Simplify replacement of date object with “today” and “yesterday” strings in Java static method

Question

I have following method that I would like to make shorter or faster if nothing else. Please all comments are welcome:

Bellow method takes a date object, formates it ("EEE hh:mma MMM d, yyyy") and then figures out if the date is today or yesterday and than, if it is, it returns "(Yesterday | Today) hh:mma" formated string.

    public static String formatToYesterdayOrToday(String date) {
    SimpleDateFormat sdf = new SimpleDateFormat("EEE hh:mma MMM d, yyyy");
    Date in = null;

    try {
        in = sdf.parse(date);
    } catch (ParseException e) {
        log.debug("Date parsing error:", e);
    }

    Calendar x = Calendar.getInstance();
    x.setTime(in);

    String hour = Integer.toString(x.get(Calendar.HOUR));
    String minute = Integer.toString(x.get(Calendar.MINUTE));
    String pm_am = x.get(Calendar.AM_PM) == Calendar.AM ? "AM" : "PM";

    x.set(Calendar.HOUR, 0);
    x.set(Calendar.HOUR_OF_DAY, 0);
    x.set(Calendar.MINUTE, 0);
    x.set(Calendar.SECOND, 0);
    x.set(Calendar.MILLISECOND, 0);

    Calendar today = Calendar.getInstance();
    today.set(Calendar.HOUR, 0);
    today.set(Calendar.HOUR_OF_DAY, 0);
    today.set(Calendar.MINUTE, 0);
    today.set(Calendar.SECOND, 0);
    today.set(Calendar.MILLISECOND, 0);

    Calendar yesterday = Calendar.getInstance();
    yesterday.set(Calendar.HOUR, 0);
    yesterday.set(Calendar.HOUR_OF_DAY, 0);
    yesterday.set(Calendar.MINUTE, 0);
    yesterday.set(Calendar.SECOND, 0);
    yesterday.set(Calendar.MILLISECOND, 0);
    yesterday.add(Calendar.DATE, -1);

    if (x.compareTo(today) == 0) {
        return "Today " + hour + ":" + minute + pm_am;
    }
    if (x.compareTo(yesterday) == 0) {
        return "Yesterday " + hour + ":" + minute + pm_am;
    }
    return date;
}

Answer 1

Here's how you could improve it with the standard API:

public static String formatToYesterdayOrToday(String date) throws ParseException {
    Date dateTime = new SimpleDateFormat("EEE hh:mma MMM d, yyyy").parse(date);
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(dateTime);
    Calendar today = Calendar.getInstance();
    Calendar yesterday = Calendar.getInstance();
    yesterday.add(Calendar.DATE, -1);
    DateFormat timeFormatter = new SimpleDateFormat("hh:mma");

    if (calendar.get(Calendar.YEAR) == today.get(Calendar.YEAR) && calendar.get(Calendar.DAY_OF_YEAR) == today.get(Calendar.DAY_OF_YEAR)) {
        return "Today " + timeFormatter.format(dateTime);
    } else if (calendar.get(Calendar.YEAR) == yesterday.get(Calendar.YEAR) && calendar.get(Calendar.DAY_OF_YEAR) == yesterday.get(Calendar.DAY_OF_YEAR)) {
        return "Yesterday " + timeFormatter.format(dateTime);
    } else {
        return date;
    }
}

Here's how you could do it with Jodatime:

public static String formatToYesterdayOrToday(String date) {
    DateTime dateTime = DateTimeFormat.forPattern("EEE hh:mma MMM d, yyyy").parseDateTime(date);
    DateTime today = new DateTime();
    DateTime yesterday = today.minusDays(1);
    DateTimeFormatter timeFormatter = DateTimeFormat.forPattern("hh:mma");

    if (dateTime.toLocalDate().equals(today.toLocalDate())) {
        return "Today " + timeFormatter.print(dateTime);
    } else if (dateTime.toLocalDate().equals(yesterday.toLocalDate())) {
        return "Yesterday " + timeFormatter.print(dateTime);
    } else {
        return date;
    }
}

Answer 2

You wrote "all comments welcome" so here's my way using joda-time. :)

I am a fan of displaying dates and times in the short and smart way of iPhone's recent calls (similar to google wave posts). That is "hh:mm" if today, "yesterday" or name of weekday if <7 days, else yyyy-MM-dd.

