How to get the type of the object poped from a stack

Question

Hi,
I have a stack which contains Boolean, Integer, MyBean objects.
Now depending on the type of object pop from stack i want to perform the different operations. Right now i m doing it like this:
Object a = stk.pop(); // stk is my stack
if ( a instanceof Object)
else if( a instanceof Boolean)
else
.}but it is not working...........
when i do like this
if(stk.pop() instanceof Boolean)
else
}it works but by this i lost the poped element............ what is the standard way to do such operations.
manish

Answer 1

Are you sure there isn't a cleaner way of doing what you are trying to achieve? You may want to take the opportunity to slightly re-think your design.
However, if you want to proceed down this route, just hold on to the object you popped, and then do the explicit case analysis on that:
Object obj = stack.pop();
if (obj instance of Boolean) {
} else if (obj instance of Integer) {
}Oh yeah, do not have the "instanceof Object" as your first check!
This will return true for any non-null reference (have a look at some java tutorials if you dont know why this is).