java - 在 Java 中用两个线程打印数字 1-20

Question

我正在尝试用两个线程打印数字 1-20:

• 偶数线 - 仅打印偶数。
• 奇数线程 - 仅打印奇数。

我还有一个用于同步的锁对象。

我的应用程序卡住了。你能告诉我问题出在哪里吗？

我的代码:

public class runIt
{

    public static void main(String[] args)
    {
        Odd odd = new Odd("odd thread");
        Even even = new Even("even thread");

        odd._t.start();
        even._t.start();

        try{
            odd._t.join();
            even._t.join();
        }
        catch (InterruptedException e){
            System.out.println(e.getMessage());
        }   
    }
}

<小时/>

public class Constants{
    static Object lock = new Object();
}

<小时/>

public class Even implements Runnable{
    Thread  _t;
    String  _threadName;

    public Even(String threadName){
        _threadName = threadName;
        _t = new Thread(this);
    }

    @Override
    public void run(){
        for (int i = 0; i < 20; i++){
            if (i % 2 == 0){
                synchronized (Constants.lock){                  
                    try{
                        Constants.lock.wait();
                        Constants.lock.notifyAll();
                    }
                    catch (InterruptedException e){
                        e.printStackTrace();
                    }
                    System.out.println(_threadName + " " + i + " ");
                }
            }
        }
    }
}

<小时/>

public class Odd implements Runnable{
    Thread  _t;
    String  _threadName;

    public Odd(String threadName){
        _threadName = threadName;
        _t = new Thread(this);

    }

    @Override
    public void run(){
        for (int i = 0; i < 20; i++){
            if (i % 2 == 1){
                synchronized (Constants.lock){                  
                    try{
                        Constants.lock.wait();
                        Constants.lock.notifyAll();
                    }
                    catch (InterruptedException e1){
                        e1.printStackTrace();
                    }
                    System.out.println(_threadName + " " + i + " ");
                }
            }
        }
    }
}

我的输出应该是:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

感谢您的帮助， 谭。

Answer 1

您可以在包声明中提到的站点中找到解释: 这是工作代码:

public class MultipleThreading {
    int count = 1;
    int MAX = 20;

    public void printOdd() {
    synchronized (this) {
        while (count < MAX) {
        while (count % 2 == 0) {
            try {
            wait();
            } catch (InterruptedException e) {
            e.printStackTrace();
            }
        }
        System.out.print(count + " ");
        count++;
        notify();
        }
    }
    }

    public void printEven() {
    synchronized (this) {
        while (count < MAX) {
        while (count % 2 == 1) {
            try {
            wait();
            } catch (InterruptedException e) {
            e.printStackTrace();
            }
        }
        System.out.print(count + " ");
        count++;
        notify();
        }
    }
    }

    public static void main(String[] args) {
    MultipleThreading mt = new MultipleThreading();
    Thread t1 = new Thread(new Runnable() {
        @Override
        public void run() {
        mt.printEven();
        }
    });
    Thread t2 = new Thread(new Runnable() {
        @Override
        public void run() {
        mt.printOdd();
        }
    });
    t1.start();
    t2.start();
    }
}