private static boolean isToday (DateTime dateTime) {
   DateMidnight today = new DateMidnight();
   return today.equals(dateTime.toDateMidnight());
}

private static boolean isYesterday (DateTime dateTime) {
   DateMidnight yesterday = (new DateMidnight()).minusDays(1);
   return yesterday.equals(dateTime.toDateMidnight());
}

private static String getDayString(Date date) {
    String s;

    if (isToday(new DateTime(date)))
        s = "Today";
    else if (isYesterday(new DateTime(date)))
        s = "Yesterday";
    else
        s = weekdayFormat.format(date);

    return s;
}

public static String getDateString_shortAndSmart(Date date) {
    String s;

    DateTime nowDT = new DateTime();
    DateTime dateDT = new DateTime(date);
    int days = Days.daysBetween(dateDT, nowDT).getDays();

    if (isToday(new DateTime(date)))
        s = getHourMinuteString(date);
    else if (days < 7)
        s = getDayString(date);
    else
        s = getDateString(date);

    return s;
}

where I use a set of SimpleDateFormat (as weekdayFormat above) to format the time to the desired strings, and where DateTime and DateMidnight are joda-time classes.

In these cases the number of elapsed days between two DateTime:s is less relevant than how people would define the time talking about it. Instead of counting days (or milliseconds as I've seen some people do) DateMidnight comes handy here, though other methods would work just as well. :)

Answer 3

Another way of comparing dates apart from the accepted answer above using java.util.Date.getTime() (note: long should be used instead of int):

Date today=new Date();
Date dateObj=null;
long diff=0;
try{
    dateObj= formater1.parse(date);
    diff=(today.getTime()-dateObj.getTime())/(86400000);
}catch(Exception e){}
String days="TODAY";
if(diff==1){
    days = "YESTERDAY";
}else if(diff>1){
    days = String.valueOf(diff) + " " +"DAYS AGO";
}

<%=days%> would return:

TODAY

YESTERDAY

x DAYS AGO

Answer 4

my understanding of the question is provide a simple method to produce output like the following:

Today at 20:00
Today at 20:30
Today at 21:00
Tomorrow at 06:45
Tomorrow at 07:00
Tomorrow at 08:15

the code below worked for me, but i am new to android and maybe others could point out if the code is not robust. in code below 'timeLong' is the time of my events in epoch time (milliseconds).

public String convertFromEpochTime (long timeLong) {
    long timeNow = System.currentTimeMillis();

    // get day in relative time
    CharSequence timeDayRelative;
    timeDayRelative = DateUtils.getRelativeTimeSpanString(timeLong, timeNow, DateUtils.DAY_IN_MILLIS, DateUtils.FORMAT_ABBREV_RELATIVE);

    // get hour in 24 hour time
    Format hourFormatter = new SimpleDateFormat("HH:mm");
    String timeHour = hourFormatter.format(timeLong);

    // Log.d(DEBUG_TAG, "time of event: " + timeDayRelative + " at " + timeHour);

    String timeDayHour = timeDayRelative + " at "+ timeHour;

    return timeDayHour;
}

Answer 5

Time Zone

The Question and the other Answers ignore the crucial issue of time zone. That input string lacks any time zone or offset-from-UTC. So that string will be parsed while assuming it represents a date-time in your JVM’s current default time zone. Risky business as (a) that assumption may be false, and (b) that default can change at any moment, even during runtime.

Locale

The Question and other Answers ignore another crucial issue: Locale. The Locale determines the human language used to translate the name of day and name of month from the input string during parsing (and generating).

If not specified the JVM’s current default Locale will be used for translation. Just as with time zone, your JVM’s default Locale can change at any moment, even during runtime.

Better to specify your desired/expected Locale.

java.time

The Question and the other Answers use the old date-time classes that have proven to be poorly designed and troublesome. Java 8 and later has the java.time framework built-in whose classes supplant the old ones.

You method to parse a string while generating a new string should be broken up into two methods. One method should parse to obtain date-time objects. The second should take date-time objects and generate the desired string output. Then each can be used separately. And this approach leads us away from thinking of strings as date-time values. Strings are textual representations of date-time values. Your business logic should focus on manipulating those date-time values as objects, not focus on strings.

Parsing

private ZonedDateTime parseLengthyString ( String input , ZoneId zoneId , Locale locale ) {
    // FIXME: Check for nulls.

    DateTimeFormatter formatter = DateTimeFormatter.ofPattern ( "EEE hh:mma MMM d, uuuu" );
    formatter = formatter.withZone ( zoneId );
    formatter = formatter.withLocale ( locale );
    ZonedDateTime zdt = null;
    try {
        zdt = ZonedDateTime.parse ( input , formatter );
    } catch ( DateTimeParseException e ) {
        // FIXME: handle exeption.
        System.out.println ( "ERROR - e: " + e );
    }
    return zdt; // FIXME: Check for null.
}

Generating

Given a ZonedDateTime in hand from the method above, we can generate a textual representation of its date-time value using a specified Locale for translation of name-of-day and name-of-month.

