Java多线程之synchronized关键字的使用

public synchronized void syzDemo(){
   System.out.println(System.currentTimeMillis());
    System.out.println("进入synchronized锁:syzDemo");
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

public synchronized static void syzDemo1(){
    System.out.println(System.currentTimeMillis());
    System.out.println("进入synchronized锁:syzDemo1");
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

public synchronized  void syzDemo2(){
    synchronized (this){
        System.out.println(System.currentTimeMillis());
        System.out.println("进入synchronized锁:syzDemo2");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
public synchronized  void syzDemo3(){
   synchronized (excelUtil.class){
       System.out.println(System.currentTimeMillis());
       System.out.println("进入synchronized锁:syzDemo3");
       try {
           Thread.sleep(1000);
       } catch (InterruptedException e) {
           e.printStackTrace();
       }
   }
}

public static void main(String[] args) {
        SyzDemo syzDemo = new SyzDemo();
        SyzDemo syzDemo1 = new SyzDemo();
        Thread thread = new Thread(()->{
            syzDemo.syzDemo();
        });
        thread.start();
        Thread thread1 = new Thread(()->{
            syzDemo1.syzDemo();
        });
        thread1.start();
    }

public static void main(String[] args) {
        SyzDemo syzDemo = new SyzDemo();
        SyzDemo syzDemo1 = new SyzDemo();
        Thread thread = new Thread(()->{
            syzDemo.syzDemo();
        });
        thread.start();
        Thread thread1 = new Thread(()->{
            syzDemo.syzDemo();
        });
        thread1.start();
    }

public static void main(String[] args) {
        SyzDemo syzDemo = new SyzDemo();
        SyzDemo syzDemo1 = new SyzDemo();
        Thread thread = new Thread(()->{
            syzDemo.syzDemo1();
        });
        thread.start();
        Thread thread1 = new Thread(()->{
            syzDemo1.syzDemo1();
        });
        thread1.start();
    }