新人问一下 Java 多线程的问题。

class Hero {
  private String name;
  public int hp = 10;

  public Hero(String str) {
    this.name = str;
  }

  public synchronized void recover() {
    this.hp += 1;
  }

  public synchronized void hurt() {
    this.hp -= 1;
  }
}

public class Test {
  public static void main(String[] args) {
    Hero garen = new Hero("garen");

    // 线程一
    new Thread(() -> {
      System.out.println(Thread.currentThread().getName() + "....");
      while (true) {
        while (garen.hp == 1) {
          continue;
        }
        try {
          Thread.sleep(200);
          garen.hurt();
          System.out.println(Thread.currentThread().getName() + "..." + "hp down-" + garen.hp);
        } catch (InterruptedException e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
        }
      }
    }).start();

    // 线程二
    new Thread(() -> {
      while (true) {
        if (garen.hp == 20) {
          continue;
        }
        try {
          Thread.sleep(400);
          garen.recover();
          System.out.println(Thread.currentThread().getName() + "....." + "hp up-" + (garen.hp));
        } catch (InterruptedException e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
        }
      }
    }).start();
  }
}

为什么线程一不执行了？是因为没有更新 garen.hp 的值吗？