorMessage, thr);
+    }
+}

core-java-modules/core-java-exceptions/src/main/java/com/baeldung/exceptions/NullOrEmptyException.java

@@ -0,0 +1,14 @@
+package com.baeldung.exceptions;
+
+public class NullOrEmptyException extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+    public NullOrEmptyException(String errorMessage) {
+        super(errorMessage);
+    }
+
+    public NullOrEmptyException(String errorMessage, Throwable thr) {
+        super(errorMessage, thr);
+    }
+}

core-java-modules/core-java-exceptions/src/test/java/com/baeldung/exceptions/CheckedUncheckedExceptionsUnitTest.java

@@ -0,0 +1,55 @@
+package com.baeldung.exceptions;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.FileNotFoundException;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests the {@link CheckedUncheckedExceptions}.
+ */
+public class CheckedUncheckedExceptionsUnitTest {
+
+    @Test
+    public void whenFileNotExist_thenThrowException() {
+        assertThrows(FileNotFoundException.class, () -> {
+            CheckedUncheckedExceptions.checkedExceptionWithThrows();
+        });
+    }
+
+    @Test
+    public void whenTryCatchExcetpion_thenSuccess() {
+        try {
+            CheckedUncheckedExceptions.checkedExceptionWithTryCatch();
+        } catch (Exception e) {
+            Assertions.fail(e.getMessage());
+        }
+    }
+
+    @Test
+    public void whenDivideByZero_thenThrowException() {
+        assertThrows(ArithmeticException.class, () -> {
+            CheckedUncheckedExceptions.divideByZero();
+        });
+    }
+
+    @Test
+    public void whenInvalidFile_thenThrowException() {
+
+        assertThrows(IncorrectFileNameException.class, () -> {
+            CheckedUncheckedExceptions.checkFile("wrongFileName.txt");
+        });
+    }
+
+    @Test
+    public void whenNullOrEmptyFile_thenThrowException() {
+        assertThrows(NullOrEmptyException.class, () -> {
+            CheckedUncheckedExceptions.checkFile(null);
+        });
+        assertThrows(NullOrEmptyException.class, () -> {
+            CheckedUncheckedExceptions.checkFile("");
+        });
+    }
+}

