同步

川长思鸟来 2022-08-09 09:27 109阅读 0赞

package comm;
    
    class Res { 
        String name;
        String sex;
    }
    
    class Input implements Runnable { 
        private Res r;
    
        public Input(Res r) {
            this.r = r;
        }
    
        public void run() {
            int x = 0;
            while (true) {
    
                synchronized (r) {  //注意，两个线程加的锁应该是一样的，否则依然不同步，
                    if (x == 0) {
                        r.name = "mike";
                        r.sex = "man";
                    } else {
                        r.name = "丽丽";
                        r.sex = "女女女";
                    }
                    x = (x + 1) % 2;
                }
            }
        }
    }
    
    class Output implements Runnable { 
        private Res r;
    
        public Output(Res r) {
            this.r = r;
        }
    
        public void run() {
            while (true)
                synchronized (r) {
                    System.out.println(r.name + " , " + r.sex);
                }
        }
    }
    
    public class InputOutoutDemo { 
    
        public static void main(String[] args) {
    
            Res r = new Res();
            Input in = new Input(r);
            Output out = new Output(r);
            Thread t1 = new Thread(in);
            Thread t2 = new Thread(out);
            t1.start();
            t2.start();
        }
    }

加的同步锁是Res r，确保两个线程的锁是同一个。

可能的输出结果是

mike , man
    mike , man
    mike , man
    mike , man
    mike , man
    mike , man
    mike , man
    mike , man
    mike , man
    mike , man
    丽丽 , 女女女
    丽丽 , 女女女
    丽丽 , 女女女
    丽丽 , 女女女

虽然输出没有出现不同步现象，但是并不是期望中的`mike , man`，`丽丽 , 女女女` 交替出现。