Parsing different date formats in a string in Java

Question

I have a string which can possibly contain a date in any of the following formats:

2001-01-05 (yyyy-mm-dd)
2001/01/05 (yyyy/mm/dd)
01/05/2001 (dd/mm/yyyy)
01-05-2001 (dd-mm-yyyy)
2001 january 5
2001 5 january
january 5 2001
5 january 2001
january 5
5 january

I want to be able to parse the particular string and extract the Date object from it.

My approach was as follows:

String[] date_formats = {
                            "yyyy-MM-dd",
                            "yyyyy/MM/dd", 
                            "dd/MM/yyyyy",
                            "dd-MM-yyyy",
                            "yyyy MMM dd",
                            "yyyy dd MMM",
                            "dd MMM yyyy",
                            "dd MMM",
                            "MMM dd",
                            "dd MMM yyyy"};

String output_date = null;
for (String formatString : date_formats)
{
     try
     {    
         Date mydate = new SimpleDateFormat(formatString).parse(token);
         SimpleDateFormat outdate = new SimpleDateFormat("yyyyMMdd");
         output_date = outdate.format(mydate);
         break;
     }
     catch (ParseException e) {
         System.out.println("Next!");
     }
 }

This doesn't seem to work as expected. Especially for dates like 5 January 2001 etc. How do I go about doing this?

@Kayaman What is wrong with the patterns? docs.oracle.com/javase/7/docs/api/java/text/… — Alagappan Ramu
– Alagappan Ramu, Commented Oct 2, 2013 at 12:37
Always provide a locale to your date format when you want to parse date in a particular language. (new SimpleDateFormat("{format}", Locale.ENGLISH);) — Arnaud Denoyelle
– Arnaud Denoyelle, Commented Oct 2, 2013 at 12:46
@Kayaman It still doesn't work properly for dates like 5 January 2001. It satisfies the yyyy MMM dd pattern and the date I end up getting is 00100624 which is totally arbitrary. — Alagappan Ramu
– Alagappan Ramu, Commented Oct 2, 2013 at 12:57
This doesn't seem to work as expected. Do you get an exception or a date which does not seems good? An example would be appreciated. — Arnaud Denoyelle
– Arnaud Denoyelle, Commented Oct 2, 2013 at 13:03

Kayaman · Accepted Answer · 2013-10-02 12:58:58Z

6

Use SimpleDateFormat.setLenient(false). This way it will not attempt to parse dates that aren't the exact format it wants.

answered Oct 2, 2013 at 12:58

Kayaman

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5 Comments

Arnaud Denoyelle Over a year ago

Good to know but useless in this case. The OP is trying each format in a try/catch statement until the end of the try statement is met.

Kayaman Over a year ago

@ArnaudDenoyelle Useless? His problem was that in some cases the non-correct patterns were parsing the values, giving arbitrary values. A situation corrected by setting lenient to false.

Arnaud Denoyelle Over a year ago

IMHO, incorrect pattern will end in the catch statement and the next one will be tried.

Alagappan Ramu Over a year ago

@ArnaudDenoyelle This has helped me in avoiding false positives when I parse the dates.

Arnaud Denoyelle Over a year ago

OK, I had a confusion about the meaning of lenient. +1 for Kayaman.

JHS · Accepted Answer · 2013-10-02 12:46:14Z

1

You need to have all formats in the date_formats array for the type of format you anticipate would be coming in.

Have a look at the SimpleDateFormat javadocs.

Have a look at the examples in the javadocs.

2001-01-05      - yyyy-MM-dd 
2001/01/05      - yyyy/MM/dd
01/05/2001      - dd/MM/yyyy 
01-05-2001      - dd-MM-yyyy 
2001 january 5  - yyyy MMMMM d
2001 5 january  - yyyy d MMMMM
january 5 2001  - MMMMM d yyyy 
5 january 2001  - d MMMMM yyyy
january 5       - MMMMM d
5 january       - d MMMMM

edited Oct 2, 2013 at 12:46

answered Oct 2, 2013 at 12:40

JHS

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6 Comments

Alagappan Ramu Over a year ago

I did have a look the docs. Aren't the patterns that I mentioned correct?

