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);
    }
}