指令重排序
阿新 • • 發佈:2018-05-18
start err exceptio ada before spa boolean class ==
@Slf4j public class SimpleHappenBefore { private static int a = 0; private static boolean flag = false; public static void main(String[] args) throws InterruptedException { for (int i = 0; i < 1000; i++) { ThreadA threadA = new ThreadA(); ThreadB threadB= new ThreadB(); threadA.start(); threadB.start(); threadA.join(); threadB.join(); a = 0; flag = false; } } static class ThreadA extends Thread { @Override public void run() { //這裏的指令重排序a = 1; flag = true; } } static class ThreadB extends Thread { @Override public void run() { if (flag) { a = a * 1; } if (a == 0) { System.out.println("ha,a==0"); } } } }
指令重排序