jave線程間通信

買賣商品來介紹：賣家首先要進貨上架商品；等待客人來買；客人把商品買完了，需要等待賣家進貨上架商品；如此循環

首先建一個代表商品的對象

public class CommondityEntity {

    private int num = 0;
    private String name = "杯子";

    public int getNum() {
        return num;
    }


    public synchronized void add(){
        ++num;
    }
    public synchronized void reduce(){
        --num;
    }
}

代表商人的線程類

public class Merch extends Thread {


    private CommondityEntity ce;

    public Merch(CommondityEntity ce) {
        this.ce = ce;
    }

    @Override
    public void run() {
        synchronized (ce) {
            try {
                super.run();
                while (true) {

                    if (ce.getNum() == 1) {
                        //進貨了，庫存已滿，等待賣出
                        ce.wait();
                    }
                    if (ce.getNum() == 0) {
                        ce.add();
                        //通知買家進貨了
                        ce.notify();
                        System.out.println("商家進貨了！現產品庫存爲" + ce.getNum() + " 等待賣出！！！");
                    }
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

代表買家的類

public class Client extends Thread {


    private CommondityEntity ce;

    public Client(CommondityEntity ce) {
        this.ce = ce;
    }


    @Override
    public void run() {
        synchronized (ce) {
            try {

                super.run();
                while (true) {
                    if (ce.getNum() == 0) {
                        //賣家的貨物已經賣光，等待商家進貨才能繼續購買
                        ce.wait();
                    }
                    if (ce.getNum() == 1) {
                        ce.reduce();
                        //通知賣家沒貨了，需要進貨  -- 喚醒線程
                        ce.notifyAll();
                        System.out.println(this.getName()+" 購買了一件商品！現產品庫存爲" + ce.getNum() + " 等待商家進貨");
                        Thread.sleep(1000);
                    }
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

 

測試：

public static void main(String[] args) {
        CommondityEntity ce = new CommondityEntity();
        Thread t = new Client(ce);
        t.setName("買家1");
        Thread t3 = new Client(ce);
        t3.setName("買家2");
        Thread t2 = new Merch(ce);
        t.start();
        t2.start();
        t3.start();
}