Srini ,
I am not 100% upto it

might be some one else in forum will put better light on it.
but whenever you will call a function, it will return a value and to retrieve a value we always declare a variable first then we call a function.
if you call this function in your oracle procedure you will write in something like this
your_cursor = call function (arguement)
in java you replace your variables by "?"
but syntax remain same.