线程交替打印A1B2C3实现二（wait/notify + synchronized）

问：线程如何交替打印A1B2C3？通过wait/notify + synchronized 实现。

import java.util.concurrent.TimeUnit;

public class WaitNotifyTest {

  public static void main(String[] args) {

    Object obj = new Object();

    new Thread(() -> {
      synchronized (obj) {
        for (char i = 'A'; i <= 'Z'; i++) {
          System.out.println(Thread.currentThread().getName() + "======== " + i);
          obj.notify();
          try {
            obj.wait();
            TimeUnit.SECONDS.sleep(1);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
        }
      }
    }, "thread-A").start();

    new Thread(() -> {
      synchronized (obj) {
        for (int i = 1; i <= 26; i++) {
          System.out.println(Thread.currentThread().getName() + "======== " + i);
          obj.notify();
          try {
            obj.wait();
            TimeUnit.SECONDS.sleep(1);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
        }
      }
    }, "thread-1").start();
  }
}