core-java-modules/core-java-io-2/.gitignore

@@ -0,0 +1,3 @@
+# Intellij
+.idea/
+*.iml

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

@@ -0,0 +1,279 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-io-2</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-io-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <!-- utils -->
+        <dependency>
+            <groupId>net.sourceforge.collections</groupId>
+            <artifactId>collections-generic</artifactId>
+            <version>${collections-generic.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${commons-math3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.decimal4j</groupId>
+            <artifactId>decimal4j</artifactId>
+            <version>${decimal4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.bouncycastle</groupId>
+            <artifactId>bcprov-jdk15on</artifactId>
+            <version>${bouncycastle.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.unix4j</groupId>
+            <artifactId>unix4j-command</artifactId>
+            <version>${unix4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.googlecode.grep4j</groupId>
+            <artifactId>grep4j</artifactId>
+            <version>${grep4j.version}</version>
+        </dependency>
+        <!-- web -->
+        <!-- marshalling -->
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <!-- logging -->
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
+            <groupId>org.slf4j</groupId>
+            <artifactId>log4j-over-slf4j</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.jayway.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>${avaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.javamoney</groupId>
+            <artifactId>moneta</artifactId>
+            <version>${moneta.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.owasp.esapi</groupId>
+            <artifactId>esapi</artifactId>
+            <version>${esapi.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.sun.messaging.mq</groupId>
+            <artifactId>fscontext</artifactId>
+            <version>${fscontext.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.codepoetics</groupId>
+            <artifactId>protonpack</artifactId>
+            <version>${protonpack.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>one.util</groupId>
+            <artifactId>streamex</artifactId>
+            <version>${streamex.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.vavr</groupId>
+            <artifactId>vavr</artifactId>
+            <version>${vavr.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh-generator-annprocess.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.hsqldb</groupId>
+            <artifactId>hsqldb</artifactId>
+            <version>${hsqldb.version}</version>
+            <scope>runtime</scope>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.asynchttpclient/async-http-client -->
+        <dependency>
+            <groupId>org.asynchttpclient</groupId>
+            <artifactId>async-http-client</artifactId>
+            <version>${async-http-client.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.opencsv</groupId>
+            <artifactId>opencsv</artifactId>
+            <version>${opencsv.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- Mime Type Resolution Libraries -->
+        <dependency>
+            <groupId>org.apache.tika</groupId>
+            <artifactId>tika-core</artifactId>
+            <version>${tika.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>net.sf.jmimemagic</groupId>
+            <artifactId>jmimemagic</artifactId>
+            <version>${jmime-magic.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-io-2</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+        <plugins>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <version>${exec-maven-plugin.version}</version>
+                <configuration>
+                    <executable>java</executable>
+                    <mainClass>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</mainClass>
+                    <arguments>
+                        <argument>-Xmx300m</argument>
+                        <argument>-XX:+UseParallelGC</argument>
+                        <argument>-classpath</argument>
+                        <classpath />
+                        <argument>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</argument>
+                    </arguments>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+                <version>${maven-javadoc-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <profiles>
+        <profile>
+            <id>integration</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>exec-maven-plugin</artifactId>
+
+                        <executions>
+                            <execution>
+                                <id>run-benchmarks</id>
+                                <!-- <phase>integration-test</phase> -->
+                                <phase>none</phase>
+                                <goals>
+                                    <goal>exec</goal>
+                                </goals>
+                                <configuration>
+                                    <classpathScope>test</classpathScope>
+                                    <executable>java</executable>
+                                    <arguments>
+                                        <argument>-classpath</argument>
+                                        <classpath />
+                                        <argument>org.openjdk.jmh.Main</argument>
+                                        <argument>.*</argument>
+                                    </arguments>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
+    <properties>
+
+        <!-- util -->
+        <bouncycastle.version>1.55</bouncycastle.version>
+        <commons-codec.version>1.10</commons-codec.version>
+        <commons-math3.version>3.6.1</commons-math3.version>
+        <decimal4j.version>1.0.3</decimal4j.version>
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <collections-generic.version>4.01</collections-generic.version>
+        <unix4j.version>0.4</unix4j.version>
+        <grep4j.version>1.8.7</grep4j.version>
+        <fscontext.version>4.6-b01</fscontext.version>
+        <protonpack.version>1.13</protonpack.version>
+        <streamex.version>0.6.5</streamex.version>
+        <vavr.version>0.9.0</vavr.version>
+        <opencsv.version>4.1</opencsv.version>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <avaitility.version>1.7.0</avaitility.version>
+
+        <!-- maven plugins -->
+        <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
+        <hsqldb.version>2.4.0</hsqldb.version>
+        <esapi.version>2.1.0.1</esapi.version>
+        <jmh-generator-annprocess.version>1.19</jmh-generator-annprocess.version>
+        <async-http-client.version>2.4.5</async-http-client.version>
+        <!-- Mime Type Libraries -->
+        <tika.version>1.18</tika.version>
+        <jmime-magic.version>0.1.5</jmime-magic.version>
+    </properties>
+
+</project>

core-java-modules/core-java-io-2/src/main/java/com/baeldung/filereader/FileReaderExample.java

@@ -0,0 +1,57 @@
+package com.baeldung.filereader;
+
+import java.io.*;
+
+public class FileReaderExample {
+
+    public static String readAllCharactersOneByOne(Reader reader) throws IOException {
+        StringBuilder content = new StringBuilder();
+        int nextChar;
+        while ((nextChar = reader.read()) != -1) {
+            content.append((char) nextChar);
+        }
+        return String.valueOf(content);
+    }
+
+    public static String readMultipleCharacters(Reader reader, int length) throws IOException {
+        char[] buffer = new char[length];
+        int charactersRead = reader.read(buffer, 0, length);
+
+
+        if (charactersRead != -1) {
+            return new String(buffer, 0, charactersRead);
+        } else {
+            return "";
+        }
+    }
+
+    public static String readFile(String path) {
+        FileReader fileReader = null;
+        try {
+            fileReader = new FileReader(path);
+            return readAllCharactersOneByOne(fileReader);
+        } catch (IOException e) {
+            e.printStackTrace();
+        } finally {
+            if (fileReader != null) {
+                try {
+                    fileReader.close();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
+        }
+        return null;
+    }
+
+    public static String readFileUsingTryWithResources(String path) {
+        try (FileReader fileReader = new FileReader(path)) {
+            return readAllCharactersOneByOne(fileReader);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+
+}

