Detailed explanation of the operation code to wake up notifyAll in Java thread

package TestThread.ThreadSynchronized;
public class TestWaitAll {
 public static void main(String[] args) {
  Test1 test1 = new Test1();
  Thread t = new Thread(test1, "线程1");
  Thread t1 = new Thread(test1, "线程2");
  Thread t2 = new Thread(test1, "线程3");
  Test2 test2 = new Test2(test1, "唤醒线程");
  t.start();
  t1.start();
  t2.start();
  try {
   Thread.sleep(2000);
  } catch (InterruptedException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  test2.start();
 }
}
class Test1 implements Runnable {
 public void run() {
  synchronized (this) {
   try {
    this.wait();
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
   System.out.println(Thread.currentThread().getName() + "当前没有被执行到！");
  }
 }
}
class Test2 extends Thread {
 private Test1 test1;
 String name;
 public Test2(Test1 test1, String name) {
  super(name);
  this.name = name;
  this.test1 = test1;
 }
 public void run() {
  synchronized (test1) {
   test1.notifyAll();// 针对当前对象执行唤醒所有线程的操作
   System.out.println(Thread.currentThread().getName() + ":唤醒线程执行成功！");
  }
 }
}