Get selected value instantly from a listbox without clicking it first

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Jan w 2016-12-10

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https://ww2.mathworks.cn/matlabcentral/answers/316305-get-selected-value-instantly-from-a-listbox-without-clicking-it-first

评论： Jan w 2016-12-17

I have a listbox on my gui. When I start the programm the first value in the listbox is selected. But the programm only registers a value when you click it first. So is there a way the programm can start my calculation without having to click the first option in the listbox?

A quick fix is to add the command to the OpeningFcn

listbox_Callback(handles.listbox, [], handles);

The problem is: This fix works fine for one listbox, but I have 3 on my gui. So when i add 3 of these commands to my openingfunction i get the error:

Reference to non-existent field

Any ideas how i can fix it?

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采纳的回答

Image Analyst 2016-12-10

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https://ww2.mathworks.cn/matlabcentral/answers/316305-get-selected-value-instantly-from-a-listbox-without-clicking-it-first#answer_246711

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As long as you filled up your listbox somehow, either in GUIDE or your OpeningFcn(), you can get any item in it without having to have the user click on one. For example to get the second item in listbox #3:

allItemsInListbox3 = handles.listbox3.String;  % Get all items from listbox3.
itemNumber2 = allItemsInListbox3{2};  % Extract only the second item from listbox3.