JUC-多线程锁Synchronized锁的八种情况2

缺乏、安全感 2024-04-06 12:43 69阅读 0赞

**情况3---加一个普通方法，此时不加时间延时**

package com.nanjing.juc;
    
    class Phone12 {
    
        public synchronized void sendSMS() throws Exception {
            //TimeUnit.SECONDS.sleep(4);//或者Thread.sleep(4000);
            System.out.println(Thread.currentThread().getName()+"---发短信---sendSMS");
        }
    
    
        //这里没有锁，不是同步方法，不受锁的影响
        public void getHello(){
            System.out.println(Thread.currentThread().getName()+"------getHello");
        }
    }
    
    public class ThreadDemo_12 {
    
        public static void main(String[] args) throws Exception {
    
            Phone12 phone12 = new Phone12();
    
            new Thread(() -> {
                try {
                    phone12.sendSMS();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }, "AA").start();
    
            Thread.sleep(100);
    
            new Thread(() -> {
                try {
                    phone12.getHello();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }, "BB").start();
        }
    }

![1dbc99b5947b4390a9178e570959aeef.png][]

因为AA线程先执行sendSMS方法，先调用先执行！

所以先打印了AA---发短信---sendSMS

后执行getHello方法，打印BB------getHello

--------------------

package com.nanjing.juc;
    
    import java.util.concurrent.TimeUnit;
    
    class Phone12 {
    
        public synchronized void sendSMS() throws Exception {
            TimeUnit.SECONDS.sleep(4);//或者Thread.sleep(4000);
            System.out.println(Thread.currentThread().getName()+"---发短信---sendSMS");
        }
    
    
        //这里没有锁，不是同步方法，不受锁的影响
        public void getHello(){
            System.out.println(Thread.currentThread().getName()+"------getHello");
        }
    }
    
    public class ThreadDemo_12 {
    
        public static void main(String[] args) throws Exception {
    
            Phone12 phone12 = new Phone12();
    
            new Thread(() -> {
                try {
                    phone12.sendSMS();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }, "AA").start();
    
            Thread.sleep(100);
    
            new Thread(() -> {
                try {
                    phone12.getHello();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }, "BB").start();
        }
    }

![878b3c034fbe411cbd513aa375f45147.png][]

如果加了延时4S，则AA线程在原地等待4秒后再打印，BB线程比AA线程

快，早就打印出了BB------getHello

总结：

getHello是一个普通方法，不受 synchronized锁的影响，不用等待锁释放。

[1dbc99b5947b4390a9178e570959aeef.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/56917aabbf224690b92e9fd0d5a9cdd7.png
[878b3c034fbe411cbd513aa375f45147.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/3ed168ca40ec409eacf78c94195b8e62.png