The answer is no. At least there is no way to do it using generic types. I would recommend a combination of generics and factory methods to do what you want.
class MyGenericClass<T extends Number> {
public static MyGenericClass<Long> newInstance(Long value) {
return new MyGenericClass<Long>(value);
}
public static MyGenericClass<Integer> newInstance(Integer value) {
return new MyGenericClass<Integer>(value);
}
// hide constructor so you have to use factory methods
private MyGenericClass(T value) {
// implement the constructor
}
// ... implement the class
public void frob(T number) {
// do something with T
}
}
This ensures that only MyGenericClass<Integer>
and MyGenericClass<Long>
instances can be created. Though you can still declare an variable of type MyGenericClass<Double>
it will just have to be null.