Validazione formato data regex su Java

Question

Mi chiedo solo se esiste un modo (forse con espressioni regolari) per verificare che un input su un'app desktop Java sia esattamente una stringa formata come: "AAAA-MM-GG".

Ho cercato ma senza successo.

Grazie

Answer 1

Usare la seguente espressione regolare:

^\d{4}-\d{2}-\d{2}$ 

come in

if (str.matches("\\d{4}-\\d{2}-\\d{2}")) { 
    ... 
} 

Con il metodo matches, le ancore ^ e $ (inizio e fine della stringa, rispettivamente,) sono implicitamente presenti.

Answer 2

È necessario più di un regex, ad esempio "9999-99-00" non è una data valida. C'è una classe creata per fare ciò. Più pesante, ma più completo.

ad es.

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); 

boolean isValidDate(string input) { 
    try { 
      format.parse(input); 
      return true; 
    } 
    catch(ParseException e){ 
      return false; 
    } 
} 

Sfortunatamente, SimpleDateFormat è sia pesante e non thread-safe.

Answer 3

Costruire una SimpleDateFormat con la maschera, e quindi chiamare: SimpleDateFormat.parse (String s, ParsePosition p)

Answer 4

Per un controllo preciso, Consideriamo un InputVerifier utilizzando il SimpleDateFormat("YYYY-MM-dd") suggerito da Steve B.

Answer 5

Mettendo tutto insieme:

• REGEX non convalida i valori (come "2010-19-19")
• SimpleDateFormat non controlla formato ("2010/01/02", "1-0002-003" sono accettate)

è necessario utilizzare sia per convalidare il formato e valore:

public static boolean isValid(String text) { 
    if (text == null || !text.matches("\\d{4}-[01]\\d-[0-3]\\d")) 
     return false; 
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); 
    df.setLenient(false); 
    try { 
     df.parse(text); 
     return true; 
    } catch (ParseException ex) { 
     return false; 
    } 
} 

---

Un ThreadLocal può essere utilizzato per evitare la creazione di un nuovo SimpleDateFormat per ogni chiamata.
E 'necessario in un contesto multithread in quanto il SimpleDateFormat non è thread-safe:

private static final ThreadLocal<SimpleDateFormat> format = new ThreadLocal<SimpleDateFormat>() { 
    @Override 
    protected SimpleDateFormat initialValue() { 
     SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); 
     df.setLenient(false); 
     System.out.println("created"); 
     return df; 
    } 
}; 

public static boolean isValid(String text) { 
    if (text == null || !text.matches("\\d{4}-[01]\\d-[0-3]\\d")) 
     return false; 
    try { 
     format.get().parse(text); 
     return true; 
    } catch (ParseException ex) { 
     return false; 
    } 
} 

(stesso può essere fatto per un Matcher, che, inoltre, non è thread-safe)

Answer 6

Questo lo farà RegEx: "^((19|20)\\d\\d)-(0?[1-9]|1[012])-(0?[1-9]|[12][0-9]|3[01])$" Questo si occuperà dei formati validi e delle date valide. Non convaliderà i giorni corretti del mese, cioè l'anno bisestile.

String regex = "^((19|20)\\d\\d)-(0?[1-9]|1[012])-(0?[1-9]|[12][0-9]|3[01])$"; 

Assert.assertTrue("Date: matched.", Pattern.matches(regex, "2011-1-1")); 
Assert.assertFalse("Date (month): not matched.", Pattern.matches(regex, "2011-13-1")); 

Buona fortuna!

Answer 7

vorrei andare con una semplice espressione regolare che controllerà che i giorni non ha più di 31 giorni e mesi non più di 12. Qualcosa di simile:

(0?[1-9]|[12][0-9]|3[01])-(0?[1-9]|1[012])-((18|19|20|21)\\d\\d) 

Questo è il formato "dd-MM- yyyy". È possibile adattarlo alle proprie esigenze (ad esempio, togliere il? Per rendere obbligatorio lo 0 iniziale - ora è facoltativo), quindi utilizzare una logica personalizzata per ridurre le regole specifiche, ad esempio anni bisestili del numero di giorni di febbraio e altro mesi numero di casi giorni. Vedi il codice DateChecker qui sotto.

