Why is this an issue?

"A rose by any other name would smell as sweet," but main by any other name would not. Just because a method has the name "main", that doesn’t make it the entry point to an application.

In Java versions prior to Java 25, the main method must have a specific signature to serve as the application entry point: it must be public static void and accept a single String [] as an argument.

Starting with Java 25, the requirements for main methods have been relaxed. The main method can now be:

• An instance method (non-static)
• Non-public (e.g., package-private or protected)
• Defined without a String [] parameter

Using main for anything other than an application entry point can be confusing to developers unfamiliar with Java, as the method name strongly suggests it is the starting point of execution. To avoid this confusion, methods with different purposes should be given other names.

Noncompliant code example

public void main(String arg) {  // Noncompliant
  // ...
}

Compliant solution

void main(String [] args) { // Compliant Java 25 instance main
  run(args[0]);
}

public void run(String arg) { // Renamed
  // ...
}

Resources

Documentation

• OpenJDK - JEP 512: Compact Source Files and Instance Main Methods