Doubt regarding static and main

[Kaush Kane]

The static functions can access only static varibales and can call other static functions.
The above being the definition of static:
How can main access non-static functions of a class via objects??

[Jan Groth]

as you say - "via object".

if you want to access anything non static from inside the main method - no way but creating a instance and call the method / field on this instance...

:-)

jan

[Kaush Kane]

if you want to access anything non static from inside the main method - no way but creating a instance and call the method / field on this instance

Does this hold true for static methods other than main??

[Campbell Ritchie]

Does this hold true for static methods other than main??

Yes.

But you ought to have as little as possible inside your main method.

public class ApplicationStarter
{
   public static void main(String[] args)
   {
       new MyApplication().start();
   }// end main method
}// end application starter class
 
public class MyApplication
{
   public void start()
   {
       WhateverYouNeedToDoToGetYourApplicationGoing();
   }// end start method
}// end my application class

[Edwin Dalorzo]

What you need to understand is that a static member belongs to no instance, but it belongs to the class itself.

On the other hand, instance members are different. There is a copy of them for every instance that you create.

When you are writing code in a static context you must be acquainted that you are not working for an specific instance, but for the class itself, and there is not a notion of an specific instance in that context.

That is why you cannot access instance members, because there is no way to know, within a static context, which specific instance of the class you maybe referring to when you access an instance member.

To illustrate it, see this code:

class Jedi{
   private String name = "Obi-wan";
 
   public static void main(String args[]){
      name = "Anakin"; //This is a compile time error
   }
 
}

The static method main cannot access the instance member "name" because it belongs to an specific instance unknown to the static context, in this case under the static context even no instance of the class Jedi exists yet.

However, this restriction does not imply that a static method cannot create instances of objects. For instance:

class Jedi{
   private String name = "Obi-wan";
 
   public static void main(String args[]){
      Jedi jedi = new Jedi();
      jedi.name = "Anakin"; //This compiles fine
   }
}

In this case there is no problem, because the main method is accessing the instance member through the specific instance it belongs to.

The conclusion is, static method cannot access instance members directly, but this does not mean that an static method cannot create new objects. If one of these objects it creates is an instance of its same class, the it could access the instance members of its same class through it.
[ June 06, 2006: Message edited by: Edwin Dalorzo ]

[Jesper de Jong]

Edwin explained it well, and The Java Tutorial on Sun's Java website also explains what 'static' means:

Understanding Instance and Class Members