To determine if the date-time is for today or yesterday, we only care about the date portion without time of day. For that we can use the LocalDate class in java.time.

private String generateLengthyString ( ZonedDateTime zdt , Locale locale ) {
    // FIXME: Check for nulls.

    // Compare the date-only value of incoming date-time to date-only of today and yesterday.
    LocalDate localDateIncoming = zdt.toLocalDate ();

    Instant instant = Instant.now ();
    ZonedDateTime now = ZonedDateTime.now ( zdt.getZone () ); // Get current date-time in same zone as incoming ZonedDateTime.
    LocalDate localDateToday = now.toLocalDate ();
    LocalDate localDateYesterday = localDateToday.minusDays ( 1 );

    DateTimeFormatter formatter = null;
    if ( localDateIncoming.isEqual ( localDateToday ) ) {
        formatter = DateTimeFormatter.ofPattern ( "'Today' hh:mma" , locale ); // FIXME: Localize "Today".
    } else if ( localDateIncoming.isEqual ( localDateYesterday ) ) {
        formatter = DateTimeFormatter.ofPattern ( "'Yesterday' hh:mma" , locale ); // FIXME: Localize "Yesterday".
    } else {
        formatter = DateTimeFormatter.ofPattern ( "EEE hh:mma MMM d, uuuu" , locale );
    }

    String output = zdt.format ( formatter );
    return output; // FIXME: Check for null.
}

Example

Exercise those two methods.

Arbitrarily choosing a time zone of America/New_York as the Question does not specify.

String input = "Sat 11:23AM Feb 6, 2016";
ZoneId zoneId = ZoneId.of ( "America/New_York" );
Locale locale = Locale.US;
ZonedDateTime zdt = this.parseLengthyString ( input , zoneId , locale );

String output = this.generateLengthyString ( zdt , locale );

By the way, you can ask java.time to automatically format the output string according to the cultural norms of the Locale instead of hard-coding a format.

String outputPerLocale = zdt.format ( DateTimeFormatter.ofLocalizedDateTime ( FormatStyle.MEDIUM ) );

Dump to console.

System.out.println ( "input: " + input + " | zdt: " + zdt + " | Instant: " + zdt.toInstant () + " | output: " | output + " + outputPerLocale: " + outputPerLocale );

input: Sat 11:23AM Feb 6, 2016 | zdt: 2016-02-06T11:23-05:00[America/New_York] | Instant: 2016-02-06T16:23:00Z | output: Today 11:23AM | outputPerLocale: Feb 6, 2016 11:23:00 AM

By the way, I suggest putting a SPACE before the AM or PM for easier reading.

Answer 6

this for today,yesterday,tomorrow

String formatDate(String fecha){

    String Rfecha=new String();
     SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy");
     //SimpleDateFormat formatter2 = new SimpleDateFormat("EEEE d MMM");
     SimpleDateFormat formatter2 = new SimpleDateFormat("E, d MMM ");
        try {
           Date hoy=new Date();

            Date date = formatter.parse(fecha);


            String pref="";
           Log.d("hoy long", ""+(hoy.getTime()/ (1000*60*60*24)));
           Log.d("date long", ""+ (date.getTime()/ (1000*60*60*24)));

           int ihoy=(int) (hoy.getTime()/ (1000*60*60*24));
           int idate=(int) (date.getTime()/ (1000*60*60*24));
           int dif=idate-ihoy;



           if(dif==0)
               pref="Today";
           if(dif==1)
               pref="Tomorrow";
           if(dif==-1)
               pref="Yesterday";

            Rfecha=pref+" "+formatter2.format(date);


        } catch (Exception e) {
            e.printStackTrace();
        }

    return Rfecha;
}

Answer 7

Look at jodatime: http://joda-time.sourceforge.net/

this is some example code from the doc:

public boolean isAfterPayDay(DateTime datetime) {
  if (datetime.getMonthOfYear() == 2) {   // February is month 2!!
    return datetime.getDayOfMonth() > 26;
  }
  return datetime.getDayOfMonth() > 28;
}

public Days daysToNewYear(LocalDate fromDate) {
  LocalDate newYear = fromDate.plusYears(1).withDayOfYear(1);
  return Days.daysBetween(fromDate, newYear);
}

public boolean isRentalOverdue(DateTime datetimeRented) {
  Period rentalPeriod = new Period().withDays(2).withHours(12);
  return datetimeRented.plus(rentalPeriod).isBeforeNow();
}

public String getBirthMonthText(LocalDate dateOfBirth) {
  return dateOfBirth.monthOfYear().getAsText(Locale.ENGLISH);
}

Answer 8

This is extended versino of Balusc's implementation.

