Custom MaskFormatter

[J Wallace]

Hello,

I am trying to create a MaskFormatter that formats an elapsed time. The number of elapsed seconds is stored as a Double and should be formatted similar to days:hh:mm:ss.sss. I have come up with an extension to MaskFormatter, inspired by http://weblogs.java.net/blog/hansmuller/archive/2005/08/using_swings_jf.html, which seems to do the job. However, a problem arises after initially inputting an elapsed time. After the initial edit, the value cannot be edited. What am I doing wrong? Here is the code with a main that illustrates the problem:

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
import java.text.ParseException;
import javax.swing.JButton;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.text.MaskFormatter;

public class ElapsedTimeFormatter extends MaskFormatter {

  private static final double SECS_PER_MIN = 60;
  private static final double SECS_PER_HOUR = 60 * SECS_PER_MIN;
  private static final double SECS_PER_DAY = 24 * SECS_PER_HOUR;

  public ElapsedTimeFormatter() {  
    try {
      setMask("###:##:##:##.###");
      setPlaceholderCharacter('_');
    } catch (ParseException e) {
      e.printStackTrace();
    }
  }

  @Override
  public Object stringToValue(String string) throws ParseException {
    if (string.contains("_")) {
      return super.stringToValue(string);
    }

    String tokens[] = string.split(":");
    double days = Double.parseDouble(tokens[0]);
    double hours = Double.parseDouble(tokens[1]);
    double mins = Double.parseDouble(tokens[2]);
    double secs = Double.parseDouble(tokens[3]);

    double elapsedSecs = (days * SECS_PER_DAY);
    elapsedSecs += (hours * SECS_PER_HOUR);
    elapsedSecs += (mins * SECS_PER_MIN);
    elapsedSecs += secs;

    return new Double(elapsedSecs);
  }

  @Override
  public String valueToString(Object value) throws ParseException {
    if (!(value instanceof Double)) {
      return super.valueToString(value);
    }

    Double d = (Double) value;

    StringBuilder result = new StringBuilder();
    result.append((d < 0 ? "-" : ""));

    int days = (int) (d / SECS_PER_DAY);
    d -= (days * SECS_PER_DAY);
    int hours = (int) (d / SECS_PER_HOUR);
    d -= (hours * SECS_PER_HOUR);
    int mins = (int) (d / SECS_PER_MIN);
    d -= (mins * SECS_PER_MIN);
    double secs = d;

    days = Math.abs(days);
    hours = Math.abs(hours);
    mins = Math.abs(mins);
    secs = Math.abs(secs);

    DecimalFormat daysFormatter = new DecimalFormat("000");
    DecimalFormat leadingZeroFormatter = new DecimalFormat("00");
    DecimalFormat decimalFormatter = new DecimalFormat("00.000");

    result.append(daysFormatter.format(days));
    result.append(":");
    result.append(leadingZeroFormatter.format(hours));
    result.append(":");
    result.append(leadingZeroFormatter.format(mins));
    result.append(":");
    result.append(decimalFormatter.format(secs));

    return result.toString();
  }

  public static void main(String[] args) throws Exception {
    MaskFormatter formatter = new ElapsedTimeFormatter();
    final JFormattedTextField tf = new JFormattedTextField(formatter);
    final JButton get = new JButton("getValue()");
    
    get.addActionListener(new ActionListener() {

      public void actionPerformed(ActionEvent e) {
        Object val = tf.getValue();
        System.out.println("val = " + val);
      }
    });

    JPanel center = new JPanel(new FlowLayout());
    JPanel south = new JPanel(new FlowLayout());

    center.add(tf);
    south.add(get);
    
    JFrame f = new JFrame("Elapsed Time Formatter");
    f.getContentPane().setLayout(new BorderLayout());
    f.getContentPane().add(center, BorderLayout.CENTER);
    f.getContentPane().add(south, BorderLayout.SOUTH);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.pack();
    f.setSize(300, 100);
    f.setVisible(true);
  }
}

Any ideas?

[Rob Camick]

Well, I don't know anything about how the formatters work but I replaced your custom methods with:

  @Override
  public Object stringToValue(String string) throws ParseException {
	Object o = super.stringToValue(string);
	System.out.println(string + " : " + o.getClass());
	return o;
  }

and the returned class is a String, not a Double so I would guess that is the difference.