Question

可以在JAVA中的同一个同步方法中一起存在wait（）和notify（），并且一个线程进入synchronized方法并等待其他方法进入相同的synchronized方法并且notifyall？我需要顺序打印线程名称。使用等待和通知，我试图使用下面的代码。以下是输出响应：

等待线程5 线程主出口等待线程2 等待线程3 等待线程4 线程开始1 等待线程1

public class Printthread实现了Runnable {

Thread t ;
static int number = 1;
boolean check = true;
public Printthread(String name)
{
    t = new Thread(this,name);
    t.start();
}

@Override
public void run() {
    // TODO Auto-generated method stub
   print();     
   System.out.println(" thread EXIT " + t.getName());
}

synchronized public void print()
{
    while(Integer.parseInt(t.getName()) != number)
    {
        try {
            System.out.println(" Waiting thread  " + t.getName());
                wait();
            System.out.println(" resumed thread started " + t.getName());
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    if(Integer.parseInt(t.getName()) == number)
    {
        System.out.println(" thread started " + t.getName());
        number = number + 1;
         notifyAll();
    }

}

}

公共类ThreadMain {

/**
 * @param args
 */
public static void main(String[] args) {
    // TODO Auto-generated method stub\

    Printthread p5 = new Printthread("5");
    Printthread p2 = new Printthread("2");
    Printthread p4 = new Printthread("4");
    Printthread p3 = new Printthread("3");
    Printthread p1 = new Printthread("1");
    System.out.println("Thread main exit");

}

}

Answer 1

你的逻辑错了。同步块不在同一个对象上，因为您正在创建5个不同的Printthread对象。对于您的问题，是的，它们可以存在于同一个同步块中。这是正确的版本：

public class PrintThread implements Runnable {
    static int number = 1;
    public PrintThread() {
        Thread t1 = new Thread(this, "1");
        Thread t2 = new Thread(this, "2");
        Thread t3 = new Thread(this, "3");
        Thread t4 = new Thread(this, "4");
        Thread t5 = new Thread(this, "5");
        t1.start();
        t2.start();
        t3.start();
        t4.start();
        t5.start();
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub
        print();
        System.out.println(" thread EXIT " + Thread.currentThread().getName());
    }

    synchronized static int getNumber() {
        return number;
    }

    synchronized static void incNumber() {
        number++;
    }

    synchronized public void print() {
        while (Integer.parseInt(Thread.currentThread().getName()) != number) {
            try {
                System.out.println(" Waiting thread  " + Thread.currentThread().getName());
                wait();
                System.out.println(" resumed thread started " + Thread.currentThread().getName());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        if (Integer.parseInt(Thread.currentThread().getName()) == number) {
            System.out.println(" thread started " + Thread.currentThread().getName());
            incNumber();
            notifyAll();
        }
    }

    public static void main(String[] args) {
        new PrintThread();
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Thread main exit");
    }
}

在JAVA中，wait（）和notify（）可以在同一个同步方法中一起存在吗？

1 个答案: