Selecting a dropdown value and getting an answer AFTER pressing button (in App Designer)

Hi there,

I've been trying to build a GUI in App Designer where:

1. you select a certain drop down value;
2. You press a button;
3. You get a message or the answer displayed in a text box, depending on the selected drop down value.

I can't seem to get this done though. I don't really know how to connect the selected drop down value to a certain outcome in the textbox, AFTER the button is pressed. In fact, I'm generally struggling with these callback functions.

Can anyone help me?

My current code is as follows:

    methods (Access = private)
       % Callback function
        function ScenarioDropDownValueChanged(app, event)
            value = app.ScenarioDropDown.Value;
        end
       % Button pushed function: BerekenenButton
        function BerekenenButtonPushed(app, event)
            if ScenarioDropDownValueChanged(value,'-kies-')
                app.BestesystemenTextArea.Value='error, select scenario'
            elseif ScenarioDropDownValueChanged(value,'Selection1')
                app.BestesystemenTextArea.Value='Systeem 1'
            else app.BestesystemenTextArea.Value='Systeem 2'
        end    
    end
       % App initialization and construction
    methods (Access = private)
      % Create UIFigure and components
        function createComponents(app)           
      % Create BerekenenButton
            app.BerekenenButton = uibutton(app.UIFigure, 'push');
            app.BerekenenButton.ButtonPushedFcn = createCallbackFcn(app, @BerekenenButtonPushed, true);
            app.BerekenenButton.FontWeight = 'bold';
            app.BerekenenButton.Position = [266 219 100 22];
            app.BerekenenButton.Text = 'Berekenen';
      % Create BestesystemenTextArea
            app.BestesystemenTextArea = uitextarea(app.UIFigure);
            app.BestesystemenTextArea.Position = [272 97 150 60];
       % Create ScenarioDropDown
            app.ScenarioDropDown = uidropdown(app.UIFigure);
            app.ScenarioDropDown.Items = {'-kies-', 'Selection1', 'Selection2', 'Selection3'};
            app.ScenarioDropDown.ValueChangedFcn = createCallbackFcn(app, @ScenarioDropDownValueChanged, true);
            app.ScenarioDropDown.Position = [281 368 145 22];
            app.ScenarioDropDown.Value = '-kies-';
      end

Thank you,

Jo

Answer 1

[Geoff Hayes]

Jo - I think that you can just access the drop down value directly from the button callback (you probably don't want to be calling ScenarioDropDownValueChanged from with the button callback). Try the following

function BerekenenButtonPushed(app, event)
    value = app.ScenarioDropDown.Value;
    if strcmpi(value,'-kies-')
        app.BestesystemenTextArea.Value='error, select scenario'
    elseif strcmpi(value,'Selection1')
        app.BestesystemenTextArea.Value='Systeem 1'
    else 
        app.BestesystemenTextArea.Value='Systeem 2'
    end    
end

I'm assuming that value is the string representing the selection from the drop down control.

[Jo River]

Thank you, that works!

[Shri.s]

How can i know the number of selected variable or part name from dropdown