JHS Over a year ago

Yes. Your formats are wrong. I have added the formats you need.

Alagappan Ramu Over a year ago

It still doesn't work properly for dates like 5 January 2001. It first satisfies the yyyy MMM dd pattern and the date I end up getting is 00100624 which is totally arbitrary.

Alagappan Ramu Over a year ago

Setting setLenient to false as suggested by Kayaman, helped in avoiding the above error.

JHS Over a year ago

But your list of "date_formats" should not have MMM. There is no date in your "possibility" list (example list) to match it.

|

Andrei Volgin · Accepted Answer · 2014-06-23 01:03:41Z

1

Instead of testing "yyyy-MM-dd", then "yyyy/MM/dd", then "yyyy.MM.dd" (used in many countries), etc., you can start by

token = token.replaceAll("-|\\.", "/");

This way all dots and dashes are replaced with "/", and you can reduce the number of formats and tries.

answered Jun 23, 2014 at 1:03

Andrei Volgin

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Comments

kai · Accepted Answer · 2013-10-02 12:52:33Z

Is this what you are looking for?

String[] date_formats = {
                        "y-M-d",
                        "y/M/d", 
                        "d/M/y",
                        "d-M-y",
                        "y M d",
                        "y d M",
                        "d M y",
                        "d M",
                        "M d",
                        "d M y"};

String output_date = null;
for (String formatString : date_formats)
{
     try
     {    
         SimpleDateFormat sf = new SimpleDateFormat(formatString);  
         output_date = "5 January 2001"; 
         Date yourDate = sf.parse(output_date);
         break;
     }
     catch (ParseException e) {
         System.out.println("Next!");
     }
 }

Mehmet Sedat Güngör · Accepted Answer · 2013-10-02 12:52:47Z

You can extract String of Date by using

String mydate = new SimpleDateFormat(formatString).format(new Date());

new Date() will return current day's date, you can change it to any date that you desire.

So if you change you code like this:

String[] date_formats = {
        "y-M-d",
        "y/M/d", 
        "d/M/y",
        "d-M-y",
        "y M d",
        "y d M",
        "d M y",
        "d M",
        "M d",
        "d M y"};

for (String formatString : date_formats)
    {
        String mydate = new SimpleDateFormat(formatString).format(new Date());
        System.out.println(mydate);
    }

You will end up with these:

serj · Accepted Answer · 2013-10-02 13:04:59Z

0

Add this date format "dd MMMMM YYYY" for "5 January 2001"

answered Oct 2, 2013 at 13:04

serj

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Comments

Anil M · Accepted Answer · 2014-01-31 05:03:59Z

0

SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
    String dateInString = formatter.format(date);

    LOG.warn("date in String "+dateInString);

make Sure that MM is in capital

answered Jan 31, 2014 at 5:03

Anil M

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Comments

Ben · Accepted Answer · 2016-05-10 10:56:09Z

Kayamans answer works, this is what it looks like in a code snippet so you can easily test it for yourself (direct copy paste from my own code):

static String[] date_formats = {
        "yyyy-MM-dd",
        "yyyy/MM/dd",
        "dd/MM/yyyy",
        "dd-MM-yyyy",
        "yyyy MMM dd",
        "yyyy dd MMM",
        "dd MMM yyyy",
        "dd MMM yyyy"};

static String[] dates = {
        "21/02/2012",
        "21-02-2012",
        "21-2-2012",
        "21 Feb 2012",
        "Feb 21 2012",//will not be parsed
        "21 februari 2012" //Dutch
};

@Test
public void test(){
    for(String date : dates) {
        parseDate(date);
        System.out.print("----------------");
    }
}

private void parseDate(String token){
    Locale dutch = new Locale("nl", "NL");
    for (String formatString : date_formats)
    {
        try
        {
            SimpleDateFormat format = new SimpleDateFormat(formatString, dutch);
            format.setLenient(false);
            Date mydate = format.parse(token);
            System.out.println(mydate.toString());
            break;
        }
        catch (ParseException e) {
            System.out.println("Next!");
        }
    }
}

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