Java Check the date format of current string is according to required format or not

Question

I wanted to know that is there any method available in Java that can do this Otherwise I may go for Regex solution  I have input string from user that can be any characters  And I want to check that the input string is according to my required date format or not    As I have input 20130925 and my required format is dd MM yyyy so  for this case I should get false   I don t want to convert this date I just want to check whether input string is according to required date format or not    I have tried following   Date date   null  try   date   new SimpleDateFormat  dd MM yyyy   parse  20130925      catch  Exception ex       do something for invalid dateformat     but my catch  Exception ex  block is unable to catch any exceptions generated by SimpleDateFormat Parse

User · Answer

You can try this to simple date format valdation   public Date validateDateFormat String dateToValdate         SimpleDateFormat formatter   new SimpleDateFormat  dd-MM-yyyy HHmmss          To make strict date format validation     formatter setLenient false       Date parsedDate   null      try           parsedDate   formatter parse dateToValdate           System out println    validated DATE TIME     formatter format parsedDate           catch  ParseException e              Handle exception           return parsedDate

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For example  if you want the date format to be  03 11 2017    if  String valueOf DateEdit getText    matches    1-9  1   0  1  1-9  1   1  1  0-9  1   2  1  0-9  1   3  1  0-1  1                       1                    0  1  1-9  1   1  1  0-2  1   1-9  1                       1                    20  2  0-9  2                 checkFormat true   else            checkFormat false    if   checkFormat     Toast makeText getApplicationContext     incorrect date format  Ex 23 06 2016   Toast LENGTH SHORT  show

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DateFormat formatter   new SimpleDateFormat  dd MM yyyy    formatter setLenient false   try       Date date  formatter parse  02 03 2010      catch  ParseException e          If input date is in different format or invalid      formatter setLenient false  will enforce strict matching   If you are using Joda-Time -   private boolean isValidDate String dateOfBirth            boolean valid   true          try               DateTimeFormatter formatter   DateTimeFormat forPattern  dd MM yyyy                DateTime dob   formatter parseDateTime dateOfBirth             catch  Exception e                valid   false                    return valid

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Regex can be used for this with some detailed info for validation  for example this code can be used to validate any date in  DD MM yyyy  format with proper date and month value and year between  1950-2050       public Boolean checkDateformat String dateToCheck              String rex    0  1  1-9  1   1-2  1  0-9  1   3  1  0-1  1                0  1  1-9  1   1  1  0-2  2                1  1  9  1  5-9  1  0-9  1   2  1  0  1   0-4  1            0-9  1   5  1  0  1               return dateToCheck matches rex

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For your case  you may use regex  boolean checkFormat   if  input matches  quot   0-9  2     0-9  2     0-9  4   quot        checkFormat true  else    checkFormat false   For a larger scope or if you want a flexible solution  refer to MadProgrammer s answer  Edit Almost 5 years after posting this answer  I realize that this is a stupid way to validate a date format  But i ll just leave this here to tell people that using regex to validate a date is unacceptable

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Disclaimer  Parsing a string back to date time value in an unknown format is inherently impossible  let s face it  what does 3 3 3 actually mean     all we can do is  best effort   Important  This solution doesn t throw an Exception  it returns a boolean  this is by design   Any Exceptions are used purely as a guard mechanism   2018  Since it s now 2018 and Java 8  has the date time API  and the rest have the ThreeTen backport   The solution remains basically the same  but becomes slightly more complicated  as we need to perform checks for    date and time date only time only   This makes it look something like     public static boolean isValidFormat String format  String value  Locale locale        LocalDateTime ldt   null      DateTimeFormatter fomatter   DateTimeFormatter ofPattern format  locale        try           ldt   LocalDateTime parse value  fomatter           String result   ldt format fomatter           return result equals value         catch  DateTimeParseException e            try               LocalDate ld   LocalDate parse value  fomatter               String result   ld format fomatter               return result equals value             catch  DateTimeParseException exp                try                   LocalTime lt   LocalTime parse value  fomatter                   String result   lt format fomatter                   return result equals value                 catch  DateTimeParseException e2                       Debugging purposes                   e2 printStackTrace                                       return false      This makes the following     System out println  isValid - dd MM yyyy with 20130925       isValidFormat  dd MM yyyy    20130925   Locale ENGLISH    System out println  isValid - dd MM yyyy with 25 09 2013       isValidFormat  dd MM yyyy    25 09 2013   Locale ENGLISH    System out println  isValid - dd MM yyyy with 25 09 2013 12 13 50       isValidFormat  dd MM yyyy    25 09 2013  12 13 50   Locale ENGLISH    System out println  isValid - yyyy-MM-dd with 2017-18--15       isValidFormat  yyyy-MM-dd    2017-18--15   Locale ENGLISH      output     isValid - dd MM yyyy with 20130925   false isValid - dd MM yyyy with 25 09 2013   true isValid - dd MM yyyy with 25 09 2013 12 13 50   false isValid - yyyy-MM-dd with 2017-18--15   false   Original Answer  Simple try and parse the String to the required Date using something like SimpleDateFormat  Date date   null  try       SimpleDateFormat sdf   new SimpleDateFormat format       date   sdf parse value       if   value equals sdf format date              date   null          catch  ParseException ex        ex printStackTrace      if  date    null           Invalid date format   else          Valid date format     You could then simply write a simple method that performed this action and returned true when ever Date was not null     As a suggestion     Updated with running example  I m not sure what you are doing  but  the following example     import java text ParseException  import java text SimpleDateFormat  import java util Date   public class TestDateParser        public static void main String   args            System out println  isValid - dd MM yyyy with 20130925       isValidFormat  dd MM yyyy    20130925             System out println  isValid - dd MM yyyy with 25 09 2013       isValidFormat  dd MM yyyy    25 09 2013             System out println  isValid - dd MM yyyy with 25 09 2013 12 13 50       isValidFormat  dd MM yyyy    25 09 2013  12 13 50                public static boolean isValidFormat String format  String value            Date date   null          try               SimpleDateFormat sdf   new SimpleDateFormat format               date   sdf parse value               if   value equals sdf format date                      date   null                          catch  ParseException ex                ex printStackTrace                      return date    null             Outputs  something like      java text ParseException  Unparseable date   20130925  isValid - dd MM yyyy with 20130925   false isValid - dd MM yyyy with 25 09 2013   true isValid - dd MM yyyy with 25 09 2013 12 13 50   false     at java text DateFormat parse DateFormat java 366      at javaapplication373 JavaApplication373 isValidFormat JavaApplication373 java 28      at javaapplication373 JavaApplication373 main JavaApplication373 java 19       Not correct  For isValidFormat  yyyy-MM-dd    2017-18--15    not throw any Exception     isValid - yyyy-MM-dd    2017-18--15   false   Seems to work as expected for me - the method doesn t rely on  nor does it throw  the exception alone to perform it s operation

User · Answer

A combination of the regex and SimpleDateFormat is the right answer i believe  SimpleDateFormat does not catch exception if the individual components are invalid meaning   Format Defined  yyyy-mm-dd input  201-0-12 No exception will be thrown This case should have been handled  But with the regex as suggested by Sok Pomaranczowy and Baby will take care of this particular case

User · Answer

Here s a simple method   public static boolean checkDatePattern String padrao  String data        try           SimpleDateFormat format   new SimpleDateFormat padrao  LocaleUtils DEFAULT LOCALE           format parse data           return true        catch  ParseException e            return false

[java] Java: Check the date format of current string is according to required format or not

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