Java.util.Calendar - milliseconds since Jan 1, 1970

Question

Program followed by output. Someone please explain to me why 10,000,000 milliseconds from Jan 1, 1970 is November 31, 1969. Well, someone please explain what\'s wrong with

Answer 1

First, c.get(Calendar.MONTH) returns 0 for Jan, 1 for Feb, etc.

Second, use DateFormat to output dates.

Third, your problems are a great example of how awkward Java's Date API is. Use Joda Time API if you can. It will make your life somewhat easier.

Here's a better example of your code, which indicates the timezone:

public static void main(String[] args) {

    final DateFormat dateFormat = SimpleDateFormat.getDateTimeInstance(DateFormat.FULL, DateFormat.FULL);

    long l = 10000000L;
    System.out.println("Long value: " + l);
    Calendar c = new GregorianCalendar();
    c.setTimeInMillis(l);
    System.out.println("Date: " + dateFormat.format(c.getTime()));

    l = 1000000000000L;
    System.out.println("\nLong value: " + l);
    c.setTimeInMillis(l);
    System.out.println("Date: " + dateFormat.format(c.getTime()));
}