Why does the following code throw an exception "IllegalMonitorStateException"?

Question

    synchronized (lock) {
        //lock.notifyAll();
        new Thread(() -> {
            System.out.println("同步代码块中创建线程...");
            try {
                lock.wait();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }).start();
    }

In this code : throw exception "IllegalMonitorStateException.