LinkedList Methods in Java

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In this post, we will learn important Java LinkedList methods with examples.

LinkedList Class Methods

The below class diagram shows a list of LinkedList class methods:

add() Method

We can add new elements to the end of the LinkedList using add() method:

        // Creating LinkedList of Strings
        LinkedList<String> list = new LinkedList<String>();

        // Using add() method to add elements in the list
        list.add("Java");
        list.add("Python");
        list.add("JavaScript");

We can add an element at the specified position in the LinkedList using add(index, element) method:

        // Adding an element at the specific position in the list
        list.add(1, "C++");

addFirst() method

We can add an element at the beginning of the LinkedList using the addFirst() method:

        // Adding elements at the beginning of the list using addFirst()
        list.addFirst("Swift");

addLast() method

We can add an element at the end of the LinkedList using the addLast() method:

        // Adding elements at the end of the list using addLast()
        list.addLast("Kotlin");

addAll() Method: 

This method is used to append all of the elements in the specified collection to the end of a list.

List<String> additionalLangs = Arrays.asList("C", "Golang");
list.addAll(additionalLangs);
System.out.println(list);  

get(int index) method

The get(int index) method is used to return the element at the specified position in the list. 

        // Creating a LinkedList of Strings
        LinkedList<String> list = new LinkedList<String>();

        // Adding elements to the LinkedList
        list.add("Java");
        list.add("Python");
        list.add("JavaScript");
        list.add("C++");
        list.add("Kotlin");

        // Accessing elements from the LinkedList
        // The get() method throws IndexOutOfBoundsException, if the specified index is out of range
        System.out.println("Element returned by get(2): " + list.get(2));

getFirst() method

The getFirst() method is used to retrieve the first element from the LinkedList.

        // The first() method returns the first element in this list
        System.out.println("Element returned by first(): " + list.getFirst());

getLast() method

The getLast() method is used to retrieve the last element from the LinkedList, which is "Kotlin" in our case.

        // The last() method returns the last element in this list
        System.out.println("Element returned by last(): " + list.getLast());

remove(int index) 

This method is used to remove an element from a specific position in a list.

        // Creating a LinkedList of Strings
        LinkedList<String> list = new LinkedList<String>();

        // Adding elements to the LinkedList
        list.add("Java");
        list.add("Python");
        list.add("JavaScript");
        list.add("C++");
        list.add("Kotlin");

        // Displaying the LinkedList
        System.out.println("Initial LinkedList: " + list);

        // The remove(int index) method removes the element at the specified position in this list
        list.remove(2);
        System.out.println("LinkedList after removing element at index 2: " + list);

remove(Object o)

This method is used to remove the first occurrence of the specified element from a list.

        // The remove(Object) method removes the first occurrence of the specified element from this list, if it is present
        list.remove("Python");
        System.out.println("LinkedList after removing 'Python': " + list);

removeFirst() Method

The removeFirst() method removes and returns the first element from this list.

  list.removeFirst();
  System.out.println("LinkedList after removing first element: " + list);

removeLast() Method

The removeLast() method removes and returns the last element from this list.

list.removeLast();
System.out.println("LinkedList after removing last element: " + list);

clear() Method

This method is used to remove all of the elements from a list.

        list.clear();
        System.out.println("LinkedList after calling clear(): " + list);

contains(Object o): 

This method is used to check if a specific element is contained in a list.

        // Creating a LinkedList of Strings
        LinkedList<String> list = new LinkedList<String>();

        // Adding elements to the LinkedList
        list.add("Java");
        list.add("Python");
        list.add("JavaScript");
        list.add("C++");
        list.add("Python");
        list.add("Kotlin");

        // Displaying the LinkedList
        System.out.println("LinkedList: " + list);

        // The contains(Object) method returns true if this list contains the specified element
        boolean found = list.contains("Python");
        System.out.println("'Python' is in the list: " + found);

indexOf(Object) method

The indexOf(Object) method returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.

        int firstIndex = list.indexOf("Python");
        System.out.println("First occurrence of 'Python' is at index: " + firstIndex);

lastIndexOf(Object)

The lastIndexOf(Object) method returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.

        int lastIndex = list.lastIndexOf("Python");
        System.out.println("Last occurrence of 'Python' is at index: " + lastIndex);

size()

This method is used to return the number of elements in a list.

        // Creating a LinkedList of Strings
        LinkedList<String> list = new LinkedList<String>();

        // Adding elements to the LinkedList
        list.add("Java");
        list.add("Python");
        list.add("JavaScript");
        list.add("C++");
        list.add("Python");
        list.add("Kotlin");
        
        int size = list.size();

        // Displaying the LinkedList size
        System.out.println("LinkedList size: " + size);

iterator()

This method is used to return an iterator over the elements in a list in the proper sequence.

        // Creating a LinkedList of Strings
        LinkedList<String> list = new LinkedList<String>();
        list.add("Java");
        list.add("Python");
        list.add("JavaScript");
        list.add("C++");

        // Using Iterator
        System.out.println("Iterating using Iterator:");
        Iterator<String> iterator = list.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }

Conclusion

In this post, we learned all the important Java LinkedList methods with examples. You can learn everything about Java LinkedList here: Learn Everything About LinkedList