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ItemStateListener in List and TextBox

Posted on 2004-08-17
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Last Modified: 2011-09-20
1. How can i detect whether the item is change in a list? E.g. user scroll up and down on the list.

2. How can i detect user is entering some word in the textbox?

thanks
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Question by:hawkly
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Expert Comment

by:jimmack
ID: 11819996
1) Off the top of my head, I'd say that you can detect the scroll actions on a list, only when a selection is made (ie. changing the state).  This is really more appropriate for a ChoiceGroup rather than a list.

2) You can't use an ItemStateListener on a TextBox, because a TextBox extends Screen, not Item.  You can have an ItemStateListener on a TextField, if that helps.
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Author Comment

by:hawkly
ID: 11826836
>> I'd say that you can detect the scroll actions on a list, only when a selection is made (ie. changing the state).  This is really more appropriate for a ChoiceGroup rather than a list.

is't something like this:
public void commandAction(Command c, Displayable s)
{
      if (c == List.SELECT_COMMAND || c == cmOkOptions)
      {
            switch (myList.getSelectedIndex())
            {
                  case 0:
                        break;
            }
      }
      else if (c == cmBackOptions)
      {
            display.setCurrent(backScreen);
      }
}

>> You can't use an ItemStateListener on a TextBox, because a TextBox extends Screen, not Item.  You can have an ItemStateListener on a TextField, if that helps.

is't possible to have onkeypress event?


Actually what i want to do is when the user is scrolling the list or entering something in the textbox then i will set display.flashBacklight(10000);

so any idea on how to implement this?

thanks
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Expert Comment

by:jimmack
ID: 11828690
The commandAction will only be called when the user activates one of the commands in the list (eg. by pressing the button in the centre of the joypad).  Moving a selection up and down in a list doesn't generate any events that you can capture.

There is no onkeypress event for the high level GUI widgets.  Canvas has keyPressed(), keyRepeated() and keyReleased().

If you're using MIDP-2.0, you could create your own CustomItems.  This should allow you to capure the keyPressed/Repeated/Released events.

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Author Comment

by:hawkly
ID: 11828813
>> The commandAction will only be called when the user activates one of the commands in the list (eg. by pressing the button in the centre of the joypad).  Moving a selection up and down in a list doesn't generate any events that you can capture.

How can i capture moving a selection up and down in a list ?

thanks
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LVL 15

Expert Comment

by:jimmack
ID: 11828857
AFAIK you can't do this.  It's totally under the control of the operating system/virtual machine implementation.
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Author Comment

by:hawkly
ID: 11828937
I'm interesting on the CustomItems. So where can find the tutorial, API and sample code?

thanks
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jimmack earned 500 total points
ID: 11829045
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