core-java-modules/core-java-io-2/src/test/java/com/baeldung/filereader/FileReaderExampleUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.filereader;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.FileReader;
+import java.io.IOException;
+
+public class FileReaderExampleUnitTest {
+
+
+    private static final String FILE_PATH = "src/test/resources/HelloWorld.txt";
+
+
+    @Test
+    public void givenFileReader_whenReadAllCharacters_thenReturnsContent() throws IOException {
+        String expectedText = "Hello, World!";
+        File file = new File(FILE_PATH);
+        try (FileReader fileReader = new FileReader(file)) {
+            String content = FileReaderExample.readAllCharactersOneByOne(fileReader);
+            Assert.assertEquals(expectedText, content);
+        }
+    }
+
+    @Test
+    public void givenFileReader_whenReadMultipleCharacters_thenReturnsContent() throws IOException {
+        String expectedText = "Hello";
+        File file = new File(FILE_PATH);
+        try (FileReader fileReader = new FileReader(file)) {
+            String content = FileReaderExample.readMultipleCharacters(fileReader, 5);
+            Assert.assertEquals(expectedText, content);
+        }
+    }
+
+    @Test
+    public void whenReadFile_thenReturnsContent() {
+        String expectedText = "Hello, World!";
+        String content = FileReaderExample.readFile(FILE_PATH);
+        Assert.assertEquals(expectedText, content);
+    }
+
+    @Test
+    public void whenReadFileUsingTryWithResources_thenReturnsContent() {
+        String expectedText = "Hello, World!";
+        String content = FileReaderExample.readFileUsingTryWithResources(FILE_PATH);
+        Assert.assertEquals(expectedText, content);
+    }
+
+}

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

@@ -0,0 +1 @@
+Hello, World!

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

@@ -207,6 +207,21 @@
                     <target>${maven.compiler.target}</target>
                 </configuration>
             </plugin>
+            
+            <plugin>
+                <!-- Build an executable JAR -->
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-jar-plugin</artifactId>
+                <version>${maven-jar-plugin.version}</version>
+                <configuration>
+                    <archive>
+                        <manifest>
+                            <addClasspath>true</addClasspath>
+                            <mainClass>com.baeldung.resource.MyResourceLoader</mainClass>
+                        </manifest>
+                    </archive>
+                </configuration>
+            </plugin>
         </plugins>
     </build>
 
@@ -274,6 +289,8 @@
         <!-- Mime Type Libraries -->
         <tika.version>1.18</tika.version>
         <jmime-magic.version>0.1.5</jmime-magic.version>
+        <maven-jar-plugin.version>3.1.0</maven-jar-plugin.version>
+
     </properties>
 
 </project>

core-java-modules/core-java-io/src/main/java/com/baeldung/resource/MyResourceLoader.java

@@ -0,0 +1,42 @@
+package com.baeldung.resource;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.stream.Collectors;
+
+public class MyResourceLoader {
+
+    private void loadFileWithReader() throws IOException {
+
+        try (FileReader fileReader = new FileReader("src/main/resources/input.txt");
+             BufferedReader reader = new BufferedReader(fileReader)) {
+            String contents = reader.lines()
+                .collect(Collectors.joining(System.lineSeparator()));
+            System.out.println(contents);
+        }
+
+    }
+
+    private void loadFileAsResource() throws IOException {
+
+        try (InputStream inputStream = getClass().getResourceAsStream("/input.txt");
+             BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream))) {
+            String contents = reader.lines()
+                .collect(Collectors.joining(System.lineSeparator()));
+            System.out.println(contents);
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+
+        MyResourceLoader resourceLoader = new MyResourceLoader();
+
+        resourceLoader.loadFileAsResource();
+        resourceLoader.loadFileWithReader();
+
+    }
+
+}

core-java-modules/core-java-io/src/test/java/org/baeldung/writetofile/JavaWriteToFileUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.io;
+package org.baeldung.writetofile;
 
 import static org.junit.Assert.assertEquals;
 

core-java-modules/core-java-jndi/pom.xml

@@ -7,6 +7,7 @@
     <groupId>com.baeldung.jndi</groupId>
     <artifactId>core-java-jndi</artifactId>
     <version>1.0-SNAPSHOT</version>
+    <name>core-java-jndi</name>
 
