I have a class like this:
public class Pojo<T, P> {}
I know at compile time the type of T but I don't know the type of P. I was wondering if something like this is possible:
Class<Integer> t = Integer.class;
field = new Pojo<Integer, t>();
If not, any alternative solution to the problem is valid ;)
EDIT: I'm trying to obtain statistics from POJO fields, ie, I have a class AirRegister with fields station, o3, so2, altitude, latitude... and I want to obtain the mode for these fields. The user can send any type with any field type to the program so until runtime the field type is unknown.
Example:
public static void main(String[] args) {
String field = args[0];
Class<fieldType> type = AirRegister.class.getDeclaredField(field).getClass();
ModeImpl<AirRegister, type> p = new ModeImpl<AirRegister, type>();
}
It is not possible. Generics are a compile-time only feature. They are used by the compiler to type-check your source code, but at run-time they are gone.
If you need to implement run-time type checking, you might use Class
instances to store the required type. Eg:
class Pojo<T> {
private Class<?> clazz;
Pojo(Class<?> clazz) {
this.clazz = clazz;
}
void doSomething(T arg1, Object arg2) {
if (!clazz.isInstance(arg2)) {
throw new ClassCastException();
}
...
}
}
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