java多线程：No enclosing instance of type ProducerConsumer is accessible. Must qualify the allocation with an enclosing instance o

最新推荐文章于 2023-05-27 09:53:43 发布

lpp014

最新推荐文章于 2023-05-27 09:53:43 发布

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文章标签： allocation 多线程 java thread string class

本文链接：https://blog.youkuaiyun.com/lpp014/article/details/5607460

本文通过Java代码展示了生产者消费者模式的实现过程。利用多线程技术，模拟了采石场生产石头并由车辆消费的过程。通过同步队列保证生产和消费的同步进行。

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public class ProducerConsumer{ 

 /**
  * @param args
  */ 
 class Car implements Runnable{
  Belt belt=null;
  boolean flag=true;
  public Car(Belt belt){
   this.belt=belt;
  }
  public void consumer(){
   try{
    Thread.sleep((int)(100*Math.random()));
   }catch(InterruptedException e){
    e.printStackTrace();
   }
   Stone stone=belt.deQueue();
   if(stone!=null)
    System.out.println(Thread.currentThread().getName()+"consumer"+stone.number+"stone");
  }
  public void run(){
   while(flag){
    consumer();
   }
  }
  public void shutdown(){
   flag=false;
  }
 }
 class QuarryingMachine implements Runnable{
        int number=0;
        Belt belt=null;
        String who;
        boolean flag=true;
        public QuarryingMachine(Belt belt){
         this.belt=belt;
        }
        public void producer(){
         try{
       Thread.sleep((int)(100*Math.random()));
      }catch(InterruptedException e){
       e.printStackTrace();
      }
         belt.enQueue(new Stone(Thread.currentThread().getName(),++number));
         System.out.println(Thread.currentThread().getName()+"produce"+number+" stone");
        }
        public void run(){
         while(flag)
          producer();
        }
        public void shutdown(){
         flag=false;
        }
 }
 class Belt{
  public static final int N0=10+1;
  Stone[] queue=new Stone[N0];
  int front=0,rear=0;
  public synchronized void enQueue(Stone stone){
   while((rear+1)%N0==front)
    try{ 
        wait();
    }catch(InterruptedException e){
     e.printStackTrace();
    }
    queue[rear]=stone;
    rear=(rear+1)%N0;
    notifyAll();
  }
  public synchronized Stone deQueue(){
   while(rear==front){
    try {
     wait();
    }catch(InterruptedException e){
     e.printStackTrace();
    }
   }
    Stone stone=queue[front];
    front=(front+1)%N0;
    notifyAll();
    return stone;
  }
 }
 class Stone{
  String who;
  int number;
  public Stone(String who,int  number){
   this.who=who;
   this.number=number;
  }
 }
 public static void main(String[] args) {
  Belt belt=new Belt();
  Car car=new Car(belt);
  QuarryingMachine q=new QuarryingMachine(belt);
  Thread car1=new Thread(car,"zhang");
  Thread car2=new Thread(car,"li");
  //Thread car3=new Thread(car,"wang");
  car1.start();
  car2.start();
  //car3.start();
  Thread q1=new Thread(car,"wang");
  Thread q2=new Thread(car,"werda");
  Thread q3=new Thread(car,"kgjh");
  q1.start();
  q2.start();
  q3.start();
  try{
   Thread.sleep(1000);
  }catch(InterruptedException e){
   e.printStackTrace();
  }
  car.shutdown();
  q.shutdown();
 } 
}
这是因为ProducerConsumer是一个动态的内部类，创建这样的对象必须有实例与之对应，程序是在静态方法中直接调用动态内部类会报这样错误。这样的错误好比类中的静态方法不能直接调用动态方法。可以把该内部类声明为static。或者不要在静态方法中调用。
那么为什么非静态方法不能调用动态方法呢，从面向对象的角度来说，动态方法与对象是联系密切的，比如发动是一个方法，它与汽车这个对象是关联的，所以只有new了汽车这个对象才能执行汽车.发动
比如本程序只需首先建个ProducerConsumer对象即可。
ProducerConsumer p=new ProducerConsumer();
Belt belt=p.new Belt();
Car car=p.new Car(belt);
QuarryingMachine q=p.new QuarryingMachine(belt);