     <parent>
         <groupId>com.baeldung</groupId>

core-java-modules/core-java-jvm/src/main/java/com/baeldung/systemgc/DemoApplication.java

@@ -0,0 +1,33 @@
+package com.baeldung.systemgc;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Scanner;
+
+import static java.util.UUID.randomUUID;
+
+public class DemoApplication {
+
+    private static final Map<String, String> cache = new HashMap<String, String>();
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        while (scanner.hasNext()) {
+            final String next = scanner.next();
+            if ("fill".equals(next)) {
+                for (int i = 0; i < 1000000; i++) {
+                    cache.put(randomUUID().toString(), randomUUID().toString());
+                }
+            } else if ("invalidate".equals(next)) {
+                cache.clear();
+            } else if ("gc".equals(next)) {
+                System.gc();
+            } else if ("exit".equals(next)) {
+                System.exit(0);
+            } else {
+                System.out.println("unknown");
+            }
+        }
+    }
+}

core-java-modules/core-java-lambdas/pom.xml

@@ -5,7 +5,7 @@
   <modelVersion>4.0.0</modelVersion>
   <artifactId>core-java-lambdas</artifactId>
   <version>0.1.0-SNAPSHOT</version>
-  <name>core-java</name>
+  <name>core-java-lambdas</name>
   <packaging>jar</packaging>
 
   <parent>

core-java-modules/core-java-lang-2/.gitignore

@@ -0,0 +1,25 @@
+*.class
+
+0.*
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+.resourceCache
+
+# Packaged files #
+*.jar
+*.war
+*.ear
+
+# Files generated by integration tests
+backup-pom.xml
+/bin/
+/temp
+
+#IntelliJ specific
+.idea/
+*.iml

core-java-modules/core-java-lang-2/README.md

@@ -0,0 +1,5 @@
+=========
+
+## Core Java Lang Cookbooks and Examples
+
+### Relevant Articles: 

core-java-modules/core-java-lang-2/pom.xml

@@ -0,0 +1,33 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>core-java-lang-2</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-lang-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-lang-2</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+    </properties>
+
+</project>

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/commandlinearguments/CliExample.java

@@ -0,0 +1,12 @@
+package com.baeldung.commandlinearguments;
+
+public class CliExample {
+
+    public static void main(String[] args) {
+        System.out.println("Argument count: " + args.length);
+        for (int i = 0; i < args.length; i++) {
+            System.out.println("Argument " + i + ": " + args[i]);
+        }
+    }
+
+}

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/commandlinearguments/CliExampleWithVarargs.java

@@ -0,0 +1,12 @@
+package com.baeldung.commandlinearguments;
+
+public class CliExampleWithVarargs {
+
+    public static void main(String... args) {
+        System.out.println("Argument count: " + args.length);
+        for (int i = 0; i < args.length; i++) {
+            System.out.println("Argument " + i + ": " + args[i]);
+        }
+    }
+
+}

core-java-modules/core-java-lang-oop-2/pom.xml

@@ -14,6 +14,19 @@
         <relativePath>../../parent-java</relativePath>
     </parent>
 
+	<dependencies>
+		<dependency>
+			<groupId>com.h2database</groupId>
+			<artifactId>h2</artifactId>
+			<version>${h2.version}</version>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+    <properties>
+        <h2.version>1.4.199</h2.version>
+    </properties>
+    
     <build>
         <finalName>core-java-lang-oop-2</finalName>
         <resources>

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/ListOfThree.java

@@ -0,0 +1,31 @@
+package com.baeldung.accessmodifiers.publicmodifier;
+
+import java.util.AbstractList;
+import java.util.Arrays;
+
+public class ListOfThree<E> extends AbstractList<E> {
+
+    private static final int LENGTH = 3;
+    private Object[] elements;
+    
+    public ListOfThree(E[] data) {
+        if(data == null 
+            || data.length != LENGTH)
+            throw new IllegalArgumentException();
+        
+        this.elements = Arrays.copyOf(data, data.length); //shallow copy
+        
+    }
+    
+    @Override
+    @SuppressWarnings("unchecked")
+    public E get(int index) {      
+        return (E)elements[index];
+    }
+    
+    @Override
+    public int size() {
+        return LENGTH;
+    }
+
+}

