生成随机数,可用于彩票

package test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Ball {

	private List<Integer> redBalls;
	private Integer blueBall;

	public Ball() {
		calculateRedBalls();
		calculateBlueBall();
	}

	private void calculateRedBalls() {
		List<Integer> balls = new ArrayList<Integer>();
		for (int i = 1; i <= 33; i++) {
			balls.add(i);
		}
		Collections.shuffle(balls);
		redBalls = new ArrayList<Integer>(balls.subList(0, 6));
		Collections.sort(redBalls);
	}

	private void calculateBlueBall() {
		blueBall = (int) (Math.random() * 16 + 1);
	}

	@Override
	public String toString() {
		return "红色球是： " + redBalls + " and蓝色球是： " + blueBall;
	}

	public static void main(String[] args) {
		Ball ball = new Ball();
		System.out.println(ball);
	}

}

以上是引用别人的，还可以有另一种方法

package test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Vector;

public class Test {
	static Random r = new Random();
	public static int getRandomIntWithinRange(int cap) {
		return r.nextInt(cap)+1;
	}
	/**
	 * @param cap 最大到多少，如35，最大到35
	 * @param count,总共产生几个数，如5，产生5个数
	 * */
	public static Vector getRandomIntArrayWithinRange(int count, int cap) {
		Vector v = new Vector();
		Vector ret = new Vector();
		for(int i=1;i<=cap;i++) {
			v.add(new Integer(i));
		}
		//确保不重复
		for(int i=1;i<=count;i++) {
			int index = getRandomIntWithinRange(cap+1-i);
			ret.add(v.remove(index-1));
		}
		Collections.sort(ret);
		return ret;
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Vector v=getRandomIntArrayWithinRange(5,35);
		String s=""+v;
		
		s=s.replace("[", "");
		s=s.replace("]", "");
	
		System.out.println(s);


	}

}