MaskFormatter stops allowing input

Question

i need a MaskFormatter which allows the user ot input time in the format hh:mm. features:
user should be able to conveniently type four digites without having to press the ":" key
the value of the JFormattedTextfield should always be of type date, never string
the problem: once i set a value, the textfield doesn't allow input anymore. here's an example:
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.JButton;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.text.MaskFormatter;
public class TimeFormatter extends MaskFormatter {
     // set mask and placeholder
     public TimeFormatter() {
          try {
               setMask("##:##");
               setPlaceholderCharacter('0');
               setAllowsInvalid(false);
               setOverwriteMode(true);
          } catch (ParseException e) {
               e.printStackTrace();
     @Override
     public Object stringToValue(String string) throws ParseException {
          SimpleDateFormat df = new SimpleDateFormat("HH:mm");
          if( string == null)
               string = "00:00";
          return df.parse(string);
     @Override
     public String valueToString(Object value) throws ParseException {
          SimpleDateFormat df = new SimpleDateFormat("HH:mm");
          if( value == null)
               value = new Date( 0);
          return df.format( (Date) value);
     public static void main(String[] args) throws Exception {
          // textfield 1: create formatter and textfield
          final MaskFormatter formatter = new TimeFormatter();
//          formatter.setValueClass(java.util.Date.class);
          final JFormattedTextField tf1 = new JFormattedTextField( formatter);
          tf1.setPreferredSize( new Dimension( 50, 22));
          // set initial value
          tf1.setValue( new Date());
          // textfield 2: create formatter and textfield
          final JFormattedTextField tf2 = new JFormattedTextField( formatter);
          tf1.setPreferredSize( new Dimension( 50, 22));
          // no initial value
          // tf1.setValue( new Date());
          // button to show current value
          JButton bt = new JButton("Show Value");
          bt.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent e) {
                    System.out.println("value 1 = " + tf1.getValue() + ", value 2 = " + tf2.getValue());
                    System.out.println("value 1 = " + tf1.getText() + ", value 2 = " + tf2.getText());
                    // System.out.println("value class: " + formatter.getValueClass());
          // main frame
          JFrame f = new JFrame();
          f.getContentPane().setLayout(new FlowLayout());
          f.getContentPane().add(tf1);
          f.getContentPane().add(tf2);
          f.getContentPane().add(bt);
          f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          f.pack();
          f.setSize(300, 100);
          f.setVisible(true);
}you see, that you can't edit the first textfield. it has a value set (current date). however, you can edit the 2nd textfield, but once that field loses the focus, you can't edit that anymore either.
does anyone know what's happening and have a solution?

Answer 1

you can lock this, i've solved it.
however, since probably more people will run into this issue, here's a quick solution:
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.JButton;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.text.MaskFormatter;
public class TimeFormatter extends MaskFormatter {
     // set mask and placeholder
     public TimeFormatter() {
          try {
               setMask("##:##");
               setPlaceholderCharacter('0');
               setAllowsInvalid(false);
               setOverwriteMode(true);
          } catch (ParseException e) {
               e.printStackTrace();
     @Override
     public Object stringToValue(String string) throws ParseException {
          return new MyDate( string);
     @Override
     public String valueToString(Object value) throws ParseException {
          if( value == null)
               return new MyDate().toString();
          return ((MyDate) value).toString();
     public static void main(String[] args) throws Exception {
          // textfield 1: create formatter and textfield
          final MaskFormatter formatter = new TimeFormatter();
          final JFormattedTextField tf1 = new JFormattedTextField( formatter);
          tf1.setPreferredSize( new Dimension( 50, 22));
          // set initial value
          tf1.setValue( new MyDate());
          // textfield 2: create formatter and textfield
          final JFormattedTextField tf2 = new JFormattedTextField( formatter);
          tf1.setPreferredSize( new Dimension( 50, 22));
          // no initial value
          // tf1.setValue( new Date());
          // button to show current value
          JButton bt = new JButton("Show Value");
          bt.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent e) {
                    System.out.println("value 1 = " + tf1.getValue() + ", value 2 = " + tf2.getValue());
                    System.out.println("value 1 = " + tf1.getText() + ", value 2 = " + tf2.getText());
                    // System.out.println("value class: " + formatter.getValueClass());
          // main frame
          JFrame f = new JFrame();
          f.getContentPane().setLayout(new FlowLayout());
          f.getContentPane().add(tf1);
          f.getContentPane().add(tf2);
          f.getContentPane().add(bt);
          f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          f.pack();
          f.setSize(300, 100);
          f.setVisible(true);
     public static class MyDate extends Date {
          public MyDate() {
               super();
          public MyDate( String time) {
               super();
               try {
                    setTime( new SimpleDateFormat("HH:mm").parse(time).getTime());
               } catch (ParseException e) {
                    e.printStackTrace();
                    setTime( 0);
          @Override
          public String toString() {
               SimpleDateFormat df = new SimpleDateFormat("HH:mm");
               return df.format( getTime());
}the problem: you mustn't use Date as an object of the formatter.
the reason: Date doesn't have a constructor that allows a string specified in "HH:mm" format. new Date("00:00") throws an
IllegalArgumentException()
in Date's
public static long parse(String s)
During text input the parser is called from Date's String parameterized constructor:
MaskFormatter's stringToValue(String value, boolean completeMatch)
calls
DefaultFormatter's stringToValue(String string)
which contains:
cons = vc.getConstructor(new Class[] { String.class });
return cons.newInstance(new Object[] { string });
and the instantiation of Date( "00:00") fails because the above mentioned IllegalArgumentException()
In short: a given MUST for the MaskFormatter is, that the used object must have a valid constructor which allows a String parameter.