Selection sort implementation

algorithms-sorting/src/main/java/com/baeldung/algorithms/selectionsort/SelectionSort.java

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+package com.baeldung.algorithms.selectionsort;
+
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class SelectionSort {
+
+    /*public static void main(final String args[]) {
+        int[] a = { 5, 4, 1, 6, 2 };
+    
+        System.out.println("Unsorted array");
+        System.out.println(IntStream.of(a)
+            .mapToObj(String::valueOf)
+            .collect(Collectors.joining(",")));
+    
+        a = sortAscending(a);
+        System.out.println("Ascending Sorted array");
+        System.out.println(IntStream.of(a)
+            .mapToObj(String::valueOf)
+            .collect(Collectors.joining(",")));
+    
+        a = sortDescending(a);
+        System.out.println("Descending Sorted array");
+        System.out.println(IntStream.of(a)
+            .mapToObj(String::valueOf)
+            .collect(Collectors.joining(",")));
+    }*/
+
+    public static void sortAscending(final int[] arr) {
+        for (int i = 0; i < arr.length - 1; i++) {
+            int minElementIndex = i;
+            for (int j = i + 1; j < arr.length; j++) {
+                if (arr[minElementIndex] > arr[j]) {
+                    minElementIndex = j;
+                }
+            }
+
+            if (minElementIndex != i) {
+                int temp = arr[i];
+                arr[i] = arr[minElementIndex];
+                arr[minElementIndex] = temp;
+            }
+            System.out.println("Iteration No. " + (i + 1));
+            System.out.println(IntStream.of(arr)
+                .mapToObj(String::valueOf)
+                .collect(Collectors.joining(",")));
+
+        }
+    }
+
+    public static void sortDescending(final int[] arr) {
+        for (int i = 0; i < arr.length - 1; i++) {
+            int maxElementIndex = i;
+            for (int j = i + 1; j < arr.length; j++) {
+                if (arr[maxElementIndex] < arr[j]) {
+                    maxElementIndex = j;
+                }
+            }
+
+            if (maxElementIndex != i) {
+                int temp = arr[i];
+                arr[i] = arr[maxElementIndex];
+                arr[maxElementIndex] = temp;
+            }
+            System.out.println("Iteration No. " + (i + 1));
+            System.out.println(IntStream.of(arr)
+                .mapToObj(String::valueOf)
+                .collect(Collectors.joining(",")));
+
+        }
+    }
+}

algorithms-sorting/src/test/java/com/baeldung/algorithms/selectionsort/SelectionSortUnitTest.java

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+package com.baeldung.algorithms.selectionsort;
+
+import static org.junit.Assert.*;
+import static org.junit.Assert.assertArrayEquals;
+
+import org.junit.Test;
+
+public class SelectionSortUnitTest {
+
+    @Test
+    public void givenUnsortedArray_whenSelectionSort_SortAscending_thenSortedAsc() {
+        int[] input = { 5, 4, 1, 6, 2 };
+        SelectionSort.sortAscending(input);
+        int[] expected = {1, 2, 4, 5, 6};
+        assertArrayEquals("the two arrays are not equal", expected, input);
+    }
+    
+    @Test
+    public void givenUnsortedArray_whenSelectionSort_SortDescending_thenSortedDesc() {
+        int[] input = { 5, 4, 1, 6, 2 };
+        SelectionSort.sortDescending(input);
+        int[] expected = {6, 5, 4, 2, 1};
+        assertArrayEquals("the two arrays are not equal", expected, input);
+    }
+}