Good day, quick question, Am trying to compare if 2 dates are the same day for the same time zone (city)Anyone have any idea why the following code holds and the other doesn't, can't seem to understand why.
SimpleDateFormat fmt = new SimpleDateFormat("EEE dd,MMM");
Date newparsetemp = fmt.parse(parsedate);
Date currentdateparse = fmt.parse(currentdate);
if(currentdateparse.equals(newparsetemp)){
//code executes
}
but if i do use this, the if condition doesn't hold
SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd");
Date newparsetemp = fmt.parse(parsedate);
Date currentdateparse = fmt.parse(currentdate);
if(currentdateparse.equals(newparsetemp)){
//does not
}
Consider using Joda-Time's LocalDate.
Date data1 = ...
Date date2 = ...
new LocalDate(date1).equals(new LocalDate(date2))
Better yet just skip Date and use LocalDate instead.
Comparing after formatting to a string is an odd thing to do. Try this instead:
Calendar cal = GregorianCalendar.getInstance();
cal.setTime(parsedate);
Calendar cal2 = GregorianCalendar.getInstance();
cal2.setTime(currentdate);
cal2.set(Calendar.HOUR, 0);
cal2.set(Calendar.MINUTE, 0);
cal2.set(Calendar.SECOND, 0);
cal2.set(Calendar.MILLISECOND, 0);
cal.set(Calendar.HOUR, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
System.out.println(cal.equals(cal2) ? "true" : "false");
Your comment about timezones needs clarification. Did you mean to say
compare if 2 dates are the same day for different time zones?
If you mean "comparing only the day of week", have you tried comparing the result of Calendar.get(Calendar.DAY_OF_WEEK) instead?
do you agree that there is a chance that two different dates from different years, in the same month and day, can match the same day of the week?
and that there's no chance of two different dates match the same day, month and year?
I've actually done this not too long ago in one of my Android apps,
public boolean isSameDay(Event otherEvent) {
if(otherEvent == null) return false;
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm");
try {
Calendar otherEventDate = Calendar.getInstance();
otherEventDate.setTime(format.parse(otherEvent.getStartTime()));
Calendar thisEventDate = Calendar.getInstance();
thisEventDate.setTime(format.parse(getStartTime()));
return (otherEventDate.get(Calendar.DAY_OF_MONTH) == thisEventDate.get(Calendar.DAY_OF_MONTH) &&
otherEventDate.get(Calendar.DAY_OF_YEAR) == thisEventDate.get(Calendar.DAY_OF_YEAR));
} catch(ParseException e) {
System.out.println(e.toString());
e.printStackTrace();
}
return false;
}
Here's the code as I did it, I'm just checking if the two events are occurring the same day. If you wish to add some more precision you'll just have to add this for yourself.
Related
I'm trying to count the days between two dates but I can't get a right result.
I did the same that someone described to me.
My result should be an int or long. For this example I would expext 11 but 10 is also fine.
That's the code:
String startDate = "2018-03-25";
String endDate = "2018-04-05";
Date startDate1 = stringToDate(startDate);
Date endDate1 = stringToDate(endDate);
long ab = daysBetween(startDate1, endDate1);
String ab1 = String.valueOf(ab);
And that's the methods:
public static long daysBetween(Date startDate, Date endDate) {
Calendar sDate = getDatePart(startDate);
Calendar eDate = getDatePart(endDate);
long daysBetween = 0;
while (sDate.before(eDate)) {
sDate.add(Calendar.DAY_OF_MONTH, 1);
daysBetween++;
}
return daysBetween;
}
public Date stringToDate(String stringDatum) {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
try {
Date date = format.parse(stringDatum);
return date;
}
catch (ParseException e) {
e.printStackTrace();
}
return null;
}
public static Calendar getDatePart(Date date){
Calendar cal = Calendar.getInstance(); // get calendar instance
cal.setTime(date);
cal.set(Calendar.HOUR_OF_DAY, 0); // set hour to midnight
cal.set(Calendar.MINUTE, 0); // set minute in hour
cal.set(Calendar.SECOND, 0); // set second in minute
cal.set(Calendar.MILLISECOND, 0); // set millisecond in second
return cal; // return the date part
}
java.util.Date, Calendar and SimpleDateFormat are part of a terrible API. They make the job of date/time handling harder than it already is.
