Best way to get maximum Date value in java?

Encapsulate the functionality you want in your own class, using Long.MAX_VALUE will most likely cause you problems.

class ExpirationDate {
    Date expires;

    boolean hasExpiration() {
        return expires == null;
    }

    Date getExpirationDate() {
        return expires;
    } 

    boolean hasExpired(Date date) {
        if (expires == null) {
            return true;
        } else {
            return date.before(expires);
        }
    }

    ...
}

Try

new Date(Long.MAX_VALUE)

which should give you the longest possible date value in Java.

+1 to the Long.MAX_VALUE suggestions. It seems that this would help you if you sort stuff by your date field.

However, instead of constructing a date from some the large constant value where ever you need the date, use a globally visible singleton to hold a Date instance that represents your special value:

class DateUtil
{
  public static final Date NO_EXPIRE = new Date( Long.MAX_VALUE );
}

Then you can use simple identity comparison (mydate == DateUtils.NO_EXPIRE) to test if a particular date is of your special case instead of obj.equals(); (ie. mydate.equals ( DateUtils.NO_EXPIRE ); )