死锁

当线程1拿到锁1的时候，打算进入锁2的代码需要锁2 当线程2拿到锁2的时候，打算进入锁1的代码需要锁1 此时程序卡死！因为线程1需要的2锁在线程2里，同时线程2需要的1锁在线程1里

死锁的实现思路两个锁嵌套
//以下为线程1执行

synchronized(锁定1)
{

　　　　synchronized(锁定2)
　　　　{
　　　　　　
       }

}

//以下为线程2执行

synchronized(锁定2)
{

　　　　synchronized(锁定1)
　　　　{
　　　　　　
       }

}

package hysy32.MultiThread;

/**
 * Created by 小管 on 2017/4/2.
 */
public class DeadLockTest {
    public static void main(String[] args) {
        LockDemo l = new LockDemo(true);
        LockDemo l1 = new LockDemo(false);
        Thread t1 = new Thread(l);
        Thread t2 = new Thread(l1);
        t1.start();
        t2.start();
    }

}

class LockDemo implements Runnable {
    private  boolean b;

    public LockDemo(boolean b) {
        this.b = b;
    }

    @Override
    public void run() {
        if (b) {
            while (true) {
                synchronized (lock.lockA) {
                    System.out.println("true...LockA");

                    synchronized (lock.lockB) {
                        System.out.println("true...LockB");
                    }
                }
            }

        } else synchronized (lock.lockB) {
            while (true) {
                System.out.println("false...LockB");

                synchronized (lock.lockA) {
                    System.out.println("false...LockA");
                }
            }
        }
    }
}

class lock {
    public static Object lockA = new Object();
    public static Object lockB = new Object();

}

　　

 

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");
                    }
                }
            }
        }
    }
}
//定义一个用于存储锁对象类。
class MyLock
{
    public static final Object LOCKA = new Object();
    public static final Object LOCKB = new Object();
}

class DeadLockTest 
{
    public static void main(String[] args) 
    {
        //创建两个线程任务。
        Test t1 = new Test(true);
        Test t2 = new Test(false);
        
        Thread t11 = new Thread(t1);
        Thread t22 = new Thread(t2);
        t11.start();
        t22.start();

    }
}