Mega Code Archive
Get a string representation of a date as it relates to the current time
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//package divestoclimb.util;
import java.text.DateFormat;
import java.util.Calendar;
import java.util.Date;
/**
* A class of utility functions for outputting date/time information relative
* to another date/time.
* TODO: localize. This would be best done by keeping this class's logic Android-
* independent so it returned some kind of structured format that could build
* an output string for format strings stored in resources.
* @author Ben Roberts (divestoclimb@gmail.com)
*/
class FriendlyDate {
/**
* Get a string representation of a date as it relates to the current time.
* @param time The Date object to use to generate the string representation
* @return A string explaining how long ago or in the future the date is from
* now.
*/
public static String format(Date time) {
return format(time, new Date());
}
// This implementation can't handle leap seconds, but it really doesn't
// need to be that precise for my purposes
public static final int MILLIS_PER_SEC=1000;
public static final int MILLIS_PER_MIN=MILLIS_PER_SEC*60;
public static final int MILLIS_PER_HR=MILLIS_PER_MIN*60;
public static final int MILLIS_PER_DAY=MILLIS_PER_HR*24;
public static final int MILLIS_PER_WEEK=MILLIS_PER_DAY*7;
/**
* Get a string representation of a date as it relates to another date.
* @param time The Date object to use to generate the string representation
* @param relative The Date object to compare against
* @return A string explaining how far behind or ahead the date is from relative.
*/
public static String format(Date time, Date relative) {
Calendar timeCal = Calendar.getInstance();
timeCal.setTime(time);
Calendar relCal = Calendar.getInstance();
relCal.setTime(relative);
// Compute the difference between these two dates in milliseconds, but
// first account for any timezone differences between the two dates.
long timeMillis = timeCal.getTimeInMillis();
timeMillis += timeCal.getTimeZone().getOffset(timeMillis);
long relMillis = relCal.getTimeInMillis();
relMillis += relCal.getTimeZone().getOffset(relMillis);
long diff = timeMillis - relMillis;
String dir = (diff < 0)? "ago":"from now";
diff = Math.abs(diff);
if(diff / MILLIS_PER_MIN < 0.2) {
return "within seconds";
}
if(diff / MILLIS_PER_MIN < 0.8) {
return "less than a minute "+dir;
}
if(diff / MILLIS_PER_MIN < 1.5) {
return "about a minute "+dir;
}
if(diff / MILLIS_PER_HR < 0.9) {
return new Integer(Math.round(diff / MILLIS_PER_MIN)).toString()+" minutes "+dir;
}
if(diff / MILLIS_PER_HR < 1.2) {
return "about an hour "+dir;
}
if(diff / MILLIS_PER_HR < 1.9) {
return "more than an hour "+dir;
}
if(diff / MILLIS_PER_DAY < 0.8) {
return new Integer(Math.round(diff / MILLIS_PER_HR)).toString()+" hours "+dir;
}
if(diff / MILLIS_PER_DAY < 1.2) {
return "about a day "+dir;
}
if(diff / MILLIS_PER_DAY < 1.9) {
return "more than a day "+dir;
}
if(diff / MILLIS_PER_WEEK < 1) {
return new Integer(Math.round(diff / MILLIS_PER_DAY)).toString()+" days "+dir;
}
if(diff / MILLIS_PER_WEEK < 1.5) {
return "about a week "+dir;
}
if(diff / MILLIS_PER_WEEK < 7) {
return new Integer(Math.round(diff / MILLIS_PER_WEEK)).toString()+" weeks "+dir;
}
// Just give the raw date
return DateFormat.getDateInstance().format(time);
}
}
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