JDK 11 vs JDK 8

Table of Contents

• 👉 What is Java 8
• 👉 What is Java 11
• 👉 Why compare Java 8 vs Java 11
• 👉 Feature-wise comparison
• 👉 Internal working differences
• 👉 Implementation in Java
• 👉 Summary
• 👉 Interview Questions

👉 What is Java 8

Java 8 was a revolutionary release that changed how developers write Java code.

🔥 Key highlights:

• Lambda expressions
• Stream API
• Functional interfaces
• Default methods in interfaces

👉 It introduced functional programming into Java.

👉 What is Java 11

Java 11 is a Long-Term Support (LTS) release that builds on Java 8 and intermediate versions.

🔥 Key highlights:

• New HTTP Client API
• String and File API enhancements
• Optional improvements
• JVM and GC optimizations
• Removal of legacy modules

👉 It focuses more on refinement and productivity.

👉 Why compare Java 8 vs Java 11

Many applications are still running on Java 8 and planning to migrate.

🔥 Reasons to compare:

• ✔ Understand real benefits of upgrading
• ✔ Learn API improvements
• ✔ Identify performance gains
• ✔ Reduce migration risks

👉 This is one of the most practical upgrade paths in enterprise Java.

👉 Feature-wise comparison

🔥 1. Functional Programming (Java 8 Strength)

Java 8 Example

import java.util.*;

public class Java8Stream {
    public static void main(String[] args) {
        List<String> list = Arrays.asList("Java", "Python", "Go");

        list.stream()
            .filter(s -> s.startsWith("J"))
            .forEach(System.out::println);
    }
}

👉 Java 8 introduced Streams and Lambdas.

Java 11 Perspective

👉 No major syntax change, but internal optimizations improved performance.

🔥 2. String API Enhancements

Java 8

public class Java8String {
    public static void main(String[] args) {
        String str = "  Hello  ";
        System.out.println(str.trim());
    }
}

Java 11

public class Java11String {
    public static void main(String[] args) {
        String str = "  Hello  ";
        System.out.println(str.strip());
        System.out.println(" ".isBlank());
        System.out.println("Hi ".repeat(3));
    }
}

⚙ Internal Difference

• trim() → ASCII-based
• strip() → Unicode-aware

👉 Better handling of international text.

🔥 3. File Handling

Java 8

import java.nio.file.*;
import java.io.IOException;

public class Java8File {
    public static void main(String[] args) throws IOException {
        Path path = Paths.get("file.txt");
        String content = new String(Files.readAllBytes(path));

        System.out.println(content);
    }
}

Java 11

import java.nio.file.*;

public class Java11File {
    public static void main(String[] args) throws Exception {
        Path path = Path.of("file.txt");
        String content = Files.readString(path);

        System.out.println(content);
    }
}

⚙ Internal Difference

• Java 11 uses optimized buffering
• Reduces memory overhead

👉 Cleaner and more efficient.

🔥 4. HTTP Client

Java 8

import java.net.*;

public class Java8Http {
    public static void main(String[] args) throws Exception {
        URL url = new URL("https://example.com");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");

        System.out.println(conn.getResponseCode());
    }
}

Java 11

import java.net.URI;
import java.net.http.*;

public class Java11Http {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()
                .uri(new URI("https://example.com"))
                .GET()
                .build();

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

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

⚙ Internal Difference

• Java 8 → Blocking I/O
• Java 11 → Non-blocking, async-ready, HTTP/2

👉 Major improvement for scalable applications.

🔥 5. Optional Improvements

Java 8

import java.util.Optional;

public class Java8Optional {
    public static void main(String[] args) {
        Optional<String> value = Optional.ofNullable(null);

        if (value.isPresent()) {
            System.out.println(value.get());
        } else {
            System.out.println("Empty");
        }
    }
}

Java 11

import java.util.Optional;

public class Java11Optional {
    public static void main(String[] args) {
        Optional<String> value = Optional.ofNullable(null);

        value.ifPresentOrElse(
                System.out::println,
                () -> System.out.println("Empty")
        );
    }
}

👉 More expressive and functional style.

🔥 6. JVM and Garbage Collection

Java 8

• Parallel GC
• CMS (deprecated later)

Java 11

• G1 GC (default)
• ZGC (experimental)

⚙ Internal Difference

• Better heap management
• Lower pause times
• Concurrent GC improvements

👉 Better performance under heavy load.

🔥 7. Modular System

Java 8

• Monolithic JDK

Java 11

• Modular system (Project Jigsaw)

⚙ Internal Working

• module-info.java
• Strong encapsulation
• Better dependency management

👉 Enables smaller runtime images.

👉 Internal working differences

Let’s simplify the core evolution:

• Java 8 → Monolithic architecture
• Java 11 → Modular runtime
• Java 8 → Blocking HTTP
• Java 11 → Async HTTP with NIO
• Java 8 → Manual file handling
• Java 11 → Optimized high-level APIs
• Java 8 → Basic string handling
• Java 11 → Unicode-aware processing

👉 Java 11 improves both developer productivity and JVM efficiency.

// Java 8 Style
import java.nio.file.*;
import java.util.*;

public class Java8Demo {
    public static void main(String[] args) throws Exception {
        Path path = Paths.get("demo.txt");
        String content = new String(Files.readAllBytes(path));

        Optional<String> optional = Optional.ofNullable(content);

        if (optional.isPresent()) {
            System.out.println(optional.get());
        }
    }
}

// Java 11 Style
import java.nio.file.*;
import java.util.*;

public class Java11Demo {
    public static void main(String[] args) throws Exception {
        Path path = Path.of("demo.txt");
        String content = Files.readString(path);

        Optional<String> optional = Optional.ofNullable(content);

        optional.ifPresent(System.out::println);
    }
}

👉 Summary

Java 8 vs Java 11 is a story of evolution.

🔥 Key takeaways:

• Java 8 introduced functional programming
• Java 11 refined APIs and improved performance
• Cleaner, more readable code
• Modern HTTP client replaces legacy APIs
• Better JVM and GC

👉 Upgrading to Java 11 is one of the easiest and most beneficial upgrades.

Also, for deeper understanding of Java internals, check https://code2java.com/jdk-11-features/

👉 Interview Questions

👉 1. What are the major differences between Java 8 and Java 11?
👉 2. How does the HTTP Client differ from HttpURLConnection?
👉 3. What improvements were made in String API?
👉 4. What is modular system in Java?
👉 5. How did Optional improve in Java 11?
👉 6. What changes were made in garbage collection?
👉 7. Why should we upgrade from Java 8 to Java 11?
👉 8. What are the key performance improvements in Java 11?