Java 9-11 Features

Java 9: The Module System (JPMS)

The Java Platform Module System allows you to modularize applications, encapsulating packages and managing dependencies explicitly.

module-info.java

module com.example.myapp {
    requires java.sql;      // Depends on java.sql module
    exports com.example.api; // Exposes com.example.api package
}

Java 10: Local Variable Type Inference (var)

You can allow the compiler to infer the type of a local variable.

var message = "Hello, Java 10"; // Inferred as String
var list = new ArrayList<String>(); // Inferred as ArrayList<String>
var stream = list.stream(); // Inferred as Stream<String>

[!NOTE] var can only be used for local variables with initializers. It cannot be used for method parameters, return types, or fields.

Java 11: HTTP Client API

A modern, standardized way to make HTTP requests, replacing HttpURLConnection.

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.body());

Other Notable Features

• String Methods (Java 11): isBlank(), lines(), strip(), repeat(n).
• Collection Factory Methods (Java 9): List.of(), Set.of(), Map.of().
• Single Source File Execution (Java 11): Run java HelloWorld.java directly without javac.

Quiz