java基础线程问题求解！

Question

为什么线程Consume 必须用构造啊？我把它改成new的形式就好使，谁能给我解释一下，谢谢！

public class PC {
    public static void main(String[] args) {
        Factory f = new Factory();
        Producer p = new Producer(f);
        Consume c = new Consume();
        new Thread(p).start();
        new Thread(c).start();
        
    }

}

//商品,货物
class Goods {
    int id;

    public Goods(int id) {
        this.id = id;
    }

    // 重写toString方法
    public String toString() {
        return "Goods : " + id;
    }
}

class Factory {
    // 记录物品个数
    int index = 0;
    Goods[] goods = new Goods[10];

    // 制造方法,每次调用，增加一个商品
    public synchronized void produce(Goods g) {
        //当容器已经满了，等待别人消费,wait，调用notify();等待别人消费后叫我再生产
        while(index == goods.length){
            try {
                this.wait();//Object类的wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        this.notify();
        goods[index] = g;
        index++;
    }

    // 消费方法
    public Goods consume() {
        synchronized (this) {
            //当容器没有商品了，等待生产者生产，自己wait，调用notify();等待别人生产后叫我去消费
            while(index == 0){
                try {
                    this.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            this.notify();
            index--;
            return goods[index];
        }
    }
}

class Producer implements Runnable {
    Factory f = null;

    public Producer(Factory f) {
        this.f = f;
    }

    public void run() {
        for (int i = 0; i < 50; i++) {
            Goods g = new Goods(i);
            f.produce(g);
            System.out.println("生产了:" + g);
            try {//生产一个睡一会儿
                Thread.sleep((int) (Math.random() * 200));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

}

class Consume implements Runnable {
    Factory f = null;
//  public Consume(Factory f){
//      this.f = f;
//  }
    public void run() {
        for (int i = 0; i < 50; i++) {
            Goods g = new Goods(i);
             f = new Factory();
            f.consume();
            System.out.println("我消费了：" + g);
            try {
                Thread.sleep((int) (Math.random() * 1000));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

Answer 1

[quote]
为什么线程Consume 必须用构造啊？
[/quote]

其实你问的问题与多线程无关。你的good实例是facotry#produce方法产生的，good的消费是facotry#consume方法消费的。你的线程无论是Producer还是Consume，都是通过调用facotry实例的相应方法来运行。所以你必须要传入facotry实例，要不然，他怎么知道是哪个facotry实例生产了good，你要消费哪个facotry实例的good