Java Development

[yogay2010]

tx for your replay. I think, i am getting closer...

No w i am getting error on

this == tabArea.getManager(); 

I tried with

this.getManager() == tabArea.getManager();

I am still getting error....i know this should be easy to do.....but i am not getting this??

could you suggest me anything??

Could post the link of the delete manager documentation please??

[arkadyz]

Oh, I see you've skipped an important step or two in your BlackBerry programming:

Here is the link (it is for the latest, 6.0.0 API, but Manager.delete() and Field.getManager() did not change much in the last... forever) - make sure you check the API documentation before asking questions here:

BlackBerry 6.0.0 API

I tend to have this page open in a separate tab at work at all times - it's that important!

There is a sticky thread in this forum with useful links for novice and experienced programmers alike - check that, too.

After you've done some studying, remember that you can search the forums before posting your question - I've found enough useful information that way.

By the way, this getManager() is logically wrong - you want to compare the tabArea's manager to this because it is the manager which is trying to delete tabArea.

[yogay2010]

tx for the quick response,

i understood that....

when we say this ....  we refrerring to the screen below manager right?

this (MainScreen)  == tabArea.getManger() (Manager)  so ....I am getting incomparable type error....

[arkadyz]

Oops... if this is a Screen, you need to compare like this:

getDelegate() == tabArea.getManager() // (in case of FullScreen and other Screens)

  or this:

getMainManager() == tabArea.getManager() // (in case of MainScreen)

You could also do the whole thing this way:

try {

  delete(tabArea);

} catch (Exception e) {

  // might want to report it - System.out.println(e.toString() + " trying to switch tabs");

}

tabArea = ...;

add(tabArea);

[yogay2010]

 Thank you for your reply...

but it's still throwing the exception when i try to delete the tab area...

public void Refresh()
 {
  final VerticalFieldManager newTab = displayTab2();
  UiApplication.getUiApplication().invokeLater(new Runnable()
  {
    public void run()
    {
      if(tabArea != null && tabArea.getManager() == getMainManager())
      {        
         delete(tabArea); ////exception
      }
         tabArea = newTab;
         add(tabArea);
    }
  });
}

[arkadyz]

Next time please quote the text of exception - it'll save the questions here.

Anyway, this should work no matter what:

Manager m;
if (tabArea != null && (m = tabArea.getManager()) != null) {
  m.delete(tabArea);
}
...

[yogay2010]

tx ....but i m still getting the following exception....

could you tell me y?

Uncaught exception thrown - IllegalArgumentException

 public void Refresh()
 {
  final VerticalFieldManager newTab = displayTab2();
   UiApplication.getUiApplication().invokeLater(new Runnable()
   {
       public void run()
      {
          Manager m;
         if (tabArea != null && (m = tabArea.getManager()) != null)
        {
            m.delete(tabArea); //here its happens tabArea --> illegalArgument
           tabArea = newTab;
           m.add(tabArea);
        }
     }
  });
}

[arkadyz]

Well,

people here are volunteers and cannot debug the code for you. When you get an exception, investigate more before posting. Debugger shows the actual classes of involved objects; you can check whether anything is null, look inside the objects at the private members, compare, analyze and think.

We are not at your keyboard watching over your shoulder - do your homework, read the documentation and think, think, think!

Only you can check what tabArea or m is, find its manager and, if necessary, its Manager's manager and what their Classes actually are. Do that, dig more, train yourself to use the debugger - you must have this skill to become successful at software development.

By the way, your code now is wrong - tabArea = newTab; and add(tabArea); (not m.add(tabArea)!) should happen outside (after) that if (tabArea != null...).

[simon_hain]

sometimes it is best to step a bit back from the code and try to visualize what it does. maybe draw something on a sheet of paper, like the structure of managers you are building.

it also helps if you give your fields self-speaking names, with "m" you will not go far. always write code with the possibility in mind that somebody else may want to check/change/view it. this includes comments, but also a self-explaining code.

when you come back to your project after a few months to do some bugfixes or add some features you will be thankful for your efforts.

and, as a plus, it also helps with your current problem.

in university we spent 4 days analyzing, drawing UML etc, then one day implementing it.