Summary of Java 9 New Features

Java 9 introduced several new features and enhancements that significantly improve the overall functionality and usability of the language. Below, we explore the main highlights of these updates:

1. Modular System (Project Jigsaw)

• Key Concept: Java 9 introduced a modular system that allows developers to create modular applications.
• Benefits:
  • Improved performance by reducing the size of Java applications.
  • Easier management of dependencies and versioning.
• Example: A module can be created using the module-info.java file, specifying the module name and its dependencies.

2. JShell: The Java Shell

• Key Concept: JShell is an interactive tool for learning and testing Java code snippets.
• Benefits:
  • Beginners can quickly experiment with Java code without creating a complete application.
• Example: Start JShell and type System.out.println("Hello, World!"); to see immediate output.

3. Enhanced Streams API

• Key Concept: The Streams API received new methods for better manipulation of data.
• Benefits:
  • Easier work with data collections and performing operations like filtering and mapping.
• Example: Use stream().filter(x -> x > 10).forEach(System.out::println); to print numbers greater than 10 from a list.

4. Private Methods in Interfaces

• Key Concept: Interfaces can now contain private methods.
• Benefits:
  • Enables code reuse within the interface, leading to cleaner and more maintainable code.
• Example:

interface MyInterface {
    private void privateMethod() {
        // Implementation
    }
    
    default void defaultMethod() {
        privateMethod();
    }
}

5. Improved Optional Class

• Key Concept: The Optional class was enhanced with new methods.
• Benefits:
  • Simplifies handling of null values and provides more functionality.
• Example: Use Optional.ofNullable(value).ifPresent(System.out::println); to print a value only if it is present.

6. New HTTP Client

• Key Concept: A new HTTP client API was introduced for making HTTP requests.
• Benefits:
  • Supports both synchronous and asynchronous requests, streamlining network communication.
• Example:

HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder().uri(URI.create("http://example.com")).build();
client.sendAsync(request, HttpResponse.BodyHandlers.ofString())
      .thenApply(HttpResponse::body)
      .thenAccept(System.out::println);

Conclusion

Java 9 brought significant enhancements that make the language more powerful and easier to use for developers at all levels. From modular programming to improved APIs, these features help streamline Java development.