Scelgo questo approccio poiché ho verificato che questo è il migliore quando si tiene conto delle prestazioni. Ho verificato questo (primo) approccio rispetto al secondo approccio di validazione di una data contro una regex che si prende cura degli altri casi d'uso, e il terzo approccio di usare la stessa semplice espressione regolare sopra in combinazione con SimpleDateFormat.parse (date).
Il primo approccio è stato 4 volte più veloce rispetto al secondo approccio, e 8 volte più veloce rispetto al terzo approccio. Vedere il controllo della data autonomo e la classe principale del tester delle prestazioni nella parte inferiore. Una cosa che ho lasciato deselezionato è l'approccio (i) del tempo di joda. (La più efficiente libreria data/ora).

codice per il controllo:

class DateChecker { 

    private Matcher matcher; 
    private Pattern pattern; 

    public DateChecker(String regex) { 
     pattern = Pattern.compile(regex); 
    } 

    /** 
    * Checks if the date format is a valid. 
    * Uses the regex pattern to match the date first. 
    * Than additionally checks are performed on the boundaries of the days taken the month into account (leap years are covered). 
    * 
    * @param date the date that needs to be checked. 
    * @return if the date is of an valid format or not. 
    */ 
    public boolean check(final String date) { 
     matcher = pattern.matcher(date); 
     if (matcher.matches()) { 
      matcher.reset(); 
      if (matcher.find()) { 
       int day = Integer.parseInt(matcher.group(1)); 
       int month = Integer.parseInt(matcher.group(2)); 
       int year = Integer.parseInt(matcher.group(3)); 

       switch (month) { 
       case 1: 
       case 3: 
       case 5: 
       case 7: 
       case 8: 
       case 10: 
       case 12: return day < 32; 
       case 4: 
       case 6: 
       case 9: 
       case 11: return day < 31; 
       case 2: 
        int modulo100 = year % 100; 
        //http://science.howstuffworks.com/science-vs-myth/everyday-myths/question50.htm 
        if ((modulo100 == 0 && year % 400 == 0) || (modulo100 != 0 && year % LEAP_STEP == 0)) { 
         //its a leap year 
         return day < 30; 
        } else { 
         return day < 29; 
        } 
       default: 
        break; 
       } 
      } 
     } 
     return false; 
    } 

    public String getRegex() { 
     return pattern.pattern(); 
    } 
} 

Data controllo/test e le prestazioni di prova:

import java.text.ParseException; 
import java.text.SimpleDateFormat; 
import java.util.ArrayList; 
import java.util.List; 
import java.util.regex.Matcher; 
import java.util.regex.Pattern; 

public class Tester { 

    private static final String[] validDateStrings = new String[]{ 
     "1-1-2000", //leading 0s for day and month optional 
     "01-1-2000", //leading 0 for month only optional 
     "1-01-2000", //leading 0 for day only optional 
     "01-01-1800", //first accepted date 
     "31-12-2199", //last accepted date 
     "31-01-2000", //January has 31 days 
     "31-03-2000", //March has 31 days 
     "31-05-2000", //May has 31 days 
     "31-07-2000", //July has 31 days 
     "31-08-2000", //August has 31 days 
     "31-10-2000", //October has 31 days 
     "31-12-2000", //December has 31 days 
     "30-04-2000", //April has 30 days 
     "30-06-2000", //June has 30 days 
     "30-09-2000", //September has 30 days 
     "30-11-2000", //November has 30 days 
    }; 
    private static final String[] invalidDateStrings = new String[]{ 
     "00-01-2000", //there is no 0-th day 
     "01-00-2000", //there is no 0-th month 
     "31-12-1799", //out of lower boundary date 
     "01-01-2200", //out of high boundary date 
     "32-01-2000", //January doesn't have 32 days 
     "32-03-2000", //March doesn't have 32 days 
     "32-05-2000", //May doesn't have 32 days 
     "32-07-2000", //July doesn't have 32 days 
     "32-08-2000", //August doesn't have 32 days 
     "32-10-2000", //October doesn't have 32 days 
     "32-12-2000", //December doesn't have 32 days 
     "31-04-2000", //April doesn't have 31 days 
     "31-06-2000", //June doesn't have 31 days 
     "31-09-2000", //September doesn't have 31 days 
     "31-11-2000", //November doesn't have 31 days 
     "001-02-2000", //SimpleDateFormat valid date (day with leading 0s) even with lenient set to false 
     "1-0002-2000", //SimpleDateFormat valid date (month with leading 0s) even with lenient set to false 
     "01-02-0003", //SimpleDateFormat valid date (year with leading 0s) even with lenient set to false 
     "01.01-2000", //. invalid separator between day and month 
     "01-01.2000", //. invalid separator between month and year 
     "01/01-2000", /// invalid separator between day and month 
     "01-01/2000", /// invalid separator between month and year 
     "01_01-2000", //_ invalid separator between day and month 
     "01-01_2000", //_ invalid separator between month and year 
     "01-01-2000-12345", //only whole string should be matched 
     "01-13-2000", //month bigger than 13 
    }; 

