Changing String Date Format

How to convert a date string to different format

I assume I have import datetime before running each of the lines of code below

datetime.datetime.strptime("2013-1-25", '%Y-%m-%d').strftime('%m/%d/%y')

prints "01/25/13".

If you can't live with the leading zero, try this:

dt = datetime.datetime.strptime("2013-1-25", '%Y-%m-%d')
print '{0}/{1}/{2:02}'.format(dt.month, dt.day, dt.year % 100)

This prints "1/25/13".

EDIT: This may not work on every platform:

datetime.datetime.strptime("2013-1-25", '%Y-%m-%d').strftime('%m/%d/%y')

Convert String Date to String date different format

SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
SimpleDateFormat format2 = new SimpleDateFormat("dd-MM-yyyy");
Date date = format1.parse("2013-02-21");
System.out.println(format2.format(date));

Convert string to date then format the date

Use SimpleDateFormat#format(Date):

String start_dt = "2011-01-01";
DateFormat formatter = new SimpleDateFormat("yyyy-MM-DD"); 
Date date = (Date)formatter.parse(start_dt);
SimpleDateFormat newFormat = new SimpleDateFormat("MM-dd-yyyy");
String finalString = newFormat.format(date);

How to convert String to Date with a specific format in java

The class Date will always contain both date a nd time information, since it represents an instant in time.

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

public class ParsingDate {

    public static void main(String[] args) {  
            DateFormat fmt = new SimpleDateFormat("dd-MM-yyyy");
            Date d;
            try {
                d = fmt.parse("04-12-2019");
                System.out.println(d);  // Wed Dec 04 00:00:00 CET 2019
            } catch (ParseException e) {
                e.printStackTrace();
            }  
        }
}

As you can see, hours, minutes, seconds and millis get all set to 0.

If you later want to output the date in string format, you need to use the DateFormat#format(Date) method:

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

public class ParsingDate {

    public static void main(String[] args) {
        DateFormat fmt = new SimpleDateFormat("dd-MM-yyyy");
        Date d = new Date();
        System.out.println(d);  // Wed Dec 04 11:24:35 CET 2019
        System.out.println(fmt.format(d)); // 04-12-2019
    }
}

If you'd rather store only date information, you could use the java.time package and make use of LocalDate.

LocalDate stores only date information, since it does not represent an instant, rather a triple of year, month and date.

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class ParsingLocalDate {

    public static void main(String[] args) {
        DateTimeFormatter fmt = DateTimeFormatter.ofPattern("dd-MM-yyyy");
        LocalDate d = LocalDate.parse("04-12-2019", fmt);
        System.out.println(d);  // 2019-12-04
    }
}

Java string to date conversion

That's the hard way, and those java.util.Date setter methods have been deprecated since Java 1.1 (1997). Moreover, the whole java.util.Date class was de-facto deprecated (discommended) since introduction of java.time API in Java 8 (2014).

Simply format the date using DateTimeFormatter with a pattern matching the input string (the tutorial is available here).

In your specific case of "January 2, 2010" as the input string:

1. "January" is the full text month, so use the MMMM pattern for it
2. "2" is the short day-of-month, so use the d pattern for it.
3. "2010" is the 4-digit year, so use the yyyy pattern for it.

String string = "January 2, 2010";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMMM d, yyyy", Locale.ENGLISH);
LocalDate date = LocalDate.parse(string, formatter);
System.out.println(date); // 2010-01-02

Note: if your format pattern happens to contain the time part as well, then use LocalDateTime#parse(text, formatter) instead of LocalDate#parse(text, formatter). And, if your format pattern happens to contain the time zone as well, then use ZonedDateTime#parse(text, formatter) instead.

Here's an extract of relevance from the javadoc, listing all available format patterns:

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