Adding a Warning Window/Message In Matlab App Designer

I am new to Matlab, and I am trying to figure out how I can show a warning message once either the user's input is zero or the edit field is left blank.

Do you guys know how to do it? I honestly do not know how to put warning message in Matlab App Designer. Thanks!

Answer 1

[Simon Chan]

You may use function uialert to deliver a message to the user via a callback

Please refer to the following example and modify using App Designer.

uif = uifigure('Position',[100 100 500 250]);
edit = uieditfield(uif,'Position',[50 50 50 30],'ValueChangedFcn',{@checkValue,uif});
function checkValue(src,event,uif)
    value = get(src,'Value');
    if isempty(value)
        uialert(uif,'Please enter a non-zero number, it is empty now','Warning','Icon','warning');
    elseif str2double(value)==0
        uialert(uif,'Please enter a non-zero number, it is zero now','Warning','Icon','warning');
    end
end

[Mayvel Reese]

Unfortunately, it does not work with me. I tried having one edit field and modifying it afterwards.

 unit=app.EditField.Value;      
            uif = uifigure('Position',[100 100 500 250]);
edit = app.EditField(uif,'Position',[50 50 50 30],'ValueChangedFcn',{@checkValue,uif});
            function checkValue(src,event,uif)
    unit = get(src,'Value');
    if isempty(unit)
        uialert(uif,'Please enter a non-zero number, it is empty now','Warning','Icon','warning');
    elseif str2double(unit)==0
        uialert(uif,'Please enter a non-zero number, it is zero now','Warning','Icon','warning');
    end
end

[Simon Chan]

Attached a demo .m file for your reference. Download and run the demo.

You may need to modify it to serve your purpose.

function Demo(src,event)
    app.figure = uifigure;
    app.edit = uieditfield(app.figure,'ValueChangedFcn',@checkValue);
    function checkValue(src,event)
        unit = get(src,'Value');
        if isempty(unit)
            uialert(app.figure,'Please enter a non-zero number, it is empty now','Warning','Icon','warning');
        elseif str2double(unit)==0
            uialert(app.figure,'Please enter a non-zero number, it is zero now','Warning','Icon','warning');
        end
    end
end

[Mayvel Reese]

Hi, thanks for this! I did it in the app designer's code view after modifying your codes but it still did not work (It only works in the command window section). Is there any way to do it in the app designer's code view section?

[Simon Chan]

Noticed that default name used in app designer is different from my previous code. So what you need to do is to modify the name to make it work. Attached is the demo running in app designer.

[Mayvel Reese]

It's now working. Thanks for your help!

[Simon Chan]

You may accept the answer if you find it useful. Thank you.