Java 8 Features with Examples: A Comprehensive Tutorial

image source: medium.com

Java 8 is a widely used programming language known for its powerful features and flexibility. Whether you are a beginner or an experienced Java developer, understanding the key features of Java 8 is crucial for writing efficient and modern code. In this tutorial, we will explore the most important Java 8 features with examples, providing you with a solid foundation to leverage the full potential of this programming language.

Introduction to Java 8

Java 8 is a major release of the Java programming language, introducing several new features and enhancements. It was released in March 2014 and has since become one of the most widely adopted versions of Java. The key goal of Java 8 was to make the language more expressive, concise, and streamlined. It introduced functional programming concepts and new APIs to simplify common programming tasks.

In today’s digital age, many people have turned to the internet to obtain certain types of knowledge. They log onto tutorials that provide a plethora of information and take their skill levels to a higher standard. Some of the tutorials are regarding Java 8 tutorials with examples.

There are several tutorials available for a program called Java 8. Anyone looking to find out more about he should consult one of the Java 8 tutorial websites. Java-8 plays a major part in creating Java programming language. In these tutorials, people will learn all about its features from the basics to the advanced concepts.

These java tutorials are generally most useful for people who are Java developers. It doesn’t matter whether someone is a beginner or an expert, but by the end of the tutorial, they will have a well-rounded understanding of this system. These java 8 tutorials are explained in simple and intuitive ways to ensure that they are easily comprehended.

It would be useful to know Java programming language before indulging too much into these articles. In any tutorial, there’s always a certain amount of knowledge that someone needs to have so that they are not confused about anything. People who don’t know anything about Java may want to look into other tutorials.

The first step of the tutorials is usually an overview of the system and its components. Users will have a solid foundation at the beginning in order to move forward to more complicated sections. They will learn about the setup, expressions, methods, and interfaces. There are also sections about streams and JavaScript. Every section is explained in full detail and with several examples. Many of the sections include examples of code as well as templates. These articles don’t just tell people what to do. They show them. They strive to ensure that everyone reading the articles reach their learning goals.

These articles are formatted in a way that is visually appealing to readers. There are bullet points used, and pictures to break up blocks of text. These sites have to make sure that people will continue reading the tutorials without getting bored. Another useful thing about these sites is their discussion forums. These forums bring users together from all around the world. Users can chat with each other and make sure that they understand the information that they’ve read. They can even pass new knowledge to others and help them become an expert with Java-8, and if you need to test your first code online without downloading it on your computer, i will recommend use these java online compilers.

Lambda Expressions

Lambda expressions are a powerful feature introduced in Java 8 that enables functional programming in Java. They allow you to treat functions as first-class citizens, enabling you to write more concise and expressive code.

Here’s an example of a lambda expression that squares a list of numbers:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

List<Integer> squares = numbers.stream()

                               .map(n -> n * n)



In this example, the lambda expression n -> n * n is used to define a function that squares each element in the numbers list. The map method applies this function to each element, and the collect method collects the results into a new list called squares.

Functional Interfaces

Functional interfaces are interfaces that have exactly one abstract method. They are a fundamental concept in functional programming and are used extensively in Java 8.

Java 8 provides several built-in functional interfaces, such as Predicate, Function, and Consumer, which can be used with lambda expressions. These interfaces enable you to pass behavior as arguments to methods, making your code more modular and reusable.

Here’s an example that demonstrates the use of functional interfaces:

List<String> names = Arrays.asList(“Alice”, “Bob”, “Charlie”, “Dave”);


     .filter(name -> name.length() > 4)



In this example, the filter method takes a Predicate as an argument, which is a functional interface that tests a condition on each element of the stream. The lambda expression name -> name.length() > 4 is used to define the condition.

Stream API

The Stream API is one of the most significant additions in Java 8. It provides a powerful and expressive way to process collections of data. Streams are a sequence of elements that can be processed in parallel or sequentially, and they support various operations such as filtering, mapping, and reducing.

Here’s an example that demonstrates the use of the Stream API:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

int sum = numbers.stream()

                 .filter(n -> n % 2 == 0)



System.out.println(“Sum of even numbers: ” + sum);


In this example, the stream method is used to convert the list of numbers into a stream. The filter method is then used to filter out odd numbers, and the mapToInt method is used to convert the filtered numbers into integers. Finally, the sum method calculates the sum of the even numbers.

Default Methods

Default methods, also known as defender methods or virtual extension methods, were introduced in Java 8 to enable backward compatibility in interfaces. They allow you to add new methods to an interface without breaking existing implementations.

