Re: Somewhere in this constructor of PriorityBlockingQueue is hard to understand

"ArrayList<Holder> al = new ArrayList<>(2);" should be "ArrayList<Holder> al = new ArrayList<>();", be the way.




At 2020-08-05 10:07:29, "Liu" <[email protected]> wrote:

import java.util.ArrayList;

import java.util.Queue;

import java.util.concurrent.PriorityBlockingQueue;




public class test16 {

    static class Holder implements Comparable<Holder> {

        int i;

        Holder(int i) {

            this.i = i;

        }

        public int compareTo(Holder h) {

            if(h == null)

                return  -1;

            return this.i - h.i;

        }

    }




    public static void main(String[] args) {

        ArrayList<Holder> al = new ArrayList<>(2);

        al.add(new Holder(1));

        al.add(new Holder(2));

        al.add(null);

        Queue a = new PriorityBlockingQueue<>(al);

    }

}



In this case, heapify() cound not find null item.

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