gistfile1.java

package test;

import java.util.Random;

public class RandomCreate {
	
	private int[] bitArray;
	
	/**
	 * overLoad
	 * @param max
	 * @return randCreate(0, max)
	 */
	public long randCreate(int max){
		return randCreate(0, max);
	}

	/**
	 * The number generated at random in the range of min to max is returned. 
	 * @param min
	 * @param max
	 * @return result
	 */
	public int randCreate(int min, int max){
		Random rand = new Random();
		int result = rand.nextInt(max-min) + min;
		return result;
	}
	
	public int[] CreateRandomArray(int n, int k){
		bitArray = new int[n];
		for(int i=0; i<n; i++){
			bitArray[i] = i;
		}
		for(int i=0; i<n; i++){
			swapArray(i, randCreate(i, n));
		}
		
		int[] bit = new int[k];
		for(int i=0; i<k; i++){
			bit[i] = bitArray[i];
		}
		return bit;
	}
	
	private void swapArray(int from, int to){
		int t = bitArray[from];
		bitArray[from] = bitArray[to];
		bitArray[to] = t;
	}
}