Java模拟标准双色球

近期一直在复习Java基础知识，确实不仅补缺查漏，还能增强记忆。同事提了个需求想要模拟一下双色球的输出，顺便练习一下刚学的Collection类。反正闲的没事，就决定练习一下。

一开始我想用Set最为简便，因为其自身值的唯一性，可以很好地去除随机值重复的问题。所以，一会儿就用Set写了下面这个版本。

/*
 *Create on Aug 20, 2012
 *
 */
package com.doubleball;

import java.util.HashSet;
import java.util.Random;
import java.util.Set;

/**
 * @author zhiguo.chen
 *
 */
public class Ball {
	Set&lt;Integer&gt; RedBall = null;
	public Set&lt;Integer&gt; getRedBall() {
		return RedBall;
	}
	public void setRedBall(Set&lt;Integer&gt; redBall) {
		RedBall = redBall;
	}

	Set&lt;Integer&gt; BlueBall = null;
	public Set&lt;Integer&gt; getBlueBall() {
		return BlueBall;
	}
	public void setBlueBall(Set&lt;Integer&gt; blueBall) {
		BlueBall = blueBall;
	}

	public Set getRedBall(int x,int y){
		Random ran = new Random();
		Set&lt;Integer&gt; tmp = new HashSet&lt;Integer&gt;();
		for(int i = 0;tmp.size()&lt;x;i++){
			tmp.add(ran.nextInt(y));
			}
		this.RedBall=tmp;
		return RedBall;
	}

	public Set getBlueBall(int x,int y){
		Random ran = new Random();
		Set&lt;Integer&gt; tmp = new HashSet&lt;Integer&gt;();
		for(int i = 0;tmp.size()&lt;x;i++){
			tmp.add(ran.nextInt(y));
			}
		this.BlueBall=tmp;
		return BlueBall;
	}
}

*Create on Aug 20, 2012

package com.doubleball;

import java.util.HashSet;

import java.util.Random;

import java.util.Set;

/**

* @author zhiguo.chen

public class Ball {

Set<Integer> RedBall = null;

public Set<Integer> getRedBall() {

return RedBall;

}

public void setRedBall(Set<Integer> redBall) {

RedBall = redBall;

}

Set<Integer> BlueBall = null;

public Set<Integer> getBlueBall() {

return BlueBall;

}

public void setBlueBall(Set<Integer> blueBall) {

BlueBall = blueBall;

}

public Set getRedBall(int x,int y){

Random ran = new Random();

Set<Integer> tmp = new HashSet<Integer>();

for(int i = 0;tmp.size()<x;i++){

tmp.add(ran.nextInt(y));

}

this.RedBall=tmp;

return RedBall;

}

public Set getBlueBall(int x,int y){

Random ran = new Random();

Set<Integer> tmp = new HashSet<Integer>();

for(int i = 0;tmp.size()<x;i++){

tmp.add(ran.nextInt(y));

}

this.BlueBall=tmp;

return BlueBall;

}

但是此方法立马被质疑，再出球的概率问题上存在纰漏。出现第1个球的概率为1/32，第2，3，4·····个球的概率都是1/32。这样是不对的，因为真实的双色球中每一个球所出现的概率是不同的，第一个球的概率为1/32，第二个球的概率为1/31，第三个球的概率为1/30···以此类推。

所以经过重新考虑，便写了下面这个标准版，是基于List完成的。

/*
 *Create on Aug 20, 2012
 *
 */
package com.doubleball;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

