MATLAB: Drop Down Menu App Designer Values

app designer

Hi, I am having an issue where the app designer GUI does not detect the default value in the drop down menu to hide something specific. For example, if the default value in the drop down menu is Option 1, the field is not hidden unless I select another Option such as Option 2 and reclick Option 1. Is there a way for app designer to detect the default drop down menu value at launch to hide something? Below is the code I wrote so far.

function DropDownValueChanged(app, event)

value = app.DropDown.Value;

if strcmp(value,'Option 1')

app.MassofobjectEditField.Visible= 'off';

else

app.MassofobjectEditField.Visible= 'on';

end

Best Answer

The code won't execute because, it is a ValueChanged function which means it has to detect a change in its value to do something. This is not the case if you start it with Option 1 and want to do something when Option 1 is selected. You first have to change to another value and then back to Option 1.

If you want MassofobjectEditField to be hidden upon starting your app, you can call

app.DropDownValueChanged(app, [])

inside your startup function after the DropDown Menu is created. (See the comment below.) The startup function executes after starting your app and can be added by clicking the green plus and choosing the StartupFcn callback.

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MATLAB: Migrating popupmenu from guide to app designer

If you want to control the drop-down menu during runtime, create the drop-down menu programmatically.

Refer here for more information about adding a drop-down menu.

The property 'Items' can be used to control what all to be listed in the drop-down menu.

Also, the 'Parent' property can be used to control where the drop-down menu needs to be placed. The position can be further finetuned by adjusting the 'Position' property.

MATLAB: Using Matlab App Designer with 2 Dependent Pop Up Menus

You can do this by using a callback on changinge the value in your first drop down. All the magic is done in

function DropDown1ValueChanged(app, event)

Here you go:

classdef app1 < matlab.apps.AppBase
    % Properties that correspond to app components
    properties (Access = public)
        UIFigure          matlab.ui.Figure
        DropDown2_2Label  matlab.ui.control.Label
        DropDown2_2       matlab.ui.control.DropDown
        DropDown1Label    matlab.ui.control.Label
        DropDown1         matlab.ui.control.DropDown
    end
    methods (Access = private)
        % Value changed function: DropDown1
        function DropDown1ValueChanged(app, event)
            value = app.DropDown1.Value;
            switch value
                case "California"
                    app.DropDown2_2.Items = {'San Diego', 'Sacaramento', 'Irvine'};
                case "Texas"
                    app.DropDown2_2.Items = {'Austin', 'Dallas', 'Houston'};
            end
                    
        end
    end
    % App initialization and construction
    methods (Access = private)
        % Create UIFigure and components
        function createComponents(app)
            % Create UIFigure
            app.UIFigure = uifigure;
            app.UIFigure.Position = [100 100 640 480];
            app.UIFigure.Name = 'UI Figure';
            % Create DropDown2_2Label
            app.DropDown2_2Label = uilabel(app.UIFigure);
            app.DropDown2_2Label.HorizontalAlignment = 'right';
            app.DropDown2_2Label.Position = [370 287 69 22];
            app.DropDown2_2Label.Text = 'DropDown2';
            % Create DropDown2_2
            app.DropDown2_2 = uidropdown(app.UIFigure);
            app.DropDown2_2.Items = {'San Diego', 'Sacaramento', 'Irvine'};
            app.DropDown2_2.Position = [454 287 100 22];
            app.DropDown2_2.Value = 'San Diego';
            % Create DropDown1Label
            app.DropDown1Label = uilabel(app.UIFigure);
            app.DropDown1Label.HorizontalAlignment = 'right';
            app.DropDown1Label.Position = [97 287 69 22];
            app.DropDown1Label.Text = 'DropDown1';
            % Create DropDown1
            app.DropDown1 = uidropdown(app.UIFigure);
            app.DropDown1.Items = {'California', 'Texas'};
            app.DropDown1.ValueChangedFcn = createCallbackFcn(app, @DropDown1ValueChanged, true);
            app.DropDown1.Position = [181 287 100 22];
            app.DropDown1.Value = 'California';
        end
    end
    methods (Access = public)
        % Construct app
        function app = app1
            % Create and configure components
            createComponents(app)
            % Register the app with App Designer
            registerApp(app, app.UIFigure)
            if nargout == 0
                clear app
            end
        end
        % Code that executes before app deletion
        function delete(app)
            % Delete UIFigure when app is deleted
            delete(app.UIFigure)
        end
    end
end

Greetins Stefan

Best Answer

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MATLAB: Migrating popupmenu from guide to app designer

MATLAB: Using Matlab App Designer with 2 Dependent Pop Up Menus

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