Synchronized

0623_Q3捕魚.java

//店鋪
public class FishShop {
	int curFishAmount=0; // 魚當前的數量
	int containment=10000; // 可存放魚獲最大容量(10000)
	int times=0; // 交易次數
	
	public synchronized void putFish(int amount, String fisherName){
		if (curFishAmount+amount<=containment){ // 當前魚獲的存量若小於最大容量
			curFishAmount+=amount; // 入存貨
			System.out.println(fisherName + "進貨 "+ amount + " 條魚," + " 目前共有 " + curFishAmount + " 條魚.");
			try{
				Thread.sleep(50);
				notify(); // 喚醒休息的漁夫 or 買家
				wait(); // 交易一次就放出 synchronized 鎖
			}catch(InterruptedException e){}
		}
		else // 倉庫爆了就慢慢等吧
			try{
				wait();
			}catch(InterruptedException e){}
	}
	
	public synchronized void takeFish(int amount, String buyerName){
		if (curFishAmount-amount >= 0){ // 當前有存貨可以購買(不為0)
			curFishAmount-=amount; // 出貨
			System.out.println(buyerName + "買走 "+ amount + " 條魚," + " 目前剩 " + curFishAmount + " 條魚.");
			times++; // 交易次數+1
			System.out.println("一共交易 " + times + " 次。"); // 驗證交易次數
			try{
				Thread.sleep(50);
				notify(); // 喚醒休息的漁夫 or 買家
				wait(); // 交易一次就放出 synchronized 鎖
			}catch(InterruptedException e){}
		}
		else // 沒有存貨就慢慢等吧
			try{
				wait();
			}catch(InterruptedException e){}
		if (times>=100) notifyAll(); // 交易 100 次囉，還在睡覺的起床收攤回家囉
	}
}

0623_Q3捕魚_main.java

// 交易
public class Trade {
	public static void main(String[] args) {
		// 店舖開張
		FishShop shop = new FishShop();
		
		// 5 個漁夫
		Fisher f1 = new Fisher(shop,"漁夫一");
		Fisher f2 = new Fisher(shop,"漁夫二");
		Fisher f3 = new Fisher(shop,"漁夫三");
		Fisher f4 = new Fisher(shop,"漁夫四");
		Fisher f5 = new Fisher(shop,"漁夫五");
		
		// 5 個買家
		Buyer b1 = new Buyer(shop,"買家1號");
		Buyer b2 = new Buyer(shop,"買家2號");
		Buyer b3 = new Buyer(shop,"買家3號");
		Buyer b4 = new Buyer(shop,"買家4號");
		Buyer b5 = new Buyer(shop,"買家5號");

		// 5個漁夫捕魚去
		new Thread(f1).start();
		new Thread(f2).start();
		new Thread(f3).start();
		new Thread(f4).start();
		new Thread(f5).start();

		// 5個買家在逛街
		new Thread(b1).start();
		new Thread(b2).start();
		new Thread(b3).start();
		new Thread(b4).start();
		new Thread(b5).start();
	}

}

0623_Q3捕魚Buyer.java

// 買家
public class Buyer implements Runnable{
	FishShop shop; // 店舖的代表
	String buyerName; // 買家的名字
	boolean canTake = true; // 可以買嗎
	
	// 將店鋪資訊傳入
	Buyer(FishShop f, String s){
		shop = f;
		buyerName = s;
	}
	public void run() {
		while (canTake){ // 如果有存貨可以買
			shop.takeFish(1000, buyerName); // 打包帶走
			if (shop.times>=100) // 如果交易 100 次
				canTake=false; // 不給買
		}
	}
}

0623_Q3捕魚Fisher.java

// 漁夫
public class Fisher implements Runnable {
	FishShop shop; // 店舖的代表
	String fisherName; // 漁夫名字
	boolean canPut = true; // 可否繼續入倉
	
	// 將店鋪資訊傳入
	Fisher(FishShop f, String s){
		shop = f;
		fisherName = s;
	}
	public void run() {
		while (canPut){ // 如果可以繼續入倉
			shop.putFish(1000, fisherName); // 丟進倉庫
			if (shop.times==100) // 如果交易 100 次了
				canPut=false; // 不給進貨
		}
	}

}