Error in app designer

47 vues (au cours des 30 derniers jours)
Vahid Abolhasannejad
Vahid Abolhasannejad le 20 Avr 2020
Commenté : Zayad le 12 Déc 2023
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.
  8 commentaires
Vahid Abolhasannejad
Vahid Abolhasannejad le 7 Avr 2021
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 le 12 Déc 2023
how did you solve it?

Connectez-vous pour commenter.

Réponses (2)

Ganesh Regoti
Ganesh Regoti le 28 Avr 2020
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
Hope this helps!
  1 commentaire
Vahid Abolhasannejad
Vahid Abolhasannejad le 7 Avr 2021
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.

Connectez-vous pour commenter.

Justi Kertusha
Justi Kertusha le 30 Nov 2023
Modifié(e) : Walter Roberson le 3 Déc 2023
% 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
% Callbacks that handle component events
% 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;
% 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
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'});
% App creation and deletion
methods (Access=public)
% Construct app
function app = LightBehaviorApp
% Create UIFigure and components
% Register the app with App Designer
registerApp(app, app.UIFigure);
% Execute the startup function
runStartupFcn(app, @startupFcn);
if nargout == 0
clear app;
% Code that executes before app deletion
function delete(app)
% Delete UIFigure when app is deleted
% 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];
This is given me an error in line 55
Error in LightBehaviorApp (line 55)
  1 commentaire
Walter Roberson
Walter Roberson le 3 Déc 2023
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.

Connectez-vous pour commenter.


En savoir plus sur Develop Apps Using App Designer dans Help Center et File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by