    /** 
    * These constants will be used to generate the valid and invalid boundary dates for the leap years. (For no leap year, Feb. 28 valid and Feb. 29 invalid; for a leap year Feb. 29 valid and Feb. 30 invalid) 
    */ 
    private static final int LEAP_STEP = 4; 
    private static final int YEAR_START = 1800; 
    private static final int YEAR_END = 2199; 

    /** 
    * This date regex will find matches for valid dates between 1800 and 2199 in the format of "dd-MM-yyyy". 
    * The leading 0 is optional. 
    */ 
    private static final String DATE_REGEX = "((0?[1-9]|[12][0-9]|3[01])-(0?[13578]|1[02])-(18|19|20|21)[0-9]{2})|((0?[1-9]|[12][0-9]|30)-(0?[469]|11)-(18|19|20|21)[0-9]{2})|((0?[1-9]|1[0-9]|2[0-8])-(0?2)-(18|19|20|21)[0-9]{2})|(29-(0?2)-(((18|19|20|21)(04|08|[2468][048]|[13579][26]))|2000))"; 

    /** 
    * This date regex is similar to the first one, but with the difference of matching only the whole string. So "01-01-2000-12345" won't pass with a match. 
    * Keep in mind that String.matches tries to match only the whole string. 
    */ 
    private static final String DATE_REGEX_ONLY_WHOLE_STRING = "^" + DATE_REGEX + "$"; 

    /** 
    * The simple regex (without checking for 31 day months and leap years): 
    */ 
    private static final String DATE_REGEX_SIMPLE = "(0?[1-9]|[12][0-9]|3[01])-(0?[1-9]|1[012])-((18|19|20|21)\\d\\d)"; 

    /** 
    * This date regex is similar to the first one, but with the difference of matching only the whole string. So "01-01-2000-12345" won't pass with a match. 
    */ 
    private static final String DATE_REGEX_SIMPLE_ONLY_WHOLE_STRING = "^" + DATE_REGEX_SIMPLE + "$"; 

    private static final SimpleDateFormat SDF = new SimpleDateFormat("dd-MM-yyyy"); 
    static { 
     SDF.setLenient(false); 
    } 

    private static final DateChecker dateValidatorSimple = new DateChecker(DATE_REGEX_SIMPLE); 
    private static final DateChecker dateValidatorSimpleOnlyWholeString = new DateChecker(DATE_REGEX_SIMPLE_ONLY_WHOLE_STRING); 

    /** 
    * @param args 
    */ 
    public static void main(String[] args) { 
     DateTimeStatistics dateTimeStatistics = new DateTimeStatistics(); 
     boolean shouldMatch = true; 
     for (int i = 0; i < validDateStrings.length; i++) { 
      String validDate = validDateStrings[i]; 
      matchAssertAndPopulateTimes(
        dateTimeStatistics, 
        shouldMatch, validDate); 
     } 

     shouldMatch = false; 
     for (int i = 0; i < invalidDateStrings.length; i++) { 
      String invalidDate = invalidDateStrings[i]; 

      matchAssertAndPopulateTimes(dateTimeStatistics, 
        shouldMatch, invalidDate); 
     } 

     for (int year = YEAR_START; year < (YEAR_END + 1); year++) { 
      FebruaryBoundaryDates februaryBoundaryDates = createValidAndInvalidFebruaryBoundaryDateStringsFromYear(year); 
      shouldMatch = true; 
      matchAssertAndPopulateTimes(dateTimeStatistics, 
        shouldMatch, februaryBoundaryDates.getValidFebruaryBoundaryDateString()); 
      shouldMatch = false; 
      matchAssertAndPopulateTimes(dateTimeStatistics, 
        shouldMatch, februaryBoundaryDates.getInvalidFebruaryBoundaryDateString()); 
     } 

