JavaAlgorithms/Sorts/InsertionSort.java

package Sorts;

import static Sorts.SortUtils.less;
import static Sorts.SortUtils.print;

class InsertionSort implements SortAlgorithm {

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

  /** Driver Code */
  public static void main(String[] args) {
    Integer[] integers = {4, 23, 6, 78, 1, 54, 231, 9, 12};
    InsertionSort sort = new InsertionSort();
    sort.sort(integers);
    print(integers); /* [1, 4, 6, 9, 12, 23, 54, 78, 231] */

    String[] strings = {"c", "a", "e", "b", "d"};
    sort.sort(strings);
    print(strings); /* [a, b, c, d, e] */
  }
}