getting time difference with string like "A minute ago" or "An hour ago" on Android

getting time difference with string like "A minute ago" or "An hour ago"
on Android

i have this code in my PHP
function nicetime($date)
{
date_default_timezone_set("Asia/Taipei");
if(empty($date)) {
return "No date provided";
}
$periods = array("second", "minute", "hour", "day", "week",
"month", "year", "decade");
$lengths = array("60","60","24","7","4.35","12","10");
$now = time();
$unix_date = strtotime($date);
// check validity of date
if(empty($unix_date)) {
return "Bad date";
}
// is it future date or past date
if($now > $unix_date) {
$difference = $now - $unix_date;
$tense = "ago";
} else {
$difference = $unix_date - $now;
$tense = "from now";
}
for($j = 0; $difference >= $lengths[$j] && $j < count($lengths)-1; $j++) {
$difference /= $lengths[$j];
}
$difference = round($difference);
if($difference != 1) {
$periods[$j].= "s";
}
return "$difference $periods[$j] {$tense}";
}
but now i want to do the same but this time in my Android. im having
trouble because the string mytime is from a database, in an SQL format.
String mytime = pref.getString("announcementtime" + count, null);
output of mytime:
2013-08-31 15:55:22
i want to convert it to:
23 minutes ago //something like this
please be aware of the default timezone and the DateTime = Now