java - 同时运行两个线程

Question

我正在尝试同时打印两个线程的名称。任何人都可以建议我做错了什么吗？我收到“IllegalMonitorStateException

//奇数线程可运行 公共(public)类 OddThread 实现 Runnable {

    MainClass obj;
    public OddThread(MainClass obj) {
        // TODO Auto-generated constructor stub
        this.obj= obj;
    }
    public void run() {
        int number=1;
        while(number <10)
        {
          obj.PrintNumbers();
          notifyAll();
          try {
            wait();
        } catch (InterruptedException e) {System.out.println("Exception in wait of OddThread");
        }
          number = number+2;

        }

    }

}

//即使线程可运行

public class EvenThread implements Runnable{

    MainClass obj;
    public EvenThread(MainClass obj)
    {
        this.obj=obj;
    }
    public void run() {
        int number=0;
        while(number<=10)
        {
          obj.PrintNumbers();
          notifyAll();
          try {
            wait();
        } catch (InterruptedException e) {
            System.out.println("Exception in wait of EvenThread");
        }
       number = number+2;
        }

    }

}

//主类

public class MainClass {
   public static void main(String[] args)
   {
       MainClass obj = new MainClass();
      // Boolean flag= true;
       EvenThread evenThread = new EvenThread(obj);
       OddThread oddThread = new OddThread(obj);
       Thread Even = new Thread(evenThread);
       Thread Odd = new Thread(oddThread);
       Even.setName("Even Thread");
       Odd.setName("Odd Thread");
       Even.start();
       Odd.start();
   }

   public synchronized void PrintNumbers()
   {
       System.out.println(Thread.currentThread().getName());
   }

}

我得到的输出是偶数线程奇数线程线程“偶数线程”中的异常 线程“奇数线程”中的异常 java.lang.IllegalMonitorStateException

Answer 1

您应该将 notifyAll() 和 wait() 包含在 synchronized (this) {} 中像:

synchronized (this) {
    notifyAll();
}

和

synchronized (this) {
    wait();
}

这些方法 notify()、notifyAll()、wait() 只能由该方法的所有者的线程调用对象的监视器，因此您必须将它们包围在同步块(synchronized block)中，如所述 Here the Object Java doc