ArrayUtil.java.html

  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