Java LinkedList

Hello there, fellow coder! Today, we’re diving into the world of Java LinkedList. Ready to explore? Let’s get started!

Introduction

Ever found yourself in a situation where you needed to store a collection of elements, but weren’t sure which data structure to use?

Well, Java LinkedList might just be the answer! LinkedList is a widely used data structure in Java, and it’s about time we unravel its mysteries.

In this tutorial, we will explore the LinkedList class, its methods, and how to use it effectively in our Java programs.

Understanding LinkedList in Java

So, what is a LinkedList? In simple terms, it’s a linear data structure where each element points to the next, just like a chain. Each element, also known as a node, contains two items: the data and a reference to the next node. Pretty neat, huh?

LinkedList Class in Java

Java provides us with a LinkedList class, which is part of the Java Collections Framework. This class comes with a bunch of handy methods that make our lives easier. Plus, it implements the List and Deque interfaces, which means it’s doubly-linked. That’s right, each node in a Java LinkedList points to both the next node and the previous one! This allows for efficient operations at both ends of the list, making it an excellent choice for certain types of problems, like implementing stacks or queues.

How to Create a LinkedList in Java

Creating a LinkedList in Java is as easy as pie. Here’s how you do it:

LinkedList<String> myList = new LinkedList<>();

In the above code, we’re creating a LinkedList named myList that will store strings. And voila! You’ve just created your very own LinkedList.

This LinkedList can now store a dynamic number of strings, and we can add or remove elements from either end in constant time.

LinkedList Methods in Java

The LinkedList class in Java is packed with useful methods. Let’s take a look at some of them:

• add(): This method appends the specified element to the end of the list.

myList.add("Apple");
myList.add("Banana");

In the above code, we’re adding “Apple” and “Banana” to our LinkedList. The LinkedList now looks like this: [Apple, Banana]

• addFirst(): This method inserts the specified element at the beginning of the list.

myList.addFirst("Apricot");

Now, “Apricot” is added to the beginning of our LinkedList, which now looks like this: [Apricot, Apple, Banana]

• addLast(): This method appends the specified element to the end of the list. It’s the same as the add(E e) method.

myList.addLast("Blueberry");

Finally, we add “Blueberry” to the end of our LinkedList. The final LinkedList looks like this: [Apricot, Apple, Banana, Blueberry]

• getFirst(): This method retrieves, but does not remove, the first element of this list, or returns null if this list is empty. Here’s an example:

myList.add("Apple");
myList.add("Banana");
String firstElement = myList.getFirst(); // Returns "Apple"

In the above code, we first add “Apple” and “Banana” to our LinkedList. We then use getFirst() to retrieve the first element, which is “Apple”.

• getLast(): This method retrieves, but does not remove, the last element of this list, or returns null if this list is empty. Here’s an example:

myList.add("Apple");
myList.add("Banana");
String lastElement = myList.getLast(); // Returns "Banana"

In the above code, we first add “Apple” and “Banana” to our LinkedList. We then use getLast() to retrieve the last element, which is “Banana”.

• removeFirst(): This method removes and returns the first element from this list. Here’s an example:

myList.add("Apple");
myList.add("Banana");
String removedElement = myList.removeFirst(); // Removes and returns "Apple"

In the above code, we first add “Apple” and “Banana” to our LinkedList. We then use removeFirst() to remove the first element, which is “Apple”. The method also returns the removed element.

• removeLast(): This method removes and returns the last element from this list. Here’s an example:

myList.add("Apple");
myList.add("Banana");
String removedElement = myList.removeLast(); // Removes and returns "Banana"

In the above code, we first add “Apple” and “Banana” to our LinkedList. We then use removeLast() to remove the last element, which is “Banana”. The method also returns the removed element.

• clear(): This method removes all of the elements from this list. The list will be empty after this call returns. Here’s an example:

myList.add("Apple");
myList.add("Banana");
myList.clear(); // Removes all elements

In the above code, we first add “Apple” and “Banana” to our LinkedList. We then use clear() to remove all elements from the LinkedList. The LinkedList is now empty.

These methods provide a lot of flexibility when working with LinkedLists in Java, allowing us to easily retrieve, add, and remove elements as needed.

LinkedList vs ArrayList in Java

When should you use LinkedList over ArrayList, or vice versa? Well, LinkedList is faster at add and remove operations, while ArrayList is faster at get and set operations. So, if you need to frequently add or remove elements, go for LinkedList. If you need random access to elements, choose ArrayList.

Java LinkedList Examples

Let’s put everything we’ve learned into practice with some code examples:

// Create a LinkedList
LinkedList<String> fruits = new LinkedList<>();

// Add elements
fruits.add("Apple");
fruits.add("Banana");
fruits.addFirst("Apricot");
fruits.addLast("Blueberry");

// Print the LinkedList
System.out.println(fruits); // Output: [Apricot, Apple, Banana, Blueberry]

In the above code, we first create a LinkedList named fruits. We then add “Apple” and “Banana” to the end of the list, “Apricot” to the beginning, and “Blueberry” to the end. Finally, we print the LinkedList, which outputs: [Apricot, Apple, Banana, Blueberry]

Let’s look at another example:

// Create a LinkedList
LinkedList<Integer> numbers = new LinkedList<>();

// Add elements
for (int i = 1; i <= 5; i++) {
    numbers.add(i);
}

// Print the LinkedList
System.out.println(numbers); // Output: [1, 2, 3, 4, 5]

In this example, we create a LinkedList named numbers. We then use a for loop to add the numbers 1 through 5 to the LinkedList. Finally, we print the LinkedList, which outputs: [1, 2, 3, 4, 5]

Conclusion

And that’s a wrap on our Java LinkedList tutorial! We’ve learned what a LinkedList is, how to create one, and how to use the LinkedList class methods. We’ve also compared LinkedList and ArrayList to help you choose the right data structure for your needs.

Frequently Asked Questions (FAQ)

LinkedList<String> myList = new LinkedList<>();

myList.add("Apple");

Related Tutorials

If you enjoyed this tutorial, you might also like these:

• Java ArrayList: A Comprehensive Guide
• Java HashSet: A Complete Tutorial
• Understanding Data Structures in Java

Remember, practice makes perfect. So, keep coding, keep exploring, and most importantly, have fun!