title: Set Button Visibility
body: <p>I added a button in layout and obtained its reference in the activity:</p>
  
  <pre><code>Button button1=(Button)findViewById(R.id.button1);
  button1.setVisiblity(View.Visible);
  </code></pre>
  
  <p>Program crashes with this code. How do I set its visibility correctly?</p>