Android application crashes, Button or Conditional won't work?

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http://stackoverflow.com – Im pretty much a newbie at this so i could use some help to know why does my app keep crashing ? I've tried a lot of ways and this is the best I've come so far. public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final TextView lastAnswer = (TextView) findViewById(R.id.textView5); final TextView answerLabel = (TextView) findViewById(R.id.textView1); final TextView answerLabel1 = (TextView) findViewById(R.id.textView2); final TextView answ (HowTos)