Easy way to generate SimpleDateFormat

Question

I am having this string "Mon Nov 11 10:36:53 GMT+02:00 2019". What is the pattern when using SimpleDateFormat();? Is there some way I can test or generate it without multiple try and error?

As an aside consider throwing away the long outmoded and notoriously troublesome `SimpleDateFormat` and friends, and adding [ThreeTenABP](https://github.com/JakeWharton/ThreeTenABP) to your Android project in order to use `java.time`, the modern Java date and time API. It is so much nicer to work with. — Ole V.V., Nov 13 '19 at 19:49
Possible duplicate of [how to parse output of new Date().toString()](https://stackoverflow.com/questions/4713825/how-to-parse-output-of-new-date-tostring) — Ole V.V., Nov 13 '19 at 19:50

score 1 · Answer 1 · answered Nov 13 '19 at 09:05

1

Try using

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy", Locale.ENGLISH);

answered Nov 13 '19 at 09:05

Md. Asaduzzaman

14,963
2
34
46

score 1 · Answer 2 · answered Nov 13 '19 at 09:22

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

public class Test{
    public static void main(String[] args) {

        //Try This

        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("EEE MMM dd hh:mm:ss 'GMT' Z yyyy");

        System.out.println(simpleDateFormat.format(new Date()));
    }
}

score 1 · Accepted Answer · answered Nov 14 '19 at 19:03

java.time and ThreeTenABP

What is the pattern when using SimpleDateFormat();?

My suggestion is that you don’t use SimpleDateFormat. That class is notoriously troublesome and long outdated. On Android — and on your API level too — you can use java.time, the modern Java date and time API.

    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("EEE MMM dd HH:mm:ss zzz yyyy", Locale.ROOT);

    String stringWereHaving = "Mon Nov 11 10:36:53 GMT+02:00 2019";
    ZonedDateTime dateTime = ZonedDateTime.parse(stringWereHaving, formatter);
    System.out.println(dateTime);

Output is:

2019-11-11T10:36:53+02:00[Etc/GMT-2]

The only confusing thing here is that the sign used in the time zone name Etc/GMT-2 has been intentionally reversed compared to normal usage.

Only if you need an old-fashioned Date object for a legacy API not yet upgraded to java.time, convert like this:

    Instant i = dateTime.toInstant();
    Date oldfashionedDate = DateTimeUtils.toDate(i);
    System.out.println(oldfashionedDate);

Mon Nov 11 09:36:53 CET 2019

Output comes from my computer in Europe/Copenhagen time zone, so the hour of day is adjusted by 1 hour compared to your input at offset `02:00. We have got the same point in time as in the string.

Is there some way I can test or generate it without multiple try and error?

There’s always Java SimpleDateFormat Online Tester. I give you the link at the bottom. I don’t know of a similar service for DateTimeFormatter. Many of the patterns are the same, also the one I am using above, so it’s probably worthwhile trying.

Question: Doesn’t java.time require Android API level 26?

java.time works nicely on both older and newer Android devices. It just requires at least Java 6.

In Java 8 and later and on newer Android devices (from API level 26) the modern API comes built-in.
In non-Android Java 6 and 7 get the ThreeTen Backport, the backport of the modern classes (ThreeTen for JSR 310; see the links at the bottom).
On (older) Android use the Android edition of ThreeTen Backport. It’s called ThreeTenABP. And make sure you import the date and time classes from org.threeten.bp with subpackages.

Links

Oracle tutorial: Date Time explaining how to use java.time.
Java Specification Request (JSR) 310, where java.time was first described.
ThreeTen Backport project, the backport of java.time to Java 6 and 7 (ThreeTen for JSR-310).
ThreeTenABP, Android edition of ThreeTen Backport
Question: How to use ThreeTenABP in Android Project, with a very thorough explanation.
Java SimpleDateFormat Online Tester

score 0 · Answer 4 · answered Nov 13 '19 at 09:02

What do you mean " Is there some way I can test or generate it without multiple try and error?"

BTW, I'm using DateFormat dateFormat = new SimpleDateFormat(<put your desired pattern here via STRING>);

and get the current date:

 Date date = new Date();
 String result = dateFormat.format(date); // formatting the date and passing it on string.

sample code:

DateFormat dateFormat = new SimpleDateFormat("MMM. dd, yyyy EEE HH:mm:ss");
Date date = new Date();

result = dateFormat.format(date);

Output : Nov. 13, 2019 Wed 17:02:00

Easy way to generate SimpleDateFormat

4 Answers4

java.time and ThreeTenABP

Question: Doesn’t java.time require Android API level 26?

Links