Detailed explanation of examples of java producers and consumers-javaTutorial-php.cn

Detailed explanation of examples of java producers and consumers

Y2J

Release： 2017-05-06 13:22:53

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The main example of this article analyzes the method of producer-consumer problem in Java. Friends who need it can refer to it

The producer and consumer problem is a classic problem in the thread model: producer and Consumers share the same storage space during the same time period. As shown in the figure below, the producer stores data in the space and the consumer retrieves the data. If no coordination is done, the following situations may occur:

Storage The space is full, and producers occupy it. Consumers wait for producers to make space and thereby remove products. Producers wait for consumers to consume products, thereby adding products to the space. Wait for each other, resulting in a deadlock.

The following example demonstrates how to solve the producer/consumer problem through threads:

/*
 author by w3cschool.cc
 ProducerConsumerTest.java
 */
public class ProducerConsumerTest {
  public static void main(String[] args) {
   CubbyHole c = new CubbyHole();
   Producer p1 = new Producer(c, 1);
   Consumer c1 = new Consumer(c, 1);
   p1.start(); 
   c1.start();
  }
}
class CubbyHole {
  private int contents;
  private boolean available = false;
  public synchronized int get() {
   while (available == false) {
     try {
      wait();
     }
     catch (InterruptedException e) {
     }
   }
   available = false;
   notifyAll();
   return contents;
  }
  public synchronized void put(int value) {
   while (available == true) {
     try {
      wait();
     }
     catch (InterruptedException e) { 
     } 
   }
   contents = value;
   available = true;
   notifyAll();
  }
}
class Consumer extends Thread {
  private CubbyHole cubbyhole;
  private int number;
  public Consumer(CubbyHole c, int number) {
   cubbyhole = c;
   this.number = number;
  }
  public void run() {
   int value = 0;
     for (int i = 0; i < 10; i++) {
      value = cubbyhole.get();
      System.out.println("消费者 #" + this.number+ " got: " + value);
     }
  }
}
class Producer extends Thread {
  private CubbyHole cubbyhole;
  private int number;
  public Producer(CubbyHole c, int number) {
   cubbyhole = c;
   this.number = number;
  }
  public void run() {
   for (int i = 0; i < 10; i++) {
     cubbyhole.put(i);
     System.out.println("生产者 #" + this.number + " put: " + i);
     try {
      sleep((int)(Math.random() * 100));
     } catch (InterruptedException e) { }
   }
  }
}

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The output result of running the above code is:

消费者 #1 got: 0
生产者 #1 put: 0
生产者 #1 put: 1
消费者 #1 got: 1
生产者 #1 put: 2
消费者 #1 got: 2
生产者 #1 put: 3
消费者 #1 got: 3
生产者 #1 put: 4
消费者 #1 got: 4
生产者 #1 put: 5
消费者 #1 got: 5
生产者 #1 put: 6
消费者 #1 got: 6
生产者 #1 put: 7
消费者 #1 got: 7
生产者 #1 put: 8
消费者 #1 got: 8
生产者 #1 put: 9
消费者 #1 got: 9

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