NullPointerException when registering the Listeners

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http://stackoverflow.com – Plase have a look at the following code MainActivity.java public class MainActivity extends Activity { private TextView words; private Map<String, String> wordsMap; private List wordList; private Animation animation1, animation2; private LinearLayout cards; private int displayIndex = 0; private static final int ENGLISH = 1; private static final int BRAZIL = 2; private int languageDisplaying; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_ma (HowTos)