java线程之Happens before规则案例详解

    static int x;
    static Object m = new Object();

    new Thread(()->{
         synchronized(m) {
         x = 10;
         }
    },"t1").start();

    new Thread(()->{
         synchronized(m) {
         System.out.println(x);
         }
    },"t2").start();
/*
运行结果:
10
*/

    volatile static int x;
    new Thread(()->{
     x = 10;
    },"t1").start();

    new Thread(()->{
     System.out.println(x);
    },"t2").start();
/*
运行结果:
10
*/

static int x;
x = 10;
new Thread(()->{
 System.out.println(x);
},"t2").start();
/*
运行结果:
10
*/

static int x;
Thread t1 = new Thread(()->{
 x = 10;
},"t1");
t1.start();
t1.join();
System.out.println(x);
/*
运行结果:
10
*/

static int x;
public static void main(String[] args) {
    
     Thread t2 = new Thread(()->{
         while(true) {
             if(Thread.currentThread().isInterrupted()) {
             System.out.println(x);
             break;
             }
         }
     },"t2");
     t2.start();
    
     new Thread(()->{
         sleep(1);
         x = 10;
         t2.interrupt();
     },"t1").start();
     while(!t2.isInterrupted()) {
         Thread.yield();
     }
     System.out.println(x);
}
/*
运行结果:
10
*/

    static int a;
    public static void main(String[] args) {
        new Thread(()->{
            System.out.println(a);
        }).start();

    }
/*
运行结果:
0
*/

volatile static int x;
static int y;
new Thread(()->{ 
 y = 10;
 x = 20;
},"t1").start();
new Thread(()->{
 // x=20 对 t2 可见, 同时 y=10 也对 t2 可见
 System.out.println(x); 
},"t2").start();
/*
运行结果:
20
*/