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/SpecialCharacters.java

@@ -0,0 +1,7 @@
+package com.baeldung.accessmodifiers.publicmodifier;
+
+public class SpecialCharacters {
+
+    public static final String SLASH = "/";
+    
+}

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/Student.java

@@ -0,0 +1,67 @@
+package com.baeldung.accessmodifiers.publicmodifier;
+
+import java.math.BigDecimal;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.Date;
+
+public class Student {
+
+    private StudentGrade grade; //new data representation
+//    private int grade; //old data representation
+    private String name;   
+    private int age;
+    
+    public void setGrade(int grade) {        
+        this.grade = new StudentGrade(grade);
+    }
+
+    public int getGrade() {
+        return this.grade.getGrade().intValue(); //int is returned for backward compatibility
+    }
+    
+    public Connection getConnection() throws SQLException {
+        
+        final String URL = "jdbc:h2:~/test";
+        return DriverManager.getConnection(URL, "sa", "");
+
+    }
+        
+    public void setAge(int age) {
+        if (age < 0 || age > 150) {
+            throw new IllegalArgumentException();
+        }
+        
+        this.age = age;
+    }
+
+    public int getAge() {
+        return age;
+    }
+    
+    @Override
+    public String toString() {
+        return this.name;
+    }
+
+    private class StudentGrade {
+        private BigDecimal grade = BigDecimal.ZERO;
+        private Date updatedAt;
+        
+        public StudentGrade(int grade) {
+            this.grade = new BigDecimal(grade);
+            this.updatedAt = new Date();
+        }
+        
+        public BigDecimal getGrade() {
+            return grade;
+        }
+        
+        public Date getDate() {
+            return updatedAt;
+        }
+        
+     }
+    
+}

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/copyconstructor/Employee.java

@@ -0,0 +1,30 @@
+package com.baeldung.copyconstructor;
+
+import java.util.Date;
+
+public class Employee {
+
+    protected int id;
+    protected String name;
+    protected Date startDate;
+
+    public Employee(int id, String name, Date startDate) {
+        this.id = id;
+        this.name = name;
+        this.startDate = startDate;
+    }
+
+    public Employee(Employee employee) {
+        this.id = employee.id;
+        this.name = employee.name;
+        this.startDate = new Date(employee.startDate.getTime());
+    }
+
+    Date getStartDate() {
+        return startDate;
+    }
+
+    public Employee copy() {
+        return new Employee(this);
+    }
+}

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/copyconstructor/Manager.java

@@ -0,0 +1,31 @@
+package com.baeldung.copyconstructor;
+
+import java.util.Date;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class Manager extends Employee {
+
+    private List<Employee> directReports;
+
+    public Manager(int id, String name, Date startDate, List<Employee> directReports) {
+        super(id, name, startDate);
+        this.directReports = directReports;
+    }
+
+    public Manager(Manager manager) {
+        super(manager.id, manager.name, manager.startDate);
+        this.directReports = manager.directReports.stream()
+          .collect(Collectors.toList());
+    }
+
+    @Override
+    public Employee copy() {
+        return new Manager(this);
+    }
+
+    List<Employee> getDirectReport() {
+        return this.directReports;
+    }
+
+}

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/core/modifiers/Employee.java

@@ -0,0 +1,59 @@
+package com.baeldung.core.modifiers;
+
+public class Employee {
+
+    private String privateId;
+    private String name;
+    private boolean manager;
+
+    public Employee(String id, String name) {
+        setPrivateId(id);
+        setName(name);
+    }
+
+    private Employee(String id, String name, boolean managerAttribute) {
+        this.privateId = id;
+        this.name = name;
+        this.privateId = id + "_ID-MANAGER";
+    }
+
+    public void setPrivateId(String customId) {
+        if (customId.endsWith("_ID")) {
+            this.privateId = customId;
+        } else {
+            this.privateId = customId + "_ID";
+        }
+    }
+
+    public String getPrivateId() {
+        return privateId;
+    }
+
+    public boolean isManager() {
+        return manager;
+    }
+
+    public void elevateToManager() {
+        if ("Carl".equals(this.name)) {
+            setManager(true);
+        }
+    }
+
+    private void setManager(boolean manager) {
+        this.manager = manager;
+    }
+
+    
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+    
+    public static Employee buildManager(String id, String name) {
+        return new Employee(id, name, true);
+    }
+    
+}

