Java(Android) convert SQLite date to "x days ago"

Question

I have:

String date = "2010-10-9 12:00:00";

I want to parse that string, then subtract that date/time from the current date/time so that I can output a string similar to "2 days ago".

Answer 1

Convert it to date. Get current date time. Calc the difference.

Answer 2

There may be a better way to do this, but this works.

String dateString = "2010-10-9 12:00:00";
String daysAgo = null;
// How many milliseconds in 1 day
final long DAY_IN_MILLIS = 86400000;
// The current timestamp in milliseconds
long now = System.currentTimeMillis();
// The format of your date string assuming the 1 am would read 01:00, not 1:00
// and Jan 1, 2010 would read 2010-1-1, not 2010-01-01
final DateFormat formatter = new SimpleDateFormat("yyyy-M-d hh:mm:ss");
// The calendar instance which adds a locale to the date
final Calendar cal = Calendar.getInstance();
try {
    // Parse the date string to return a Date object
    Date date = formatter.parse(dateString);
    // Set the calendar with our date object
    cal.setTime(date);
    // Get the millis timestamp of your date string
    long then = cal.getTimeInMillis();
    // Calculate the difference
    long difference = now - then;
    int ago = 0;
    // If the difference is greater than one day
    if (difference >= DAY_IN_MILLIS) {
        // Find the product
        ago = (int) (difference / DAY_IN_MILLIS);
        // Format your new string
            // You may want to check if(ago>1) here
        daysAgo = String.format("%d day(s) ago", ago);
    }
    // Write the result to Logcat
    Log.d(TAG, daysAgo);

} catch (ParseException e) {
    Log.e(TAG, e.getLocalizedMessage());
}   

Answer 3

This is a helper class I'm using, extending the standard DateUtils of Android. It has an advanced logic, that for timestamps of today, it would display the seconds or minutes or hours, while for other timestamps it would display the date.

You can adjust the logic to your needs in the getTimeDiffString method. As parameter, you would parse the timestamp of Date date = formatter.parse(dateString); that you're fetching in above code.

The code logic complies with the 'timestamp display' as you know if from Facebook or Twitter.

public class DateTimeUtils extends DateUtils {

     private static String mTimestampLabelYesterday;
     private static String mTimestampLabelToday;
     private static String mTimestampLabelJustNow;
     private static String mTimestampLabelMinutesAgo;
     private static String mTimestampLabelHoursAgo;
     private static String mTimestampLabelHourAgo;

    /**
     * Singleton contructor, needed to get access to the application context & strings for i18n
     * @param context Context
     * @return DateTimeUtils singleton instanec
     * @throws Exception
     */
     public static DateTimeUtils getInstance(Context context) {
         mCtx = context;
         if (instance == null) {
             instance = new DateTimeUtils();
             mTimestampLabelYesterday = context.getResources().getString(R.string.WidgetProvider_timestamp_yesterday);
             mTimestampLabelToday = context.getResources().getString(R.string.WidgetProvider_timestamp_today);
             mTimestampLabelJustNow = context.getResources().getString(R.string.WidgetProvider_timestamp_just_now);
             mTimestampLabelMinutesAgo = context.getResources().getString(R.string.WidgetProvider_timestamp_minutes_ago);
             mTimestampLabelHoursAgo = context.getResources().getString(R.string.WidgetProvider_timestamp_hours_ago);
             mTimestampLabelHourAgo = context.getResources().getString(R.string.WidgetProvider_timestamp_hour_ago);
         }
         return instance;
     }

    /**
     * Checks if the given date is yesterday.
     *
     * @param date - Date to check.
     * @return TRUE if the date is yesterday, FALSE otherwise.
     */
    public static boolean isYesterday(long date) {

        final Calendar currentDate = Calendar.getInstance();
        currentDate.setTimeInMillis(date);

        final Calendar yesterdayDate = Calendar.getInstance();
        yesterdayDate.add(Calendar.DATE, -1);

        return yesterdayDate.get(Calendar.YEAR) == currentDate.get(Calendar.YEAR) && yesterdayDate.get(Calendar.DAY_OF_YEAR) == currentDate.get(Calendar.DAY_OF_YEAR);
    }

    public static String[] weekdays = new DateFormatSymbols().getWeekdays(); // get day names
    public static final long millisInADay = 1000 * 60 * 60 * 24;


    ...

    /**
     * Displays a user-friendly date difference string
     * @param timedate Timestamp to format as date difference from now
     * @return Friendly-formatted date diff string
     */
    public String getTimeDiffString(long timedate) {
        Calendar startDateTime = Calendar.getInstance();
        Calendar endDateTime = Calendar.getInstance();
        endDateTime.setTimeInMillis(timedate);
        long milliseconds1 = startDateTime.getTimeInMillis();
        long milliseconds2 = endDateTime.getTimeInMillis();
        long diff = milliseconds1 - milliseconds2;

        long hours = diff / (60 * 60 * 1000);
        long minutes = diff / (60 * 1000);
        minutes = minutes - 60 * hours;
        long seconds = diff / (1000);

        boolean isToday = DateTimeUtils.isToday(timedate);
        boolean isYesterday = DateTimeUtils.isYesterday(timedate);

        if (hours > 0 && hours < 12) {
            return hours==1? String.format(mTimestampLabelHourAgo,hours) : String.format(mTimestampLabelHoursAgo,hours);
        } else if (hours <= 0) {
            if (minutes > 0)
                return String.format(mTimestampLabelMinutesAgo,minutes);
            else {
                return mTimestampLabelJustNow;
            }
        } else if (isToday) {
            return mTimestampLabelToday;
        } else if (isYesterday) {
            return mTimestampLabelYesterday;
        } else if (startDateTime.getTimeInMillis() - timedate < millisInADay * 6) {
            return weekdays[endDateTime.get(Calendar.DAY_OF_WEEK)];
        } else {
            return formatDateTime(mCtx, timedate, DateUtils.FORMAT_NUMERIC_DATE);
        }
    }

} 

while strings.xml holds:

<string name="WidgetProvider_timestamp_today">Today</string>
<string name="WidgetProvider_timestamp_yesterday">Yesterday</string>
<string name="WidgetProvider_timestamp_hour_ago">%s hours ago</string>
<string name="WidgetProvider_timestamp_hours_ago">%s hours ago</string>
<string name="WidgetProvider_timestamp_minutes_ago">%s minutes ago</string>
<string name="WidgetProvider_timestamp_just_now">Just now</string>