     dateTimeStatistics.calculateAvarageTimesAndPrint(); 
    } 

    private static void matchAssertAndPopulateTimes(
      DateTimeStatistics dateTimeStatistics, 
      boolean shouldMatch, String date) { 
     dateTimeStatistics.addDate(date); 
     matchAndPopulateTimeToMatch(date, DATE_REGEX, shouldMatch, dateTimeStatistics.getTimesTakenWithDateRegex()); 
     matchAndPopulateTimeToMatch(date, DATE_REGEX_ONLY_WHOLE_STRING, shouldMatch, dateTimeStatistics.getTimesTakenWithDateRegexOnlyWholeString()); 
     boolean matchesSimpleDateFormat = matchWithSimpleDateFormatAndPopulateTimeToMatchAndReturnMatches(date, dateTimeStatistics.getTimesTakenWithSimpleDateFormatParse()); 
     matchAndPopulateTimeToMatchAndReturnMatchesAndCheck(
       dateTimeStatistics.getTimesTakenWithDateRegexSimple(), shouldMatch, 
       date, matchesSimpleDateFormat, DATE_REGEX_SIMPLE); 
     matchAndPopulateTimeToMatchAndReturnMatchesAndCheck(
       dateTimeStatistics.getTimesTakenWithDateRegexSimpleOnlyWholeString(), shouldMatch, 
       date, matchesSimpleDateFormat, DATE_REGEX_SIMPLE_ONLY_WHOLE_STRING); 

     matchAndPopulateTimeToMatch(date, dateValidatorSimple, shouldMatch, dateTimeStatistics.getTimesTakenWithdateValidatorSimple()); 
     matchAndPopulateTimeToMatch(date, dateValidatorSimpleOnlyWholeString, shouldMatch, dateTimeStatistics.getTimesTakenWithdateValidatorSimpleOnlyWholeString()); 
    } 

    private static void matchAndPopulateTimeToMatchAndReturnMatchesAndCheck(
      List<Long> times, 
      boolean shouldMatch, String date, boolean matchesSimpleDateFormat, String regex) { 
     boolean matchesFromRegex = matchAndPopulateTimeToMatchAndReturnMatches(date, regex, times); 
     assert !((matchesSimpleDateFormat && matchesFromRegex)^shouldMatch) : "Parsing with SimpleDateFormat and date:" + date + "\nregex:" + regex + "\nshouldMatch:" + shouldMatch; 
    } 

    private static void matchAndPopulateTimeToMatch(String date, String regex, boolean shouldMatch, List<Long> times) { 
     boolean matches = matchAndPopulateTimeToMatchAndReturnMatches(date, regex, times); 
     assert !(matches^shouldMatch) : "date:" + date + "\nregex:" + regex + "\nshouldMatch:" + shouldMatch; 
    } 

    private static void matchAndPopulateTimeToMatch(String date, DateChecker dateValidator, boolean shouldMatch, List<Long> times) { 
     long timestampStart; 
     long timestampEnd; 
     boolean matches; 
     timestampStart = System.nanoTime(); 
     matches = dateValidator.check(date); 
     timestampEnd = System.nanoTime(); 
     times.add(timestampEnd - timestampStart); 
     assert !(matches^shouldMatch) : "date:" + date + "\ndateValidator with regex:" + dateValidator.getRegex() + "\nshouldMatch:" + shouldMatch; 
    } 

    private static boolean matchAndPopulateTimeToMatchAndReturnMatches(String date, String regex, List<Long> times) { 
     long timestampStart; 
     long timestampEnd; 
     boolean matches; 
     timestampStart = System.nanoTime(); 
     matches = date.matches(regex); 
     timestampEnd = System.nanoTime(); 
     times.add(timestampEnd - timestampStart); 
     return matches; 
    } 

    private static boolean matchWithSimpleDateFormatAndPopulateTimeToMatchAndReturnMatches(String date, List<Long> times) { 
     long timestampStart; 
     long timestampEnd; 
     boolean matches = true; 
     timestampStart = System.nanoTime(); 
     try { 
      SDF.parse(date); 
     } catch (ParseException e) { 
      matches = false; 
     } finally { 
      timestampEnd = System.nanoTime(); 
      times.add(timestampEnd - timestampStart); 
     } 
     return matches; 
    } 

