Implicit classes and instance main (3rd preview)

Key points

• A first Java program forces a beginner to meet public, static, void, String[] before printing anything.
• An implicit class lets a file with no class declaration hold methods directly.
• The main method can be an instance method, and can take no arguments at all.
• The compiler still creates a real class - this is syntax, not a new runtime model.
• By its third preview here it was clearly heading for final, which it reached in Java 25.

Example

// Java 23 preview (JEP 477) - the whole file would be:
//
//   void main() {
//       System.out.println("Hello");
//   }
//
// Java 21 needs every word of this before a beginner can print anything:
public class Main {
    public static void main(String[] args) {
        System.out.println("Hello");
        System.out.println("public  - why does a beginner need visibility?");
        System.out.println("static  - why before objects are taught?");
        System.out.println("String[] args - never used in lesson one");
    }
}

Implicit classes shrink the on-ramp for learners without changing what the JVM runs.