Java中Runnable和Thread的区别

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为什么用Runnable接口，好处如下：

1. 实现 Runnable 接口可以避免Thread单继承的问题，给你这个Runnable 再继承一次的机会

2. Runnable接口可以实现变量共享，如下卖票的例子 tickets 变量全局共享

public class SellTickets implements Runnable{private int tickets = 5;Object obj = new Object();public SellTickets() {// TODO Auto-generated constructor stub}public void run() {// TODO Auto-generated method stubwhile(true){synchronized (obj) {if(tickets>0){   <span style="color:#FF0000;">//共享资源的判断都要放在同步块里</span>--tickets; System.out.println(Thread.currentThread().getName() +"there were " + tickets +" left");obj.notify();try {obj.wait();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}//System.out.println(Thread.currentThread().getName() +" whoami");}else{obj.notify(); <span style="color:#FF0000;">// 注意这边一定要 notify，不然倒数第二个线程 在wait后没有线程唤醒它</span>break;}}}}public static void main(String[] args) {Runnable st1 = new SellTickets();Thread t1 = new Thread(st1);Thread t2 = new Thread(st1);Thread t3 = new Thread(st1);t1.start();t2.start();t3.start();}}

output:

Thread-0there were 4 left
Thread-2there were 3 left
Thread-1there were 2 left
Thread-2there were 1 left
Thread-0there were 0 left

生产者消费者代码

public class ProducerConsumerTest {

   public static void main(String[] args) {
       // TODO Auto-generated method stub
       BreadStore bstore = new BreadStore();
       Runnable p = new Producer(bstore);
       Runnable c = new Consumer(bstore);
       Thread t1 = new Thread(p);
       Thread t2 = new Thread(p);
       Thread t3 = new Thread(p);
       t1.start();
       t2.start();
       t3.start();

       Thread c1 = new Thread(c);
       Thread c2 = new Thread(c);
       Thread c3 = new Thread(c);
       c1.start();
       c2.start();
       c3.start();
   }
}

class Producer implements Runnable{
   private BreadStore breadstore = null;
   public Producer(BreadStore breadstore){
       this.breadstore = breadstore;
   }


   void produce(){
       String tname = Thread.currentThread().getName();
       breadstore.produce(tname);
   }

   public void run() {
       while(true){
           try {
               Thread.sleep(1000); //sleep 可以让cpu 分配资源可以其他线程，而不用 sync wait notifys
           } catch (InterruptedException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
           }
           produce();
       }

   }
}

class Consumer implements Runnable{
   private BreadStore breadstore = null;

   public Consumer(BreadStore breadstore){
       this.breadstore = breadstore;
   }


   void get(String tname){
       breadstore.get(tname);
   }

   public void run() {
       while(true){
           try {
               Thread.sleep(1000); //模拟生产或者消费时间时间可以随机
           } catch (InterruptedException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
           }
           String tname = Thread.currentThread().getName();
           get(tname);
       }

   }
}

class BreadStore{
   int size = 0;
   final int capability = 30;
   synchronized void produce(String tname){
       if (size < capability){
           System.out.println(tname + "just produce a bread: " + ++size + " loaves of bread remained");
       }else {
           System.out.println(tname + "we have enough breads");
       }
   }
   synchronized void get(String tname){
       if(size > 0){
           System.out.println(tname + "just get a bread:" + --size + " loaves of bread remained");
       }else{
           System.out.println(tname + "there is no bread left");
       }
   }
}

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