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Java Collections - PriorityQueue.add() Examples

Java Collections Java Java API

Class:

java.util.PriorityQueue

Method:

public boolean add(E e)

Inserts the specified element into this priority queue. Call to this method is forwarded to offer() method.

Examples

package com.logicbig.example.priorityqueue;

import java.util.PriorityQueue;

public class AddExample {

    public static void main(String... args) {
        PriorityQueue<String> pq = new PriorityQueue<>();
        pq.add("one");
        pq.add("two");
        System.out.println(pq);
    }
}

Output

[one, two]

PriorityQueue does not allow null elements:

package com.logicbig.example.priorityqueue;

import java.util.PriorityQueue;

public class AddExample2 {

    public static void main(String... args) {
        PriorityQueue<String> pq = new PriorityQueue<>();
        pq.add(null);
    }
}

Output

Caused by: java.lang.NullPointerException
	at java.base/java.util.PriorityQueue.offer(PriorityQueue.java:337)
	at java.base/java.util.PriorityQueue.add(PriorityQueue.java:323)
	at com.logicbig.example.priorityqueue.AddExample2.main(AddExample2.java:15)
	... 6 more

See Also