What is a simple way to create a text field (or such) that only allows the user to enter ints/doubles in Java?

Question

I am looking for a way to ensure that my text field (JTextField, JFormattedTextField) is returning a double or int rather than a string when I call .getText(). What is the best way to do this (if possible)?

Thanks!

badPanda :D

Answer 1

1. Register InputVerifier and call method getValue from JFormattedTextField

   public class FormattedTextFieldVerifier extends InputVerifier {
       public boolean verify(JComponent input) {
        if (input instanceof JFormattedTextField) {
            JFormattedTextField ftf = (JFormattedTextField)input;
            AbstractFormatter formatter = ftf.getFormatter();
            if (formatter != null) {
                String text = ftf.getText();
                try {
                     formatter.stringToValue(text);
                     return true;
                 } catch (ParseException pe) {
                     return false;
                 }
             }
         }
         return true;
     }
     public boolean shouldYieldFocus(JComponent input) {
         return verify(input);
     }
   

   }

Answer 2

I would check the input in the textbox callback and simply make the box red or create an alert message nearby. You can remove the non-numeric character from the textbox string.

Answer 3

Use JFormattedTextField.