Develop Reference

Date selector based on months in Java

I have code in Java for Selenium Webdriver TestNG. Is for comparing if the date on the website is same as today date.
Problem is that date on webpage dateOnWebpage for 11th April 2018 is in format
Today 4/11/2018
So I made selecter to compare date formats if months < 10 if(javaDateSelector < 10) than date to compare is in format M/dd/yyyy else is in format MM/dd/yyyy.
Is there better way to code it than I made it? Because I needed to parse date to string and than to int to compare it and code is quite long.
#Test(priority=3)
public void test3DateCheck() throws Exception
{
String dateOnWebpage = driver.findElement(By.xpath("//div[#id='homeCalendarSection']/div/div[2]/table/tbody/tr/td/div/ul/li")).getText();
System.out.println("Today Date on webpage is : " + dateOnWebpage);
//DateFormat dateFormat1 = new SimpleDateFormat("M/dd/yyyy");
DateFormat dateFormat1 = new SimpleDateFormat("MM");
Date date = new Date();
String javaDate1 = dateFormat1.format(date);
int javaDateSelector = Integer.parseInt(javaDate1);
if(javaDateSelector < 10)
{
DateFormat dateFormat2 = new SimpleDateFormat("M/dd/yyyy");
String javaDate2 = dateFormat2.format(date);
System.out.println("Today Date from Java is : " + javaDate2);
Assert.assertEquals(dateOnWebpage, "Today " + javaDate2);
}
else
{
DateFormat dateFormat3 = new SimpleDateFormat("MM/dd/yyyy");
String javaDate3 = dateFormat3.format(date);
System.out.println("Today Date from Java is : " + javaDate3);
Assert.assertEquals(dateOnWebpage, "Today " + javaDate3);
}
}

If you don’t care whether the date on the web page is written with leading zero for month and day of month or not and just want to test whether the date is correct:
DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("'Today' M/d/uuuu");
LocalDate today = LocalDate.now(ZoneId.of("Pacific/Norfolk"));
System.out.println("Today is " + today);
LocalDate observedDate = LocalDate.parse(dateOnWebpage, dateFormatter);
Assert.assertEquals(today, observedDate);
Rather than testing the string I am parsing the date and testing it. Even though the pattern has one M and one d in it, parsing two-digit months and two-digits day of month poses no problem.
If on the other hand you also want to test that the date on the web page is written without any leading zeroes, it’s best to test the string, like you already did:
DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("M/d/uuuu");
LocalDate today = LocalDate.now(ZoneId.of("Pacific/Norfolk"));
String todayString = today.format(dateFormatter);
System.out.println("Today is " + todayString);
Assert.assertEquals("Today " + todayString, dateOnWebpage);
Again, even though the pattern has one M and one d in it, two digits will be printed if the month or the day of month is greater than 9. What else could the format method do? If you require two-digit day of month always, put dd in the format pattern string.
In both snippets please fill in your desired time zone where I put Pacific/Norfolk since it is never the same date everywhere on the globe.
I am using and recommending java.time, the modern Java date and time API. DateFormat and SimpleDateFormat are not only long outdated, they are also notoriously troublesome. Date is just as outdated. I would avoid those classes completely. The modern API is generally so much nicer to work with.
Link: Oracle tutorial: Date Time explaining how to use java.time.

