Is there a way to force validation after a Format is applied to a JFormattedTextField?

Question

The first thing I do is create a NumberFormat that is appropriate to my needs:

this.format = NumberFormat.getIntegerInstance();
this.format.setMinimumIntegerDigits(6);
this.format.setMaximumIntegerDigits(6);
this.format.setGroupingUsed(false);

I then apply it to a JFormattedTextField:

this.fld_id = new JFormattedTextField(this.format);

I then set this field's InputVerifier, like so:

this.fld_id.setInputVerifier(new IdVerifier());

My IdVerifier simply looks to see that the entered text conforms to a regular expression:

private class IdVerifier extends InputVerifier {
        public boolean verify(final JComponent arg0) {
            final JFormattedTextField verifyJTF = (JFormattedTextField) arg0;

            if (!verifyJTF.getText().matches("\\d{6}")) {
                return false;
            }

            return true;
        }

        public boolean shouldYieldFocus(final JComponent arg0) {
            if (!this.verify(arg0)) {
                arg0.setBackground(Color.RED);
            } else {
                arg0.setBackground(UIManager.getColor("TextField.background"));
            }

            return true;
        }
}

However, when I do this, I enter a value into the JFormattedTextField, let's say "1". This gets reformatted to "000001" by the NumberFormatter. However, in this example, the background of the text field is still set to red.

What is the correct way to ensure that the formatted contents of the JFormattedTextField are what gets consumed by the InputVerifier? I expected the default behavior to be that the focus is lost, the formatter is applied, then the input is verified. However, that's clearly not the case.

Answer 1

Looking at the definition for InputVerifier, it does not sound like GUI work should be taking place inside either the verify or shouldYieldFocus methods. The InputVerifier is solely intended to make the decision as to whether focus should jump from one field to another.

I think you'd be better off attaching an ActionListener to your JFormattedTextField and then simply calling your regex and red-painting code in the body of that listener. Then the check will be made each time the content of the text field changes.

Answer 2

Change the regular expression to be \\d{1,6}, it probably doesn't accept the leading zeros as a number