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to determine whether the any string is a datetime use java [duplicate]

I know this question is asked quite a bit, and obviously you can't parse any arbitrary date. However, I find that the python-dateutil library is able to parse every date I throw at it, all while requiring absolutely zero effort in figuring out a date format string. Joda time is always sold as being a great Java date parser, but it still requires you to decide what format your date is in before you pick a Format (or create your own). You can't just call DateFormatter.parse(mydate) and magically get a Date object back.
For example, the date "Wed Mar 04 05:09:06 GMT-06:00 2009" is properly parsed with python-dateutil:
import dateutil.parser
print dateutil.parser.parse('Wed Mar 04 05:09:06 GMT-06:00 2009')
but the following Joda time call doesn't work:
String date = "Wed Mar 04 05:09:06 GMT-06:00 2009";
DateTimeFormatter fmt = ISODateTimeFormat.dateTime();
DateTime dt = fmt.parseDateTime(date);
System.out.println(date);
And creating your own DateTimeFormatter defeats the purpose, since that seems to be the same as using SimpleDateFormatter with the correct format string.
Is there a comparable way to parse a date in Java, like python-dateutil? I don't care about errors, I just want it to mostly perfect.

Your best bet is really asking help to regex to match the date format pattern and/or to do brute forcing.
Several years ago I wrote a little silly DateUtil class which did the job. Here's an extract of relevance:
private static final Map<String, String> DATE_FORMAT_REGEXPS = new HashMap<String, String>() {{
put("^\\d{8}$", "yyyyMMdd");
put("^\\d{1,2}-\\d{1,2}-\\d{4}$", "dd-MM-yyyy");
put("^\\d{4}-\\d{1,2}-\\d{1,2}$", "yyyy-MM-dd");
put("^\\d{1,2}/\\d{1,2}/\\d{4}$", "MM/dd/yyyy");
put("^\\d{4}/\\d{1,2}/\\d{1,2}$", "yyyy/MM/dd");
put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}$", "dd MMM yyyy");
put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}$", "dd MMMM yyyy");
put("^\\d{12}$", "yyyyMMddHHmm");
put("^\\d{8}\\s\\d{4}$", "yyyyMMdd HHmm");
put("^\\d{1,2}-\\d{1,2}-\\d{4}\\s\\d{1,2}:\\d{2}$", "dd-MM-yyyy HH:mm");
put("^\\d{4}-\\d{1,2}-\\d{1,2}\\s\\d{1,2}:\\d{2}$", "yyyy-MM-dd HH:mm");
put("^\\d{1,2}/\\d{1,2}/\\d{4}\\s\\d{1,2}:\\d{2}$", "MM/dd/yyyy HH:mm");
put("^\\d{4}/\\d{1,2}/\\d{1,2}\\s\\d{1,2}:\\d{2}$", "yyyy/MM/dd HH:mm");
put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}\\s\\d{1,2}:\\d{2}$", "dd MMM yyyy HH:mm");
put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}\\s\\d{1,2}:\\d{2}$", "dd MMMM yyyy HH:mm");
put("^\\d{14}$", "yyyyMMddHHmmss");
put("^\\d{8}\\s\\d{6}$", "yyyyMMdd HHmmss");
put("^\\d{1,2}-\\d{1,2}-\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd-MM-yyyy HH:mm:ss");
put("^\\d{4}-\\d{1,2}-\\d{1,2}\\s\\d{1,2}:\\d{2}:\\d{2}$", "yyyy-MM-dd HH:mm:ss");
put("^\\d{1,2}/\\d{1,2}/\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "MM/dd/yyyy HH:mm:ss");
put("^\\d{4}/\\d{1,2}/\\d{1,2}\\s\\d{1,2}:\\d{2}:\\d{2}$", "yyyy/MM/dd HH:mm:ss");
put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd MMM yyyy HH:mm:ss");
put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd MMMM yyyy HH:mm:ss");
}};
/**
* Determine SimpleDateFormat pattern matching with the given date string. Returns null if
* format is unknown. You can simply extend DateUtil with more formats if needed.
* #param dateString The date string to determine the SimpleDateFormat pattern for.
* #return The matching SimpleDateFormat pattern, or null if format is unknown.
* #see SimpleDateFormat
*/
public static String determineDateFormat(String dateString) {
for (String regexp : DATE_FORMAT_REGEXPS.keySet()) {
if (dateString.toLowerCase().matches(regexp)) {
return DATE_FORMAT_REGEXPS.get(regexp);
}
}
return null; // Unknown format.
}
(cough, double brace initialization, cough, it was just to get it all to fit in 100 char max length ;) )
You can easily expand it yourself with new regex and dateformat patterns.

