Static methods

[Sri Enga]

This is a question from Marcus : ---
public class Scope{
private int i;
public static void main(String argv[]){
Scope s = new Scope();
s.amethod();
}//End of main
public static void amethod(){
System.out.println(i);
}//end of amethod
}//End of class
1) A value of 0 will be printed out
2) Nothing will be printed out
3) A compile time error
4) A compile time error complaining of the scope of the variable i
Ans: is 3 Why?
Can any one explain

[Michael Burke]

Static methods can only access static members.

[Sean Casey]

There is a compiler error because you have a static method accessing a non static variable:
public static void amethod(){
System.out.println(i);}
variable i is not static.

[mita]

It won't compile here

--public static void amethod(){
System.out.println(i);--
as i is not static & a static method amethod() is trying to access it directly.
Thanks

[Lala Viswanath]

Originally posted by Sean Casey:
There is a compiler error because you have a static method accessing a non static variable:
public static void amethod(){
System.out.println(i);}
variable i is not static.

[ryan burgdorfer]

I take it the main method is an exception, since it is in fact able to access non-static vars?

[Rosie Vogel]

Ryan, could you provide an example of what you mean please?

[ryan burgdorfer]

Here is an example of what I mean by my previous post:

class A {
    int i = 1;
    public void aMethod() {
        System.out.println("aMethod called!");
    }
    public static void main(String[] args) {
        A a = new A();
        System.out.println(a.i);
        a.aMethod();
    }
}

Notice that the main method is of course static, yet it accesses the non-static variable i AND the non-static method aMethod() of class A...

[Susmita Ganguly]

Ryan
In your example you are creating an instance of class A and then accessing the non static method and variable of that instance which is legal. [You will not be able to do a.i if i was declared private]. It is different from accessing the variable directly. If you refer the variable i directly it is assumed that you mean 'this.i'; 'this' is not present when you are in a static method.
Susmita

[sharad chaudhary]

Originally posted by Susmita Ganguly:
Ryan
In your example you are creating an instance of class A and then accessing the non static method and variable of that instance which is legal. [You will not be able to do a.i if i was declared private]. It is different from accessing the variable directly. If you refer the variable i directly it is assumed that you mean 'this.i'; 'this' is not present when you are in a static method.
Susmita

-----------------------------------------------------------------
Even if the variable i is declared private then also we can access it by a.i in our main method.It's fully valid and in the scope of the class even if it is declared private because we are accessing it from within the class itself.
Sharad

[Susmita Ganguly]

Sharad
With the example we were discussing on, are you sure we can access variable i even if it were private ? I am just trying to clear my understanding.

[ryan burgdorfer]

I tried the same code with i declared as private, and indeed it still worked as before...
BUT, I tried printing i WITHOUT first creating an instance of class A, and the compiler complained that I was trying to make a static reference to a non-static variable. Interesting...it appears that you can only access non-static variables via objects...I guess this makes sense, since without a reference to an object of class A, the variable i is implicitly static.