synchronized 锁的是方法还是对象还是类？测试实例

package com.swt.lock;

public class Test02 {
    public static void main(String[] args) throws InterruptedException {
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                SyncMethod syncMethod = new SyncMethod();
                syncMethod.sysn1();
            }
        });
        thread.start();
        thread = new Thread(new Runnable() {
            @Override
            public void run() {
                SyncMethod syncMethod = new SyncMethod();
                syncMethod.sysn2();
            }
        });
        thread.start();
        thread.join();
    }
}

class SyncMethod {
    public synchronized void sysn1() {
        for (int i = 0; i < 100; i++) {
            System.out.println("sysn1 " + i);
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    public synchronized void sysn2() {
        for (int i = 0; i < 100; i++) {
            System.out.println("sysn2 " + i);
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

　　输出结果可以看到，两个线程是交替执行。

sysn1 0
sysn2 0
sysn2 1
sysn1 1
sysn2 2
sysn1 2
sysn2 3
sysn1 3
sysn2 4

　　

package com.swt.lock;

public class Test02 {
    public static void main(String[] args) throws InterruptedException {
        SyncMethod syncMethod = new SyncMethod();
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                syncMethod.sysn1();
            }
        });
        thread.start();
        thread = new Thread(new Runnable() {
            @Override
            public void run() {
                syncMethod.sysn2();
            }
        });
        thread.start();
        thread.join();
    }
}

class SyncMethod {
    public synchronized void sysn1() {
        for (int i = 0; i < 100; i++) {
            System.out.println("sysn1 " + i);
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    public synchronized void sysn2() {
        for (int i = 0; i < 100; i++) {
            System.out.println("sysn2 " + i);
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

　　输出结果可以看到，两个线程是顺序执行

sysn1 0
sysn1 1
sysn1 2
...
sysn1 98
sysn1 99
sysn2 0
sysn2 1
sysn2 2
sysn2 3