Java Collection: PriorityQueue

A PriorityQueue is used when the objects are supposed to be processed based on priority instead of their arrival time.

A few important facts about PriorityQueue are as follows:

1. It doesn't permit NULL objects.
2. Non-comparable objects can not be used to form a priority queue.

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Hierarchy of PriorityQueue class

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It inherits methods from AbstractQueue and implements Serializable, Iterable, Collection, Queue interfaces.

Source code of Item.java

package com.t4b.test; public class Item { String name; int id; double price; public Item(String name, int id, double price) { super(); this.name = name; this.id = id; this.price = price; } @Override public String toString() { return "Item [name=" + name + ", id=" + id + ", price=" + price + "]"; } }

Source code of TestMain.java

package com.t4b.test; import java.util.Iterator; import java.util.PriorityQueue; public class TestMain { public static void main(String[] args) { PriorityQueue<Item> pq = new PriorityQueue<Item>(); pq.add(new Item("Apple", 1, 150.0)); pq.add(new Item("Grape", 2, 250.0)); pq.add(new Item("Mango", 3, 10)); pq.add(new Item("Pine Apple", 4, 100)); Iterator<Item> itr = pq.iterator(); while (itr.hasNext()) { System.out.println(itr.next()); } } }

Happy Exploring!