How do I disable a dropdown option?

On my GUI on the appbuilder I have two dropdown menus with the same options, app.dropdown1 and app.dropdown2. Their Items are a1, a2, a3, and a4. How can I make it so that if I choose an item on dropdown1 it turns the visibility of it off on dropdown2.

Desired output: if dropdown1's value = a1 on dropdown2 only (a2,a3,a4) should be visible

Answer 1

[Voss]

str = app.dropdown1.String; % store dropdown1's list of options
str(app.dropdown1.Value) = []; % remove the selected one
app.dropdown2.String = str; % apply it to dropdown2

Run those lines in dropdown1's Callback function. You probably also want to update app.dropdown2's Value property.

[hbcukid]

I got an error

Unrecognized method, property, or field 'String' for class 'matlab.ui.control.DropDown'.

[Kevin Holly]

try app.dropdown1.Items instead of String

[hbcukid]

Matrix index is out of range for deletion