Java 队列的使用

BlockQueue 的核心方法

 add方法实例，队列大小是3  当add第四个元素时报错

package com.example.starter;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;


public class BlockingQueueDemo {
  public static void main(String[] args) {
    //List list = null;
    BlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
    System.out.println(blockingQueue.add("a"));
    System.out.println(blockingQueue.add("b"));
    System.out.println(blockingQueue.add("c"));

    System.out.println(blockingQueue.add("x"));
  }
}

输出

 remove,当没有元素可以remove的时候 抛异常

package com.example.starter;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;


public class BlockingQueueDemo {
  public static void main(String[] args) {
    //List list = null;
    BlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
    System.out.println(blockingQueue.add("a"));
    System.out.println(blockingQueue.add("b"));
    System.out.println(blockingQueue.add("c"));
    
    System.out.println(blockingQueue.remove());
    System.out.println(blockingQueue.remove());
    System.out.println(blockingQueue.remove());
    System.out.println(blockingQueue.remove());
  }
}

offer,队列满了再次插入报false

package com.example.starter;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;


public class BlockingQueueDemo {
  public static void main(String[] args) {
    //List list = null;
    BlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
    System.out.println(blockingQueue.offer("a"));
    System.out.println(blockingQueue.offer("a"));
    System.out.println(blockingQueue.offer("a"));
    System.out.println(blockingQueue.offer("x"));
  }
}

poll方法：没有还回null

package com.example.starter;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;


public class BlockingQueueDemo {
  public static void main(String[] args) {
    //List list = null;
    BlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
    System.out.println(blockingQueue.offer("a"));
    System.out.println(blockingQueue.offer("a"));
    System.out.println(blockingQueue.offer("a"));
    //System.out.println(blockingQueue.offer("x"));
    System.out.println(blockingQueue.poll());
    System.out.println(blockingQueue.poll());
    System.out.println(blockingQueue.poll());
    System.out.println(blockingQueue.poll());

  }
}

 结果

 add 和take

package com.example.starter;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

public class BlockingQueueDemo {
  public static void main(String[] args) throws InterruptedException {
    BlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
    blockingQueue.put("a");
    blockingQueue.put("a");
    blockingQueue.put("a");
    blockingQueue.put("x");
    System.out.println("===============================================");
    blockingQueue.take();
    blockingQueue.take();
    blockingQueue.take();
    blockingQueue.take();
  }
}

offer

package com.example.starter;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;

public class BlockingQueueDemo {
  public static void main(String[] args) throws InterruptedException {
    BlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
    blockingQueue.offer("a",2, TimeUnit.SECONDS);
    blockingQueue.offer("a",2, TimeUnit.SECONDS);
    blockingQueue.offer("a",2, TimeUnit.SECONDS);
    blockingQueue.offer("a",2, TimeUnit.SECONDS);
    
  }
}