老师我做力扣有道题我是通过volatile来控制并发访问的1114. 按序打印 但是volatile使用static修饰后为什么答案错误了想了好久没想明白

private volatile int flag = 1;

class Foo {
    /**
     * 线程 A   无需条件即可执行
     * 线程 B   flag = 2 可执行
     * 线程 C   flag = 3 可执行
     */
    private volatile int flag = 1;
    public Foo(){}
    public void first(Runnable printFirst) throws InterruptedException {
        printFirst.run();
        //标记线程2可以开始运行
        flag = 2;
    }
    public void second(Runnable printSecond) throws InterruptedException {
        //不满足空循环
        while (flag != 2){}
        printSecond.run();
        //标记线程3可以开始运行
        flag = 3;
    }
    public void third(Runnable printThird) throws InterruptedException {
        //不满足空循环
        while (flag != 3){}
        printThird.run();
    }
}

private static volatile int flag = 1;

class Foo {
    /**
     * 线程 A   无需条件即可执行
     * 线程 B   flag = 2 可执行
     * 线程 C   flag = 3 可执行
     */
    private static volatile int flag = 1;
    public Foo(){}
    public void first(Runnable printFirst) throws InterruptedException {
        //标记线程2可以开始运行
        printFirst.run();
        flag = 2;
    }
    public void second(Runnable printSecond) throws InterruptedException {
        //不满足空循环
        while (flag != 2){}
        printSecond.run();
        flag = 3;
    }
    public void third(Runnable printThird) throws InterruptedException {
        //不满足空循环
        while (flag != 3){}
        printThird.run();
    }
}