How To Add Element To LinkedList?

In this article, we will see, how to add an element to linkedlist. LinkedList class provide various methods to add an element to the lnikedlist. We will cover these methods with example.

Introduction

LinkedList class is present in the java.util package.

LinkedList internally uses doubly linkedlist for storing the variables. That’s why LinkedList is preferred when our frequeent operatioon is insertion and deletion.

We can add an element to the LinkedList using add() method. There are two type of the add() method.

1. add(E e)
2. add(int index,E element)
3. addFirst(E e)
4. addLast(E e)

The add() method will append an alement to the end of the list. The add(int index, E element) method wil add the element at the specified index index.

Since LinkedList internally use doubly linkedlist structure to storethe data, it provide two aditional method to add the elements using addFirst(E e) and addLast(E e)

Let’s see this both the method one by one.

1. add(E e)

The method signature for this is given below,

public boolean add(E e).

This method appends the specified element e to the end of the list.

This method returns true if the element is added to the list otherwise, it returns false.

I have given a java program to add an element to the end of the list using the add(E e) method.

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import java.util.LinkedList;

/**
 * A Java program to add an element to the LinkedList.
 * 
 * The add(E e) method will add an element to 
 * the end of the linkedList.
 * 
 * @author coderolls.com
 *
 */
public class LinkedListAddExample {

	public static void main(String[] args) {
		
		LinkedList<String> linkedList = new LinkedList<String>();
		
		//adding elements to the linkedList
		linkedList.add("John");
		linkedList.add("Peter");
		
		System.out.println(linkedList);// [John, Peter]
		
		// adding an element to the linkedList
		// element will be added to the end of the linkedList
		linkedList.add("Noah");
		
		System.out.println(linkedList); // [John, Peter, Noah]
	}
}

Output:

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[John, Peter]
[John, Peter, Noah]

2. add(int index, E element)

The method signature forthis method is given below.

1
public void add(int index, E element)

This method adds the specified element element at the specified index index.

This method has a return type as void so, it will not return anything.

Below, we will see a java program to add an element at the specified index in LinkedList.

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import java.util.LinkedList;

/**
 * A Java program to add an element to the linkedlist
 * at the specific index.
 * 
 * The add(int index, E element) method will add 
 * an element at the specified index in LinkedList.
 * 
 * @author coderolls.com
 *
 */
public class LinkedListAddExample2 {

	public static void main(String[] args) {
		
		LinkedList<String> linkedList = new LinkedList<String>();
		
		//adding elements to the linkedList using normal add method
		linkedList.add("John");
		linkedList.add("Peter");
        linkedList.add("Karan");
		
		System.out.println(linkedList);// [John, Peter, Karan]
		
		// adding an element to  the LinkedList at index 1
		linkedList.add(1, "Noah");
		
		System.out.println(linkedList); // [John, Noah, Peter, Karan]
	}
}

Output:

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[John, Peter, Karan]
[John, Noah, Peter, Karan]

3. addFirst(E e)

We know that LinkedList internally uses the doubly linkedlist structure to store the data. To provide features like a doubly linkedlist, LinkedList class has a special addFirst(E e) method to add the element at the beiginneing to the list.

I have written a separate detailed article about the addFirst(E e) method. Read How To Add Element At The Beginning Of LinkedList?

4. addLast(E e)

We know that LinkedList internally uses the doubly linkedlist structure to store the data. To provide features like a doubly linkedlist, LinkedList class has a special addLast(E e) method to add the element to the end of the list.

This method is equivalent to the add(E e) method.

I have written a separate detailed article about the addLast(E e) method. Read LinkedList addLast(E e) Method

Conclusion

We can add element to the LinkedList using add() method in two ways.

1. add(E e) - It will add an element to the end of the LinkedList
2. add(int index, E element)- This method will add an element at the specified index
3. addFirst(E e) - This method will add an element at the beginning of the list
4. addLast(E e) - This method will add an element to the end of the list

The example java programs given in the above tutorial can be found at this GitHub Repository.

Let me know you thoughts or suggestions on the topic discussed above in comment section below.