BAEL-1211 Bubble Sort in Java (#2744)

* BAEL-815 Introduction to JGraphT

* BAEL-815 Move code from libraries to algorithms

* BAEL-1211 Bubble Sort in Java

* BAEL-1211 Bubble Sort in Java

* BAEL-1211 Bubble Sort in Java

* BAEL-1211 Bubble Sort in Java

* BAEL-1211 Fix conflict

algorithms/src/main/java/com/baeldung/algorithms/bubblesort/BubbleSort.java

@@ -0,0 +1,41 @@
+package com.baeldung.algorithms.bubblesort;
+
+import java.util.stream.IntStream;
+
+public class BubbleSort {
+
+    public void bubbleSort(Integer[] arr) {
+        int n = arr.length;
+        IntStream.range(0, n - 1)
+            .forEach(i -> {
+                IntStream.range(i + 1, n - i)
+                    .forEach(j -> {
+                        if (arr[j - 1] > arr[j]) {
+                            int temp = arr[j];
+                            arr[j] = arr[j - 1];
+                            arr[j - 1] = temp;
+                        }
+                    });
+            });
+    }
+
+    public void optimizedBubbleSort(Integer[] arr) {
+        int i = 0, n = arr.length;
+        boolean swapNeeded = true;
+        while (i < n - 1 && swapNeeded) {
+            swapNeeded = false;
+            for (int j = i + 1; j < n - i; j++) {
+                if (arr[j - 1] > arr[j]) {
+                    int temp = arr[j - 1];
+                    arr[j - 1] = arr[j];
+                    arr[j] = temp;
+                    swapNeeded = true;
+                }
+            }
+            if (!swapNeeded)
+                break;
+            i++;
+        }
+    }
+
+}

algorithms/src/test/java/com/baeldung/algorithms/bubblesort/BubbleSortTest.java

@@ -0,0 +1,26 @@
+package com.baeldung.algorithms.bubblesort;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class BubbleSortTest {
+
+    @Test
+    public void givenIntegerArray_whenSortedWithBubbleSort_thenGetSortedArray() {
+        Integer[] array = { 2, 1, 4, 6, 3, 5 };
+        Integer[] sortedArray = { 1, 2, 3, 4, 5, 6 };
+        BubbleSort bubbleSort = new BubbleSort();
+        bubbleSort.bubbleSort(array);
+        assertArrayEquals(array, sortedArray);
+    }
+
+    @Test
+    public void givenIntegerArray_whenSortedWithOptimizedBubbleSort_thenGetSortedArray() {
+        Integer[] array = { 2, 1, 4, 6, 3, 5 };
+        Integer[] sortedArray = { 1, 2, 3, 4, 5, 6 };
+        BubbleSort bubbleSort = new BubbleSort();
+        bubbleSort.optimizedBubbleSort(array);
+        assertArrayEquals(array, sortedArray);
+    }
+}