synchronized(this)和synchronized(A.class)

1. synchronized(this) 只能锁当前对象
2. synchronized(A.class) 锁类，对类的所有实例生效

public class LockDemo{

    public void method1() {
        synchronized (this) {
            System.out.println("method1 start");
        }
    }

    public void method2() {
        synchronized (this) {
            System.out.println("method2 start");
        }
    }

}

-- 相当于--

public class LockDemo{

    public synchronized void method1() {
        System.out.println("method1 start");
    }

    public synchronized void method2() {
        System.out.println("method2 start");
    }

}

 

public class LockDemo{

    public void method1() {
        synchronized (LockDemo.class) {
            System.out.println("method1 start");
        }
    }

    public void method2() {
        synchronized (LockDemo.class) {
            System.out.println("method2 start");
        }
    }
}


-- 相当于--

public class LockDemo{

    public static synchronized void method1() {
        System.out.println("method1 start");
    }

    public static synchronized void method2() {
        System.out.println("method2 start");
    }
}