How to create an empty edit field (numeric) in app designer

Question

John Cadigan 2019-4-5

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回答： Juan Andrés Martin 2023-8-3

I am writing an app that has a user enter a quantity in a numeric Edit Field. The field starts off with a default value of 0 so that the user has to delete the 0 and then enter the number. Is there a way to get the default to be empty rather than a 0?

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Marc Youcef 2019-8-13

I was searching for same request but apprently there is no way to do that using uinumericeditfield as this edit field forces you to have at list a numeric value. Which is a pain when you do not want the user to necessarly enter something in, you get a 0 value instead of empty field...

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Answer 1

Gonzalo Montero 2019-12-12

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I'm looking for the same feature, it's a pity that is not possible!

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Answer 2

sing 2022-4-20

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A workoaround solution is to set the color of the text equal to the box's background (typically white).

E.g.:

app.editfield.FontColor=[1 1 1]

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Chris 2022-4-20

Using a string editField then and a ValueChangingFcn call back to set the color back to black? Sounds like a good option.

sing 2022-4-20

编辑：sing 2022-4-20

Exactly, then when you need to write a value in the numeric box that you want to be visibile you just need to set app.editfield.FontColor=[0 0 0] and then you can assign the value you like to it, app.editfield.Value=yourvalue

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Answer 3

Chris 2019-8-13

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Can you make the input a text field and reject anything that does not convert to a number?

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Marc Youcef 2019-8-13

Yes, this is the only solution I thought about. Unfortunately in my case I was trying to take advantage of the 'uinumericeditfield' functionnality which is doing exactly this for you and wanted to simply add an 'empty by default' option.

frankenberry 2020-5-21

在 MATLAB Online 中打开

I was able to use a blank text area to accept only numbers. I'm not sure how good it is or if it helps you at all. The only problem I have with this is that if the field is blank, it should also give an error. That is, I get an error if the value is not a number and the error box pops up or if it is blank, I should get an error. I need to code that part yet. I tested this and it works in my app. I don't get an error when numbers are entered.

 % Value changed function: NEQO_A4_pistol
        function NEQO_A4_pistolValueChanged(app, event)
           value = app.NEQO_A4_pistol.Value;
           string(value);
            if isempty(str2num(value))
                app.NEQO_A4_pistol.Value,value;'0';
                uialert(app.UIFigure, {'You need to enter a number','Click OK and enter a number value'}, 'Error', 'Icon', 'Error');
                app.NEQO_A4_pistol.Value = '';
            elseif ~isempty(str2num(value))
                app.NEQO_A4_pistol.Value,value;'0', '1', '2', '3', '4', '5', '6', '7', '8', '9';
                %uialert(app.UIFigure, {'You entered a number! WOOHOO!'}, 'Info', 'Icon', 'info');
            end
        end