MATLAB App Listbox items not changing

2022 2 19
1 个回答
更新时间：2022 2 20
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I am trying to modify the default values of a listbox in a Matlab App (Item 1, Item 2...) by using the following code:
value = app.CountryListBox.Value; %Default value that appears when I created a callback for the listbox
first_cell_column=covid_data(:,1); %Extract the first column of my cell array, which contains the name of the countries
first_unique_column=unique(first_cell_column); %Remove repeated names
countries=(first_unique_column(first_unique_column~="Country")).'; %Remove the tag "country" and transpose my column vector to a row vector (1x195)
app.CountryListBox.Items=countries; %Assign my cell row vector to the CountryListBox Items object
However, when I run the app, the Listbox remains unchanged, with the same default values. No error or warning appears on the program neither. What am I doing wrong?

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回答（1 个）

Cris LaPierre
Cris LaPierre 2022-2-19
编辑：Cris LaPierre 2022-2-19

0 个投票

Where have you placed the code in your app? It appears to be in your listbox ValueChanged callback. That means this function will not execute until you select a different item in your listbox.
Try selecting item2 or item3. Your listbox should update. Or at least this callback funciton will execute.

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It appeared automatically here:
% Value changed function: CountryListBox
function CountryListBoxValueChanged(app, event)
first_cell_column=covid_data(:,1);
first_unique_column=unique(first_cell_column);
countries=(first_unique_column(first_unique_column~="Country")).';
app.CountryListBoxValueChanged.Items={'countries'};
Right after the StartUpFcn. How do I select item 2 or 3?
Ok, it's solved! I put the exact same code on the StartUp function, and it worked. Now I understand what you mean by selecting the second item...Thank you!

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