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package myapp.kit.quickstart.utils;

import java.util.Comparator;

import java.util.Queue;

/**

 * priority queue (heap) demo.

 *

 * @author huangdingsheng

 * @version 1.0, 2020/5/8

 */

public class PriorityQueue {

  public static void main(String[] args) {

    // min heap, process custom data struct

    Queue<Node> minHeap = new java.util.PriorityQueue<>(new Comparator<Node>(){

      @Override

      public int compare(Node o1, Node o2) {

        return o1.v - o2.v;

      }

    });

    // do sth...

    minHeap.add(new Node(1, 2));

    minHeap.add(new Node(2, 9));

  }

  // custom data struct

  static class Node {

    int k;

    int v;

    public Node(int k, int v) {

      this.k = k;

      this.v = v;

    }

  }

}

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import java.util.PriorityQueue;

public class PriorityQueueTest3

{

 public static void main(String[] args)

 {

 PriorityQueue pq = new PriorityQueue();

 pq.offer(6);

 pq.offer(-3);

 pq.offer(0);

 pq.offer(9);

 System.out.println(pq);

 }

}

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import java.util.PriorityQueue;

public class PriorityQueueTest3

{

 public static void main(String[] args)

 {

 PriorityQueue pq = new PriorityQueue();

 pq.offer(6);

 pq.offer(-3);

 pq.offer(0);

 pq.offer(9);

 int len = pq.size();//这里之所以取出.size()大小，因为每一次poll()之后size大小都会变化，所以不能作为for循环的判断条件

 for(int i=0;i<len;i++){

  System.out.print(pq.poll()+" ");

 }

 System.out.println();

 }

}