Unable to check valid date using SimpleParseDate.parse

Question

I am trying to check a date for validation. Below is my code. When I check for the date 12/12/2014XYZ, SimpleDateFormat.parse does not throw exception. With other invalid dates like 13/13/2014 it is throwing exception.

public class DateCheck{

    public static void main(String[] args) {
        SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
        sdf.setLenient(false);
        try {
            sdf.parse("12/31/2014XYZ");
            System.out.println("Valid Date");
        } catch (Exception e) {
            System.out.println("Invalid Date");

        }
    }
}

I googled a lot but could not find the proper solution.

Related question: http://stackoverflow.com/questions/3025942/is-this-a-java-dateformat-bug — aioobe, Sep 29 '14 at 09:43

score 3 · Accepted Answer · edited May 23 '17 at 10:26

Use a ParsePosition as follows:

try {
    String input = "12/31/2014XYZ";

    ParsePosition pp = new ParsePosition(0);
    sdf.parse(input, pp);

    // Make sure the entire string was parsed
    if (pp.getIndex() != input.length())
        throw new Exception();

    System.out.println("Valid Date");
} catch (Exception e) {
    System.out.println("Invalid Date");
}

Similar questions:

score 0 · Answer 2 · answered Sep 29 '14 at 09:35

0

This is as described in the Javadoc:

Parses text from the beginning of the given string to produce a date. The method may not use the entire text of the given string.

So your observation is the behaviour that is expected and described.

answered Sep 29 '14 at 09:35

Uwe Plonus

9,803
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score 0 · Answer 3 · answered Sep 29 '14 at 09:37

0

As you have told the date format "MM/dd/yyyy" so it will check only first four characters after "/"

if you write the date as "12/31/XYZ2014" it will throw an exception and invalid date will be printed.

answered Sep 29 '14 at 09:37

faisalbhagat

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24
27

Ruchira Gayan Ranaweera · Answer 4 · 2014-09-29T09:57:03.657

0

From Java doc.

Parses text from the beginning of the given string to produce a date. The method may not use the entire text of the given string.

So it will take 12/31/2014 only from 12/31/2014XYZ and take as valid format.

Eg:

SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
try {
    java.util.Date date=sdf.parse("12/31/2014AnyThing");
    System.out.println("Valid Date "+date);
   } catch (ParseException e) {
    System.out.println("Invalid Date");
   }
try {
    java.util.Date date=sdf.parse("AnyThing12/31/2014");
    System.out.println("Valid Date "+date);
   } catch (ParseException e) {
    System.out.println("Invalid Date");
  }

Out put:

  Valid Date Wed Dec 31 00:00:00 IST 2014
  Invalid Date

Same as here.

   SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
    try {
        java.util.Date date=sdf.parse("12/31/2014XYZ");
        System.out.println("Valid Date "+date);
    } catch (ParseException e) {
        System.out.println("Invalid Date");

    }

    try {
        java.util.Date date=sdf.parse("XYZ12/31/2014");
        System.out.println("Valid Date "+date);
    } catch (ParseException e) {
        System.out.println("Invalid Date");

    }

Out put:

   Valid Date Wed Dec 31 00:00:00 IST 2014
   Invalid Date

Edit:

@aioobe answer will provide the solution for not take this as valid date format.

edited Sep 29 '14 at 09:57

answered Sep 29 '14 at 09:37

Ruchira Gayan Ranaweera

34,993
17
75
115

But it doesn't work for the example provided by the OP: "12/31/2014XYZ" – aioobe Sep 29 '14 at 09:41
"12/31/2014XYZ" does't look like a valid date to me. – aioobe Sep 29 '14 at 09:44
@aioobe am I saying any different thing? – Ruchira Gayan Ranaweera Sep 29 '14 at 09:45
Yes: `Valid Date Wed Dec 31 00:00:00 IST 2014` – aioobe Sep 29 '14 at 09:46
@aioobe that's why i am saying `12/31/2014XYZ` considered as valid one since post `XYZ` is ignore as it clearly said in http://docs.oracle.com/javase/8/docs/api/java/text/DateFormat.html#parse-java.lang.String- – Ruchira Gayan Ranaweera Sep 29 '14 at 09:48
@aioobe Now you tell me what is the meaning of this `But it doesn't work for the example provided by the OP: "12/31/2014XYZ"` – Ruchira Gayan Ranaweera Sep 29 '14 at 09:48
The OP clearly stated that he does *not* want "12/31/2014XYZ" to be considered a valid date. Your answer is basically "It *is* a valid date, see the docs". – aioobe Sep 29 '14 at 09:49
@aioobe i said why it is happening. – Ruchira Gayan Ranaweera Sep 29 '14 at 09:50
...which of course is of very limited help to the OP :-) – aioobe Sep 29 '14 at 09:54
@aioobe seems to be you are master in this particular question since past. :) – Ruchira Gayan Ranaweera Sep 29 '14 at 09:55
@aioobe I keep this answer since I feel It should be. And updated my answer mentioning the solution is in your answer. and 1+ – Ruchira Gayan Ranaweera Sep 29 '14 at 09:58

Unable to check valid date using SimpleParseDate.parse

4 Answers4