Error in app designer

I have faced an error in my code like it says

Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.

on the following statement:

% Component initialization
    methods (Access = private)

It's a solid statement at the end of code and I cannot change it at all. Does anybody know how to fix this problem? since it doesn't allow me to run the program.

Thank you.

Vahid.

[Walter Roberson]

The first thing I would look for is whether the classdef line is missing or commented out, or there is code before the classdef line.

[Vahid Abolhasannejad]

Thank you Walter for your message,

I have my own code above this statement. I have actually designed an application. Here is some lines above and more lines bellow this statement:

% Button pushed function: VisualizeOriginalChannelButton
        function VisualizeOriginalChannelButtonPushed(app, event)
            
        end
        end
    end

    % Component initialization
    methods (Access = private)

        % Create UIFigure and components
        function createComponents(app)

            % Create UIFigure and hide until all components are created
            app.UIFigure = uifigure('Visible', 'off');
            app.UIFigure.Position = [100 100 1316 959];
            app.UIFigure.Name = 'MATLAB App';

            % Create UIAxes
            app.UIAxes = uiaxes(app.UIFigure);
            title(app.UIAxes, 'ECG Diagram')
            xlabel(app.UIAxes, 'Time')
            ylabel(app.UIAxes, 'Voltage')
            app.UIAxes.Position = [71 474 927 447];

            % Create VisualizationPannelPanel
            app.VisualizationPannelPanel = uipanel(app.UIFigure);
            app.VisualizationPannelPanel.Title = 'Visualization Pannel';
            app.VisualizationPannelPanel.Position = [111 202 210 221];

            % Create CannelNoDropDownLabel
            app.CannelNoDropDownLabel = uilabel(app.VisualizationPannelPanel);
            app.CannelNoDropDownLabel.HorizontalAlignment = 'right';
            app.CannelNoDropDownLabel.Position = [12 156 66 22];
            app.CannelNoDropDownLabel.Text = 'Cannel No.';

            % Create CannelNoDropDown
            app.CannelNoDropDown = uidropdown(app.VisualizationPannelPanel);
            app.CannelNoDropDown.Items = {'Chennel 1', 'Channel 2'};
            app.CannelNoDropDown.Position = [93 156 100 22];
            app.CannelNoDropDown.Value = 'Chennel 1';

            % Create VisualizeOriginalChannelButton
            app.VisualizeOriginalChannelButton = uibutton(app.VisualizationPannelPanel, 'push');
            app.VisualizeOriginalChannelButton.ButtonPushedFcn = createCallbackFcn(app, @VisualizeOriginalChannelButtonPushed, true);
            app.VisualizeOriginalChannelButton.Position = [29 110 156 22];
            app.VisualizeOriginalChannelButton.Text = 'Visualize Original Channel';

            % Create VisualizeCleanChannelButton
            app.VisualizeCleanChannelButton = uibutton(app.VisualizationPannelPanel, 'push');
            app.VisualizeCleanChannelButton.Position = [29 70 156 22];
            app.VisualizeCleanChannelButton.Text = 'Visualize Clean Channel';

            % Create ClearPlotButton
            app.ClearPlotButton = uibutton(app.VisualizationPannelPanel, 'push');
            app.ClearPlotButton.Position = [29 31 156 22];
            app.ClearPlotButton.Text = 'Clear Plot';

            % Create Panel
            app.Panel = uipanel(app.UIFigure);
            app.Panel.Title = 'Panel';
            app.Panel.Position = [538 201 452 221];

            % Create ChannelNoDropDownLabel
            app.ChannelNoDropDownLabel = uilabel(app.Panel);
            app.ChannelNoDropDownLabel.HorizontalAlignment = 'right';
            app.ChannelNoDropDownLabel.Position = [15 156 72 22];
            app.ChannelNoDropDownLabel.Text = 'Channel No.';

            % Create ChannelNoDropDown
            app.ChannelNoDropDown = uidropdown(app.Panel);
            app.ChannelNoDropDown.Items = {'Channel 1', 'Channel 2', ''};
            app.ChannelNoDropDown.Position = [102 156 100 22];
            app.ChannelNoDropDown.Value = 'Channel 1';

            % Create FromTimeEditFieldLabel
            app.FromTimeEditFieldLabel = uilabel(app.Panel);
            app.FromTimeEditFieldLabel.HorizontalAlignment = 'right';
            app.FromTimeEditFieldLabel.Position = [24 115 63 22];
            app.FromTimeEditFieldLabel.Text = 'From Time';