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/core/modifiers/ExampleClass.java

@@ -0,0 +1,10 @@
+package com.baeldung.core.modifiers;
+
+public class ExampleClass {
+
+    public static void main(String[] args) {
+        Employee employee = new Employee("Bob","ABC123");
+        employee.setPrivateId("BCD234");
+        System.out.println(employee.getPrivateId());
+    }
+}

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/core/modifiers/PublicOuterClass.java

@@ -0,0 +1,16 @@
+package com.baeldung.core.modifiers;
+
+public class PublicOuterClass {
+
+    public PrivateInnerClass getInnerClassInstance() {
+        PrivateInnerClass myPrivateClassInstance = this.new PrivateInnerClass();
+        myPrivateClassInstance.id = "ID1";
+        myPrivateClassInstance.name = "Bob";
+        return myPrivateClassInstance;
+    }
+
+    private class PrivateInnerClass {
+        public String name;
+        public String id;
+    }
+}

core-java-modules/core-java-lang-oop-2/src/test/java/com/baeldung/accessmodifiers/PublicAccessModifierUnitTest.java

@@ -0,0 +1,93 @@
+package com.baeldung.accessmodifiers;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.api.TestInstance.Lifecycle;
+import com.baeldung.accessmodifiers.publicmodifier.ListOfThree;
+import com.baeldung.accessmodifiers.publicmodifier.Student;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import java.math.BigDecimal;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@TestInstance(Lifecycle.PER_CLASS)
+public class PublicAccessModifierUnitTest {
+
+    @Test
+    public void whenUsingBigDecimalIntValueMethod_correspondingIntIsReturned() {
+        assertEquals(0, new BigDecimal(0).intValue()); //instance member
+    }
+    
+    @Test
+    public void whenUsingIntegerMaxValueField_maxPossibleIntValueIsReturned() {
+        assertEquals(2147483647, Integer.MAX_VALUE); //static field
+    }
+    
+    @Test
+    public void whenChangingStudentInternalRepresentation_clientCodeWillNotBreak() {
+        
+        Student student = new Student();
+        student.setGrade(100);
+        
+        assertEquals(100, student.getGrade());
+    }
+    
+    @Test
+    public void whenUsingEntrySet_keyValuePairsAreReturned() {
+        
+        Map<String, String> mapObject = new HashMap<String, String>();
+        mapObject.put("name", "Alex");
+       
+        for(Map.Entry<String, String> entry : mapObject.entrySet()) {
+            assertEquals("name", entry.getKey());
+            assertEquals("Alex", entry.getValue());
+        }
+        
+    }
+    
+    @Test
+    public void whenUsingStringToLowerCase_stringTurnsToLowerCase() {
+        assertEquals("alex", "ALEX".toLowerCase());
+    }
+
+    @Test
+    public void whenParsingStringOne_parseIntReturns1() {
+        assertEquals(1, Integer.parseInt("1"));
+    }
+    
+    @Test
+    public void whenConnectingToH2_connectionInstanceIsReturned() throws SQLException {
+
+        final String url = "jdbc:h2:~/test";
+        Connection conn = DriverManager.getConnection(url, "sa", "");
+        assertNotNull(conn);
+    }
+
+    @Test
+    public void whenCreatingCustomList_concreteAndInheritedMethodsWork() {
+
+        String[] dataSet1 = new String[] {"zero", "one", "two"};
+        
+        List<String> list1 = new ListOfThree<String>(dataSet1);
+        
+        //our implemented methods
+        assertEquals("one", list1.get(1));
+        assertEquals(3, list1.size());
+
+        //inherited implementations
+        assertEquals(1, list1.indexOf("one"));
+        
+        String[] dataSet2 = new String[] {"two", "zero", "one"};
+        List<String> list2 = new ListOfThree<String>(dataSet2);
+        
+        assertTrue(list1.containsAll(list2));
+    }
+    
+}

