interface problem

[adam Lui]

"you can declare variables inside an interface, but you cant change their values in a class that implements the interface."

I dont really get it...

Can anyone show me an example demonstrates the point?

[ahmed yehia]

Because interface variables are by default public static final, you cant change their values.

[Keith Flo]

This is true even if 'public static final' is not included in the variable declaration. (see K&B p. 22)

For example:

interface Foo {
int BAR = 42;
void go();
}

In this example BAR is a constant and is 'public static final' by default.

[chander shivdasani]

consider an interface
interface if {
int i = 20;
}

in this case i by default is public static final .So you cant change the value of i in any class that implements the interface.