Date Zero Validation In Java

I have a method taking Date field as a input parameter.

public static String formatDate(Date inputDate) {
    // if user send the date with inputDate= new Date(00000000) or new Date(0L) because it is Java default date.
    I have to send the exception error with message Invalid date.

What I did is something as below, But I am unable to get the error while passing the invalid date of zero count-from-epoch like "new Date( 0L )" as inputDate parameter.

public static String formatDate(Date inputDate) {
    if (null == inputDate)
        throw new FieldFormatException("Empty date field.");

    try {
        SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd");
        return formatter.format(inputDate);
    } catch (Exception ex) {
        throw new FieldFormatException("Exception in formatting date field." + ex);
Jon Skeet

It sounds like you just want:

if (inputDate == null || inputDate.getTime() == 0L)

That will detect if inputDate is null or represents the Unix epoch.

As noted in the comments though:

  • Rejecting a single value is kinda dangerous - why is new Date(0) "wrong" but new Date(1) "right"?
  • This prevents you accepting legitimate input that happens to be the Unix epoch


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