Java LinkedList: Features, Methods, and Example Usage

Introduce Java LinkedList and give examples

In Java, a LinkedList is a part of the Java Collections Framework and is implemented as a doubly linked list. It allows for the storage of a sequence of elements, where each element (or node) contains a reference to both the next and the previous node in the sequence. This structure allows for efficient insertion and removal of elements from both ends of the list, making it a good choice for scenarios where frequent modifications to the list are required.

Key Features of LinkedList:

• Dynamic Size: Unlike arrays, linked lists can grow and shrink in size dynamically.
• Efficient Insertions/Deletions: Adding or removing elements from the beginning or end of the list is efficient (O(1) time complexity).
• Order Preservation: Elements are stored in the order they are added.

Common Methods:

• add(E e): Appends the specified element to the end of the list.
• addFirst(E e): Inserts the specified element at the beginning of the list.
• addLast(E e): Appends the specified element to the end of the list (same as add).
• remove(Object o): Removes the first occurrence of the specified element from the list.
• removeFirst(): Removes and returns the first element from the list.
• removeLast(): Removes and returns the last element from the list.
• get(int index): Returns the element at the specified position in the list.
• size(): Returns the number of elements in the list.

Example Usage of LinkedList:

Here’s a simple example demonstrating how to use a LinkedList in Java:

import java.util.LinkedList;

public class LinkedListExample {
    public static void main(String[] args) {
        // Create a LinkedList
        LinkedList<String> linkedList = new LinkedList<>();

        // Add elements to the LinkedList
        linkedList.add("Apple");
        linkedList.add("Banana");
        linkedList.add("Cherry");
        linkedList.addFirst("Mango"); // Adding at the beginning
        linkedList.addLast("Orange");  // Adding at the end

        // Display the LinkedList
        System.out.println("LinkedList: " + linkedList);

        // Access elements
        String firstElement = linkedList.get(0);
        System.out.println("First Element: " + firstElement);

        // Remove elements
        linkedList.remove("Banana"); // Remove by value
        linkedList.removeFirst();     // Remove first element
        linkedList.removeLast();      // Remove last element

        // Display the LinkedList after removals
        System.out.println("LinkedList after removals: " + linkedList);

        // Size of the LinkedList
        System.out.println("Size of LinkedList: " + linkedList.size());
    }
}

Output:

LinkedList: [Mango, Apple, Banana, Cherry, Orange]
First Element: Mango
LinkedList after removals: [Apple, Cherry]
Size of LinkedList: 2

Conclusion:

The LinkedList class in Java is a versatile data structure that is particularly useful when you need to frequently add or remove elements. It provides a simple and efficient way to manage a collection of items while maintaining their order.