Question

I have method look like

doSomething( Class<T> valueType)

i call pass value like

Map.class, Long.class

as parameter into above method. If i want to use generic. how should i pass the value into above method? doSomething(Class<Map>); doesnt work

Answer 1

Map.class returns an object of type Class<Map>, Long.class returns an object of type Class<Long>.

So to pass Map.class your T needs to me Map.
If you want your T to be a generic, say ArrayList<String>, then that’s not possible.
The reason is that generics in Java use type erasure, which means that the generic type is only there at compile time, but it’s erased at run time. Thus there doesn’t exists something like ArrayList<String>.class.

Java generics are quite different that C# generics in this sense.