Question

How can I access a private field of an inner class in another package which extends another inner class in yet another package by using reflection (package java.lang.reflect)?

package MainPackage;
import java.lang.reflect.Field;

class PrimaryClass
{
    public static void main(String[] args)
    {
        AuxiliaryPackage.TerciaryClass.BugattiVeyron bugattiVeyron = 
            (new AuxiliaryPackage.TerciaryClass()).new BugattiVeyron(
                new MainPackage.SecondaryClass());        

        System.out.println("Name: "+ bugattiVeyron.name);
        System.out.println("Tires type: " + bugattiVeyron.tiresType);
        try
        {
            Class bugattiVeyronClass = bugattiVeyron.getClass();
            Field invisibleField1 = bugattiVeyronClass.getDeclaredField("topSpeed");
            invisibleField1.setAccessible(true);
            System.out.println(invisibleField1.get(bugattiVeyron));
            Field invisibleField2 = bugattiVeyronClass.getDeclaredField("tamperedOdometer");
            invisibleField2.setAccessible(true);
            System.out.println(invisibleField2.get(bugattiVeyron));
        }
        catch (Exception e)
        {
            /* I ALWAYS GET AN EXCEPTION !! */
            /* I need a change to be done IN the TRY block. */
            /* WHEN THE BugattiVeyron class DOES NOT EXTEND another inner class, NO EXCEPTION. */
            /* See at the end for a detail of the just mentioned case. */
            System.out.println("An exception has occurred.");
            System.err.println(e.getMessage());
            e.printStackTrace();
        }
    }
}



package MainPackage;
public class SecondaryClass
{
    public class SportsCar
    {
        /* Public fields. Accesible from any package. */
        public String name = new String();

        /* Protected fields. Accesible from the same package and subclasses in any package */
        protected String tiresType = new String();

        /* Package fields. No explicit modifier. Accessible from the same package only. */
        int topSpeed; //km per hour

        /* Private fields. Accessible from the same class only. */
        private boolean tamperedOdometer;

        /* Default constructor */
        public SportsCar()
        {
            name = "Sports car";
            tiresType = "Race";
            topSpeed = 250;
            tamperedOdometer = false;
        }

        public SportsCar(String name, String tiresType, int topSpeed, boolean tamperedOdometer)
        {
            this.name = name;
            this.tiresType = tiresType;
            this.topSpeed = topSpeed;
            this.tamperedOdometer = tamperedOdometer;
        }     
    }
}



package AuxiliaryPackage;
public class TerciaryClass
{
    public class BugattiVeyron extends MainPackage.SecondaryClass.SportsCar
    {
        /* Default constructor */
        public BugattiVeyron(MainPackage.SecondaryClass secondaryClass)
        {
            secondaryClass.super("Buggati Veyron", "Michelin Pilot Sport PS2 PAX", 431, false);
        }
    }
}

When the BugattiVeyron class does not extend anything (after a few changes in the code) I instantiate it like this:

AuxiliaryPackage.TerciaryClass.BugattiVeyron bugattiVeyron = (new
        AuxiliaryPackage.TerciaryClass()).new BugattiVeyron();

… and no exception rises… So what should I change in the try block to get things done well?

Thanks in advance!!

EDIT 1.
I didn’t mean to yell. I thought that the intro might get lost because of the length of the post. I have included the stackTrace. I apologize. This is my second question.

Here is the first exception (The other one is similar):

java.lang.NoSuchFieldException: topSpeed
        at java.lang.Class.getDeclaredField(Unknown Source)
        at MainPackage.PrimaryClass.main(PrimaryClass.java:17)

The line 17 is:
Field invisibleField1 = bugattiVeyronClass.getDeclaredField(“topSpeed”);

EDIT 2.
I know it does NOT look like a “good programming pattern”. This is about a research on the limits of java.lang.reflect.

EDIT 3: THE ANSWER.
I want to thank all those who were kind and patient to me and, tried to provide answers. Finally, I got the solution from vsb. So, it took around an hour to get the answer since I posted the question. A record! My first question has not received any attention at all since March the 1st.

Answer 1

This code works.

        Class bugattiVeyronClass = bugattiVeyron.getClass();
        Class sportsCarClass = bugattiVeyronClass.getSuperclass();
        Field invisibleField1 = sportsCarClass.getDeclaredField("topSpeed");
        Field invisibleField2 = sportsCarClass.getDeclaredField("tamperedOdometer");

BugattiVeyron class doesn’t have these fields, they are from superclass and must be accessed correspondingly.

You can use following method to find field in the class hierarchy:

private static Field getDeclaredFieldInHierarchy(Class<?> clazz, String fieldName) {
    if (clazz == null) {
        return null;
    }
    try {
        return clazz.getDeclaredField(fieldName);
    } catch (NoSuchFieldException e) {
        return getDeclaredFieldInHierarchy(clazz.getSuperclass(), fieldName);
    }
}

But please consider another way to solve your problem. It’s very bad style and should only be used when absolutely necessary.