volatile
volatile关键字具有可见性和有序性，但是不具有原子性。
public class VolatileTestDemo {
public static volatile int _longVal = 0;
private static int NUM = 10000000;
public static void main(String[] args) {
Thread t1 = new Thread(new LoopVolatile());
t1.start();
Thread t2 = new Thread(new LoopVolatile());
t2.start();
while (t1.isAlive() || t2.isAlive()) {
}
// 期待 20000000
System.out.println("final val is: " + _longVal);
System.out.println("\nvolatile不具有原子性 \n");
}
private static class LoopVolatile implements Runnable {
public void run() {
long val = 0;
while (val < NUM) {
_longVal++;
val++;
}
}
}
}
结果如下
每次执行结果都不同