Make yourself a favor and use a decent date/time library: https://github.com/JakeWharton/ThreeTenABP - here's a nice tutorial on how to use it - How to use ThreeTenABP in Android Project
With this API, it's so easy to do what you want:
LocalDate startDate = LocalDate.parse("2018-03-25");
LocalDate endDate = LocalDate.parse("2018-04-05");
long daysBetween = ChronoUnit.DAYS.between(startDate, endDate); // 11
I've chosen to use LocalDate based on your code: the inputs have only day, month and year, and you're setting the hour/minute/seconds to zero, so I understand that you don't care about the time of the day to calculate the difference - which makes LocalDate the best choice.
Date and Calendar represent a specific point in time, and Calendar also uses a timezone, so Daylight Saving changes might affect the results, depending on the device's default timezone. Using a LocalDate avoids this problem, because this class doesn't have a timezone.
But anyway, I've tested your code and also got 11 as result, so it's not clear what problems you're facing.
private static long daysBetween(Date date1, Date date2){
return (date2.getTime() - date1.getTime()) / (60*60*24*1000);
}
I want to do something like:
Date date = new Date(); // current date
date = date - 300; // substract 300 days from current date and I want to use this "date"
How to do it?
Java 8 and later
With Java 8's date time API change, Use LocalDate
LocalDate date = LocalDate.now().minusDays(300);
Similarly you can have
LocalDate date = someLocalDateInstance.minusDays(300);
Refer to https://stackoverflow.com/a/23885950/260990 for translation between java.util.Date <--> java.time.LocalDateTime
Date in = new Date();
LocalDateTime ldt = LocalDateTime.ofInstant(in.toInstant(), ZoneId.systemDefault());
Date out = Date.from(ldt.atZone(ZoneId.systemDefault()).toInstant());
Java 7 and earlier
Use Calendar's add() method
Calendar cal = Calendar.getInstance();
cal.setTime(dateInstance);
cal.add(Calendar.DATE, -30);
Date dateBefore30Days = cal.getTime();
#JigarJoshi it's the good answer, and of course also #Tim recommendation to use .joda-time.
I only want to add more possibilities to subtract days from a java.util.Date.
Apache-commons
One possibility is to use apache-commons-lang. You can do it using DateUtils as follows:
Date dateBefore30Days = DateUtils.addDays(new Date(),-30);
Of course add the commons-lang dependency to do only date subtract it's probably not a good options, however if you're already using commons-lang it's a good choice. There is also convenient methods to addYears,addMonths,addWeeks and so on, take a look at the api here.
Java 8
Another possibility is to take advantage of new LocalDate from Java 8 using minusDays(long days) method:
LocalDate dateBefore30Days = LocalDate.now(ZoneId.of("Europe/Paris")).minusDays(30);
Simply use this to get date before 300 days, replace 300 with your days:
Date date = new Date(); // Or where ever you get it from
Date daysAgo = new DateTime(date).minusDays(300).toDate();
Here,
DateTime is org.joda.time.DateTime;
Date is java.util.Date
Java 8 Time API:
Instant now = Instant.now(); //current date
Instant before = now.minus(Duration.ofDays(300));
Date dateBefore = Date.from(before);
As you can see HERE there is a lot of manipulation you can do. Here an example showing what you could do!
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Calendar cal = Calendar.getInstance();
//Add one day to current date.
cal.add(Calendar.DATE, 1);
System.out.println(dateFormat.format(cal.getTime()));
//Substract one day to current date.
cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
System.out.println(dateFormat.format(cal.getTime()));
/* Can be Calendar.DATE or
* Calendar.MONTH, Calendar.YEAR, Calendar.HOUR, Calendar.SECOND
*/
With Java 8 it's really simple now:
LocalDate date = LocalDate.now().minusDays(300);
A great guide to the new api can be found here.
In Java 8 you can do this:
Instant inst = Instant.parse("2018-12-30T19:34:50.63Z");
// subtract 10 Days to Instant
Instant value = inst.minus(Period.ofDays(10));
// print result
System.out.println("Instant after subtracting Days: " + value);
I have created a function to make the task easier.