/**
 * @author zhiguo.chen
 *
 */
public class ListBall {
	List&lt;Integer&gt; RedBall;
	public List&lt;Integer&gt; getRedBall() {
		return RedBall;
	}
	public void setRedBall(List&lt;Integer&gt; redBall) {
		RedBall = redBall;
	}
	List&lt;Integer&gt; BlueBall;
	public List&lt;Integer&gt; getBlueBall() {
		return BlueBall;
	}
	public void setBlueBall(List&lt;Integer&gt; blueBall) {
		BlueBall = blueBall;
	}

	public List getRedBall(int x,int y){
		List tmp = new ArrayList();
		Random ran = new Random();
		int temp;
		//int total = y;
		for(int i=1;i&lt;=x;i++){
			tmp.add(i);
		}
		for(int i =1;i&lt;=y;i++){
			temp=ran.nextInt(x--);
			System.out.println("此球的概率为："+(double)1/(x+1));
			System.out.println("第"+i+"位红球为"+(tmp.get(temp)));
			tmp.remove(temp);
		}
		return RedBall;
	}

	public void getBlueBall(int x){

		Random ran = new Random();
		System.out.println("=================================");		
		System.out.println("篮球即特别号码为："+(ran.nextInt(x)+1));

	}
}

*Create on Aug 20, 2012

package com.doubleball;

import java.util.ArrayList;

import java.util.List;

import java.util.Random;

/**

* @author zhiguo.chen

public class ListBall {

List<Integer> RedBall;

public List<Integer> getRedBall() {

return RedBall;

}

public void setRedBall(List<Integer> redBall) {

RedBall = redBall;

}

List<Integer> BlueBall;

public List<Integer> getBlueBall() {

return BlueBall;

}

public void setBlueBall(List<Integer> blueBall) {

BlueBall = blueBall;

}

public List getRedBall(int x,int y){

List tmp = new ArrayList();

Random ran = new Random();

int temp;

//int total = y;

for(int i=1;i<=x;i++){

tmp.add(i);

}

for(int i =1;i<=y;i++){

temp=ran.nextInt(x--);

System.out.println("此球的概率为："+(double)1/(x+1));

System.out.println("第"+i+"位红球为"+(tmp.get(temp)));

tmp.remove(temp);

}

return RedBall;

}

public void getBlueBall(int x){

Random ran = new Random();

System.out.println("=================================");

System.out.println("篮球即特别号码为："+(ran.nextInt(x)+1));

}

然后下面是主函数所存在的类。

/*
 *Create on Aug 20, 2012
 *
 *TODO 
 */
package com.doubleball;

import java.util.Random;
import java.util.Set;

/**
 * @author zhiguo.chen
 *
 */
public class DoubleBall {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Random ran = new Random();
		//System.out.println(ran.nextInt(32));

		Ball ball = new Ball();
		Set RedBall =ball.getRedBall(6, 32);
		Set BlueBall = ball.getBlueBall(1,16);
		System.out.println("==========双色球大开奖============");
//		System.out.println("红球为："+RedBall);
//		System.out.println("蓝球为："+BlueBall);

		ListBall lb = new ListBall();
		lb.getRedBall(32, 6);

		lb.getBlueBall(16);
	}

}

*Create on Aug 20, 2012

*TODO

package com.doubleball;

import java.util.Random;

import java.util.Set;

/**

* @author zhiguo.chen

public class DoubleBall {

/**

* @param args

public static void main(String[] args) {

// TODO Auto-generated method stub

Random ran = new Random();

//System.out.println(ran.nextInt(32));

Ball ball = new Ball();

Set RedBall =ball.getRedBall(6, 32);

Set BlueBall = ball.getBlueBall(1,16);

System.out.println("==========双色球大开奖============");

// System.out.println("红球为："+RedBall);

// System.out.println("蓝球为："+BlueBall);

ListBall lb = new ListBall();

lb.getRedBall(32, 6);

lb.getBlueBall(16);

}

其实整个都很简单，只是简单地事情让我重新构思了两次，让我觉得这件事情应该记录下来。还有就是网上的很多版本都是基于上面第一个Set版本做的，其实是不对的，功能虽然正确，但是内在的概率问题并不正确。如有错误，请您指正。

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Java模拟标准双色球

《Java模拟标准双色球》有2个想法