Java linkedlist addfirst - Java LinkedList addFirst() Method with Examples

Java linkedlist addfirst – In the previous article, we have discussed about Java LinkedList addAll() Method with Examples

In this article we are going to see the use of Java LinkedList addFirst() method with suitable examples.

Java LinkedList addFirst() Method with Examples

Linkedlist addfirst: This java.util.LinkedList.addFirst() method adds/inserts an element to the LinkedList at the first index position.

It always returns true as the collection need a return value in the signature when an element is added.

If we don’t insert any element inside the addFirst() method then it will show NullPointerException.

Syntax:

LinkedListName.addFirst(Object element)

Where,

LinkedListName refers to the name of your LinkedList.
Object element refers to the element that will be added into the LinkedList.
int index refers to the index value of the object element.

Let’s see different examples to understand it more clearly.

Example with String Type LinkedList
Example with Integer Type LinkedList

Example-1: Java LinkedList addFirst() Method – Example with String Type LinkedList

Create a new LinkedList of type String.
Add string elements into the LinkedList using the add() method.
Display the LinkedList elements.
Add another new element to the LinkedList using addFirst( ).
Print the new LinkedList.

Program:

import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
        // Create a LinkedList of string datatype
        LinkedList<String> l = new LinkedList<String>();
        // Adding some elements to the LinkedList
        l.add("Hello");
        l.add("this");
        l.add("is");
        l.add("a");
        l.add("Linked List");
        // Prints the LinkedList elements
        System.out.println("The elements in the LinkedList are: "+l);
        // Adding a new element to the LinkedList
        l.addFirst("Welcome");
        // Prints the new LinkedList elements
        System.out.println("The new elements in the LinkedList are: "+l);    
    }
}

Output:

The elements in the LinkedList are: [Hello, this, is, a, Linked List]
The new elements in the LinkedList are: [Welcome, Hello, this, is, a, Linked List]

Example-2: Java LinkedList addFirst() Method – Example with Integer Type LinkedList

Create a new LinkedList of type Integer.
Add Integer elements into the LinkedList using the add() method.
Display the LinkedList elements.
Add another new element to the LinkedList using addFirst( ).
Print the new LinkedList.

Program:

import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
        // Create a LinkedList of Integer datatype
        LinkedList<Integer> l = new LinkedList<Integer>();
        // Adding some elements to the LinkedLists
        l.add(2);
        l.add(52);
        l.add(13);
        l.add(17);
        l.add(1);
        // Prints the LinkedList elements
        System.out.println("The elements in the LinkedList are: "+l);
        // Adding a new element to the LinkedList
        l.addFirst(99);
        // Prints the new LinkedList elements
        System.out.println("The new elements in the LinkedList are: "+l);
    }
}

Output:

The elements in the LinkedList are: [2, 52, 13, 17, 1]
The new elements in the LinkedList are: [99, 2, 52, 13, 17, 1]

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