core-java-modules/core-java-lang-oop-2/src/test/java/com/baeldung/copyconstructor/EmployeeUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.copyconstructor;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+import java.util.Date;
+
+import org.junit.Test;
+
+public class EmployeeUnitTest {
+    @Test
+    public void givenCopyConstructor_whenDeepCopy_thenDistinct() {
+        Date d1 = new Date(123);
+        Employee e1 = new Employee(1, "Baeldung", d1);
+        Employee e2 = new Employee(e1);
+        assertEquals(d1, e1.getStartDate());
+        assertEquals(d1, e2.getStartDate());
+
+        d1.setTime(456);
+        assertEquals(d1, e1.getStartDate());
+        assertNotEquals(d1, e2.getStartDate());
+    }
+
+    @Test
+    public void givenCopyMethod_whenCopy_thenDistinct() {
+        Date d1 = new Date(123);
+        Employee e1 = new Employee(1, "Baeldung", d1);
+        Employee e2 = e1.copy();
+        assertEquals(d1, e1.getStartDate());
+        assertEquals(d1, e2.getStartDate());
+
+        d1.setTime(456);
+        assertEquals(d1, e1.getStartDate());
+        assertNotEquals(d1, e2.getStartDate());
+    }
+}

core-java-modules/core-java-lang-oop-2/src/test/java/com/baeldung/copyconstructor/ManagerUnitTest.java

@@ -0,0 +1,67 @@
+package com.baeldung.copyconstructor;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+
+import org.junit.Test;
+
+public class ManagerUnitTest {
+    @Test
+    public void givenCopyConstructor_whenDeepCopy_thenDistinct() {
+        Date startDate = new Date(123);
+        Employee e1 = new Employee(1, "Baeldung", startDate);
+        Employee e2 = new Employee(e1);
+        List<Employee> directReports = new ArrayList<Employee>();
+        directReports.add(e1);
+        directReports.add(e2);
+
+        Manager m1 = new Manager(1, "Baeldung Manager", startDate, directReports);
+        Manager m2 = new Manager(m1);
+        List<Employee> directReports1 = m1.getDirectReport();
+        List<Employee> directReports2 = m2.getDirectReport();
+        assertEquals(directReports1.size(), directReports2.size());
+        assertArrayEquals(directReports1.toArray(), directReports2.toArray());
+
+        // clear m1's direct reports list. m2's list should not be affected
+        directReports.clear();
+        directReports1 = m1.getDirectReport();
+        directReports2 = m2.getDirectReport();
+        assertEquals(0, directReports1.size());
+        assertEquals(2, directReports2.size());
+
+    }
+
+    @Test
+    public void givenCopyMethod_whenCopy_thenDistinct() {
+        Date startDate = new Date(123);
+        Employee e1 = new Employee(1, "Baeldung", startDate);
+        Employee e2 = new Employee(e1);
+        List<Employee> directReports = new ArrayList<Employee>();
+        directReports.add(e1);
+        directReports.add(e2);
+
+        // a Manager object whose declaration type is Employee.
+        Employee source = new Manager(1, "Baeldung Manager", startDate, directReports);
+        Employee clone = source.copy();
+
+        // after copy, clone should be still a Manager object.
+        assertTrue(clone instanceof Manager);
+        List<Employee> directReports1 = ((Manager) source).getDirectReport();
+        List<Employee> directReports2 = ((Manager) clone).getDirectReport();
+        assertEquals(directReports1.size(), directReports2.size());
+        assertArrayEquals(directReports1.toArray(), directReports2.toArray());
+
+        // clear source's direct reports list. clone's list should not be affected
+        directReports.clear();
+        directReports1 = ((Manager) source).getDirectReport();
+        directReports2 = ((Manager) clone).getDirectReport();
+        assertEquals(0, directReports1.size());
+        assertEquals(2, directReports2.size());
+
+    }
+}

core-java-modules/core-java-lang-operators/src/main/java/com/baeldung/booleanoperators/Car.java

@@ -0,0 +1,36 @@
+package com.baeldung.booleanoperators;
+
+public class Car {
+
+    private boolean diesel;
+    private boolean manual;
+
+    public Car(boolean diesel, boolean manual) {
+        this.diesel = diesel;
+        this.manual = manual;
+    }
+
+    public boolean isDiesel() {
+        return diesel;
+    }
+
+    public boolean isManual() {
+        return manual;
+    }
+
+    static Car dieselAndManualCar() {
+        return new Car(true, true);
+    }
+
+    static Car dieselAndAutomaticCar() {
+        return new Car(true, false);
+    }
+
+    static Car oilAndManualCar() {
+        return new Car(false, true);
+    }
+
+    static Car oilAndAutomaticCar() {
+        return new Car(false, false);
+    }
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/booleanoperators/XorUnitTest.java

