给静态方法加锁锁的是类

给静态方法加锁

public class Test {
    synchronized static void fun1() throws InterruptedException {
        System.out.println("加锁的方法1开始执行");
        Thread.sleep(2000);
        System.out.println("加锁的方法1执行结束");
    }

    synchronized static void fun2() throws InterruptedException {
        System.out.println("加锁的方法2开始执行");
        Thread.sleep(2000);
        System.out.println("加锁的方法2执行结束");
    }

    public static void main(String[] args) {
        Test obj1 = new Test();
        Test obj2 = new Test();

        new Thread(() -> {
            try {
                obj1.fun1();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();

        new Thread(() -> {
            try {
                obj2.fun2();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();
    }
}

效果：

image.png

给普通方法加锁

public class Test {
    synchronized void fun1() throws InterruptedException {
        System.out.println("加锁的方法1开始执行");
        Thread.sleep(2000);
        System.out.println("加锁的方法1执行结束");
    }

    synchronized void fun2() throws InterruptedException {
        System.out.println("加锁的方法2开始执行");
        Thread.sleep(2000);
        System.out.println("加锁的方法2执行结束");
    }

    public static void main(String[] args) {
        Test obj1 = new Test();
        Test obj2 = new Test();

        new Thread(() -> {
            try {
                obj1.fun1();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();

        new Thread(() -> {
            try {
                obj2.fun2();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();
    }
}

效果：

image.png