There is a nice library called Natty which I think fits your purposes:
Natty is a natural language date parser written in Java. Given a date
expression, natty will apply standard language recognition and translation
techniques to produce a list of corresponding dates with optional parse and
syntax information.
You can also try it online!

You could try dateparser.
It can recognize any String automatically, and parse it into Date, Calendar, LocalDateTime, OffsetDateTime correctly and quickly(1us~1.5us).
It doesn't based on any natural language analyzer or SimpleDateFormat or regex.Pattern.
With it, you don't have to prepare any appropriate patterns like yyyy-MM-dd'T'HH:mm:ss.SSSZ or yyyy-MM-dd'T'HH:mm:ss.SSSZZ:
Date date = DateParserUtils.parseDate("2015-04-29T10:15:00.500+0000");
Calendar calendar = DateParserUtils.parseCalendar("2015-04-29T10:15:00.500Z");
LocalDateTime dateTime = DateParserUtils.parseDateTime("2015-04-29 10:15:00.500 +00:00");
All works fine, please enjoy it.

What I have seen done is a Date util class that contains several typical date formats. So, when DateUtil.parse(date) is called, it tries to parse the date with each date format internally and only throws exceptions if none of the internal formats can parse it.
It is basically a brute force approach to your problem.

//download library: org.ocpsoft.prettytime.nlp.PrettyTimeParser
String str = "2020.03.03";
Date date = new PrettyTimeParser().parseSyntax(str).get(0).getDates().get(0);
System.out.println(date)

I have no idea about this parsing how to do in python. In java we can do like this
SimpleDateFormat sdf1 = new SimpleDateFormat("dd-MM-yyyy");
java.util.Date normalDate = null;
java.sql.Date sqlDate = null;
normalDate = sdf1.parse(date);
sqlDate = new java.sql.Date(normalDate.getTime());
System.out.println(sqlDate);
i think like java some predefined functions will be there in python. You can follow this method.
This methods parse the String date to Sql Date (dd-MM-yyyy);
import java.text.SimpleDateFormat;
import java.text.ParseException;
public class HelloWorld{
public static void main(String []args){
String date ="26-12-2019";
SimpleDateFormat sdf1 = new SimpleDateFormat("dd-MM-yyyy");
java.util.Date normalDate = null;
java.sql.Date sqlDate = null;
if( !date.isEmpty()) {
try {
normalDate = sdf1.parse(date);
sqlDate = new java.sql.Date(normalDate.getTime());
System.out.println(sqlDate);
} catch (ParseException e) {
}
}
}
}
execute this!

Convert UTC into Local Time on Android

In my project, I have get the API response in json format. I get a string value of time in UTC time format like this Jul 16, 2013 12:08:59 AM.
I need to change this into Local time.
That is where ever we use this the app needs to show the local time. How to I do this?
Here is some Code I have tried:
String aDate = getValue("dateTime", aEventJson);
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("MMM dd, yyyy HH:mm:ss z");
simpleDateFormat.setTimeZone(TimeZone.getDefault());
String formattedDate = simpleDateFormat.format(aDate);
Assume aDate contains Jul 16, 2013 12:08:59 AM

Here's my attempt:
String dateStr = "Jul 16, 2013 12:08:59 AM";
SimpleDateFormat df = new SimpleDateFormat("MMM dd, yyyy HH:mm:ss a", Locale.ENGLISH);
df.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date = df.parse(dateStr);
df.setTimeZone(TimeZone.getDefault());
String formattedDate = df.format(date);
Also notice the "a" for the am/pm marker...

