多线程之如何证明sychronized的this锁存在

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这边是一个简单的线程调用

public class SynchronizedThis {

    public static void main(String[] args) {

        ThisLock thisLock = new ThisLock();
        new Thread("T1") {
            @Override
            public void run() {
                thisLock.m1();
            }
        }.start();

        new Thread("T2") {
            @Override
            public void run() {
                thisLock.m2();
            }
        }.start();
    }
}

class ThisLock {
    
    public void m1() {
            try {
                System.out.println(Thread.currentThread().getName());
                Thread.sleep(10_000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
    }

    public void m2() {
            try {
                System.out.println(Thread.currentThread().getName());
                Thread.sleep(10_000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
    }
}

从输出可以看出T1,T2是同时输出的，下面加上sychronized改造一下

​
class ThisLock {

    private final Object LOCK = new Object();

    public  void m1() {
        synchronized(this) {
            System.out.println(this.getClass().getName());
            try {
                System.out.println(Thread.currentThread().getName());
                Thread.sleep(10_000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }

    public synchronized void m2() {
            try {
                System.out.println(Thread.currentThread().getName());
                Thread.sleep(10_000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
    }
}

​

发现这两个锁的是同一个东西,所以一个先输出一个后输出

class ThisLock {

    private final Object LOCK = new Object();

    public  void m1() {
        synchronized(LOCK) {
            try {
                System.out.println(Thread.currentThread().getName());
                Thread.sleep(10_000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }

    public  synchronized void m2() {
            try {
                System.out.println(Thread.currentThread().getName());
                Thread.sleep(10_000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
    }
}
​

最后锁的是一个对象，然后输出发现是同时输出的，说明是两个不同的锁，一个是LOCK锁，一个是this锁