How to mask and format an input field at the same time?

Question

Dear Experts,
I need to have an input field, which has the following behavior:
1. The input field accepts only number, i.e. characters other than number are ignored (not displayed on the text field).
2. The number is automatically formatted to ###,###,### as the user enter the number.
Example as the user enter 1-2-3-4-5-6-7, the sequence of number displayed in the text field is:
1
12
123
1,234
12,345
123,456
1,234,567
I have done the following:
import java.awt.*;
import javax.swing.*;
import java.text.*;
import javax.swing.text.*;
class FormattedTFDemo {
     NumberFormat cf;
     JLabel jlab;
     JFormattedTextField jftfSalary;
     JFormattedTextField jftfEmpID;
     JButton jbtnShow;
     public FormattedTFDemo() {
          JFrame jfrm = new JFrame("JFormattedTextField");
          jfrm.getContentPane().setLayout(new FlowLayout());
          jfrm.setSize(240, 270);
          jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          try {
               MaskFormatter mf = new MaskFormatter("###,###,###");
               jftfEmpID = new JFormattedTextField(mf);
          } catch (ParseException exc){
               System.out.println("Invalid Format");
               return;
          jftfEmpID.setColumns(15);
          cf = new DecimalFormat("###,###,###");
          jftfSalary = new JFormattedTextField(cf);
          jftfSalary.setColumns(15);
          jftfSalary.setValue(new Integer(7000));
          jfrm.getContentPane().add(new JLabel("First field"));
          jfrm.getContentPane().add(jftfEmpID);
          jfrm.getContentPane().add(new JLabel("Second field"));
          jfrm.getContentPane().add(jftfSalary);
          jfrm.setVisible(true);
     public static void main(String[] args) {
          SwingUtilities.invokeLater(new Runnable() {
               public void run() {
                    new FormattedTFDemo();
}The "First field" adopts no. 1 behavior, i.e. it does not allow any character other than numbers, but the "," are always displayed and the number displayed as I enter 1-2-3-4-5-6-7 are:
1 , ,
12 , ,
123, ,
123,4 ,
123,45 ,
123,456,
123,456,7
which is not according to behavior no. 2
The "Second field" displayed 1,234,567 only after the focus left the text field and not while typing. Moreover, characters other than number can still be displayed and only rejected after the focus left the text field.
I need a guide of what text field and what filter / format / mask I should use. Am I correct to use JFormattedTextField? Is the only way to accomplish this by using JTextField and create my own PlainDocument for the textfield, where
I rebuild the displayed output after each character is entered?
Thanks for any advice,
Patrick

Answer 1

So exactly what do you want the user to put in? and what do you want to see?
I need to have an input field, which has the following behavior:
1. The input field accepts only number, i.e. characters other than number are ignored (not displayed on the text field).
2. The number is automatically formatted to ###,###,### as the user enter the number.
Example as the user enter 1-2-3-4-5-6-7, the sequence of number displayed in the text field is:
1
12
123
1,234
12,345
123,456
1,234,567The user should type only numbers and when he types other than numbers, the field ignore it.
What I want to see, as the user, for example, types 1-2-3-4-5-t-6-7 is:
1
12
123
1,234
12,345
<beep / ignore> (because t is invalid)
123,456
1,234,567
Thus, I need a guide of what swing components should I use to accomplish this task. If you can give me the code, that will be perfect.
Hope you can advise me,
Patrick