22.0 多线程的加锁与通信

蚂蚁吃蛋糕

package study;

class Cake implements Runnable{
	int count = 10;
	
	public void run() {
		while(true) {
			if(count>2) {
			if(Thread.currentThread().getName().equals("一号")) {
				eat();
			}else if(Thread.currentThread().getName().equals("二号")) {
				eat();
			}
			}else {
				break;
			}
		}
	}
	public synchronized void eat() {
		System.out.println(Thread.currentThread().getName()+"得到");
		count=count-2;
	}
}


public class Exercise {

	public static void main(String[] args) {
		Cake c = new Cake();
		Thread t1 = new Thread(c,"一号");
		Thread t2 = new Thread(c,"二号");
		t1.start();
		t2.start();
	}

}

有100个窗口卖500张车票

package study;

import javax.sound.midi.Track;

class K395 implements Runnable{
	int ticket=500;
	int k=0,a=0;//a为车厢.k为号码
	public void run() {
		while(true) {
			if(ticket==0) {
				System.out.println("票已全部售完");
				break;
			}else{
				buy();
			}
		}
	}
	public synchronized void buy() {
		if(ticket>0) {
			ticket--;
			k++;
			if(k==61) {
				a++;
				k=1;
			}
			System.out.println(Thread.currentThread().getName()+"售出一张车票，座位号是："+a+"车厢"+k+"号， 还余"+ticket+"张票。");
		}
	}
}

public class exercise {
	public static void main(String[] args) {
		K395 k=new K395();
		Thread[] T=new Thread[100];
		for(int i=0;i<T.length;i++) {
			T[i]=new Thread(k,"窗口"+i);
			T[i].start();
		}
	}
}

到包子店买包子,但店家没有零钱

package study;
class Shop implements Runnable{
	int five=0,ten=0,twenty=0;
	public void run() {
		if(Thread.currentThread().getName().equals("一号")) {
			buy(20);
		}else if(Thread.currentThread().getName().equals("二号")) {
			buy(10);
		}else if(Thread.currentThread().getName().equals("三号")) {
			buy(5);
		}if(Thread.currentThread().getName().equals("四号")) {
			buy(5);
		}
	}
	
	public synchronized void buy(int n){
		if(n==5) {
			five++;
			System.out.println(Thread.currentThread().getName()+"得到了"+five+"***"+ten+"***"+twenty);
		}else if(n==10) {
			while(five<1) {
				try {
					wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
			ten++;
			five--;
			System.out.println(Thread.currentThread().getName()+"得到了"+five+"***"+ten+"***"+twenty);
		}else if(n==20) {
			while(five<3 && !(five>=1 && ten>=1)) {
				try {
					wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
			if(five>=3) {
				five=five-3;
				twenty++;
				System.out.println(Thread.currentThread().getName()+"得到了"+five+"***"+ten+"***"+twenty);
			}else if(five>=1&&ten>=1){
				five--;
				ten--;
				twenty++;
				System.out.println(Thread.currentThread().getName()+"得到了"+five+"***"+ten+"***"+twenty);
			}
		}
		notifyAll();
	}
}

public class Exercise {
	public static void main(String[] args) {
	Shop s = new Shop();
	Thread t1 = new Thread(s, "一号");
	Thread t2 = new Thread(s, "二号");
	Thread t3 = new Thread(s, "三号");
	Thread t4 = new Thread(s, "四号");
	t1.start();
	t2.start();
	t3.start();
	t4.start();
	try {
		t1.join();
		t2.join();
		t3.join();
		t4.join();
/*
 * thread.Join把指定的线程加入到当前线程，可以将两个交替执行的线程合并为顺序执行的线程。
 * 比如在线程B中调用了线程A的Join()方法，直到线程A执行完毕后，才会继续执行线程B。
 * join方法必须在线程start方法调用之后调用才有意义
 */
	} catch (InterruptedException e) {
		e.printStackTrace();
	}
	}

}