@@ -0,0 +1,69 @@
+package com.baeldung.booleanoperators;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class XorUnitTest {
+
+    @Test
+    void givenDieselManualCar_whenXorOldSchool_thenFalse() {
+        Car car = Car.dieselAndManualCar();
+        boolean dieselXorManual = (car.isDiesel() && !car.isManual()) || (!car.isDiesel() && car.isManual());
+        assertThat(dieselXorManual).isFalse();
+    }
+
+    @Test
+    void givenDieselAutomaticCar_whenXorOldSchool_thenTrue() {
+        Car car = Car.dieselAndAutomaticCar();
+        boolean dieselXorManual = (car.isDiesel() && !car.isManual()) || (!car.isDiesel() && car.isManual());
+        assertThat(dieselXorManual).isTrue();
+    }
+
+    @Test
+    void givenNonDieselManualCar_whenXorOldSchool_thenTrue() {
+        Car car = Car.oilAndManualCar();
+        boolean dieselXorManual = (car.isDiesel() && !car.isManual()) || (!car.isDiesel() && car.isManual());
+        assertThat(dieselXorManual).isTrue();
+    }
+
+    @Test
+    void givenNonDieselAutomaticCar_whenXorOldSchool_thenFalse() {
+        Car car = Car.oilAndAutomaticCar();
+        boolean dieselXorManual = (car.isDiesel() && !car.isManual()) || (!car.isDiesel() && car.isManual());
+        assertThat(dieselXorManual).isFalse();
+    }
+
+    @Test
+    void givenDieselManualCar_whenXor_thenFalse() {
+        Car car = Car.dieselAndManualCar();
+        boolean dieselXorManual = car.isDiesel() ^ car.isManual();
+        assertThat(dieselXorManual).isFalse();
+    }
+
+    @Test
+    void givenDieselAutomaticCar_whenXor_thenTrue() {
+        Car car = Car.dieselAndAutomaticCar();
+        boolean dieselXorManual = car.isDiesel() ^ car.isManual();
+        assertThat(dieselXorManual).isTrue();
+    }
+
+    @Test
+    void givenNonDieselManualCar_whenXor_thenTrue() {
+        Car car = Car.oilAndManualCar();
+        boolean dieselXorManual = car.isDiesel() ^ car.isManual();
+        assertThat(dieselXorManual).isTrue();
+    }
+
+    @Test
+    void givenNonDieselAutomaticCar_whenXor_thenFalse() {
+        Car car = Car.oilAndAutomaticCar();
+        boolean dieselXorManual = car.isDiesel() ^ car.isManual();
+        assertThat(dieselXorManual).isFalse();
+    }
+    
+    @Test
+    void givenNumbersOneAndThree_whenXor_thenTwo() {
+        assertThat(1 ^ 3).isEqualTo(2);
+    }
+}

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

@@ -3,13 +3,10 @@
 ## Core Java Lang Cookbooks and Examples
 
 ### Relevant Articles: 
-- [Guide to Java Reflection](http://www.baeldung.com/java-reflection)
+
 - [Generate equals() and hashCode() with Eclipse](http://www.baeldung.com/java-eclipse-equals-and-hashcode)
 - [Chained Exceptions in Java](http://www.baeldung.com/java-chained-exceptions)
-- [Call Methods at Runtime Using Java Reflection](http://www.baeldung.com/java-method-reflection)
 - [Iterating Over Enum Values in Java](http://www.baeldung.com/java-enum-iteration)
-- [Changing Annotation Parameters At Runtime](http://www.baeldung.com/java-reflection-change-annotation-params)
-- [Dynamic Proxies in Java](http://www.baeldung.com/java-dynamic-proxies)
 - [Java Double Brace Initialization](http://www.baeldung.com/java-double-brace-initialization)
 - [Guide to the Diamond Operator in Java](http://www.baeldung.com/java-diamond-operator)
 - [Comparator and Comparable in Java](http://www.baeldung.com/java-comparator-comparable)