App immediately crash

public class FactBook extends ContextWrapper {

    public String[] mFacts;

    public FactBook(Context base) {
        super(base);
    }

    // Fields (Member Variables) - Properties about the object
//    private final String[] mFacts = new String[]{
//            "Ants stretch when they wake up in the morning.",
//            "Ostriches can run faster than horses.",
//            "Olympic gold medals are actually made mostly of silver.",
//            "You are born with 300 bones; by the time you are an adult you will have 206.",
//            "It takes about 8 minutes for light from the Sun to reach Earth.",
//            "Some bamboo plants can grow almost a meter in just one day.",
//            "The state of Florida is bigger than England.",
//            "Some penguins can leap 2-3 meters out of the water.",
//            "On average, it takes 66 days to form a new habit.",
//            "Mammoths still walked the earth when the Great Pyramid was being built." };

    // Methods - Action the object can take
    public String getFact() {
        // Get the fact from XML file - strings.xml
        Resources res = getResources();
        mFacts = res.getStringArray(R.array.fact_book_en);
        // Randomly select a fact
        String fact;
        Random randomGenerator = new Random();
        int randomNumber = randomGenerator.nextInt(mFacts.length);
        fact = mFacts[randomNumber];
        return fact;
    }



}

private String mFact = mFactBook.mFacts[0];