I should like to contribute the modern answer. While SimpleDateFormat was the class we had for parsing and formatting date-times in 2013 (apart from Joda-Time), it is now long outdated, and we have so much better in java.time or JSR-310, the modern Java date and time API that came out with Java 8 in 2014.
But most Android devices still don’t run Java 8, I hear you say. Fortunately you can still use the modern Java date and time API on them through the ThreeTenABP, the backport of JSR-310 to Android Java 7. Details are in this question: How to use ThreeTenABP in Android Project.
Now the code is:
DateTimeFormatter formatter
= DateTimeFormatter.ofPattern("MMM dd, uuuu hh:mm:ss a", Locale.ENGLISH);
String aDate = "Jul 16, 2013 12:08:59 AM";
String formattedDate = LocalDateTime.parse(aDate, formatter)
.atOffset(ZoneOffset.UTC)
.atZoneSameInstant(ZoneId.systemDefault())
.format(formatter);
System.out.println(formattedDate);
Since my computer is running Europe/Copenhagen time zone, which in July is 2 hours ahead of UTC, this prints
Jul 16, 2013 02:08:59 AM
Further points:
Since you have AM in your string, I assumed your hours are within AM, from 1 through 12. To parse and format them correctly you need lowercase h in the format pattern string. Uppercase H is for hour-of-day from 0 through 23.
Prefer to give an explcit locale to the formatter (whether SimpleDateFormat or DateTimeFormatter). If no locale is given, the formatter will use the device’s default locale. “Jul” and “AM” are in English, and your code may run nicely on many devices until one day it runs on a device with non-English locale and crashes, and you have a hard time figuring out why.
If you can, give the desired time zone explictly, for example as ZoneId.of("Asia/Kolkata"). The JVM’s default time zone may be changed by other parts of your program or other programs running in the same JVM, so is not reliable.

1.Local to UTC Converter
public static String localToUTC(String dateFormat, String datesToConvert) {
String dateToReturn = datesToConvert;
SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
sdf.setTimeZone(TimeZone.getDefault());
Date gmt = null;
SimpleDateFormat sdfOutPutToSend = new SimpleDateFormat(dateFormat);
sdfOutPutToSend.setTimeZone(TimeZone.getTimeZone("UTC"));
try {
gmt = sdf.parse(datesToConvert);
dateToReturn = sdfOutPutToSend.format(gmt);
} catch (ParseException e) {
e.printStackTrace();
}
return dateToReturn;
}
2. UTC to Local Converter
public static String uTCToLocal(String dateFormatInPut, String dateFomratOutPut, String datesToConvert) {
String dateToReturn = datesToConvert;
SimpleDateFormat sdf = new SimpleDateFormat(dateFormatInPut);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
Date gmt = null;
SimpleDateFormat sdfOutPutToSend = new SimpleDateFormat(dateFomratOutPut);
sdfOutPutToSend.setTimeZone(TimeZone.getDefault());
try {
gmt = sdf.parse(datesToConvert);
dateToReturn = sdfOutPutToSend.format(gmt);
} catch (ParseException e) {
e.printStackTrace();
}
return dateToReturn; }

//your UTC time var
long time = UTCtime;
//convert it
Time timeFormat = new Time();
timeFormat.set(time+TimeZone.getDefault().getOffset(time));
//use the value
long localTime = timeFormat.toMillis(true);

Use the following code.
TimeZone defaultTimeZone = TimeZone.getDefault();
String strDefaultTimeZone = defaultTimeZone.getDisplayName(false, TimeZone.SHORT);
//The code you use
String aDate = getValue("dateTime", aEventJson);
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("MMM dd, yyyy HH:mm:ss z");
simpleDateFormat.setTimeZone(TimeZone.getTimeZone(strDefaultTimeZone));
String formattedDate = simpleDateFormat.format(aDate);
This should work.

This is how i do it on android Build.VERSION.SDK_INT < 26
int offset = TimeZone.getDefault().getRawOffset();
String str_date='20:30 12-01-2021';
DateFormat formatter = new SimpleDateFormat("HH:mm dd-MM-yyy",Locale.US);
Date date = formatter.parse(str_date);
long utcTime = date.getTime() + (3600000*3);
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm dd/MM/yyyy", Locale.US);
String dateStr = sdf.format(utcTime + offset);
System.out.println(dateStr);
As my server sends the time with -3 timezone i have to add (3600*3) to getTime and i save it into utcTime, this way utcTime is in UTC. And then i add to utcTime the offset of the phone current timezone.
In my case as my timezone is -3 its prints:
20:30 12/01/2021
But if i change my time zone the date also changes.

