Close

Java Collections - ArrayDeque.peek() Examples

Java Collections Java Java API

Class:

java.util.ArrayDeque

Method:

public E peek()

Retrieves, but does not remove, the head of the queue represented by this deque, or returns null if this deque is empty.

This method is equivalent to peekFirst().

Examples

package com.logicbig.example.arraydeque;

import java.util.ArrayDeque;
import java.util.List;

public class PeekExample {

    public static void main(String... args) {
        ArrayDeque<Integer> ad = new ArrayDeque<>(List.of(3, 8, 5, 7));
        System.out.println(ad);
        Integer element = ad.peek();
        System.out.println(element);
        System.out.println(ad);
    }
}

Output

[3, 8, 5, 7]
3
[3, 8, 5, 7]

package com.logicbig.example.arraydeque;

import java.util.ArrayDeque;
import java.util.List;

public class PeekExample2 {

    public static void main(String... args) {
        ArrayDeque<Integer> ad = new ArrayDeque<>();
        Integer element = ad.peek();
        System.out.println(element);
    }
}

Output

null

See Also