Focus / Action / Key Listeners

[k4ghg]

Hi - I have 4 JTextArea in a frame. I an try to add a listener so if text area 2 loses focus, the input would be check and if it meets a certain condition the focus would go to text area 4.

Do I need a key listener or an event listener? Also how do I create the handler? Does it need to be a class? Any help would be appreciated. Thanks - Ronnie

 

[prosper]

your JFrame has to implement FocusListener and add focuslistener to the four textarea.

http://java.sun.com/docs/books/tutorial/uiswing/events/focuslistener.html

http://java.sun.com/docs/books/tutorial/uiswing/events/example-1dot4/DocumentEventDemo.java

 

[hganywhere]

Implementing a focusListener per JComponent although works for a limited nos of components, is quite long and drawn out when you have many fields to provide validation.

Why don't you use an InputVerifer class, you can then centralise all your validation logic in one place and do not need to have loads of component.addXXXXListener(...) methods.

 

[timw]

Yes, I recently made use of the (new in 1.4) InputVerifier class and it works a treat.

Tim

 

[hganywhere]

Forgive me if i'm wrong but I recall using the InputVerifier class since release v1.3 ?

 

[timw]

Well spotted. It was introduced in 1.3. That's what comes with being too busy to check my facts and trusting to memory.

Tim