Use this code:
public static String stringDateWithTimezone(Date date, String pattern, TimeZone timeZone) {
try {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern, Locale.US);
if (timeZone != null) {
simpleDateFormat.setTimeZone(timeZone);
}
return simpleDateFormat.format(date);
} catch (Exception e) {
Timber.e(e);
return null;
}
}
call in another class:
String dateUtc = DateUtil.stringDateWithTimezone(new Date(), "yyyy-MM-dd hh:mm:ss", TimeZone.getTimeZone("UTC"));

Parse a date with the timezone "Etc/GMT"

My first attempt was:
DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
Date date = formatter.parse(string);
It throws ParseException, so I found this hack:
DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
TimeZone timeZone = TimeZone.getTimeZone("Etc/GMT");
formatter.setTimeZone(timeZone);
Date date = formatter.parse(string);
It did not work either, and now I'm stuck. It parses without problems if I just change the timezone to "GMT".
edit: An example string to parse would be "2011-11-29 10:40:24 Etc/GMT"
edit2: I would prefer not to remove timezone information completely. I am coding a server that receives the date from an external user, so perhaps other dates will have other timezones.
To be more precise: This specific date I receive is from the receipt from the apple server after making an in app purchase on an iphone app, but I could also receive dates from other sources.

Don't know if this question is still relevant to you, but if you use Joda time, this'll work:
DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss ZZZ").parseDateTime(s)
Without Joda time the following will work (bit more work though):
String s = "2011-11-29 10:40:24 Etc/GMT";
// split the input in a date and a timezone part
int lastSpaceIndex = s.lastIndexOf(' ');
String dateString = s.substring(0, lastSpaceIndex);
String timeZoneString = s.substring(lastSpaceIndex + 1);
// convert the timezone to an actual TimeZone object
// and feed that to the formatter
TimeZone zone = TimeZone.getTimeZone(timeZoneString);
DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
formatter.setTimeZone(zone);
// parse the timezoneless part
Date date = formatter.parse(dateString);

It didn't work for me either the thing is I tried setting TimeZone of SimpleDateFormatter to "Etc/GMT" and then formatted a new date here is the output:
2011-11-30 10:46:32 GMT+00:00
So Etc/GMT is being translated as GMT+00:00
If you really want to stick to parse "2011-09-02 10:26:35 Etc/GMT" then following will help too without even considering explicit Timezone change:
java.text.SimpleDateFormat isoFormat = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss 'Etc/GMT'");
isoFormat.parse("2010-05-23 09:01:02 Etc/GMT");
Works fine.

Following code is working for me
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
sdf.setTimeZone(TimeZone.getTimeZone("Etc/GMT"));
try { System.out.println( sdf.parse("2011-09-02 10:26:35 Etc/GMT") );
} catch (ParseException e){
e.printStackTrace();
}

Java ParseException while attempting String to Date parsing

I'm having a hard time Parsing/Formatting a Date string received back from a web service. I've attempted multiple approaches, but with no luck.
Sample Date String:
2011-10-05T03:00:00Z
Exception:
W/System.err(10072): java.text.ParseException: Unparseable date: "2011-10-05T05:00:00Z" (at offset 10)
W/System.err(10072): at java.text.DateFormat.parse(DateFormat.java:626)
Sample Code:
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:SSSS");
Date date = formatter.parse(info.AiringTime);
I've found that if I remove the "T" between the date and the time and replace it with a space, it will format just fine. Anybody have any suggestions?
--UPDATE--
After looking deeper into the API documentation, I found this:
All response DateTime values are in UTC format. You need to apply the UTC offset to calculate the local time for display.
DateTime is a date-and-time value specified in one of the following formats:
UTC format: YYYY-MM-DDThh:mm:ssZ. For example: 2011-03-15T02:00:00Z.
Local time with an offset: YYYY-MM-DDThh:mm:ss + or - hh:mm (positive or negative offset). For example, for US Pacific time: 2011-03-14T06:00:00 -08:00.
Any suggestions on the UTC format approach?

You could try:
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
String dateString = dateString.replace("Z", "GMT+00:00");
Date date = dateFormat.parse(dateString);
The above code should correctly handle the case where a timezone is specified in the date. As Z represents the UTC/GMT timezone it is replaced by GMT so the SimpleDateFormat can interpret it correctly (i would love to know a cleaner way of handling this bit if anyone knows one).

