      1  import java.util.Random;

      2

      3  /**

      4     This class contains utility methods for array manipulation.

      5  */

      6  public class ArrayUtil

      7  {

      8     private static Random generator = new Random();

      9

     10     /**

     11        Creates an array filled with random values.

     12        @param length the length of the array

     13        @param n the number of possible random values

     14        @return an array filled with length numbers between

     15        0 and n - 1

     16     */

     17     public static int[] randomIntArray(int length, int n)

     18     {

     19        int[] a = new int[length];

     20        for (int i = 0; i < a.length; i++)

     21        {

     22           a[i] = generator.nextInt(n);

     23        }

     24

     25        return a;

     26     }

     27

     28     /**

     29        Swaps two entries of an array.

     30        @param a the array

     31        @param i the first position to swap

     32        @param j the second position to swap

     33     */

     34     public static void swap(int[] a, int i, int j)

     35     {

     36        int temp = a[i];

     37        a[i] = a[j];

     38        a[j] = temp;

     39     }

     40  }

     41