class HelloWorld {
static void main(String args[]) {
System.out.println("Hello World");
}
}

Congratulations! You just successfully compiled and (hopefully) executed your first Java program! :-)

But in the above mentioned program, it does not contain public, even then it executes and prints "Hello World".

Please do consider that a beginner is asking this question.

My guess is that since you ran the program from the same directory that you made and stored the program, that everything turned out okay.

But! In the future, not putting public there may haunt you!

This restriction is there only for JVM since only for JVM, it is the entry point. Am I right ?

So, if a question is asked what is the right signature for main() method entry point of an application, what should be the answer in the following.

And, by the way, it's:

static public void main (String[] args)

or

In directory c:\tony I have the following

//File Xclass.java
package tony
public class Xclass {
	static void main(String[] args) {  // <--- NOTICE NO public
	
		//Do my stuff...
		system.out.println("Result is...");
	}
}	

java Xclass
or more precisely:
java tony.Xclass
I will get an error to the effect that java could not find a public static void main(String[] args) because that main() has only package access and not public as required.

So for it to work always, the method has to be public.

The JLS says this . The entry point of any application which is the main method has to be public static void main(String[] someName) { }. What tony told was as per the JLS spec.

Other than this Java behaves as told in JLS. The compiler checks All access levels (public/protected/package/private..) at the compile time itself whether the accessed member of the other class is in fact really obeys the rules defined for access levels. I tried to give you an example. Compile this. You will get compile time error. It would't even pass the compile check.
Compile like this. Your current dir has to be in classPath.
javac -d . Point.java
javac -d . PlusPoint.java
regds
maha anna

//Point.java
package points;
public class Point {
	public static void public_static_printMe() {
		System.out.println("I am from points.Point.public_static_printMe()");
	}
	protected static void protected_static_printMe() {
		System.out.println("I am from points.Point.protected_static_printMe()");
	}
	static void package_static_printMe() {
		System.out.println("I am from points.Point.package_static_printMe()");
	}
	private static void private_static_printMe() {
		System.out.println("I am from points.Point.private_static_printMe()");
	}
}
//PlusPoint.java
package morepoints;
import points.Point;
public class PlusPoint {
	public static void main(String[] args) {
		Point.public_static_printMe();
		Point.protected_static_printMe();
		Point.package_static_printMe();
		Point.private_static_printMe();
     }
}

If you use older versions of JDK, it might throw an
error, jdk 1.2 compiles and runs fine.