When i can use navigationClick(),fieldchagedListner() or focusListner()?

I am very confused with the Event Handling in Blackberry. I facing many problems when i am using navigationC开发者_运维技巧lick(),fieldchagedListner() or focusListner().

Sometimes navigationClick() works and sometimes not.Same situation with other two. So i want to know when and how i can use above event handling methods in BlackBerry.

Please help me to come out from this problem.

fieldChangedListener: user has changed the state of the field and you want to listen that event. e.g. click on the buttonfield, text change in the editfield.

focusListerner: You just want to listen focus change event of the field. e.g. FOCUS_GAINED, FOCUS_LOST

navigationClick: BitmapField is not click-able by default but if you want a click event for bitmapfield , you can use navigationCick to listen trackball press on the bitmapfield.

Note: FieldChangedListener and focusListener are just a listener pattern.

using navigationClick you can create your own clickListener for buttonfield and using keychar() you can create your own textChangeListener for editfield.