            % Create FromTimeEditField
            app.FromTimeEditField = uieditfield(app.Panel, 'numeric');
            app.FromTimeEditField.Position = [102 115 100 22];

            % Create ToTimeEditFieldLabel
            app.ToTimeEditFieldLabel = uilabel(app.Panel);
            app.ToTimeEditFieldLabel.HorizontalAlignment = 'right';
            app.ToTimeEditFieldLabel.Position = [40 70 48 22];
            app.ToTimeEditFieldLabel.Text = 'To Time';

            % Create ToTimeEditField
            app.ToTimeEditField = uieditfield(app.Panel, 'numeric');
            app.ToTimeEditField.Position = [103 70 99 22];

            % Create FromTimeEditField_2Label
            app.FromTimeEditField_2Label = uilabel(app.Panel);
            app.FromTimeEditField_2Label.HorizontalAlignment = 'right';
            app.FromTimeEditField_2Label.Position = [232 115 63 22];
            app.FromTimeEditField_2Label.Text = 'From Time';

            % Create FromTimeEditField_2
            app.FromTimeEditField_2 = uieditfield(app.Panel, 'numeric');
            app.FromTimeEditField_2.Position = [310 115 100 22];

            % Create ToTimeEditField_2Label
            app.ToTimeEditField_2Label = uilabel(app.Panel);
            app.ToTimeEditField_2Label.HorizontalAlignment = 'right';
            app.ToTimeEditField_2Label.Position = [247 70 48 22];
            app.ToTimeEditField_2Label.Text = 'To Time';

            % Create ToTimeEditField_2
            app.ToTimeEditField_2 = uieditfield(app.Panel, 'numeric');
            app.ToTimeEditField_2.Position = [310 70 100 22];

            % Create CompareECGButton
            app.CompareECGButton = uibutton(app.Panel, 'push');
            app.CompareECGButton.Position = [35 20 179 22];
            app.CompareECGButton.Text = 'Compare ECG ';

            % Create ClearPlotButton_2
            app.ClearPlotButton_2 = uibutton(app.Panel, 'push');
            app.ClearPlotButton_2.Position = [279 20 100 22];
            app.ClearPlotButton_2.Text = 'Clear Plot';

            % Create UITable
            app.UITable = uitable(app.UIFigure);
            app.UITable.ColumnName = {'Clean Time Periods'};
            app.UITable.RowName = {};
            app.UITable.Position = [358 202 139 221];

            % Show the figure after all components are created
            app.UIFigure.Visible = 'on';
        end
    end

[Walter Roberson]

methods is only permitted inside a classdef . For example it might start

classdef PPPH < matlab.apps.AppBase

    % Properties that correspond to app components
    properties (Access = public)

Your line with function VisualizeOriginalChannelButtonPushed should have appeared much further down in the file, in a methods section.

[Mohammad Sami]

Did you accidently used additional "end" keywords in the editable portion of your code ?

% Button pushed function: VisualizeOriginalChannelButton
        function VisualizeOriginalChannelButtonPushed(app, event)
            
        end
        end
    end

[Vahid Abolhasannejad]

I just coppied some parts of the code. Those "end" statements correspond with the above code parts.

[Walter Roberson]

We need the actual code to examine, not just a subset of it, as the parts you are cutting out might be the parts the problem is occuring in.

[Vahid Abolhasannejad]

Hello Walter, thank you for your comment. That part I mentioned was among the defauls of the code that could not be changed. So the problem was solved. Thanks again for your help.

[Zayad]

how did you solve it?

Answer 1

[Ganesh Regoti]

Hi Vahid,

By the error statement, I would say it might be a syntactical error. Go through the code to check if it is properly formatted and ended. Regarding the solid statements,

1. When you create an app from app designer, there is a default code generated based on the components which is non-editable.
2. When you add callbacks, properties, methods, an editable area is created with declarations where you can edit/add your code.

Here are the links you refer to for more information

https://www.mathworks.com/help/matlab/app-designer.html

https://www.mathworks.com/help/matlab/creating_guis/create-a-simple-app-or-gui-using-app-designer.html

Hope this helps!

[Vahid Abolhasannejad]

Hello Ganesh, thank you for your comment. That part I mentioned was among the defauls of the code that could not be changed. So the problem was solved. Thanks again for your help.

