Java is one of the most widely used languages in the enterprise world. Many backend applications, banking systems, REST APIs, microservices, and enterprise platforms still run on versions like Java 8, Java 11, or Java 17.

But when working on real-world projects, a very common question arises:

What really changes between Java 8, Java 11, and Java 17?

In this article, we will look at the main differences between these versions, why they remain important, and which one is best to use in modern projects.

1. Why Compare Java 8, 11, and 17?

Java 8, Java 11, and Java 17 marked important milestones in the evolution of the language.

• Java 8 modernized the way code is written with lambdas, streams, and functional programming.
• Java 11 consolidated a more modular and modern stage of the JDK.
• Java 17 became a widely used foundation for current projects with Spring Boot 3, modern Jakarta EE, and cloud-native applications.

In many companies, we still find legacy applications in Java 8, intermediate projects in Java 11, and recent developments in Java 17.

2. Quick Summary

3. Java 8: The Great Modern Leap

Java 8 was one of the most important versions of the language. Before Java 8, writing code to iterate through lists, filter data, or pass behavior as a parameter was much more verbose.

Java 8 introduced features that changed the way we write code.

Main Features of Java 8

• Lambda expressions.
• Stream API.
• Functional interfaces.
• Method references.
• Optional.
• New date API with java.time.
• Default methods in interfaces.

Example before Java 8

List<String> names = Arrays.asList("Ana", "Luis", "Carlos");

for (String name : names) {
    if (name.startsWith("A")) {
        System.out.println(name);
    }
}

Example with Java 8

List<String> names = Arrays.asList("Ana", "Luis", "Carlos");

names.stream()
     .filter(name -> name.startsWith("A"))
     .forEach(System.out::println);

The code with Java 8 is more declarative. Instead of saying exactly how to traverse the list, we express what we want to obtain.

4. Stream API in Java 8

The Stream API allows you to work with collections in a more expressive way.

Example:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6);

List<Integer> evenNumbers = numbers.stream()
        .filter(n -> n % 2 == 0)
        .collect(Collectors.toList());

System.out.println(evenNumbers);

Result:

[2, 4, 6]

This is very useful for transforming, filtering, sorting, or grouping data.

5. New Date API in Java 8

Before Java 8, working with dates using Date or Calendar was cumbersome.

Java 8 introduced java.time, a much clearer API.

LocalDate currentDate = LocalDate.now();
LocalDate deliveryDate = currentDate.plusDays(7);

System.out.println(deliveryDate);

You can also work with date and time:

LocalDateTime now = LocalDateTime.now();

System.out.println(now);

java.time is more readable, safer, and better suited for modern applications.

6. Java 11: A Cleaner Version Ready for Services

Java 11 arrived after the change in the Java release cycle. It is a widely used version in companies because it allowed migration from Java 8 to a more modern base without making too big a leap.

Main Features of Java 11

• New standard HTTP Client.
• Use of var in lambda parameters.
• New methods in String.
• New methods for files.
• Execution of .java files without prior manual compilation.
• Removal of some legacy modules from the JDK.
• Performance and security improvements.

7. HTTP Client in Java 11

Previously, many projects used external libraries such as Apache HttpClient, OkHttp, or RestTemplate to make HTTP requests.

Java 11 incorporated a standard HTTP client in the java.net.http package.

Example:

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class HttpClientExample {

    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("https://api.github.com"))
                .GET()
                .build();

        HttpResponse<String> response = client.send(
                request,
                HttpResponse.BodyHandlers.ofString()
        );

        System.out.println(response.statusCode());
        System.out.println(response.body());
    }
}

This makes it possible to consume REST APIs using only the JDK, without adding an external HTTP client library.