JavaAlgorithms/Sorts/SelectionSort.java

package Sorts;

public class SelectionSort implements SortAlgorithm {

  /**
   * Generic selection sort algorithm in increasing order.
   *
   * @param arr the array to be sorted.
   * @param <T> the class of array.
   * @return sorted array.
   */
  @Override
  public <T extends Comparable<T>> T[] sort(T[] arr) {
    int n = arr.length;
    for (int i = 0; i < n - 1; i++) {
      int minIndex = i;
      for (int j = i + 1; j < n; j++) {
        if (arr[minIndex].compareTo(arr[j]) > 0) {
          minIndex = j;
        }
      }
      if (minIndex != i) {
        T temp = arr[i];
        arr[i] = arr[minIndex];
        arr[minIndex] = temp;
      }
    }
    return arr;
  }

  /** Driver Code */
  public static void main(String[] args) {

    Integer[] arr = {4, 23, 6, 78, 1, 54, 231, 9, 12};
    SelectionSort selectionSort = new SelectionSort();
    Integer[] sorted = selectionSort.sort(arr);
    for (int i = 0; i < sorted.length - 1; ++i) {
      assert sorted[i] <= sorted[i + 1];
    }

    String[] strings = {"c", "a", "e", "b", "d"};
    String[] sortedStrings = selectionSort.sort(strings);
    for (int i = 0; i < sortedStrings.length - 1; ++i) {
      assert strings[i].compareTo(strings[i + 1]) <= 0;
    }
  }
}