title: Running OnTrigger() on Content_main crush
body: <p>i got an OnTrigger that is created on content_main</p>
  
  <pre><code>public class ContainMain extends Activity implements OnTriggerListener {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          SlideBar slideToUnLock = (SlideBar)findViewById(R.id.slideBar);
          slideToUnLock.setOnTriggerListener(this);
      }
  
      @Override
      public void onTrigger() {
          Log.d("Teset", "Slide Trigged");
      }
  
  }
  </code></pre>
  
  <p>when i run the app on content_main it display Log.d
  when i run it in activity_main it crush and the error log said Null pointer</p>