多线程并发操作，停车以及出车库过程模拟，多个线程通信过程。

package test;
public class Test {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		boolean[] p = new boolean[3];
		for (int i = 0; i < 3; i++) {
			p[i] = false;
		}
		Park pa = new Park(p);
		new Tpark("小明", pa).start();
		new Tpark("小张", pa).start();
		new Tpark("小红", pa).start();
		new Tpark("小李", pa).start();
		new C_park(2, pa).start();
	}
}
class Park {
	public boolean[] p = new boolean[3];
	public int PP = 0;

	public Park() {
	};

	public Park(boolean[] p) {
		this.p = p;
	};
}
class Tpark extends Thread {  //停车
	private Park p;
	private boolean flag = true;  //用来标志是否已经停车
	public Tpark() {
	}
	public Tpark(String name, Park p) {
		super(name);
		this.p = p;
	}
	public void run() {
		synchronized (p) {
			while (flag) {
				if (p.PP < 3) {
					int x = 0;
					for (int i = 0; i < 3; i++) {
						if (p.p[i] == false) {
							p.p[i] = true;
							System.out.println(Thread.currentThread().getName() + "停入" + (i + 1) + "号车库");
							flag = false;
							break;

						}
					}
					for (int i = 0; i < 3; i++) {
						if (p.p[i] == true) {
							x++;
						}
					}
					p.PP = x;
				} else {
					System.out.println("抱歉，" + Thread.currentThread().getName() + " 先生（女士）,停车位目前已满，请您稍作等待！！！");
					try {
						p.wait();
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}
		}
	}

}

class C_park extends Thread {  //出库
	private Park p;
	private int no;

	public C_park() {
	}

	public C_park(int no, Park p) {
		this.no = no;
		this.p = p;
	}

	public void run() {
		synchronized (p) {
			p.p[no - 1] = false;
			p.PP--;
			System.out.println(no + "号车位已空闲");
			p.notifyAll();
		}
	}
}

运行结果：

小明停入1号车库
小李停入2号车库
小红停入3号车库
抱歉，小张 先生（女士）,停车位目前已满，请您稍作等待！！！
2号车位已空闲
小张停入2号车库