Reformatting a Date from DD-MMM-YYYY to YYYYDDMM or YYYYMMDD

I'm trying to use Java 8 to re-format today's date but I'm getting the following error:
java.time.format.DateTimeParseException: Text '09-OCT-2017' could not be parsed:
Unable to obtain LocalDate from TemporalAccessor:
{WeekBasedYear[WeekFields[SUNDAY,1]]=2017, MonthOfYear=10, DayOfYear=9},ISO of type java.time.format.Parsed
Code:
public static String formatDate(String inputDate, String inputDateFormat, String returnDateFormat){
try {
DateTimeFormatter inputFormatter = new DateTimeFormatterBuilder().parseCaseInsensitive().appendPattern(inputDateFormat).toFormatter(Locale.ENGLISH);
LocalDate localDate = LocalDate.parse(inputDate, inputFormatter);
DateTimeFormatter outputFormatter = DateTimeFormatter.ofPattern(returnDateFormat);
String formattedString = localDate.format(outputFormatter);
return formattedString;
} catch (DateTimeParseException dtpe) {
log.error("A DateTimeParseException exception occured parsing the inputDate : " + inputDate + " and converting it to a " + returnDateFormat + " format. Exception is : " + dtpe);
}
return null;
}
I previously tried using SimpleDateFormat, but the problem is my inputDateFormat format is always in uppercase DD-MMM-YYYY, which was giving me incorrect results, so I tried using parseCaseInsensitive() to ignore the case sensitivity.

In the comments you told that the input format is DD-MMM-YYYY. According to javadoc, uppercase DD is the day of year field, and YYYY is the week based year field (which might be different from the year field).
You need to change them to lowercase dd (day of month) and yyyy (year of era). The parseCaseInsensitive() only takes care of the text fields - in this case, the month name (numbers are not affected by the case sensitivity - just because the month is in uppercase, it doesn't mean that the numbers patterns should also be).
The rest of the code is correct. Example (changing the format to yyyyMMdd):
String inputDate = "09-OCT-2017";
DateTimeFormatter inputFormatter = new DateTimeFormatterBuilder()
.parseCaseInsensitive()
// use "dd" for day of month and "yyyy" for year
.appendPattern("dd-MMM-yyyy")
.toFormatter(Locale.ENGLISH);
LocalDate localDate = LocalDate.parse(inputDate, inputFormatter);
// use "dd" for day of month and "yyyy" for year
DateTimeFormatter outputFormatter = DateTimeFormatter.ofPattern("yyyyMMdd");
String formattedString = localDate.format(outputFormatter);
System.out.println(formattedString); // 20171009
The output of the code above is:
20171009
Regarding your other comment about not having control over the input pattern, one alternative is to manually replace the letters to their lowercase version:
String pattern = "DD-MMM-YYYY";
DateTimeFormatter inputFormatter = new DateTimeFormatterBuilder()
.parseCaseInsensitive()
// replace DD and YYYY with the lowercase versions
.appendPattern(pattern.replace("DD", "dd").replaceAll("YYYY", "yyyy"))
.toFormatter(Locale.ENGLISH);
// do the same for output format if needed
I don't think it needs a complex-replace-everything-in-one-step regex. Just calling the replace method multiple times can do the trick (unless you have really complex patterns that would require lots of different and complex calls to replace, but with only the cases you provided, that'll be enough).

I hope I got you right.
Formatting a String to LocalDate is acutally pretty simple. Your date format is that here right 09-Oct-2017?
Now you just need use the split command to divide that into a day, month and year:
String[] tempStr = inputDate.split("-");
int year = Integer.parseInt(tempStr[2]);
int month = Integer.parseInt(tempStr[1]);
int day = Integer.parseInt(tempStr[0]);
After that it´s pretty easy to get that to LocalDate:
LocalDate ld = LocalDate.of(year, month, day);
I hope that helps.

String date into Epoch time

I am little bit confused in dates. I am currently working on the weather app and everything works fine .. I just wanna handle this type of format into my own desirable format.
2017-09-10T18:35:00+05:00
I just wanna convert this date into Epoch Time and then I settle the date in my desire format ::
for J-SON
or i wanna convert this date into less figure i.e Sun , 9 september 9:23 Am etc.
http://dataservice.accuweather.com/currentconditions/v1/257072?apikey=JTgPZ8wN9VUy07GaOODeZfZ3sAM12irH&language=en-us&details=true

