Can anyone tell me how to use Java Keylistener to add validations in my java gui form??
eg. I have a textfield. I want to enter only alphabets in it. I dont want any numerics. So when a user tries to type a numeric value in it, I want to prompt a message. But how can I have do it in java?
Can use of keylistener be helpful??

  1. don't use KeyListener for JTextComponents, use DocumentListener,

  2. use JFormattedTextField,

  3. I'd be to use DocumentFilter with Pattern, filtering for non_alphabets chars, then there no needed any prompt about non_number char is inputed,

Ofcourse , you have to use KeyListener.

Go through KeyListener and KeyEvent classes . The KeyEvent class will be useful for comparing what keys have been pressed.

Google some keylistener examples and based upon that build your own logic.

For example , if you dont want to allow numerics, then you can place a simple IF statement

if(pressed key = KeyEvent.VK_0 || pressed key = KeyEvent.VK_1 .........upto 9)
  JOption.ShowMessageDialog(this,"you have pressed a numeric key ...");

No, you don't have to use KeyListener.
mKorbel's advice is good. Apart from anything else his approach will also handle copy/paste into the field correctly. It also uses classes that Sun/Oracle have already written for this purpose, so no need to re-invent the wheel.