Answer 2

[Justi Kertusha]

% LightBehaviorApp.m
classdef LightBehaviorApp < matlab.apps.AppBase
    % Properties that correspond to app components 
    properties (Access=public)
        UIFigure matlab.ui.Figure 
        Material1EditField matlab.ui.control.NumericEditField 
        Material2EditField matlab.ui.control.NumericEditField 
        IncidentAngleEditField matlab.ui.control.NumericEditField 
        CalculateButton matlab.ui.control.Button 
        TrajectoryAxes matlab.ui.control.UIAxes 
    end
    % Callbacks that handle component events
    methods(Access=private)
        % Code that executes after component creation 
        function startupFcn(app)
            % Set default values for the indices of refraction
            app.Material1EditField.Value = 1.5; 
            app.Material2EditField.Value = 1.0;
            app.IncidentAngleEditField.Value = 45;
        end
        % Button pushed function
        function CalculateButtonPushed(app, ~)
            % Get user inputs
            n1 = app.Material1EditField.Value; 
            n2 = app.Material2EditField.Value; 
            incidentAngle = app.IncidentAngleEditField.Value;
            % Calculate refraction angle using Snell's Law
            refractedAngle = asind((n1/n2) * sind(incidentAngle));
            % Plot the trajectory of light within each medium
            cla(app.TrajectoryAxes); 
            hold(app.TrajectoryAxes, 'on'); 
            plot(app.TrajectoryAxes, [0, cosd(incidentAngle)], [0, sind(incidentAngle)]); 
            plot(app.TrajectoryAxes, [0, cosd(refractedAngle)], [-sind(incidentAngle), -sind(incidentAngle)]);
            hold(app.TrajectoryAxes, 'off'); 
            axis(app.TrajectoryAxes, 'equal');
            title(app.TrajectoryAxes, 'Light Trajectory'); 
            legend(app.TrajectoryAxes, {'Incident Ray', 'Refracted Ray'}); 
        end 
    end
    % App creation and deletion 
    methods (Access=public)
        % Construct app 
        function app = LightBehaviorApp
            % Create UIFigure and components 
            createComponents(app);
            % Register the app with App Designer
            registerApp(app, app.UIFigure);
            % Execute the startup function
            runStartupFcn(app, @startupFcn); 
            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
    % Function to create and configure UI components
    methods (Access=private)
        function createComponents(app)
            % Create UIFigure and set its properties
            app.UIFigure = matlab.ui.Figure('Visible', 'off');
            app.UIFigure.Position = [100, 100, 600, 400];
            app.UIFigure.Name = 'LightBehaviorApp';
            % Create Material1EditField component
            app.Material1EditField = matlab.ui.control.NumericEditField(app.UIFigure);
            app.Material1EditField.Position = [100, 300, 100, 30];
            app.Material1EditField.String = '1.5';
            app.Material1EditField.Label = 'Material 1 Refractive Index';
            % Create Material2EditField component
            app.Material2EditField = matlab.ui.control.NumericEditField(app.UIFigure);
            app.Material2EditField.Position = [100, 250, 100, 30];
            app.Material2EditField.String = '1.0';
            app.Material2EditField.Label = 'Material 2 Refractive Index';
            % Create IncidentAngleEditField component
            app.IncidentAngleEditField = matlab.ui.control.NumericEditField(app.UIFigure);
            app.IncidentAngleEditField.Position = [100, 200, 100, 30];
            app.IncidentAngleEditField.String = '45';
            app.IncidentAngleEditField.Label = 'Incident Angle';
            % Create CalculateButton component
            app.CalculateButton = matlab.ui.control.Button(app.UIFigure);
            app.CalculateButton.Position = [250, 200, 100, 30];
            app.CalculateButton.Text = 'Calculate';
            app.CalculateButton.ButtonPushedFcn = @app.CalculateButtonPushed;
            % Create TrajectoryAxes component
            app.TrajectoryAxes = matlab.ui.control.UIAxes(app.UIFigure);
            app.TrajectoryAxes.Position = [400, 100, 150, 200];
        end
    end
end

This is given me an error in line 55

Error in LightBehaviorApp (line 55)

createComponents(app);

[Walter Roberson]

            app.Material1EditField = matlab.ui.control.NumericEditField(app.UIFigure);

When you call matlab.ui.control.NumericEditField directly, then any parameters you pass must be paired, property/value form. When you call it directly, it does not accept a figure positionally.

You should be calling uieditfield(app.UIFigure,"numeric") instead.