How to force JFormattedTextField value to change dynamically

Question

I want to see a formatted number when I enter a number into a JFormattedTextField . For example, when a user typed in 124451000, it must be seen as 124.451.000 onscreen dynamically and not when a user presses Tab or Enter key.

I want to put a dot when the fourth number has been typed in, right after the third number (for example, like 2.566).

---

public class MyDocListener implements DocumentListener{
     NumberFormat nf = NumberFormat.getIntegerInstance(Locale.GERMAN); 
     NumberFormatter nff = new NumberFormatter(nf);
     DefaultFormatterFactory factory = new DefaultFormatterFactory(nff);
     final String newline = "\n";

    public void insertUpdate(DocumentEvent e) {
        updateLog(e, "inserted into");
        NumberFormat numberFormatter = new DecimalFormat("#,###,###"); 
        // I put this code to change the format.
    }
    public void removeUpdate(DocumentEvent e) {
        updateLog(e, "removed from");
    }
    public void changedUpdate(DocumentEvent e) {
        //Plain text components don't fire these events.
    }

    public void updateLog(DocumentEvent e, String action) {
    Document doc = (Document)e.getDocument();
    int changeLength = e.getLength();
    displayArea.append(
        changeLength + " character" +
        ((changeLength == 1) ? " " : "s ") +
        action + doc.getProperty("name") + "." + newline +
        "  Text length = " + doc.getLength() + newline);
}


 }

Well I tried this code, I could not run, My JFormattedTextField in another class, I could not succced in another class.I could not access to object which is in another class.

Answer 1

Would adding a DocumentListener help in this situation?

http://docs.oracle.com/javase/7/docs/api/javax/swing/event/DocumentListener.html

Create the Listener with a reference to the JFormattedTextField, and do your formatting within the Listener.

Answer 2

What is wrong with this code.I can't change JformattedTextfield's format. I use different classes

My main class

import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.FlowLayout;
public class MainClass extends JFrame {
private JPanel contentPane;
private JFormattedTextField MyTextField;
public static void main(String[] args) {
    new MainClass();
}
public MainClass() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(new FlowLayout(FlowLayout.CENTER, 5, 5));
    MyTextField=new JFormattedTextField();
    MyTextField.setColumns(20);
    MyTextField.getDocument().addDocumentListener(new MyDocumentListener());
    contentPane.add(MyTextField);
    this.setVisible(true);
  }
 }

MyDocumentListener class

import java.text.NumberFormat;
import java.util.Locale;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.NumberFormatter;
public class MyDocumentListener implements DocumentListener{
    NumberFormat fmt;
    public void insertUpdate(DocumentEvent e) {
    fmt = NumberFormat.getCurrencyInstance(Locale.GERMAN);
    MainClass.MyTextField.setFormat(fmt);//I get error in this this line.
                                               //MyTextField is invisible here
}
public void removeUpdate(DocumentEvent e) {
    //
}
public void changedUpdate(DocumentEvent e) {
    //
}
}