title: Android: view/ drawable custom styles possible?
body: <p>What I'd like to do is change the state (really, the background) of an EditText to reflect validity of its contents. E.g. if the user enters 999 where 999 is contextually invalid, the EditText should have a red border in place of the default orange border, likewise once the text is valid it should have a green border. </p>
  
  <p>Methods I've explored:</p>
  
  <ol>
  <li>Changing the style of the EditText programmatically via something like editor.setStyle(R.styles.SomeID). Seems to be impossible within android.  </li>
  <li>Adding custom states (state_valid, state_invalid) in R.attr, associating them with red/ green 9-patches, then calling drawable.setState() with one of these states. This worked in the sense that the state could be read back via getState(), but the border did not change colour.</li>
  <li>Setting the background resource directly upon detection of (in)validity. This works ok, causing the correct visual effect, but seems a little hokey, and allows only one state (e.g. I have to manually check for whether the EditText is pressed, enabled etc).</li>
  </ol>
  
  <p>Given limited UI real-estate I am hesitant to introduce a separate UI element to visually feedback the text's validity to the user, hence my desire to display it in the EditText itself.</p>
  
  <p>So.. is this something that's even feasible? It seems like a fairly common use case, so has anyone achieved what I'm trying to do in a straightforward and elegant manner? </p>