Java Language - 131 - New Language Features

Exploring Java 9 and Beyond – New Language Features

Java has been evolving rapidly, introducing a wide range of new language features in Java 9 and subsequent versions. These features enhance code readability, maintainability, and productivity. In this article, we will delve into some of the significant language features introduced in Java 9 and beyond.

1. The ‘var’ Keyword

Java 10 introduced the ‘var’ keyword, which allows for local variable type inference. With ‘var,’ you can declare local variables without explicitly specifying their types, making code more concise while maintaining strong typing. For example:


var name = "John";
var age = 30;

In this code, the type of ‘name’ is inferred as a String, and the type of ‘age’ is inferred as an int.

2. Private Interface Methods

Java 9 introduced the ability to declare private methods in interfaces. These private methods can be used to avoid code duplication and improve the organization of interface code. Private interface methods are often used to implement shared logic among multiple default methods within an interface.


public interface MyInterface {
    default void publicMethod() {
        // Public method implementation
    }

    private void privateMethod() {
        // Private method implementation
    }
}

3. Immutable Collections

Java 9 introduced a set of immutable collection factories for creating unmodifiable lists, sets, and maps. These collections are useful when you want to ensure that data cannot be modified after creation. For example:


List<String> names = List.of("Alice", "Bob", "Charlie");
Set<Integer> numbers = Set.of(1, 2, 3, 4);
Map<String, Integer> scores = Map.of("Alice", 95, "Bob", 87);

4. Diamond Operator for Anonymous Classes

In Java 9 and later versions, the diamond operator can be used with anonymous inner classes to improve code readability. Previously, you had to specify the generic type on both the left and right sides when creating an anonymous inner class. With the diamond operator, you can simplify this process:


List<String> names = new ArrayList<>() {
    {
        add("Alice");
        add("Bob");
        add("Charlie");
    }
};

5. Multi-Resolution Image API

Java 9 introduced the Multi-Resolution Image API, which provides a way to represent and work with images at multiple resolutions. This is particularly useful for applications that need to adapt to various display resolutions, such as on different devices or screen sizes.


Image image = Image.of("myImage.jpg");
Image highResImage = image.resolution(2);
Image lowResImage = image.resolution(0.5);

6. Stream API Improvements

Java 9 and subsequent versions have enhanced the Stream API with new methods that simplify common operations. Some of the new methods include ‘takeWhile,’ ‘dropWhile,’ and ‘ofNullable.’ These methods make it easier to work with streams, filter elements, and handle null values in a more expressive way.


List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6, 7, 8, 9);
List<Integer> result = numbers.stream()
    .takeWhile(n -> n < 5)
    .collect(Collectors.toList());

7. Improved Process API

Java 9 introduced several enhancements to the Process API, making it easier to interact with and control external processes. The new API allows you to create, manage, and monitor processes in a more straightforward manner.


ProcessBuilder builder = new ProcessBuilder("java", "-version");
Process process = builder.inheritIO().start();
int exitCode = process.waitFor();

8. Module System

Although not a language feature, the introduction of the module system (JPMS) in Java 9 has a significant impact on code organization and modularity. It allows you to create modular applications, manage dependencies, and improve encapsulation. Modules are a crucial part of Java 9 and beyond.

9. HTTP/2 Client

Java 9 introduced a new HTTP client that supports the HTTP/2 protocol, offering improved performance and flexibility when making HTTP requests. The ‘HttpClient’ class provides a more modern and versatile way to work with web services.


HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
    .uri(new URI("https://example.com/api/data"))
    .GET()
    .build();
HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());

10. Stack-Walking API

Java 9 introduced the Stack-Walking API, which allows you to traverse the call stack programmatically. This feature is useful for debugging, profiling, and generating diagnostic information.


StackWalker walker = StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE);
walker.forEach(frame -> System.out.println(frame.getClassName() + "." + frame.getMethodName()));

Conclusion

Java 9 and the subsequent versions have introduced a plethora of new language features and APIs that enhance the Java language’s expressiveness, productivity, and adaptability. These features, including the ‘var’ keyword, private interface methods, immutable collections, and more, offer developers improved tools for writing efficient and maintainable code in modern Java applications.

Java Language – 131 – New Language Features