title: Text field validation in JavaFX
body: <p>In a text field i want to perform a operation in the following way:</p>
  
  <p>-> a default text 00:00:00 is set for time as the text field is for time and the character length of the field is 8.</p>
  
  <p>-> if the cursor is in position 0(zero) and if i press a number key it should replace the position 0 value and move the cursor to next position.</p>
  
  <pre><code>   eg : 00:00:00
          20:00:00
  </code></pre>
  
  <p>explanation : now the cursor z in position 0 and i press the key 2 it should replace the value 0 in position 0 and move to position 1</p>
  
  <p>when i press any non-numeric key it should not replace any of the value but the cursor should move to next position.</p>