How to change foreground/text color of JFormattedTextField on its input text not obeying the RegEx format?

Question

I am following, http://www.java2s.com/Tutorial/Java/0240__Swing/RegexFormatterwithaJFormattedTextField.htm . In the given example, How to change foreground/text color of JFormattedTextField on its input text not obeying the RegEx format of the formatter?

Answer 1

You can change the foreground color of the JFormattedTextField when the user attempts to change focus using an InputVerifier . Starting from this complete example , condition the color in your implementation of shouldYieldFocus() .

@Override
public boolean shouldYieldFocus(JComponent input) {
    if (verify(input)) {
        tf.setValue(date);
        tf.setForeground(Color.black);
        return true;
    } else {
        tf.setForeground(Color.red);
        return false;
    }
}

To see changes while typing, use a DocumentListener that evaluates DateFormat instances in a similar way.