Get Static Variable from Dynamic Class

Question

I'm fairly new to Java and some of the concepts are still fuzzy, so I'm sorry if my question is a bit confusing.

I have a class Food, like so:

public Class Food {

   // some unrelated methods and constructor

And then I have a bunch of subclasses of the Food class, all with a static variable "calories":

public Class Banana extends Food{

    public static int calories = 100;

    // more unrelated methods and the constructor

and:

public Class Chicken extends Food{

    public static int calories = 300;

    // more unrelated methods and the constructor

and so on...

As you can see, each subclass of Food has its own static "calories" variable with some unique value. It should also be noted that this calories variable needs to be changed sometimes; this is why it's not a const.

I also have another class Eater:

public Class Eater {

    // constructor:

    public int mealcalories;

    public Eater(Class c) {

        this.mealcalories = c.calories;

As you can tell, I want to pass in the name of some Food subclass, e.g. Banana, into the constructor of an Eater class instance like this:

public Eater myEater = new Eater(Banana.class);

And then myEater's "mealcalories" variable should have a value of 100.

However, this isn't what's happening. I'm getting an error saying:

java: cannot find symbol
symbol: variable calories
location: variable c of type java.lang.Class

Can anyone help me on how to fix this and how to properly get the calories variable from whatever Class c I pass into it?

Note: this isn't actually what I'm coding, I've just simplified it to make it more understandable.

I'm having a hard time understanding what the top answer of that question means. Could you please explain it? — Anish Shanbhag, May 31 '18 at 00:01
Now I am getting two errors: `NoSuchFieldException` and `IllegalAccessException` — Anish Shanbhag, May 31 '18 at 00:08
https://docs.oracle.com/javase/tutorial/essential/exceptions/catchOrDeclare.html — shmosel, May 31 '18 at 00:16
Thank you! Surrounding it with a try/catch worked. I just have one more question: how would you do this if `calories` was an ArrayList? Is there anything like `getArrayList`? — Anish Shanbhag, May 31 '18 at 00:27
Use `get()` and cast the result. Note that this design has a bad smell. There's probably a better way to accomplish what you're after than relying on reflection. — shmosel, May 31 '18 at 00:29
Would I be able to do something like `.add(parameter)` to the resulting ArrayList? — Anish Shanbhag, May 31 '18 at 00:34
I'm getting an error saying it can't add anything to the ArrayList — Anish Shanbhag, May 31 '18 at 00:46
We're straying from the original question. If you have another question, post it separately. — shmosel, May 31 '18 at 00:52

Get Static Variable from Dynamic Class

0 Answers0