ThreeTenABP
The other answers are correct, but outdated before they were written. These days I recommend you use the modern Java date and time API known as JSR-310 or java.time. Your date-time string format is ISO 8601, which the modern classes “understand” as their default.
Can you use the modern API on Android yet? Most certainly! The JSR-310 classes have been backported to Android in the ThreeTenABP project. All the details are in this question: How to use ThreeTenABP in Android Project.
long epochTime = OffsetDateTime.parse("2017-09-10T18:35:00+05:00")
.toInstant()
.getEpochSecond();
The result is 1505050500.
Edit: Arvind Kumar Avinash correctly points out in a comment: You do not need to convert an OffsetDateTime to an Instant to get the epoch seconds. You can simply use OffsetDateTime#toEpochSecond.
Example of how to convert this into a human-readable date and time:
String formattedDateTime = Instant.ofEpochSecond(epochTime)
.atZone(ZoneId.of("Africa/Lusaka"))
.format(DateTimeFormatter.ofPattern("EEE, d MMMM h:mm a", Locale.ENGLISH));
This produces Sun, 10 September 3:35 PM. Please provide the correct region and city for the time zone ID you want. If you want to rely on the device’s time zone setting, use ZoneId.systemDefault(). See the documentation of DateTimeFormatter.ofPattern() for the letters you may use in the format pattern string, or use DateTimeFormatter.ofLocalizedDateTime() for one of your locale’s default formats.

Use a SimpleDateFormat instance to parse the string into a Date object:
DateFormat parser = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssX");
Date date = parser.parse("2017-09-10T18:35:00+05:00");
And then use another SimpleDateFormat to display it:
DateFormat format = new SimpleDateFormat("EEE, dd MMMMM h:mm a");
String formatted = format.format(date); // Sun, 10 September 1:35 PM

You can use SimpleDate formatter to parse you date as string into epoch
String input = "2017-09-10T18:35:00+05:00";
SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
try {
Date date = sf.parse(input);
long dateInEpochFormatInMilliSeconds = date.getTime();
//if you want this in seconds then
long dateInEpochFormatInSeconds = date.getTime()/1000L;
//if you want to show only date month and year then
SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
String date = sdf.format(dateInEpochFormatInMilliSeconds);
//This date String will contain the date in dd-MM-yyyy format
} catch (ParseException| ArithmeticException e) {
e.printStackTrace();
}

String time_at_which_weather_capture = "Time : ";
DateFormat dateFormat = new SimpleDateFormat("EEE,d M yyyy h:MM a");
long timeInMillieSec = 0 ;
try {
Date date = dateFormat.parse(readyToUpdate.getTime());
timeInMillieSec = date.getTime();
} catch (ParseException e) {
e.printStackTrace();
}
time.setText(time_at_which_weather_capture + String.valueOf(time_fetcher(timeInMillieSec)));
public String time_fetcher (long time_coming_to_its_original_form) {
Date date = new Date (time_coming_to_its_original_form);
SimpleDateFormat sdf = new SimpleDateFormat("EEE, d M yyyy h:MM a");
return sdf.format(date);
}

Fast way to parse a Long date into Month-Day-Year String

How do you parse a Long date like: 1366222239935 into a String of space-separated Month-Day-Year? Like into "Apr 18 2013"
Passing it on a java.util.Date and to a String will give a String of date which contains so many info that I don't need for rendering in my GWT application.
Need to do this style since I will be passing the result into 3 <span> elements; so actually the space-separated date will be split into parts:
Month
Day
Year

As gwt won't support SimpleDateFormat
instead use Gwt DateTimeFormat
DateTimeFormat f = DateTimeFormat.getFormat("dd-MMM-yyyy");
String datestring =f.format(dateGeneratedbyLong);
And make sure the DateTimeFormat import also which you can use both client and server side .
There is another class with same name but package is different which is client(restricts you to use on client side only )

try to use SimpleDataFormat check http://docs.oracle.com/javase/1.4.2/docs/api/java/text/SimpleDateFormat.html>
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd/MM/yy");
String dateAsString = simpleDateFormat.format(new Date());

You could convert it to a Date and then manually build your String like this.-
Date date = new Date(timeInMils);
String res = date.get(Calendar.MONTH) + " " +
date.get(Calendar.DAY_OF_MONTH) + " " +
date.get(Calendar.YEAR);

