What is the maximum number of type parameters you used in a java class?
Example for 4:
class MyClass<A, B, C, D> {
}
views:
88answers:
5
+3
A:
Never used more then 2. Actually, I've never seen more then 2 type parameters in any class in java.* package.
Roman
2010-03-20 10:01:42
I've used 5, it is rare, but when you have a need for it you can actually make the code simpler. My current code has something like: public interface Parser<S, R, A, X extends ResultTransformer<S, R, A>> where S is the source to transform from, R is type to transform to, A is the additional argument that the transformer takes, and X is the transformer. Once I did that I deleted a huge amount of code and everything got simpler. Not typical, but I have done similar things before with good effect.
TofuBeer
2010-03-20 10:20:11
+1 At least more than type parameters makes code calling the class very much unreadable.
Helper Method
2010-03-20 11:39:28
A:
The representation of type parameters in the JDK 1.5 or greater classfile format don't impose any limits on the number of type parameters. So I would say there is no limit. (The information is in this document ... search for the word "signature".)
By contrast, the number of methods, fields and interfaces is 2**16 because the classfile format has a 16 bit counts for these in the ClassFile descriptor.
Stephen C
2010-03-20 10:14:36
A:
I have a Quadruple class which is a poor man's tuple. Obviously, it takes four parameters.
quant_dev
2010-03-20 10:16:21
+1
A:
I think I was once trying to create a framework for board-based games that took 7 type parameters. I never completed it but it’s quite probable that that list would have grown some more. :)
public interface Board<B extends Board<B, C, M, P, Pi, S, T>, C extends BoardColor, M extends Move<M, P, Pi, S>, P extends BoardPlayer<B, C, M, P, Pi, S, T>, Pi extends BoardPiece<B, C, M, P, Pi, S, T>, S extends BoardState<B, C, M, P, Pi, S, T>, T extends BoardTile<B, C, M, P, Pi, S, T>> {
…
}
Bombe
2010-03-20 10:21:02
A:
When using Functional Java library, you quite often need four to five type parameters. For instance, see this example. More examples here.
missingfaktor
2010-03-29 18:39:11