public RelativeTimeDateFormat() 
{
  
    this.startTime = System.currentTimeMillis();
}

 public StringBuffer format(Date date,
    StringBuffer sbuf,
    FieldPosition fieldPosition) 
{
    //System.err.println(":"+ date.getTime() + " - " + startTime);
    return sbuf.append((date.getTime() - startTime));
}

Appends to sbuf the number of milliseconds elapsed since the start of the application.

 public Date parse(String s,
    ParsePosition pos) 
{
    return null;
}

This method does not do anything but return null.