Try,
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");

This pattern should parse the date you provide: "yyyy-MM-dd'T'HH:mm:ss'Z'".
If you want to use SimpleDateFormat and you have a limited number of variations, you can create separate formatters for each pattern and chain them:
Date date = formatter1.parse(info.AiringTime);
if (date == null)
{
date = formatter2.parse(info.AiringTime);
if (date == null)
{
date = formatter2.parse(info.AiringTime);
if (date == null)
{
date = formatter3.parse(info.AiringTime);
}
}
}
or put them in a list and iterate until non-null or no more formatters.
If you have too many patterns for this to be practical, you can parse it yourself or try one of these libraries.

This worked for me
SimpleDateFormat isoDateFormat = new SimpleDateFormat("yyyy-mm-dd'T'hh:mm:ss'Z'");
SimpleDateFormat viewFriendlyDateFormat = new SimpleDateFormat("dd/MMM/yyyy hh:mm:ss aaa");
String viewFriendlyDate = "";
try {
Date date = isoDateFormat.parse(timestamp);
viewFriendlyDate = viewFriendlyDateFormat.format(date);
} catch (ParseException e) {
e.printStackTrace();
}

SimpleDateFormat isoDateFormat = new SimpleDateFormat("yyyy-mm-dd'T'hh:mm:ss'Z'");
SimpleDateFormat viewFriendlyDateFormat = new SimpleDateFormat("dd/MMM/yyyy hh:mm:ss aaa");
String viewFriendlyDate = "";
try {
Date date = isoDateFormat.parse(timestamp);
viewFriendlyDate = viewFriendlyDateFormat.format(date);
} catch (ParseException e) {
e.printStackTrace();
}

Parse any date in Java

I know this question is asked quite a bit, and obviously you can't parse any arbitrary date. However, I find that the python-dateutil library is able to parse every date I throw at it, all while requiring absolutely zero effort in figuring out a date format string. Joda time is always sold as being a great Java date parser, but it still requires you to decide what format your date is in before you pick a Format (or create your own). You can't just call DateFormatter.parse(mydate) and magically get a Date object back.
For example, the date "Wed Mar 04 05:09:06 GMT-06:00 2009" is properly parsed with python-dateutil:
import dateutil.parser
print dateutil.parser.parse('Wed Mar 04 05:09:06 GMT-06:00 2009')
but the following Joda time call doesn't work:
String date = "Wed Mar 04 05:09:06 GMT-06:00 2009";
DateTimeFormatter fmt = ISODateTimeFormat.dateTime();
DateTime dt = fmt.parseDateTime(date);
System.out.println(date);
And creating your own DateTimeFormatter defeats the purpose, since that seems to be the same as using SimpleDateFormatter with the correct format string.
Is there a comparable way to parse a date in Java, like python-dateutil? I don't care about errors, I just want it to mostly perfect.

