how to write a perfect shuffle method in java

                                    public static int[] RandomizeArray(int a, int b){
		Random rgen = new Random();  // Random number generator		
		int size = b-a+1;
		int[] array = new int[size];
 
		for(int i=0; i< size; i++){
			array[i] = a+i;
		}
 
		for (int i=0; i<array.length; i++) {
		    int randomPosition = rgen.nextInt(array.length);
		    int temp = array[i];
		    array[i] = array[randomPosition];
		    array[randomPosition] = temp;
		}
 
		for(int s: array)
			System.out.println(s);
 
		return array;
	}