title: how to set an alert box
body: <p>in my app i have placed three edit boxes with a ok button. Before pressing the ok button the user must enter all the edit text fields, if any of the edit text is been left empty i want to give an alert box.</p>
  
  <p>in the edit text box the field name such as "Name", "Age" should be in diminished and when it is clicked it must get disappeared. </p>
  
  <p>How to do this , pls anyone help me</p>