java中synchronized可见性问题

Question

java中synchronized可见性问题
同步代码块不是说能保证可见性吗 怎么还线程0感知不到total=1

Answer 1

package csdn20230129;

/**
 * @Description
 * @Author wangFei
 * @Date 2023/1/30 10:15
 * @Version 1.0
 **/
public class Test {
    int total = 0;
    public static void main(String[] args) throws InterruptedException {
        Test test = new Test();
        test.a();

        test.b();
    }

    public synchronized void a() {
        new Thread(() -> {
            System.out.println("a线程 " + Thread.currentThread().getName() + " 执行");
            synchronized (this) {
                while (total == 0);
                System.out.println("a-1-end");
            }
        }).start();
    }

    public synchronized void b() {
        new Thread(() -> {
            System.out.println("b线程 " + Thread.currentThread().getName() + " 执行");
            total = 1;
            System.out.println("b线程 " + Thread.currentThread().getName() + " 执行完毕，当前total=" + total);
        }).start();
    }
}