Prevent user to move to next text field unless valid input is entered

Question

I am developing a Java Swing Application.

The application ends with a form to take the customers information (name, last name, email, gender, etc)

I am trying to validate the text fields in a way that when the application is launched focus will go on the first text box (first name). I want the user to not be able to leave the box until they have entered a valid name (no numbers, punctuation and so on).

So far I am using JOptionPane.showMessageDialog(null, "") to output messages to the user, and the textfields are rigged with lost focus listeners.

Unfortunately even after looking online, I am not able to find a solution to validating these boxes.

Action Plan:

Focus on first textfield >>> Unable to leave unless valid input is entered >> messages outputted to user >> validation completed >> focus set on next field >> and so on.

Help would be appreciated.

*Why* are you wanting to do this? It sounds pointlessly irritating. — chrylis -cautiouslyoptimistic-, Jan 11 '16 at 17:38
Well the idea is to make sure that the correct information is entered. All the information will be stored in a database. — JSint, Jan 11 '16 at 17:44
@Dan: your answer is wrong. This is exactly what an InputVerifier is for. — Hovercraft Full Of Eels, Jan 11 '16 at 17:44
Please see [these links](https://www.google.com/?gws_rd=ssl#q=java+swing+jtextfield+inputverifier+site:http:%2F%2Fstackoverflow.com%2F) for more on this. — Hovercraft Full Of Eels, Jan 11 '16 at 17:47
I was replying to you Dan, but looks like I was to late =/ Thanks for trying to help. — JSint, Jan 11 '16 at 17:51
Take a look at [Validating Input](http://docs.oracle.com/javase/tutorial/uiswing/misc/focus.html#inputVerification) or, which I prefer [this](http://stackoverflow.com/questions/25274566/how-can-i-change-the-highlight-color-of-a-focused-jcombobox/25276658#25276658) — MadProgrammer, Jan 11 '16 at 20:01

Dan · Answer 1 · 2016-01-11T17:44:00.237

Try something along the lines of the following code for listener

class CustomFocusListener implements FocusListener
{
    @Override
    public void focusGained(FocusEvent e)
    {

    }

    @Override
    public void focusLost(FocusEvent e)
    {
        validateText();
        if(validateFailed) {
            myJTextField.grabFocus();
        }
    }
}

As for upon launch just try

myFirstJTextField.grabFocus();

Look into JComponent.grabFocus() for more information.

Prevent user to move to next text field unless valid input is entered

1 Answers1