    private static FebruaryBoundaryDates createValidAndInvalidFebruaryBoundaryDateStringsFromYear(int year) { 
     FebruaryBoundaryDates februaryBoundaryDates; 
     int modulo100 = year % 100; 
     //http://science.howstuffworks.com/science-vs-myth/everyday-myths/question50.htm 
     if ((modulo100 == 0 && year % 400 == 0) || (modulo100 != 0 && year % LEAP_STEP == 0)) { 
      februaryBoundaryDates = new FebruaryBoundaryDates(
        createFebruaryDateFromDayAndYear(29, year), 
        createFebruaryDateFromDayAndYear(30, year) 
        ); 
     } else { 
      februaryBoundaryDates = new FebruaryBoundaryDates(
        createFebruaryDateFromDayAndYear(28, year), 
        createFebruaryDateFromDayAndYear(29, year) 
        ); 
     } 
     return februaryBoundaryDates; 
    } 

    private static String createFebruaryDateFromDayAndYear(int day, int year) { 
     return String.format("%d-02-%d", day, year); 
    } 

    static class FebruaryBoundaryDates { 
     private String validFebruaryBoundaryDateString; 
     String invalidFebruaryBoundaryDateString; 
     public FebruaryBoundaryDates(String validFebruaryBoundaryDateString, 
       String invalidFebruaryBoundaryDateString) { 
      super(); 
      this.validFebruaryBoundaryDateString = validFebruaryBoundaryDateString; 
      this.invalidFebruaryBoundaryDateString = invalidFebruaryBoundaryDateString; 
     } 
     public String getValidFebruaryBoundaryDateString() { 
      return validFebruaryBoundaryDateString; 
     } 
     public void setValidFebruaryBoundaryDateString(
       String validFebruaryBoundaryDateString) { 
      this.validFebruaryBoundaryDateString = validFebruaryBoundaryDateString; 
     } 
     public String getInvalidFebruaryBoundaryDateString() { 
      return invalidFebruaryBoundaryDateString; 
     } 
     public void setInvalidFebruaryBoundaryDateString(
       String invalidFebruaryBoundaryDateString) { 
      this.invalidFebruaryBoundaryDateString = invalidFebruaryBoundaryDateString; 
     } 
    } 

    static class DateTimeStatistics { 
     private List<String> dates = new ArrayList<String>(); 
     private List<Long> timesTakenWithDateRegex = new ArrayList<Long>(); 
     private List<Long> timesTakenWithDateRegexOnlyWholeString = new ArrayList<Long>(); 
     private List<Long> timesTakenWithDateRegexSimple = new ArrayList<Long>(); 
     private List<Long> timesTakenWithDateRegexSimpleOnlyWholeString = new ArrayList<Long>(); 
     private List<Long> timesTakenWithSimpleDateFormatParse = new ArrayList<Long>(); 
     private List<Long> timesTakenWithdateValidatorSimple = new ArrayList<Long>(); 
     private List<Long> timesTakenWithdateValidatorSimpleOnlyWholeString = new ArrayList<Long>(); 
     public List<String> getDates() { 
      return dates; 
     } 
     public List<Long> getTimesTakenWithDateRegex() { 
      return timesTakenWithDateRegex; 
     } 
     public List<Long> getTimesTakenWithDateRegexOnlyWholeString() { 
      return timesTakenWithDateRegexOnlyWholeString; 
     } 
     public List<Long> getTimesTakenWithDateRegexSimple() { 
      return timesTakenWithDateRegexSimple; 
     } 
     public List<Long> getTimesTakenWithDateRegexSimpleOnlyWholeString() { 
      return timesTakenWithDateRegexSimpleOnlyWholeString; 
     } 
     public List<Long> getTimesTakenWithSimpleDateFormatParse() { 
      return timesTakenWithSimpleDateFormatParse; 
     } 
     public List<Long> getTimesTakenWithdateValidatorSimple() { 
      return timesTakenWithdateValidatorSimple; 
     } 
     public List<Long> getTimesTakenWithdateValidatorSimpleOnlyWholeString() { 
      return timesTakenWithdateValidatorSimpleOnlyWholeString; 
     } 
     public void addDate(String date) { 
      dates.add(date); 
     } 
     public void addTimesTakenWithDateRegex(long time) { 
      timesTakenWithDateRegex.add(time); 
     } 
     public void addTimesTakenWithDateRegexOnlyWholeString(long time) { 
      timesTakenWithDateRegexOnlyWholeString.add(time); 
     } 
     public void addTimesTakenWithDateRegexSimple(long time) { 
      timesTakenWithDateRegexSimple.add(time); 
     } 
     public void addTimesTakenWithDateRegexSimpleOnlyWholeString(long time) { 
      timesTakenWithDateRegexSimpleOnlyWholeString.add(time); 
     } 
     public void addTimesTakenWithSimpleDateFormatParse(long time) { 
      timesTakenWithSimpleDateFormatParse.add(time); 
     } 
     public void addTimesTakenWithdateValidatorSimple(long time) { 
      timesTakenWithdateValidatorSimple.add(time); 
     } 
     public void addTimesTakenWithdateValidatorSimpleOnlyWholeString(long time) { 
      timesTakenWithdateValidatorSimpleOnlyWholeString.add(time); 
     } 

