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in my swing application I have a combo box with an ItemListener that does X if the user changes the value (via itemStateChanged()). However I also have a different function that changes the value of that combo box. In this case I do not want X to be done.

Is there a way to find out if the state change was caused by user interaction or from a function?

Thank you!

Edit: I used the flag method. Thanks for the quick answers. I just want to add, that itemStatechanged is actually called twice, once for deselection and once for selection. This needs to be dealt with otherwise the flag won't have any effect. The problem is discussed here.

Community
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NiklasMM
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  • possible duplicate of [Java Swing Combobox removeAllItems calling ItemStateChanged also?](http://stackoverflow.com/questions/10202718/java-swing-combobox-removeallitems-calling-itemstatechanged-also) – Andrew Thompson Apr 26 '12 at 09:14

3 Answers3

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There are 2 ways to do the check:

  1. Define a flag isUser. The flag is true by default. Before changing programmatically set it to false and reset after setting the combo-box value. In the listener just check the flag and skip the action if necessary.
  2. Keep a reference to the listener and remove it before setting value, adding after.
Andrew Thompson
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StanislavL
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    3.rd way is use [disadvantage from Focus with un_safe KeyListener added to the internal JList](http://stackoverflow.com/a/9991314/714968), nothing safiest for JComboBox (my view) – mKorbel Apr 26 '12 at 08:55
  • @mKorbel Maybe now, that code will 'have its day in the sun'. :) – Andrew Thompson Apr 26 '12 at 09:18
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From what I understand you could very easily sort out your problem using a flag. Just make a boolean flag, e.g. isDoneByMethod which will be on entrance to a method set to true and at the end set to false and between these two do the operation on the combobox. Then inside the itemStateChanged() check for the value of the isDoneByMethodflag and act accordingly.

Boro
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I have the similar kind of situation where I need to differentiate two cases. Both options discussed here (flag and removal/addition of listener) do not work all the time, as the item listener is asynchronously called on EDT thread. However remove and adding the particular item listener is more safe . To further ensure that all the previous actions will be dealt before you add the item listener, I use fireEvents() just before adding the listener again.

mediterranean
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