title: Difference between R.layout and android.R.layout
body: <p>What is the difference between</p>
  
  <pre><code>   setContentView(R.layout.main);
  </code></pre>
  
  <p>and</p>
  
  <pre><code>ArrayAdapter arrayAdapter = new ArrayAdapter(this,
                  android.R.layout.simple_spinner_dropdown_item, sarray);
  </code></pre>
  
  <p>What is the difference between <code>R.layout</code> and <code>android.R.layout</code>?</p>