Extending both T and SomeInterface<T> in Java
I want to create a class that takes two parameters. One should be typed simply as T. The other should be typed as something that extends both T and SomeInterface<T>
. When I attempt this with
public class SomeClass<T, S extends SomeInterface<T> & T>
then Java complains with
"The type T is not an inte开发者_如何学JAVArface; it cannot be specified as a bounded parameter"
and if instead I attempt to create an interface for S with
public interface TandSomeInterface<T> extends SomeInterface<T>, T
then Java complains with
"Cannot refer to the type parameter T as a supertype"
Is there any way to do this in Java? I think you can do it in C++...?
You can't create an interface that extends the type parameter T
since there's no contract that would guarantee T
to be an interface. And of course interface extending a class is not allowed.
this works if you extend an interface as well:
public class SomeClass<T extends I, S extends SomeInterface<T> & I>
but maybe it's not exactly what you want ...
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