計算兩個long型時間差

public static String getTimeFromLong(long diff) {
        final String HOURS = "h";
        final String MINUTES = "min";
        //final String SECONDS = "sec";

        final long MS_IN_A_DAY = 1000 * 60 * 60 * 24;
        final long MS_IN_AN_HOUR = 1000 * 60 * 60;
        final long MS_IN_A_MINUTE = 1000 * 60;
        final long MS_IN_A_SECOND = 1000;
        //Date currentTime = new Date();
        //long numDays = diff / MS_IN_A_DAY;
        //diff = diff % MS_IN_A_DAY;
        long numHours = diff / MS_IN_AN_HOUR;
        diff = diff % MS_IN_AN_HOUR;
        long numMinutes = diff / MS_IN_A_MINUTE;
        diff = diff % MS_IN_A_MINUTE;
        //long numSeconds = diff / MS_IN_A_SECOND;
        diff = diff % MS_IN_A_SECOND;
        //long numMilliseconds = diff;

        StringBuffer buf = new StringBuffer();
        if (numHours > 0) {
            buf.append(numHours + " " + HOURS + ", ");
        }

        if (numMinutes > 0) {
            buf.append(numMinutes + " " + MINUTES);
        }

        //buf.append(numSeconds + " " + SECONDS);

        String result = buf.toString();

        if (numMinutes < 1) {
            result = "< 1 minute";
        }

        return result;
    }

生成結果是 “5 h ,4 min”;有需要多少天多少秒的打開註釋即可。