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Unnamed Classes and Instance Main Methods

JEP-445

Ever found Java's "Hello, World!" program a bit too complex?
Java's complexity can be daunting for beginners.
No more unnecessary clutter in simple programs.

Classic Approach

Classic Hello, World! program that is often used as the first program for Java students:

public class HelloWorld { 
    static String greeting = "Hello, World!";

    public static void main(String[] args) {
        System.out.println(String.format(":%s\n:%s\n:%s", HelloWorld.class.getName(), greeting,
                "Subscribe us on youtube.com/@semusings"));        
    }
}

java --source 22 --enable-preview HelloWorld.java

In this approach -> too much code, too many concepts, too many constructs

Mordern Approach

Allow to lunch instance main methods. Such methods are not static, need not be public, and need not have a String[] parameter.

class HelloWorldUsingInstanceMethod {

    String greeting = "Hello, World!";

    void main() {
        System.out.println(String.format(":%s\n:%s\n:%s", getClass().getName(), greeting,
                "Subscribe us on youtube.com/@semusings"));
    }

}

java --source 22 --enable-preview HelloWorldUsingInstanceMethod.java

Mordern Approach (contd.)

Unnamed classes to make the class declaration implicit

String greeting = "Hello, World!";

void main() {
    System.out.println(String.format(":%s\n:%s\n:%s", getClass().getName(), greeting,
            "Subscribe us on youtube.com/@semusings"));
}

java --source 22 --enable-preview HelloWorldUsingUnnamedClass.java

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References