Write only one number in text field

Question

How can i let user write only one number in text field? Other should be consume.

I have code for write number.

private boolean number(char zn){
    if(zn>='0' && zn<='9')
        return true;

    return false; 
    }

Why use a text field? It seems more appropiate to use a select here. — SJuan76, May 15 '14 at 20:27
What "text field" are you talking about? Your question is anemic on important details, and you should consider improving it. — Hovercraft Full Of Eels, May 15 '14 at 20:28
The window should have a limit. It may take only one character, and should be a number. Needs a condition that prevents enter more than one character. — user3636661, May 15 '14 at 20:33
What window? Are you talking about a GUI? Swing? What? Please don't assume that we can read minds or see code not shown. Again, please try to improve your question. Please tell the important details. — Hovercraft Full Of Eels, May 15 '14 at 20:35
Also this method could be deleted and you could use `Character.isDigit(zn);`. — Alexis C., May 15 '14 at 20:35
I assume you are looking for this(DocumentFilter) http://stackoverflow.com/questions/5662651/how-to-implement-in-java-jtextfield-class-to-allow-entering-only-digits — Abu Sulaiman, May 15 '14 at 20:40
If this is Swing you could use a JFormattedTextField, with a MaskFormatter or similar. — Mark W, May 15 '14 at 20:41
Im sorry, i just dont know what u need to know. Its GUI and im using swing. — user3636661, May 15 '14 at 20:42

Hovercraft Full Of Eels · Accepted Answer · 2014-05-15T21:44:09.530

You state that this is a Swing question, and so I assume that you are using a JTextField. If so, you have one of two possible solutions here:

Use a JFormattedTextField and use a MaskFormatter, something simple like "#" should probably work perfectly here.
Or get the JTextField's Document and set its DocumentFilter with one that restricts input to as you deserve it. I think that this would be unnecessarily complex for you, and I recommend the first option.

Check the tutorial on how to use JFormattedTextFields which you can find here: JFormattedTextField Tutorial. It will explain all of the above including how to use a mask formatter with JFormattedTextFields.

Also please check Jon Skeet's blog on Writing the Perfect Question. Writing questions on this and other sites is a learned skill which can get better with study and effort. The tips that this blog contains will help you so that you'll know what information to include in your question so that the volunteers helping you don't have to guess at things. They will appreciate it, and you'll likely get better and quicker answers.

I did it and its working but i still dont understand how it works. Why should i use try catch? http://pastebin.com/Ac2Z9yqr — user3636661, May 15 '14 at 22:09

Write only one number in text field

1 Answers1