title: App crash on view change
body: <p>Im trying to make the contentView change on a button click, but the app crash when i start it by some reason.</p>
  
  <p>This is my onCreate method</p>
  
  <pre><code>@Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
       b1 = (Button) findViewById(R.id.bStart);
       b1.setOnClickListener((OnClickListener) mHandler);
      mHandler = new View.OnClickListener() {
          public void onClick(View v) {
                switch(v.getId()) {
                  case R.id.bStart:
                    // it was the first button
                      setContentView(R.layout.cards);
                    break;
  
                }
            }
      };}
  </code></pre>