package com.thread;public class SynWindow implements Runnable {	Object object;	Object object2;	String name;	static int count=10;	public SynWindow(String name,Object object,Object object2) {		// TODO Auto-generated constructor stub		this.object = object;		this.object2 = object2;		this.name = name;	}	public void serviceWindow() {				while(count>0){				synchronized (object) {					synchronized (object2) {						System.out.PRintln(getName()+"服務"+count+"號客戶");						count-=1;						object2.notify();					}					try {						object.wait();					} catch (Exception e) {						// TODO: handle exception					}				}		}			}	@Override	public void run() {		// TODO Auto-generated method stub		serviceWindow();	}		public String getName() {		return name;	}	public void setName(String name) {		this.name = name;	}	public static void main(String[] args) {		// TODO Auto-generated method stub		Object a = new Object();		Object b = new Object();		Object c = new Object();		SynWindow s1 = new SynWindow("窗口一", a, b);		SynWindow s2 = new SynWindow("窗口二", b, c);		SynWindow s3 = new SynWindow("窗口三", c, a);		Thread t1 = new Thread(s1);		Thread t2 = new Thread(s2);		Thread t3 = new Thread(s3);		t1.start();		try {			t1.sleep(100);		} catch (Exception e) {			// TODO: handle exception		}		t2.start();		t3.start();	}}一段synchronized的代碼被一個線程執行之前，他要先拿到執行這段代碼的權限，在java里邊就是拿到某個同步對象的鎖（一個對象只有一把鎖）； 如果這個時候同步對象的鎖被其他線程拿走了，他（這個線程）就只能等了（線程阻塞在鎖池等待隊列中）。 取到鎖后，他就開始執行同步代碼(被synchronized修飾的代碼）；線程執行完同步代碼后馬上就把鎖還給同步對象，其他在鎖池中等待的某個線程就可以拿到鎖執行同步代碼了。這樣就保證了同步代碼在統一時刻只有一個線程在執行。