For 7 days after dateString: dateCalculate(dateString,"yyyy-MM-dd",7);
To get 7 days upto dateString: dateCalculate(dateString,"yyyy-MM-dd",-7);
public static String dateCalculate(String dateString, String dateFormat, int days) {
Calendar cal = Calendar.getInstance();
SimpleDateFormat s = new SimpleDateFormat(dateFormat);
try {
cal.setTime(s.parse(dateString));
} catch (ParseException e) {
e.printStackTrace();
}
cal.add(Calendar.DATE, days);
return s.format(cal.getTime());
}
You may also be able to use the Duration class. E.g.
Date currentDate = new Date();
Date oneDayFromCurrentDate = new Date(currentDate.getTime() - Duration.ofDays(1).toMillis());
You can easily subtract with calendar with SimpleDateFormat
public static String subtractDate(String time,int subtractDay) throws ParseException {
Calendar cal = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm", Locale.ENGLISH);
cal.setTime(sdf.parse(time));
cal.add(Calendar.DATE,-subtractDay);
String wantedDate = sdf.format(cal.getTime());
Log.d("tag",wantedDate);
return wantedDate;
}
I'm facing some problems in comparing the current date and the date which is retrieved from Database.I just retrieved date from DataBase and Stored in a Date variable like this
String due_date_task = cursor.getString(cursor.getColumnIndex(dueDateOfTask));
SimpleDateFormat currentFormater = new SimpleDateFormat("dd/MM/yyyy");
Date date1 = currentFormater.parse(due_date_task);
Now,what i want is should check whether date which is retrieved from DataBase is Equivalent to CurrentDate or not.
Calendar currentDate = Calendar.getInstance();
Date date2 = currentDate.getTime();
if(date1.equals(date2))
System.out.println("Today Task");
i just want to check like this.Thanks in advance
For exact match including milliseconds, use getTime:
if(date.getTime() == date1.getTime()){
//do something
}
You can use this function:
private boolean compareDates(Calendar objCal1, Calendar objCal2) {
return ((objCal1.get(Calendar.YEAR) == objCal2.get(Calendar.YEAR))
&& (objCal1.get(Calendar.DAY_OF_YEAR) == objCal2.get(Calendar.DAY_OF_YEAR)));
}
creating the calendar objects:
Calendar objCal1 = new GregorianCalendar().setTime(date);
Calendar objCal2 = new GregorianCalendar().setTime(date1);
Try this way to get the current date,
Calendar calCurr = Calendar.getInstance();
Log.i("Time in mili of Current - Normal", ""+calCurr.getTimeInMillis()); // see what it gives? dont know why?
Date date = new Date();
calCurr.set(date.getYear()+1900, date.getMonth()+1, date.getDate(), date.getHours(), date.getMinutes(), date.getSeconds());// so added one month to it
Log.i("Time in mili of Current - after update", ""+calCurr.getTimeInMillis()); // now get correct
now create Calendar object for database value,
String due_date_task = cursor.getString(cursor.getColumnIndex(dueDateOfTask));
SimpleDateFormat currentFormater = new SimpleDateFormat("dd/MM/yyyy");
Date date = currentFormater.parse(due_date_task);
Calendar start = Calendar.getInstance();
start.set(date.getYear(), date.getMonth(), date.getDate(), date.getHours(), date.getMinutes(), date.getSeconds());
and now Compare both the Calendar objects
if(calCurr.equals(start))
I have a question related to conversion/formatting of date.
I have a date,say,workDate with a value, eg: 2011-11-27 00:00:00
From an input textbox, I receive a time value(as String) in the form "HH:mm:ss", eg: "06:00:00"
My task is to create a new Date,say,newWorkDate, having the same year,month,date as workDate,and time to be the textbox input value.
So in this case, newWorkDate should be equal to 2011-11-27 06:00:00.
Can you help me figure out how this can be achieved using Java?
Here is what I have so far:
SimpleDateFormat df = new SimpleDateFormat("HH:mm:ss");
//Text box input is converted to Date format -what will be the default year,month and date set here?
