Java案例:双色球的实现

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//随机生成双色球号码

//案例：6颗红球(33选1) 1颗蓝球(16选1)

代码实现如下：

import java.util.Random;import java.util.Arrays;//包含Arrayspublic class HelloWorld {public static void main(String[] args){String[] getball = getBalls();System.out.println(Arrays.toString(getball));}public static String[] getBalls(){//随机生成双色球号码//案例：6颗红球(33选1)  1颗蓝球(16选1)String []pool = {"01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31","32","33"};//用一个数组存放6个蓝色的球String[] balls = new String[6];int length = 0 ;//从pool数组中随机选取6个球，放入数组中，并且不能有重复/* * 1、如何随机取 *    Random r = new Random(); *    r.nextInt(n); //取到0到n之间的随机数 * 2、如果不重复 *   一个下标的球被使用我们给它加个标识 *   boolean[] flag  = new bootlean[pool.length];数组中元素默认为false */boolean[] used = new boolean[pool.length];Random r = new Random();while(true){int index = r.nextInt(pool.length);//说明该下标已经被使用过if(used[index])continue ; //结束本次循环，继续下一次循环balls[length++] = pool[index];//把选中的球放入球数组used[index] = true ;//把选中的球标识为已经使用过。if(length == balls.length) //如果下标等于6，证明选完了 break ;}//红色的球已经选完了Arrays.sort(balls);//扩容一个空间，最后一个放蓝球//balls = Arrays.copyOf(balls,balls.length+1); 不知道为什么不行，疑惑中String []str = new String[balls.length+1]; //所以我只能使用这种老土的方法来实现数组扩容了for(int i = 0 ; i < balls.length ; i++)str[i] = balls[i];balls = str ;//balls = Arrays.copyOf(balls,balls.length+1);//蓝色的球16选1即可balls[balls.length-1] = pool[r.nextInt(16)]; return balls ;}}

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