PriorityQueue removeIf(Predicate) in Java

removeIf(Predicate): This method is available in java.util.PriorityQueue class of Java.

Syntax:

boolean java.util.PriorityQueue.removeIf(Predicate<? super K> filter)

This method takes one argument. This method removes all of the elements of this collection that satisfy the given predicate.

Parameters: One parameter is required for this method.

filter: a predicate that returns true for elements to be removed.

Returns: true if any elements were removed.

Throws:

NullPointerException - if the specified filter is null

Approach 1: When no exception

Java

import java.util.PriorityQueue;
import java.util.function.Predicate;

public class PriorityQueueremoveIf {
    public static void main(String[] args) {

        PriorityQueue<Integer> priorityQueue = 
                   new PriorityQueue<Integer>();

        priorityQueue.add(12);
        priorityQueue.add(5);
        priorityQueue.add(10);
        priorityQueue.add(2);

        Predicate<Integer> filter = (i -> (i < 7));

        System.out.println(priorityQueue.removeIf(filter));

    }
}

Output:

true

Approach 2: NullPointerException 

Java

import java.util.PriorityQueue;
import java.util.function.Predicate;

public class PriorityQueueremoveIf {
    public static void main(String[] args) {

        PriorityQueue<Integer> priorityQueue = 
                      new PriorityQueue<Integer>();

        priorityQueue.add(12);
        priorityQueue.add(5);
        priorityQueue.add(10);
        priorityQueue.add(2);

        Predicate<Integer> filter = null;

        System.out.println(priorityQueue.removeIf(filter));

    }
}

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.base/java.util.Objects.requireNonNull(Objects.java:208)
	at java.base/java.util.PriorityQueue.removeIf(PriorityQueue.java:894)