Accessing super class's hidden fields while using reflection

Question

I will explain it through an example since I am not able to explain the problem.

Let's take 2 classes as below,

public class Vehicle {
    public String series = "Sedan";
}

public class Audi extends Vehicle {
    public String series = "A8";
}

Now, I want to get both the series of Vehicle and Audi. So I can use,

Audi audi = new Audi();
Vehicle vehicle = audi;
String audiSeries = audi.series; //This will give me "A8"
String vehicleSeries = vehicle.series; //This will give me "Sedan"

Here comes my problem: But If I don't have access to Vehicle and Audi classes during compilation and can only use reflection to get the object, how can I get the vehicle's series.

Class audiClass = Class.forName("Audi");
Class vehicleClass = Class.forName("Vehicle");

Object audiObj = audiClass.newInstance();
Field audiSeries = audiClass.getField("series");

System.out.println(audiSeries.get(audiObj));

Output: A8

Is there anyway to get Vehicle class' series field "Sedan" in the above method.

P.S: I cannot change the design to avoid this problem.

Answer 1

I was suprised myself, that you can access the Vehicle's Field by just casting ist to a Vehicle.

Your Approch works, you just have to go the last step by using the Field from the Vehicle-Class:

Audi audi = new Audi();
Vehicle vehicle = audi;
String audiSeries = audi.series; 
System.out.println("direct-audi: " + audiSeries);
String vehicleSeries = vehicle.series; 
System.out.println("direct-vehicle: " + vehicleSeries);


Class audiClass = Class.forName(Audi.class.getName());
Class vehicleClass = Class.forName(Vehicle.class.getName());


Object audiObj = audiClass.newInstance();
Field audiSeriesField = audiClass.getField("series");
Field vehicleSeriesField = vehicleClass.getField("series");

System.out.println("reflection-audi: " + audiSeriesField.get(audiObj));
System.out.println("reflection-vehicle: " +  vehicleSeriesField.get(audiObj));

Result:

direct-audi: A8
direct-vehicle: Sedan
reflection-audi: A8
reflection-vehicle: Sedan

If you dont Know the Superclass Name you can just use Class vehicleClass = audiClass.getSuperclass();