Generics and getClass

[JavaEnquirer]

Anyone know how I go about getting the class of a generic type e.g. I'd
like to be able to do the following:

Class clazz = T.getClass();

Seems a strange request, but without going into detail, I need to be
able to do this. I don't have access to an instance of type T and do
not want to pass an instance in either. In fact, I need to create an
instance of type T inside of a class paramaterised with type T.

many thanks in advance.

 

[Oliver Wong]

Anyone know how I go about getting the class of a generic type e.g. I'd
like to be able to do the following:

Class clazz = T.getClass();

Not possible. The generic type information is erased at runtime.

Seems a strange request, but without going into detail, I need to be
able to do this. I don't have access to an instance of type T and do
not want to pass an instance in either. In fact, I need to create an
instance of type T inside of a class paramaterised with type T.

many thanks in advance.

The solution I've most commonly seen is to pass in an instance of
Class<T>.

E.g.

String foo = makeMeThisObject(String.class);

- Oliver

 

[Roedy Green]

Seems a strange request, but without going into detail, I need to be
able to do this. I don't have access to an instance of type T and do
not want to pass an instance in either. In fact, I need to create an
instance of type T inside of a class paramaterised with type T.

the problem is type erasure. All record of what T was is gone by run
time. T is usually just an Object by then.

 

[JavaEnquirer]

The solution I've most commonly seen is to pass in an instance of
Class<T>.

E.g.

String foo = makeMeThisObject(String.class);

- Oliver

Cheers Oliver, I feared that I'd have to do that, though, fear is too
strong a word!!!

 

[darkaico]

There is a way to obtain the Class of the generic object.
For example in a method inside your class

public Class getGenericClass() {
Class result = null;
Type type = this.getClass().getGenericSuperclass();

if(type instanceof ParameterizedType){
ParameterizedType pt = (ParameterizedType) type;
Type[] fieldArgTypes = pt.getActualTypeArguments();
result = (Class) fieldArgTypes[0];
}

return result;
}

In bold lines you could see that "this" is refered to the class that is impelementing the generic object

hope you could continue with this clean solution