Why are interface variables static and final by default in Java?
A:
What meaning would an instance of an interface have? By DEFINITION an interface is abstract and cannot be instantiated. Thus no instance variables, static only.
JUST MY correct OPINION
2010-03-12 05:49:57
Abstract classes can have instance variables as well as implemented functions. Interfaces can't.
dan04
2010-03-12 06:13:39
Isn't it a coincidence, then, that I didn't mention abstract classes?
JUST MY correct OPINION
2010-03-12 07:54:34
he's pointing out that abstract classes are by definition abstract and cannot be instantiated. But somehow they *can* have instance variables. Your reasoning is unsound.
Philip Potter
2010-03-12 08:50:40
A:
Because anything else is part of the implementation, and interfaces cannot contain any implementation.
Amir Afghani
2010-03-12 05:50:13
To indicate that its a constant. Java doesn't have a const keyword. static final is how you declare constants.
Amir Afghani
2010-03-12 06:01:33
+2
A:
From www.codestyle.org:
Interface variables are static because Java interfaces cannot be instantiated in their own right; the value of the variable must be assigned in a static context in which no instance exists. The final modifier ensures the value assigned to the interface variable is a true constant that cannot be re-assigned by program code.
cherouvim
2010-03-12 05:54:15
A:
static - because Interface cannot have any instance. and final - because we do not need to change it.
Webbisshh
2010-03-12 05:54:58
+1
A:
Because Sun incorrectly decided developers didn't need a const keyword.
Spencer Ruport
2010-03-12 05:56:57