$cat PrivateMain.java
package test;
public class PrivateMain {
    protected  static void main( String [] args ) {
        System.out.println( "Hello, I'm proctected and I'm running");
    }
}
class PublicMain {
    public static void main( String [] args ) {
        PrivateMain.main( args );
    }
}
$javac -d . PrivateMain.java
$java test.PrivateMain
Main method not public.
$java test.PublicMain
Hello, I'm proctected and I'm running

public static void callMain() {
      main( new String[]{} );
 }

class A {
  private static void main(String arg[])
  {
  System.out.print(2+3);
  }
}