so I have this class in Java:
public class Foo<T>{
}
and inside this class I want to know if T implements certain interface.
The following code DOES NOT work but it's the idea of what I want to accomplish:
if(T.class implements SomeInterface){
// do stuff
}
so I want to check if the class T
that was passed to Foo have implements SomeInterface
on its signature.
Is it possible? How?
Generics, oddly enough, use extends
for interfaces as well.1 You'll want to use:
public class Foo<T extends SomeInterface>{
//use T as you wish
}
This is actually a requirement for the implementation, not a true/false check.
For a true/false check, use unbounded generics(class Foo<T>{
) and make sure you obtain a Class<T>
so you have a refiable type:
if(SomeInterface.class.isAssignableFrom(tClazz));
where tClazz
is a parameter of type java.lang.Class<T>
.
If you get a parameter of refiable type, then it's nothing more than:
if(tParam instanceof SomeInterface){
but this won't work with just the generic declaration.
1If you want to require extending a class and multiple interfaces, you can do as follows: <T extends FooClass & BarInterface & Baz>
The class(only one, as there is no multiple inheritance in Java) must go first, and any interfaces after that in any order.