That Long number is simply the number of milliseconds since the JavaScript epoch (1/1/1970 at midnight, UTC time). So, instead of parsing it, use the constructor for the Date object:
var myDate = new Date(1366222239935);
alert(myDate);
That will show "Wed Apr 17 2013 11:10:39 GMT-0700 (Pacific Daylight Time)". I am in PST, but it will default to whatever timezone you have in your locale settings.
Inside a GWT app in Java, simply do:
Date date=new Date(1366222239935);
Then you can use SimpleDateFormat to render it as "dd/MM/yy".
See http://www.w3schools.com/jsref/jsref_obj_date.asp

Do like this
Date d = new Date();
d.setTime(1366222239935l);
System.out.println(d);
SimpleDateFormat sdf = new SimpleDateFormat("MMMM dd yyyy");
try {
System.out.println(sdf.format((d)));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

long diff = 1366222239935l;
Date date = new Date(diff);
SimpleDateFormat sdf = new SimpleDateFormat("dd-MMM-yyyy");
System.out.println(sdf.format(date));

Calendar date to yyyy-MM-dd format in java

How to convert calendar date to yyyy-MM-dd format.
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, 1);
Date date = cal.getTime();
SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
String date1 = format1.format(date);
Date inActiveDate = null;
try {
inActiveDate = format1.parse(date1);
} catch (ParseException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
This will produce inActiveDate = Wed Sep 26 00:00:00 IST 2012. But what I need is 2012-09-26. My purpose is to compare this date with another date in my database using Hibernate criteria. So I need the date object in yyyy-MM-dd format.

A Java Date is a container for the number of milliseconds since January 1, 1970, 00:00:00 GMT.
When you use something like System.out.println(date), Java uses Date.toString() to print the contents.
The only way to change it is to override Date and provide your own implementation of Date.toString(). Now before you fire up your IDE and try this, I wouldn't; it will only complicate matters. You are better off formatting the date to the format you want to use (or display).
Java 8+
LocalDateTime ldt = LocalDateTime.now().plusDays(1);
DateTimeFormatter formmat1 = DateTimeFormatter.ofPattern("yyyy-MM-dd", Locale.ENGLISH);
System.out.println(ldt);
// Output "2018-05-12T17:21:53.658"
String formatter = formmat1.format(ldt);
System.out.println(formatter);
// 2018-05-12
Prior to Java 8
You should be making use of the ThreeTen Backport
The following is maintained for historical purposes (as the original answer)
What you can do, is format the date.
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, 1);
SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
System.out.println(cal.getTime());
// Output "Wed Sep 26 14:23:28 EST 2012"
String formatted = format1.format(cal.getTime());
System.out.println(formatted);
// Output "2012-09-26"
System.out.println(format1.parse(formatted));
// Output "Wed Sep 26 00:00:00 EST 2012"
These are actually the same date, represented differently.

Your code is wrong. No point of parsing date and keep that as Date object.
You can format the calender date object when you want to display and keep that as a string.
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, 1);
Date date = cal.getTime();
SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
String inActiveDate = null;
try {
inActiveDate = format1.format(date);
System.out.println(inActiveDate );
} catch (ParseException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}