Try this, i implemented it using joda-datatime2.2.jar and SimpleDateFormat

import java.text.SimpleDateFormat;
import java.util.Date;
import org.joda.time.DateMidnight;
import org.joda.time.DateTime;
import org.joda.time.Days;
public class SmartDateTimeUtil {
private static String getHourMinuteString(Date date){
    SimpleDateFormat hourMinuteFormat = new SimpleDateFormat(" h:m a");
    return hourMinuteFormat.format(date);
}

private static String getDateString(Date date){
    SimpleDateFormat dateStringFormat = new SimpleDateFormat("EEE',' MMM d y',' h:m a");
    return dateStringFormat.format(date);
}

private static boolean isToday (DateTime dateTime) {
       DateMidnight today = new DateMidnight();
       return today.equals(dateTime.toDateMidnight());
}

private static boolean isYesterday (DateTime dateTime) {
       DateMidnight yesterday = (new DateMidnight()).minusDays(1);
       return yesterday.equals(dateTime.toDateMidnight());
}

private static boolean isTomorrow(DateTime dateTime){
    DateMidnight tomorrow = (new DateMidnight()).plusDays(1);
       return tomorrow.equals(dateTime.toDateMidnight());
}
private static String getDayString(Date date) {
        SimpleDateFormat weekdayFormat = new SimpleDateFormat("EEE',' h:m a");
        String s;
        if (isToday(new DateTime(date)))
            s = "Today";
        else if (isYesterday(new DateTime(date)))
            s = "Yesterday," + getHourMinuteString(date);
        else if(isTomorrow(new DateTime(date)))
            s = "Tomorrow," +getHourMinuteString(date);
        else
            s = weekdayFormat.format(date);
        return s;
}

public static String getDateString_shortAndSmart(Date date) {
        String s;
        DateTime nowDT = new DateTime();
        DateTime dateDT = new DateTime(date);
        int days = Days.daysBetween(dateDT, nowDT).getDays();   
        if (isToday(new DateTime(date)))
            s = "Today,"+getHourMinuteString(date);
        else if (days < 7)
            s = getDayString(date);
        else
            s = getDateString(date);
        return s;
}

}

Simple cases to use and test the Util class:

import java.util.Calendar;
import java.util.Date;

public class SmartDateTimeUtilTest {
    public static void main(String[] args) {
        System.out.println("Date now:"+SmartDateTimeUtil.getDateString_shortAndSmart(new Date()));
        System.out.println("Date 5 days before :"+SmartDateTimeUtil.getDateString_shortAndSmart(getFutureDay(-5)));
        System.out.println("Date 1 day before :"+SmartDateTimeUtil.getDateString_shortAndSmart(getFutureDay(-1)));
        System.out.println("Date last month:"+SmartDateTimeUtil.getDateString_shortAndSmart(getFutureMonth(-1)));
        System.out.println("Date last year:"+SmartDateTimeUtil.getDateString_shortAndSmart(getFutureDate(-1)));
        System.out.println("Date 1 day after :"+SmartDateTimeUtil.getDateString_shortAndSmart(getFutureDay(1)));
    }
    public static Date getFutureDate(int numberOfYears){
        Calendar c = Calendar.getInstance();
        c.setTime(new Date());
        c.add(Calendar.YEAR, numberOfYears); 
        return c.getTime();
    }
    public static Date getFutureMonth(int numberOfYears){
        Calendar c = Calendar.getInstance();
        c.setTime(new Date());
        c.add(Calendar.MONTH, numberOfYears); 
        return c.getTime();
    }

    public static Date getFutureDay(int numberOfYears){
        Calendar c = Calendar.getInstance();
        c.setTime(new Date());
        c.add(Calendar.DATE, numberOfYears); 
        return c.getTime();
    }
}

Answer 9

I know I am late to this party. But I have shortest solution for this problem. If you want to show "Today" or "Yesterday" based on the Date then you just need to use this

String strDate = "";
if (DateUtils.isToday(date.getTime()))
    strDate = "Today";
else if (DateUtils.isToday(date.getTime() + DateUtils.DAY_IN_MILLIS))
    strDate = "Yesterday";

here variable date is the Date object.