请教一下，为什么我无法叫醒wait的线程？
public class ThreadTest3 { public static void main(String[] args) throws InterruptedException { new MyThread(); MyThread mt = new MyThread(); Thread t = new Thread(mt); t.start(); for(int i = 0;i < 20; i++){ System.out.println("我是主线程。i: " + i); Thread.sleep(1000); if(i == 10){new MyThread().call();} } } }class MyThread implements Runnable{ Thread th1; public void run() { for(int i = 0;i < 10;i++){ System.out.println("我是二线程。i: " + i); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } if(i == 5){ wat(); } } } public synchronized void call() notifyAll(); } public synchronized void wat(){ try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } } }public class ThreadTest3 { public static void main(String[] args) throws InterruptedException { new MyThread(); MyThread mt = new MyThread(); Thread t = new Thread(mt); t.start(); for(int i = 0;i < 20; i++){ System.out.println("我是主线程。i: " + i); Thread.sleep(1000); if(i == 10){ mt.call(); } } } }class MyThread implements Runnable{ public void run() { for(int i = 0;i < 10;i++){ System.out.println("我是二线程。i: " + i); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } if(i == 5){ this.wat(); } } } public synchronized void call(){ this.notifyAll(); } public synchronized void wat(){ try { this.wait(); } catch (InterruptedException e) { e.printStackTrace(); } }