如何在java类中等待活动完成后再继续？

public class WaitAndNotifyExample {
    private static final Object lock = new Object();
    private static boolean activityCompleted = false;

    public static void main(String[] args) {
        Thread waitingThread = new Thread(() -> {
            synchronized (lock) {
                while (!activityCompleted) {
                    try {
                        lock.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                // 活动完成后继续执行的代码
                System.out.println("Activity completed. Continue execution.");
            }
        });

        Thread activityThread = new Thread(() -> {
            // 模拟活动的耗时操作
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (lock) {
                activityCompleted = true;
                lock.notifyAll();
            }
        });

        waitingThread.start();
        activityThread.start();
    }
}