title: Validating EditText content as soon as user enters data
body: <p>I have 2 EditText widgets ,one takes username and other takes password.When the user enters username in First EditText ,the text should be validated (It should accept only characters no digits) when the focus is on the first EditText. How to achieve this.
  It needs to display error message using setError() method in EditText when the user enters wrong data.</p>