Java Collections - ArrayDeque.getFirst() Examples

Class:

java.util.ArrayDeque

Method:

public E getFirst()

Retrieves, but does not remove, the first element of this deque. This method differs from peekFirst() only in that it throws an exception if this deque is empty.

Examples

package com.logicbig.example.arraydeque;

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

public class GetFirstExample {

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

Output

3
3
8

package com.logicbig.example.arraydeque;

import java.util.ArrayDeque;

public class GetFirstExample2 {

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

Output

Caused by: java.util.NoSuchElementException
	at java.base/java.util.ArrayDeque.getFirst(ArrayDeque.java:399)
	at com.logicbig.example.arraydeque.GetFirstExample2.main(GetFirstExample2.java:14)
	... 6 more

Java Collections - ArrayDeque.getFirst() Examples

Class:

Method:

Examples

Output

Output

See Also