這是一個生產者和消費者的例子。消費者從倉庫取物品，生產者向倉庫增加商品。

當商品說達到最大時，不能繼續增加商品，應該通知其他線程去取商品。

同樣，當倉庫商品為空時，無法取商品，而是通知其他線程增加商品。

這裏用到線程的兩個常用的方法：notifyAll和wait方法。

package code.thread;
//Product and Custom
public class ProAndCus {
    public static void main(String[] args) {
        Store store = new Store(10);
        Custom custom 
 
= new Custom(store);
        Product product = new Product(store);
        Custom custom2 = new Custom(store);
        Product product2 = new Product(store);
        
        custom.start();
        product.start();
        custom2.start();
        product2.start();
    }
}
//商品倉庫
class Store {
    //最大儲存商品數
 

    private final int MAX_SIZE;
    //當前商品數
    private int count;
    
    public Store(int size) {
        MAX_SIZE = size;
        count = 0;
    }
    
    //增加商品
    public synchronized void add() {
        if(count>=MAX_SIZE) {
            System.out.println(Thread.currentThread().getName()+"  Store is full, please to get. count:"+count);
            
 
try{
                this.wait();
            }catch(InterruptedException e) {
                e.printStackTrace();
            }
        }else{
            System.out.println(Thread.currentThread().getName()+" custom :current count: "+count);
            count++;
            this.notifyAll();
        }
    }
    
    //移除商品
    public synchronized void remove() {
        if(count<=0) {
            System.out.println(Thread.currentThread().getName()+"  Store is empty,please input.  count:"+count);
            try{
                this.wait();
            }catch(InterruptedException e){
                e.printStackTrace();
            }
        }else{
            count--;
            System.out.println(Thread.currentThread().getName()+"  product: current count: "+count);
            this.notifyAll();
        }
    }
}
//消費者
class Custom extends Thread {
    Store store;
    public Custom(Store store) {
        this.store = store;
    }
    @Override
    public void run() {
        while(true){
            store.remove();
            try {
                Thread.sleep(1500);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}
//生產者
class Product extends Thread {
    Store store;
    public Product(Store store) {
        this.store = store;
    }
    
    @Override
    public void run() {
        while(true){
            store.add();
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

多線程簡單實例（2）生產者和消費者