java.time
The answer by MadProgrammer is correct, especially the tip about Joda-Time. The successor to Joda-Time is now built into Java 8 as the new java.time package. Here's example code in Java 8.
When working with date-time (as opposed to local date), the time zone in critical. The day-of-month depends on the time zone. For example, the India time zone is +05:30 (five and a half hours ahead of UTC), while France is only one hour ahead. So a moment in a new day in India has one date while the same moment in France has “yesterday’s” date. Creating string output lacking any time zone or offset information is creating ambiguity. You asked for YYYY-MM-DD output so I provided, but I don't recommend it. Instead of ISO_LOCAL_DATE I would have used ISO_DATE to get this output: 2014-02-25+05:30
ZoneId zoneId = ZoneId.of( "Asia/Kolkata" );
ZonedDateTime zonedDateTime = ZonedDateTime.now( zoneId );
DateTimeFormatter formatterOutput = DateTimeFormatter.ISO_LOCAL_DATE; // Caution: The "LOCAL" part means we are losing time zone information, creating ambiguity.
String output = formatterOutput.format( zonedDateTime );
Dump to console…
System.out.println( "zonedDateTime: " + zonedDateTime );
System.out.println( "output: " + output );
When run…
zonedDateTime: 2014-02-25T14:22:20.919+05:30[Asia/Kolkata]
output: 2014-02-25
Joda-Time
Similar code using the Joda-Time library, the precursor to java.time.
DateTimeZone zone = new DateTimeZone( "Asia/Kolkata" );
DateTime dateTime = DateTime.now( zone );
DateTimeFormatter formatter = ISODateTimeFormat.date();
String output = formatter.print( dateTime );
ISO 8601
By the way, that format of your input string is a standard format, one of several handy date-time string formats defined by ISO 8601.
Both Joda-Time and java.time use ISO 8601 formats by default when parsing and generating string representations of various date-time values.

java.util.Date object can't represent date in custom format instead you've to use SimpleDateFormat.format method that returns string.
String myString=format1.format(date);

public static void main(String[] args) {
Calendar cal = Calendar.getInstance();
cal.set(year, month, date);
SimpleDateFormat format1 = new SimpleDateFormat("yyyy MM dd");
String formatted = format1.format(cal.getTime());
System.out.println(formatted);
}

In order to parse a java.util.Date object you have to convert it to String first using your own format.
inActiveDate = format1.parse( format1.format(date) );
But I believe you are being redundant here.

Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, 7);
Date date = c.getTime();
SimpleDateFormat ft = new SimpleDateFormat("MM-dd-YYYY");
JOptionPane.showMessageDialog(null, ft.format(date));
This will display your date + 7 days in month, day and year format in a JOption window pane.

public static String ThisWeekStartDate(WebDriver driver) {
Calendar c = Calendar.getInstance();
//ensure the method works within current month
c.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
System.out.println("Before Start Date " + c.getTime());
Date date = c.getTime();
SimpleDateFormat dfDate = new SimpleDateFormat("dd MMM yyyy hh.mm a");
String CurrentDate = dfDate.format(date);
System.out.println("Start Date " + CurrentDate);
return CurrentDate;
}
public static String ThisWeekEndDate(WebDriver driver) {
Calendar c = Calendar.getInstance();
//ensure the method works within current month
c.set(Calendar.DAY_OF_WEEK, Calendar.SATURDAY);
System.out.println("Before End Date " + c.getTime());
Date date = c.getTime();
SimpleDateFormat dfDate = new SimpleDateFormat("dd MMM yyyy hh.mm a");
String CurrentDate = dfDate.format(date);
System.out.println("End Date " + CurrentDate);
return CurrentDate;
}

I found this code where date is compared in a format to compare with date field in database...may be this might be helpful to you...
When you convert the string to date using simpledateformat, it is hard to compare with the Date field in mysql databases.
So convert the java string date in the format using select STR_to_DATE('yourdate','%m/%d/%Y') --> in this format, then you will get the exact date format of mysql date field.
http://javainfinite.com/java/java-convert-string-to-date-and-compare/

My answer is for kotlin language.
You can use SimpleDateFormat to achieve the result:
val date = Date(timeInSec)
val formattedDate = SimpleDateFormat("yyyy-MM-dd", Locale("IN")).format(date)
for details click here.
OR
Use Calendar to do it for you:
val dateObject = Date(timeInMillis)
val calendarInstance = Calendar.getInstance()
calendarInstance.time = dateObject
val date = "${calendarInstance.get(Calendar.YEAR)}-${calendarInstance.get(Calendar.MONTH)}-${calendarInstance.get(Calendar.DATE)}"
For more details check this answer.

I don't know about y'all, but I always want this stuff as a one-liner. The other answers are fine and dandy and work great, but here is it condensed to a single line. Now you can hold less lines of code in your mind :-).
Here is the one Liner:
String currentDate = new SimpleDateFormat("yyyy-MM-dd").format(new Date());