/*

虽然同步的出现解决了线程安全问题。

但是也带来了一些弊端：

1，效率会降低。

2，容易引发死锁。

死锁经常出现的状况为：同步嵌套。

*/

class Test implements Runnable{	private boolean flag;	Test(boolean flag)	{		this.flag = flag;	}	public void run()	{		if(flag)		{			while(true)			{				synchronized(MyLock.locka)				{					System.out.println(Thread.currentThread().getName()+"...if......locka");					synchronized(MyLock.lockb)					{						System.out.println(Thread.currentThread().getName()+"...if......lockb");											}				}			}		}		else		{			while(true)			{				synchronized(MyLock.lockb)				{					System.out.println(Thread.currentThread().getName()+"...else..........lockb");					synchronized(MyLock.locka)					{						System.out.println(Thread.currentThread().getName()+"...else..........locka");											}				}			}		}	}}class MyLock{	public static Object locka = new Object();	public static Object lockb = new Object();}class DeadLockTest {	public static void main(String[] args) 	{		Test t1 = new Test(true);		Test t2 = new Test(false);		Thread th1 = new Thread(t1,"Сǿ");		Thread th2 = new Thread(t2,"κӆ");		th1.start();		th2.start();	}}