Question

I have an Object called CAR declared as follows:

public class Car{
   public int NumberOfWheels;
}  

and using another class I can retrieve three of its subclasses.
As follows:

public TruckA getCarA(int param){
   return new TruckA () {NumberOfWheels = param} 
}
public TruckB getCarB(int param){
   return new TruckB () {NumberOfWheels = param} 
}
public TruckC getCarC(int param){
   return new TruckC () {NumberOfWheels = param} 
}

How do I write in using generics ?
(I know it is too simple, I need an example for a more complicated case)

I want to create a method that creates a new (T), enters the parameter and returns it.

something like

public TruckC getCarC(int param){
   return getTruck<TruckC>(param)
}

Only that :
1. TruckA/B/C dont have constructor.
2. Car has no constructor. initialized using {}.
3. The method should receive only classes that derive from Car so that it can use its initialization ( {} ).

(something equivalent to ?? extends ? in java generics)
Possible ?

Thanks.

Answer 1

private static T GetTruck<T>(int param) where T : Car, new()
{
    return new T() {NumberOfWheels = param} ;
}