You can use the Calendar
class to convert Date
public long getDifference()
{
SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd kk:mm:ss z yyyy");
Date d = sdf.parse("Mon May 27 11:46:15 IST 2013");
Calendar c = Calendar.getInstance();
c.setTime(d);
long time = c.getTimeInMillis();
long curr = System.currentTimeMillis();
long diff = curr - time; //Time difference in milliseconds
return diff/1000;
}