Here’s an example that demonstrates the use of default methods:

interface Vehicle {

    void start();

    default void stop() {

        System.out.println(“Stopping the vehicle”);



class Car implements Vehicle {

    public void start() {

        System.out.println(“Starting the car”);



Car car = new Car();

car.start(); // Output: Starting the car

car.stop();  // Output: Stopping the vehicle


In this example, the Vehicle interface defines a default method stop(). The Car class implements the Vehicle interface and provides its own implementation of the start() method. When calling the stop() method on a Car object, the default implementation from the Vehicle interface is used.

Optional Class

The Optional class was introduced in Java 8 to handle the absence of a value. It provides a way to avoid null pointer exceptions and write more robust code.

Here’s an example that demonstrates the use of the Optional class:

Optional<String> name = Optional.ofNullable(getName());


if (name.isPresent()) {

    System.out.println(“Name: ” + name.get());

} else {

    System.out.println(“Name not available”);


In this example, the Optional class is used to wrap a potentially null value returned by the getName() method. The isPresent() method checks if the value is present, and the get() method retrieves the value if it exists. If the value is not present, the code inside the else block is executed.

Date and Time API

Java 8 introduced a new Date and Time API that provides a more comprehensive and flexible way to work with dates and times. The new API addresses many of the shortcomings of the old Date and Calendar classes and makes date and time manipulation easier.

Here’s an example that demonstrates the use of the Date and Time API:

LocalDateTime now = LocalDateTime.now();

DateTimeFormatter formatter = DateTimeFormatter.ofPattern(“yyyy-MM-dd HH:mm:ss”);

String formattedDateTime = now.format(formatter);

System.out.println(“Current date and time: ” + formattedDateTime);

In this example, the LocalDateTime class is used to represent the current date and time. The DateTimeFormatter class is used to format the date and time according to the specified pattern. The formatted date and time are then printed to the console.

Method References

Method references provide a concise and readable way to refer to methods or constructors without invoking them. They can be used instead of lambda expressions when the lambda expression simply calls an existing method or constructor.

Here’s an example that demonstrates the use of method references:

List<String> names = Arrays.asList(“Alice”, “Bob”, “Charlie”);




In this example, the map method is used with a method reference String::toUpperCase to convert each element of the stream to uppercase. The forEach method is then used with a method reference System.out::println to print each element.

Parallel Streams

Parallel streams are a feature of the Stream API that allows you to process elements concurrently, taking advantage of multi-core processors. They can significantly improve the performance of computationally intensive operations.

Here’s an example that demonstrates the use of parallel streams:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

int sum = numbers.parallelStream()

                 .filter(n -> n % 2 == 0)



System.out.println(“Sum of even numbers: ” + sum);


In this example, the parallelStream method is used instead of the stream method to create a parallel stream. The rest of the code is the same as the previous example, but the processing of elements is done in parallel, potentially utilizing multiple threads.


The CompletableFuture class is a powerful addition to Java 8 that enables asynchronous programming and non-blocking IO operations. It provides a flexible way to compose and combine asynchronous computations, making it easier to write concurrent and scalable code.

Here’s an example that demonstrates the use of CompletableFuture:

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> “Hello”)

                                                   .thenApplyAsync(s -> s + ” World”)



In this example, a CompletableFuture is created using the supplyAsync method, which performs a computation asynchronously and returns a result. The thenApplyAsync method is then used to apply a function to the result of the previous stage. Finally, the thenAcceptAsync method is used to consume the final result and print it to the console.

Now that you have a solid understanding of Java 8 features, it’s time to put your knowledge into practice. Explore the list of Java 8 tutorial websites mentioned below to further enhance your skills:

Java 8 Tutorial with Example Websites

  1. Tutorials Point

  2. Java Guides

  3. Digital Ocean

  4. Mkyong

  5. How to do in Java

  6. Java Code Geeks

  7. Study To Night

  8. Winter be

  9. Java Brahman

  10. Java Made So Easy

Visit these websites to access comprehensive Java 8 tutorials, examples, and discussions. By leveraging the knowledge shared in these tutorials, you can become an expert in Java 8 and take advantage of its powerful features in your projects.

Remember, practice makes perfect. Keep coding, exploring, and expanding your Java 8 skills, and you’ll be well on your way to becoming a proficient Java developer.


In this tutorial, we explored the most important features of Java 8 with examples. From lambda expressions and functional interfaces to the Stream API and CompletableFuture, Java 8 provides powerful tools to write more expressive and efficient code. By mastering these features, you can take your Java programming skills to the next level and create robust and modern applications.



Christian Corwin - Your Guide to Knowledge, I cover these topics Free Education, Tutorials, AI, and Travel. As an avid explorer of the digital realm, I'm passionate about sharing my knowledge on free education, guiding you through tutorials, unraveling the wonders of AI, and taking you on captivating journeys around the globe. With years of professional experience in these domains, I'm committed to delivering reliable, well-researched, and informative content. Join me in this exciting adventure as we learn, create, and explore together. Let's embark on a journey of discovery!

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button