This week's book giveaway is in the General Computing forum.
We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line!
See this thread for details.
The moose likes Beginning Java and the fly likes question about static variable's residence Big Moose Saloon
  Search | Java FAQ | Recent Topics
Register / Login


JavaRanch » Java Forums » Java » Beginning Java
Reply Bookmark "question about static variable Watch "question about static variable New topic
Author

question about static variable's residence

Javed Mohammed
Greenhorn

Joined: Sep 29, 2005
Posts: 17
Hi,

I understand that an object and its instance variables reside on heap, when the object is created.
Each object will have its own copy of instance variables.

Where and when does a static variable reside. If I am right, it does need an object to be created. Also, when two objects of the class are created, boh objects share the same copy of the static variable. Hence, the static variable is not living inside the object, then where is it?

Thanks and Regards,

Javed.
Eric McIntyre
Greenhorn

Joined: Mar 03, 2005
Posts: 26
Originally posted by Javed Mohammed:
Where and when does a static variable reside.
A static variable comes into existence when the class is loaded.

If I am right, it does need an object to be created.
No, a static variable does not need to have any objects created. Any statement that references a class will cause it to be loaded (and therefore init its static members) if it is not already.
or even just
Layne Lund
Ranch Hand

Joined: Dec 06, 2001
Posts: 3061
Eric is correct, if he means that the static variables don't need an object of the class that contains them. However, there IS an object created when a class is loaded. The object is of type Class and represents the class. I don't know if static variables are associated with this object or not. This is one nice thing about Java: general you don't have to worry about these details. Of course, it is sometimes interesting to learn about just as an academic pursuit.

Layne


Java API Documentation
The Java Tutorial
Javed Mohammed
Greenhorn

Joined: Sep 29, 2005
Posts: 17
OOPS.......I did mean to say that static varibales does not need an object, that was a typing mistake.

"An object is created when class is loaded", this answers my queston.

Thanks everybody.
Layne Lund
Ranch Hand

Joined: Dec 06, 2001
Posts: 3061
Just to clarify, let's say you have a class named MyClass. The object created that I mentioned is NOT an object of type MyClass. It is an object created from java.lang.Class. This object represents the MyClass type.

Like I said, I am not sure if the static variables are associated with this class or not. You may want to check out the Java Language Specification (JLS) to see what it says.

Layne
 
I agree. Here's the link: http://ej-technologies/jprofiler - if it wasn't for jprofiler, we would need to run our stuff on 16 servers instead of 3.
 
subject: question about static variable's residence
 
Similar Threads
where does static variable reside
static modifier
Why does this give a stackoverflowerror?
object and instance variable says that they can change at runtime.
instance as an object