[java] How to parse a date?

I am trying to parse this date with SimpleDateFormat and it is not working:

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

public class Formaterclass {
    public static void main(String[] args) throws ParseException{
        String strDate = "Thu Jun 18 20:56:02 EDT 2009";
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
        Date dateStr = formatter.parse(strDate);
        String formattedDate = formatter.format(dateStr);
        System.out.println("yyyy-MM-dd date is ==>"+formattedDate);
        Date date1 = formatter.parse(formattedDate);

        formatter = new SimpleDateFormat("dd-MMM-yyyy");
        formattedDate = formatter.format(date1);
        System.out.println("dd-MMM-yyyy date is ==>"+formattedDate);
    }
}

If I try this code with strDate="2008-10-14", I have a positive answer. What's the problem? How can I parse this format?

PS. I got this date from a jDatePicker and there is no instruction on how modify the date format I get when the user chooses a date.

The problem is that you have a date formatted like this:

Thu Jun 18 20:56:02 EDT 2009

But are using a SimpleDateFormat that is:

yyyy-MM-dd

The two formats don't agree. You need to construct a SimpleDateFormat that matches the layout of the string you're trying to parse into a Date. Lining things up to make it easy to see, you want a SimpleDateFormat like this:

EEE MMM dd HH:mm:ss zzz yyyy
Thu Jun 18 20:56:02 EDT 2009

Check the JavaDoc page I linked to and see how the characters are used.

In response to: "How to convert Tue Sep 13 2016 00:00:00 GMT-0500 (Hora de verano central (México)) to dd-MM-yy in Java?", it was marked how duplicate

Try this: With java.util.Date, java.text.SimpleDateFormat, it's a simple solution.

public static void main(String[] args) throws ParseException {

    String fecha = "Tue Sep 13 2016 00:00:00 GMT-0500 (Hora de verano central (México))";
    Date f = new Date(fecha);

    SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
    sdf.setTimeZone(TimeZone.getTimeZone("-5GMT"));
    fecha = sdf.format(f);
    System.out.println(fecha);
}

How about getSelectedDate? Anyway, specifically on your code question, the problem is with this line:

new SimpleDateFormat("yyyy-MM-dd");

The string that goes in the constructor has to match the format of the date. The documentation for how to do that is here. Looks like you need something close to "EEE MMM d HH:mm:ss zzz yyyy"

We now have a more modern way to do this work.

java.time

The java.time framework is bundled with Java 8 and later. See Tutorial. These new classes are inspired by Joda-Time, defined by JSR 310, and extended by the ThreeTen-Extra project. They are a vast improvement over the troublesome old classes, java.util.Date/.Calendar et al.

Note that the 3-4 letter codes like EDT are neither standardized nor unique. Avoid them whenever possible. Learn to use ISO 8601 standard formats instead. The java.time framework may take a stab at translating, but many of the commonly used codes have duplicate values.

By the way, note how java.time by default generates strings using the ISO 8601 formats but extended by appending the name of the time zone in brackets.

String input = "Thu Jun 18 20:56:02 EDT 2009";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern ( "EEE MMM d HH:mm:ss zzz yyyy" , Locale.ENGLISH );
ZonedDateTime zdt = formatter.parse ( input , ZonedDateTime :: from );

Dump to console.

System.out.println ( "zdt : " + zdt );

When run.

zdt : 2009-06-18T20:56:02-04:00[America/New_York]

Adjust Time Zone

For fun let's adjust to the India time zone.

ZonedDateTime zdtKolkata = zdt.withZoneSameInstant ( ZoneId.of ( "Asia/Kolkata" ) );

zdtKolkata : 2009-06-19T06:26:02+05:30[Asia/Kolkata]

Convert to j.u.Date

If you really need a java.util.Date object for use with classes not yet updated to the java.time types, convert. Note that you are losing the assigned time zone, but have the same moment automatically adjusted to UTC.

java.util.Date date = java.util.Date.from( zdt.toInstant() );