假设车库有3个车位，写一个程序模拟多个用户开车离开，停车入库的效果。

import java.util.Random;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Executor pool=Executors.newCachedThreadPool();
		Pos pos=new Pos();
		for(int i=1;i<=10;++i)
			pool.execute(new Car(i, pos));
	}

}
class Pos{
	boolean[] wei=new boolean[3];
	public Pos(){
		for(int i=0;i<wei.length;++i)
			wei[i]=true;
	}
	public int tiche(Car car){
		while(true)
			synchronized (Pos.class) {
				for(int i=0;i<wei.length;++i)
					if(wei[i]){
						wei[i]=false;
						System.out.println(car.name+"停在"+i+"号库");
						return i;
					}
			}
	}
	public void out(Car car){
		while(true)
			synchronized (Pos.class) {				
				wei[car.num]=true;
				System.out.println(car.name+"离开"+car.num+"号库");
				return;					
			}
	}
}
class Car implements Runnable{
	int name;
	int num;
	Pos pos;
	
	public Car(int name, Pos pos) {
		super();
		this.name = name;
		this.pos = pos;
	}

	@Override
	public void run() {
		// TODO Auto-generated method stub
		this.num = pos.tiche(this);
		try {
			Thread.sleep(Math.abs(new Random().nextInt())%10000);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		pos.out(this);
		
	}
}