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javadatedate-formatsimpledateformat
Rohan K
Rohan K

Reputation: 177

Custom String from ISO Compliant Date

I am getting a date string as 2014-01-11-T00:00:00Z I want to convert this date to 20140111 i.e YYYYMMDD it should be a string.

Any standard method/function to achieve above?

Upvotes: 1

Views: 1311

Answers (5)

Basil Bourque
Basil Bourque

Reputation: 338775

Update: This Answer is now obsolete. See the modern solution using java.time in the Answer by Avinash.

Joda-Time

This date-time work is much easier with the Joda-Time 2.3 library.

String input = "2014-01-11T00:00:00Z";  // In standard ISO 8601 format.
DateTime dateTime = new DateTime( input, DateTimeZone.UTC );  // Parse string into date-time object.
DateTimeFormatter formatter = ISODateTimeFormat.basicDate();  // Factory to make a formatter.
String output = formatter.print( dateTime );  // Generate string from date-Time object.

Upvotes: 0

Arvind Kumar Avinash
Arvind Kumar Avinash

Reputation: 79085

java.time

Your date-time string, 2014-01-11-T00:00:00Z is a bit weird as I have never seen such a date-time string where there is a hyphen (-) before T. For this kind of string, the following pattern meets the parsing requirement:

yyyy-M-d-'T'H:m:sXXX

Also, with java.time API, I recommend you replace y with u as explained in this answer. For the output string, you do NOT need to define any pattern as there already exists an inbuilt DateTimeFormatter for this pattern: DateTimeFormatter.BASIC_ISO_DATE.

Demo:

import java.time.OffsetDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class Main {
    public static void main(String args[]) {
        DateTimeFormatter dtfInput = DateTimeFormatter.ofPattern("u-M-d-'T'H:m:sXXX", Locale.ENGLISH);
        OffsetDateTime odt = OffsetDateTime.parse("2014-01-11-T00:00:00Z", dtfInput);
        System.out.println(odt);

        String output = odt.toLocalDate().format(DateTimeFormatter.BASIC_ISO_DATE);
        System.out.println(output);
    }
}

Output:

2014-01-11T00:00Z
20140111

Note:

  1. Had your date-time string been ISO 8601 compliant, you would NOT have needed to use a DateTimeFormatter object explicitly for parsing i.e. you could have simply parsed it as
    OffsetDateTime odt = OffsetDateTime.parse("2014-01-11T00:00:00Z");
  1. The Z in the date-time stands for Zulu which specifies UTC time (that has a timezone offset of +00:00 hours) in ISO 8601 standard. Thus, this solution will also work for a date-time string like 2014-01-11-T00:00:00+02:00 which has a timezone offset of +02:00 hours.
  2. In case, you need a java.util.Date object from this object of OffsetDateTime, you can do so as follows:
    Date date = Date.from(odt.toInstant());

Learn more about the the modern date-time API* from Trail: Date Time.

Note that the legacy date-time API (java.util date-time types and their formatting API, SimpleDateFormat) are outdated and error-prone. It is recommended to stop using them completely and switch to java.time API. Just for the sake of completeness, I am providing you with a solution using the legacy API.

Using the legacy API:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;

public class Main {
    public static void main(String args[]) throws ParseException {
        SimpleDateFormat sdfInput = new SimpleDateFormat("yyyy-M-d-'T'H:m:sXXX", Locale.ENGLISH);

        SimpleDateFormat sdfOutput = new SimpleDateFormat("yyyyMMdd", Locale.ENGLISH);
        sdfOutput.setTimeZone(TimeZone.getTimeZone("Etc/UTC"));// Change it as required

        Date date = sdfInput.parse("2014-01-11-T00:00:00Z");

        String output = sdfOutput.format(date);
        System.out.println(output);
    }
}

Output:

20140111

* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.

Upvotes: 1

Meno Hochschild
Meno Hochschild

Reputation: 44061

Here an improved version of given answer by @drkunibar:

SimpleDateFormat inFormat = new SimpleDateFormat("yyyy-MM-dd-'T'HH:mm:ss'Z'");
inFormat.setTimeZone(TimeZone.getTimeZone("GMT")); // Z denotes UTC in ISO-8601
Date inDate = inFormat.parse("2014-01-11-T00:00:00Z");

SimpleDateFormat outFormat = new SimpleDateFormat("yyyyMMdd");
outFormat.setTimeZone(TimeZone.getTimeZone("...")); // set your timezone explicitly!
String output = outFormat.format(inDate);

System.out.println("Date: " + output);

Note that the format YYYYMMDD is also ISO-8601-compliant (a so-called basic calendar date). The question you have to ask yourself is in which timezone you want to get your output. If in UTC you have to set "GMT", too. Without setting timezone it can happen that your output date differs from input UTC date by one day dependent where your default system timezone is (for example US is several hours behind UTC, in this case one calendar day before UTC midnight).

Upvotes: 0

Goufalite
Goufalite

Reputation: 2363

Take a look at this thread for Date formatting in Java using Zoulou notation :

Converting ISO 8601-compliant String to java.util.Date

Then create a new SimpleDateFormat using the "yyyyMMdd" format string.

Upvotes: 0

drkunibar
drkunibar

Reputation: 1337

Take this

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateFormat {

    public static void main(String[] args) throws ParseException {
        SimpleDateFormat inFormat = new SimpleDateFormat("yyyy-MM-dd-'T'HH:mm:ss'Z'");
        Date inDate = inFormat.parse("2014-01-11-T00:00:00Z");

        SimpleDateFormat outFormat = new SimpleDateFormat("yyyyMMdd");
        String output = outFormat.format(inDate);

        System.out.println("Date: " + output);

    }
}

Upvotes: 0

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