Date textBoxTime = df.parse(minorMandatoryShiftStartTimeStr);
Date workDate = getWorkDate();
int year = Integer.parseInt(DateHelper.getYYYYMMDD(workDate).substring(0, 4));
int month = Integer.parseInt(DateHelper.getYYYYMMDD(workDate).substring(4, 6));
int date = Integer.parseInt(DateHelper.getYYYYMMDD(workDate).substring(6, 8));
Date newWorkDate = DateHelper.createDate(year, month, day);
//not sure how to set the textBox time to this newWorkDate.
[UPDATE]: Thx for the help,guys!Here is the updated code based on all your suggestions..Hopefully this will work.:)
String[] split = textBoxTime.split(":");
int hour = 0;
if (!split[0].isEmpty)){
hour = Integer.parseInt(split[0]);}
int minute = 0;
if (!split[1].isEmpty()){
minute = Integer.parseInt(split[1]);}
int second = 0;
if (!split[2].isEmpty()){
second = Integer.parseInt(split[2]);}
Calendar cal=Calendar.getInstance();
cal.setTime(workDate);
cal.set(Calendar.HOUR, hour);
cal.set(Calendar.MINUTE, minute);
cal.set(Calendar.SECOND, second);
Date newWorkDate = cal.getTime();
A couple of hints:
Use a Calendar object to work with the dates. You can set the Calendar from a Date so the way you create the dates textBoxTime and workDate are fine.
Set the values of workDate from textBoxTime using the setXXX methods on Calendar class (make workDate a Calendar)
You can use SimpleDateFormat to format as well as parse. Use this to produce the desired output.
You should be able to do this with no string parsing and just a few lines of code.
Since you already have the work date, all you need to do is convert your timebox to seconds and add it to your date object.
Use Calendar for date Arithmetic.
Calendar cal=Calendar.getInstance();
cal.setTime(date);
cal.add(Calendar.HOUR, hour);
cal.add(Calendar.MINUTE, minute);
cal.add(Calendar.SECOND, second);
Date desiredDate = cal.getTime();
You may need the following code.
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class DateFormat {
public static void main(String[] args) {
try {
SimpleDateFormat simpleDateFormat1 = new SimpleDateFormat("yyyy-MM-dd");
Date workDate = simpleDateFormat1.parse("2011-11-27");
Calendar workCalendar= Calendar.getInstance();
workCalendar.setTime(workDate);
SimpleDateFormat simpleDateFormat2 = new SimpleDateFormat("HH:mm:ss");
Calendar time = Calendar.getInstance();
time.setTime(simpleDateFormat2.parse("06:00:00"));
workCalendar.set(Calendar.HOUR_OF_DAY, time.get(Calendar.HOUR_OF_DAY));
workCalendar.set(Calendar.MINUTE, time.get(Calendar.MINUTE));
workCalendar.set(Calendar.SECOND, time.get(Calendar.SECOND));
Date newWorkDate = workCalendar.getTime();
SimpleDateFormat simpleDateFormat3 = new SimpleDateFormat(
"yyyy-MM-dd hh:mm:ss");
System.out.println(simpleDateFormat3.format(newWorkDate));
} catch (NumberFormatException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
}
Hope this would help you.
I was trying with:
new Date("13:00")
All I care about is the time of day and that when compared new Date("12:00") is less than new Date("13:00"). Is there no library for that?
If you create two Dates and set only the hours and minutes (e.g. by parsing with a time format pattern or by setting fields in a Calendar) you can compare them.
java.util.Date provides before and after methods for date comparison. It also implements Comparable#compareTo, so you can test for before/equals/after in one invocation.
// get dates using format/parse
DateFormat format = new SimpleDateFormat("HH:mm");
Date date1 = format.parse("13:00");
Date date2 = format.parse("13:00");
// use Date comparison methods
boolean before = date1.before(date2);
System.err.println(before);
// use compareTo
int compare = date1.compareTo(date2);
System.err.println(compare);
// get dates using Calendar
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR, 12);
calendar.set(Calendar.MINUTE, 0);
date1 = calendar.getTime();
calendar.set(Calendar.HOUR, 13);
date2 = calendar.getTime();
If the times are in "HH:mm" format you can just compare the strings.
String time1 = "12:00";
String time2 = "13:00";
int compared = time1.compareTo(time2); // compared == -1
JodaTime is very popular in Java. Take a look at LocalTime.