Java direct insertion sort algorithm implementation

Foreword: an original idea of falling in love with Java has never gone away: "it's important to share my learning, no matter how advanced the technology is."

Tool class Swapper, the later algorithm will use this tool class:

package com.meritit.sortord.util;
/**
 * One util to swap tow element of Array
 * 
 * @author ysjian
 * @version 1.0
 * @email ysjian_pingcx@126.com
 * @QQ 646633781
 * @telephone 18192235667
 * @csdnBlog http://blog.csdn.net/ysjian_pingcx
 * @createTime 2013-12-20
 * @copyRight Merit
 */
public class Swapper {
 private Swapper() {
 }
 
 public static <T extends Comparable<T>> void swap(int oneIndex,
   int anotherIndex, T[] array) {
  if (array == null) {
   throw new NullPointerException("null value input");
  }
  checkIndexs(oneIndex, anotherIndex, array.length);
  T temp = array[oneIndex];
  array[oneIndex] = array[anotherIndex];
  array[anotherIndex] = temp;
 }
 
 public static void swap(int oneIndex, int anotherIndex, int[] array) {
  if (array == null) {
   throw new NullPointerException("null value input");
  }
  checkIndexs(oneIndex, anotherIndex, array.length);
  int temp = array[oneIndex];
  array[oneIndex] = array[anotherIndex];
  array[anotherIndex] = temp;
 }
 
 private static void checkIndexs(int oneIndex, int anotherIndex,
   int arrayLength) {
  if (oneIndex < 0 || anotherIndex < 0 || oneIndex >= arrayLength
    || anotherIndex >= arrayLength) {
   throw new IllegalArgumentException(
     "illegalArguments for tow indexs [" + oneIndex + ","
       + oneIndex + "]");
  }
 }
}

Direct insertion sort, InsertionSortord:

package com.meritit.sortord.insertion;
/**
 * Insertion sort order, time complexity is O(n2)
 * 
 * @author ysjian
 * @version 1.0
 * @email ysjian_pingcx@126.com
 * @QQ 646633781
 * @telephone 18192235667
 * @csdnBlog http://blog.csdn.net/ysjian_pingcx
 * @createTime 2013-12-31
 * @copyRight Merit
 * @since 1.5
 */
public class InsertionSortord {
 private static final InsertionSortord INSTANCE = new InsertionSortord();
 private InsertionSortord() {
 }
 
 public static InsertionSortord getInstance() {
  return INSTANCE;
 }
 /**
  * Sort the array of <code>int</code> with insertion sort order
  * 
  * @param array
  *            the array of int
  */
 public void doSort(int... array) {
  if (array != null && array.length > 0) {
   int length = array.length;
   // the circulation begin at 1,the value of index 0 is reference
   for (int i = 1; i < length; i++) {
    if (array[i] < array[i - 1]) {
     // if value at index i is lower than the value at index i-1
     int vacancy = i; // record the vacancy as i
     // set a sentry as the value at index i
     int sentry = array[i];
     // key circulation ,from index i-1 ,
     for (int j = i - 1; j >= 0; j--) {
      if (array[j] > sentry) {
       
       array[j + 1] = array[j];
       vacancy = j;
      }
     }
     // set the sentry to the new vacancy
     array[vacancy] = sentry;
    }
   }
  }
 }
 /**
  * Sort the array of generic <code>T</code> with insertion sort order
  * 
  * @param array
  *            the array of generic
  */
 public <T extends Comparable<T>> void doSortT(T[] array) {
  if (array != null && array.length > 0) {
   int length = array.length;
   for (int i = 1; i < length; i++) {
    if (array[i].compareTo(array[i - 1]) < 0) {
     T sentry = array[i];
     int vacancy = i;
     for (int j = i - 1; j >= 0; j--) {
      if (array[j].compareTo(sentry) > 0) {
       array[j + 1] = array[j];
       vacancy = j;
      }
     }
     array[vacancy] = sentry;
    }
   }
  }
 }
}

Test TestInsertionSortord:

package com.meritit.sortord.insertion;
import java.util.Arrays;

public class TestInsertionSortord {
 public static void main(String[] args) {
  InsertionSortord insertSort = InsertionSortord.getInstance();
  int[] array = { 3, 5, 4, 2, 6 };
  System.out.println(Arrays.toString(array));
  insertSort.doSort(array);
  System.out.println(Arrays.toString(array));
  System.out.println("---------------");
  Integer[] array1 = { 3, 5, 4, 2, 6 };
  System.out.println(Arrays.toString(array1));
  insertSort.doSortT(array1);
  System.out.println(Arrays.toString(array1));
 }
}