title: Center message in a default AlertDialog
body: <p>I have created an Alert Dialog, and i want to know how to set the gravity of the message as center:</p>
  
  <pre><code>Dialog dialog;
  AlertDialog.Builder builder = new AlertDialog.Builder(this);
  builder.setMessage(completedMessage());
  dialog = builder.create();
  </code></pre>
  
  <p>here is the completedMessage() method:</p>
  
  <pre><code>private String completedMessage() {
    String[] messages = getResources().getStringArray(R.array.success);
    String completeMsg =  "\n";
    int messagei= (int) Math.floor(Math.random() * messages.length); 
    completeMsg += messages[messagei];
  
    return completeMsg;
  </code></pre>
  
  <p>}</p>
  
  <p>and here is the arrays.success:</p>
  
  <pre><code>&lt;string-array name="success"&gt;
      &lt;item&gt;You got it!&lt;/item&gt;
      &lt;item&gt;Success!&lt;/item&gt;
      &lt;item&gt;Done!&lt;/item&gt;
      &lt;item&gt;Great job, young Padawan.&lt;/item&gt;
  &lt;/string-array&gt;
  </code></pre>
  
  <p>no title, no buttons, no list, just the message, and i want to show it centered, no matter the string length.</p>
  
  <p>I have tried:</p>
  
  <pre><code>Dialog dialog;
  AlertDialog.Builder builder = new AlertDialog.Builder(this);
  builder.setMessage(completedMessage());
  dialog = builder.show();
  TextView messageView = (TextView)dialog.findViewById(android.R.id.message);
  messageView.setGravity(Gravity.CENTER_VERTICAL);
  </code></pre>
  
  <p>But this changes nothing.</p>
  
  <p>Btw, the message shows in the box like having a padding on top and left, but no padding on the bottom nor right.</p>