MATLAB: How to solve “Parse error at METHODS: usage might be invalid MATLAB syntax.”? (MATLAB 2017b)

matlab app designer

Good day all.

I have an issue on running an application in App Designer as when I tried to simulate the designed app, the error occured:

Error using DRS
Error: File: DRS.mlapp Line: 94 Column: 5
Illegal use of reserved keyword "methods".

And when I put cursor on methods and it shows:

"Parse error at METHODS: usage might be invalid MATLAB syntax"

This problem occured when I tried to link the selections in drop-down menu to another three panels that have connection between it.

The code that I used is shown below:

% Value changed function: DropDown  
function DropDownValueChanged(app, event)
value = app.DropDown.Value;
% Hide all the panels
    app.PanelA.Visible = 'off';
        app.PanelB.Visible = 'off';
        app.PanelC.Visible = 'off';
      
%If Panel A is selected, show panel 1
        if strcmp(value,'Panel A')
            app.PanelA.Visible = 'on';
        elseif strcmp(value,'Panel B')
            app.PanelB.Visible = 'on';
        elseif strcmp(value,'Panel C')
            app.PanelC.Visible = 'on';
end 
end

I have lost the direction, which part that I actually did wrong? May I ask the opinion from the community?

Thank you in advanced.

Best Answer

Hi,

The error might pop-up due to no matching end for the method block created by you in the App Designer Code. You also can’t create one method block inside another method block. I suggest you to search your code for any such cases.

Hope this helps!

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The concerned teams have been informed of this issue in tooltips. They might be looking into it for the upcoming releases.

Hope this helps!

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

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