java PriorityQueue priority queue using

 

Sample Code

package com.example.base.concurrent;

import java.util.Comparator;
import java.util.PriorityQueue;

public class MyPriorityQueue {

    public static void main(String[] args) {
        foo();
    }
    
    private static void foo() {
        PriorityQueue<User> queue = generateQueue(null);
        System.out.println("******read queue without order******");
        for (User user : queue) {
            System.out.println(user);
        }
        //queue = generateQueue();
        System.out.println ( "****** Read Order Queue with ******" );
         the while (! Queue.isEmpty ()) { 
            System.out.println (queue.poll ()); 
        } 
        
        // use the comparator generated when the queue does not use class Comparable interface 
        queue generateQueue = ((X, Y) -> {
             int Delta = y.getAge () - x.getAge ();
             return Delta <0 -1: (? == 0 0 Delta:? 1 ); 
        }); 
        System.out.println ( "****** ****** Comparator the Read Queue with the Order" );
         the while (! queue.isEmpty ()) { 
            System.out.println (queue.poll ());  
        }
    }

     / ** 
     * @param comparator priority queue elemental comparator for comparing 
     * If not null, the elemental parity comparator, comparator precedence 
     * if null, use of the method elements compareTo (Comparable interface need to inherit ) 
     * @return 
     * / 
    Private  static PriorityQueue <the User> generateQueue (Comparator <the User> Comparator) { 
        PriorityQueue <the User> Queue = new new PriorityQueue <> (Comparator);
         for ( int I = 30; I> 20 is; i-- ) { 
            queue.add ( new new the User (I, "GC" + I)); 
        } 
        return Queue; 
    }
    
     Private static class User implements Comparable<User> {
        private int age;
        private String name;
        
        public User(int age, String name) {
            this.age = age;
            this.name = name;
        }
        public int getAge() {
            return age;
        }
        @Override
        public int compareTo(User o) {
            int delta = this.getAge() - o.getAge();
            return delta < 0 ? -1 : (delta == 0 ? 0 : 1);
        }
        @Override
        public String toString() {
            return "User [age=" + age + ", name=" + name + "]";
        }
    }
}

operation result

******read queue without order******
User [age=21, name=gc21]
User [age=22, name=gc22]
User [age=25, name=gc25]
User [age=24, name=gc24]
User [age=23, name=gc23]
User [age=29, name=gc29]
User [age=26, name=gc26]
User [age=30, name=gc30]
User [age=27, name=gc27]
User [age=28, name=gc28]
******read queue with order******
User [age=21, name=gc21]
User [age=22, name=gc22]
User [age=23, name=gc23]
User [age=24, name=gc24]
User [age=25, name=gc25]
User [age=26, name=gc26]
User [age=27, name=gc27]
User [age=28, name=gc28]
User [age=29, name=gc29]
User [age=30, name=gc30]
******read queue with order2******
User [age=30, name=gc30]
User [age=29, name=gc29]
User [age=28, name=gc28]
User [age=27, name=gc27]
User [age=26, name=gc26]
User [age=25, name=gc25]
User [age=24, name=gc24]
User [age=23, name=gc23]
User [age=22, name=gc22]
User [age=21, name=gc21]