[FunFacts Android App] problem on getting data.

Hi everybody. I just ended the first android course and i realize my super cool fun facts app. Before moving to next course i decided to a dive a little bit deeper in android coding by evolving this app.

Since now i had no problem with coding but now i'm little bit stucked; What i'm trying to achieve is grabbing Facts from an xml instead of an array. And that's fine because i did it but now i would like change things once more.

This is my starting point: i realized this xml and coded a function that grab the file, parse xml into an array and then it return the fact:

<?xml version="1.0" encoding="utf-8"?>
<resources name>
    <string-array name="facts">
        <item>facts1</item>
        <item>fact2</item>
        <item>fact3</item>
    </string-array>
</resources>

public class FactBook{

    public String getFact(String[] facts){
        Random randomGenerator = new Random();
        int randomNumber = randomGenerator.nextInt(facts.length);

        return facts[randomNumber];
    }

}

Resources res = getResources();
        final String[] xmlToArray = res.getStringArray(R.array.facts);
        String fact = mFactBook.getFact(xmlToArray);
        factLabel.setText(fact);

and that's fine. Now i want to associate an image to each block of facts that will be displayed just above the fact as category image and this is my xml now:

<?xml version="1.0" encoding="utf-8"?>
<resources name="facts">
    <string-array name="category1">
        <item>facts1</item>
        <item>fact2</item>
        <item>fact3</item>
    </string-array>
    <string-array name="category2">
        <item>fact1</item>
        <item>fact2</item>
        <item>fact3</item>
        <item>fact4</item>
    </string-array>
</resources>

This one (OFC) not working anymore and i can't even find the proper way to do it.

final String[] xmlToArray = res.getStringArray(R.array.facts);

Any tips or suggestion on how to do it? and what you think about my previous code, is it bad? Thanks a lot.