Your best bet is really asking help to regex to match the date format pattern and/or to do brute forcing.
Several years ago I wrote a little silly DateUtil class which did the job. Here's an extract of relevance:
private static final Map<String, String> DATE_FORMAT_REGEXPS = new HashMap<String, String>() {{
put("^\\d{8}$", "yyyyMMdd");
put("^\\d{1,2}-\\d{1,2}-\\d{4}$", "dd-MM-yyyy");
put("^\\d{4}-\\d{1,2}-\\d{1,2}$", "yyyy-MM-dd");
put("^\\d{1,2}/\\d{1,2}/\\d{4}$", "MM/dd/yyyy");
put("^\\d{4}/\\d{1,2}/\\d{1,2}$", "yyyy/MM/dd");
put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}$", "dd MMM yyyy");
put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}$", "dd MMMM yyyy");
put("^\\d{12}$", "yyyyMMddHHmm");
put("^\\d{8}\\s\\d{4}$", "yyyyMMdd HHmm");
put("^\\d{1,2}-\\d{1,2}-\\d{4}\\s\\d{1,2}:\\d{2}$", "dd-MM-yyyy HH:mm");
put("^\\d{4}-\\d{1,2}-\\d{1,2}\\s\\d{1,2}:\\d{2}$", "yyyy-MM-dd HH:mm");
put("^\\d{1,2}/\\d{1,2}/\\d{4}\\s\\d{1,2}:\\d{2}$", "MM/dd/yyyy HH:mm");
put("^\\d{4}/\\d{1,2}/\\d{1,2}\\s\\d{1,2}:\\d{2}$", "yyyy/MM/dd HH:mm");
put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}\\s\\d{1,2}:\\d{2}$", "dd MMM yyyy HH:mm");
put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}\\s\\d{1,2}:\\d{2}$", "dd MMMM yyyy HH:mm");
put("^\\d{14}$", "yyyyMMddHHmmss");
put("^\\d{8}\\s\\d{6}$", "yyyyMMdd HHmmss");
put("^\\d{1,2}-\\d{1,2}-\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd-MM-yyyy HH:mm:ss");
put("^\\d{4}-\\d{1,2}-\\d{1,2}\\s\\d{1,2}:\\d{2}:\\d{2}$", "yyyy-MM-dd HH:mm:ss");
put("^\\d{1,2}/\\d{1,2}/\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "MM/dd/yyyy HH:mm:ss");
put("^\\d{4}/\\d{1,2}/\\d{1,2}\\s\\d{1,2}:\\d{2}:\\d{2}$", "yyyy/MM/dd HH:mm:ss");
put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd MMM yyyy HH:mm:ss");
put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd MMMM yyyy HH:mm:ss");
}};
/**
* Determine SimpleDateFormat pattern matching with the given date string. Returns null if
* format is unknown. You can simply extend DateUtil with more formats if needed.
* #param dateString The date string to determine the SimpleDateFormat pattern for.
* #return The matching SimpleDateFormat pattern, or null if format is unknown.
* #see SimpleDateFormat
*/
public static String determineDateFormat(String dateString) {
for (String regexp : DATE_FORMAT_REGEXPS.keySet()) {
if (dateString.toLowerCase().matches(regexp)) {
return DATE_FORMAT_REGEXPS.get(regexp);
}
}
return null; // Unknown format.
}
(cough, double brace initialization, cough, it was just to get it all to fit in 100 char max length ;) )
You can easily expand it yourself with new regex and dateformat patterns.

There is a nice library called Natty which I think fits your purposes:
Natty is a natural language date parser written in Java. Given a date
expression, natty will apply standard language recognition and translation
techniques to produce a list of corresponding dates with optional parse and
syntax information.
You can also try it online!

You could try dateparser.
It can recognize any String automatically, and parse it into Date, Calendar, LocalDateTime, OffsetDateTime correctly and quickly(1us~1.5us).
It doesn't based on any natural language analyzer or SimpleDateFormat or regex.Pattern.
With it, you don't have to prepare any appropriate patterns like yyyy-MM-dd'T'HH:mm:ss.SSSZ or yyyy-MM-dd'T'HH:mm:ss.SSSZZ:
Date date = DateParserUtils.parseDate("2015-04-29T10:15:00.500+0000");
Calendar calendar = DateParserUtils.parseCalendar("2015-04-29T10:15:00.500Z");
LocalDateTime dateTime = DateParserUtils.parseDateTime("2015-04-29 10:15:00.500 +00:00");
All works fine, please enjoy it.

What I have seen done is a Date util class that contains several typical date formats. So, when DateUtil.parse(date) is called, it tries to parse the date with each date format internally and only throws exceptions if none of the internal formats can parse it.
It is basically a brute force approach to your problem.

//download library: org.ocpsoft.prettytime.nlp.PrettyTimeParser
String str = "2020.03.03";
Date date = new PrettyTimeParser().parseSyntax(str).get(0).getDates().get(0);
System.out.println(date)

I have no idea about this parsing how to do in python. In java we can do like this
SimpleDateFormat sdf1 = new SimpleDateFormat("dd-MM-yyyy");
java.util.Date normalDate = null;
java.sql.Date sqlDate = null;
normalDate = sdf1.parse(date);
sqlDate = new java.sql.Date(normalDate.getTime());
System.out.println(sqlDate);
i think like java some predefined functions will be there in python. You can follow this method.
This methods parse the String date to Sql Date (dd-MM-yyyy);
import java.text.SimpleDateFormat;
import java.text.ParseException;
public class HelloWorld{
public static void main(String []args){
String date ="26-12-2019";
SimpleDateFormat sdf1 = new SimpleDateFormat("dd-MM-yyyy");
java.util.Date normalDate = null;
java.sql.Date sqlDate = null;
if( !date.isEmpty()) {
try {
normalDate = sdf1.parse(date);
sqlDate = new java.sql.Date(normalDate.getTime());
System.out.println(sqlDate);
} catch (ParseException e) {
}
}
}
}
execute this!