Using Regex in String.matches in java to match a date format

Question

Validating the given date against the format dd/mm/yyyy.
Valid = 1
Not Valid = -1
Example1:
Input= 12/06/1987
output=1
Example2:
Input= 03/1/1987
output=-1

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class CheckDateFormat {
    public static void main(String[] args) {
        String s1="29/02/2006";
        getvalues(s1);
    }
    public static void getvalues(String s1) {
        if(s1.matches("[0-9]{2}[/][0-9]{2}[/][0-9]{4}"))
        {
            SimpleDateFormat sdf=new SimpleDateFormat("dd/MM/yyyy");
            sdf.setLenient(false);
            try {
                Date d1=sdf.parse(s1);
                System.out.println(1);
            } catch (ParseException e) {
                //e.printStackTrace();//Always going to catch block
                System.out.println(-1);
            }
        }
        else
            System.out.println(-1);
    }
}

The problem with the code is that it it always returns -1.
It always enters the catch block and gives a ParseException.
Is there any problem with the Regex?

you should do your homework by yourself. search for online regex testers and try it there — LiranBo
– LiranBo, Commented Oct 19, 2015 at 7:47
You're also confusing "returning" and "printing". You should also inform your teacher that Java has a boolean type, that should be used here instead of 1/-1. And it enter the catch block because there are only 28 days in february 2006. So the date 29/02/2006 is invalid. — JB Nizet
– JB Nizet, Commented Oct 19, 2015 at 7:49
Are you trying to validate date or just validate the format? If you are validating date strictly the exception you got was correct ,since 29/02/2006 is invalid. — Tom Sebastian
– Tom Sebastian, Commented Oct 19, 2015 at 8:36

anubhava · Accepted Answer · 2015-10-19 07:53:00Z

8

Problem is this line:

sdf.setLenient(false);

and this date:

String s1="29/02/2006";

As 2006 wasn't a leap year making your date invalid and with lenient set to false date parse call is failing and throwing ParseException.

Problem will be fixed if you comment out sdf.setLenient(false); line:

or use a valid date:

String s1="29/02/2008";

Since 2008 was a leap year making 29th Feb a valid date.

answered Oct 19, 2015 at 7:53

anubhava

790k67 gold badges603 silver badges671 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Ayan Over a year ago

Yes it did work. Problem was with leap year date. Got to learn through my mistake. Thank you

Ayan Over a year ago

Sorry friend I still don't have 15 reputation so can't vote. Will mark it as soon as i can. Thank you once again

anubhava Over a year ago

No you don't need 15 reps to accept an answer. Click on the link I provided in comment above to see how to accept an answer. You just need to click the tick mark on top-left of my answer and it will turn green. You will also get 2 points for that.

Jens · Accepted Answer · 2015-10-19 07:56:53Z

0

You do not need a regex. If you get a ParseException you can return -1 else you return 1:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class CheckDateFormat {
    public static void main(String[] args) {
        String s1="29/02/2006";
        System.out.println(getvalues(s1));
    }
    public static int getvalues(String s1) {
        SimpleDateFormat sdf=new SimpleDateFormat("dd/MM/yyyy");
        sdf.setLenient(false);
        try {
            Date d1=sdf.parse(s1);
            System.out.println(1);
        } catch (ParseException e) {
            return -1;
        }
        return 1;
    }
}

edited Oct 19, 2015 at 7:56

answered Oct 19, 2015 at 7:50

Jens

69.6k15 gold badges107 silver badges133 bronze badges

Comments

Dinesh Peiris · Accepted Answer · 2015-10-19 08:31:58Z

0

Exception is thrown due to following line. Comment it off.

sdf.setLenient(false);

answered Oct 19, 2015 at 8:31

Dinesh Peiris

561 bronze badge

Comments

Vogel612 · Accepted Answer · 2015-10-19 09:05:57Z

0

As the year 2006 was not leap year, using String s1="29/02/2006"; will throw a parse exception.

Try with other dates it will work fine.

edited Oct 19, 2015 at 9:05

Vogel612

5,6535 gold badges54 silver badges79 bronze badges

answered Oct 19, 2015 at 8:34

Gaurav

443 bronze badges

Collectives™ on Stack Overflow

Using Regex in String.matches in java to match a date format

4 Answers 4

3 Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

3 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related