     private void calculateAvarageTimesAndPrint() { 
      long[] sumOfTimes = new long[7]; 
      int timesSize = timesTakenWithDateRegex.size(); 
      for (int i = 0; i < timesSize; i++) { 
       sumOfTimes[0] += timesTakenWithDateRegex.get(i); 
       sumOfTimes[1] += timesTakenWithDateRegexOnlyWholeString.get(i); 
       sumOfTimes[2] += timesTakenWithDateRegexSimple.get(i); 
       sumOfTimes[3] += timesTakenWithDateRegexSimpleOnlyWholeString.get(i); 
       sumOfTimes[4] += timesTakenWithSimpleDateFormatParse.get(i); 
       sumOfTimes[5] += timesTakenWithdateValidatorSimple.get(i); 
       sumOfTimes[6] += timesTakenWithdateValidatorSimpleOnlyWholeString.get(i); 
      } 
      System.out.println("AVG from timesTakenWithDateRegex (in nanoseconds):" + (double) sumOfTimes[0]/timesSize); 
      System.out.println("AVG from timesTakenWithDateRegexOnlyWholeString (in nanoseconds):" + (double) sumOfTimes[1]/timesSize); 
      System.out.println("AVG from timesTakenWithDateRegexSimple (in nanoseconds):" + (double) sumOfTimes[2]/timesSize); 
      System.out.println("AVG from timesTakenWithDateRegexSimpleOnlyWholeString (in nanoseconds):" + (double) sumOfTimes[3]/timesSize); 
      System.out.println("AVG from timesTakenWithSimpleDateFormatParse (in nanoseconds):" + (double) sumOfTimes[4]/timesSize); 
      System.out.println("AVG from timesTakenWithDateRegexSimple + timesTakenWithSimpleDateFormatParse (in nanoseconds):" + (double) (sumOfTimes[2] + sumOfTimes[4])/timesSize); 
      System.out.println("AVG from timesTakenWithDateRegexSimpleOnlyWholeString + timesTakenWithSimpleDateFormatParse (in nanoseconds):" + (double) (sumOfTimes[3] + sumOfTimes[4])/timesSize); 
      System.out.println("AVG from timesTakenWithdateValidatorSimple (in nanoseconds):" + (double) sumOfTimes[5]/timesSize); 
      System.out.println("AVG from timesTakenWithdateValidatorSimpleOnlyWholeString (in nanoseconds):" + (double) sumOfTimes[6]/timesSize); 
     } 
    } 

    static class DateChecker { 

     private Matcher matcher; 
     private Pattern pattern; 

     public DateChecker(String regex) { 
      pattern = Pattern.compile(regex); 
     } 

     /** 
     * Checks if the date format is a valid. 
     * Uses the regex pattern to match the date first. 
     * Than additionally checks are performed on the boundaries of the days taken the month into account (leap years are covered). 
     * 
     * @param date the date that needs to be checked. 
     * @return if the date is of an valid format or not. 
     */ 
     public boolean check(final String date) { 
      matcher = pattern.matcher(date); 
      if (matcher.matches()) { 
       matcher.reset(); 
       if (matcher.find()) { 
        int day = Integer.parseInt(matcher.group(1)); 
        int month = Integer.parseInt(matcher.group(2)); 
        int year = Integer.parseInt(matcher.group(3)); 

        switch (month) { 
        case 1: 
        case 3: 
        case 5: 
        case 7: 
        case 8: 
        case 10: 
        case 12: return day < 32; 
        case 4: 
        case 6: 
        case 9: 
        case 11: return day < 31; 
        case 2: 
         int modulo100 = year % 100; 
         //http://science.howstuffworks.com/science-vs-myth/everyday-myths/question50.htm 
         if ((modulo100 == 0 && year % 400 == 0) || (modulo100 != 0 && year % LEAP_STEP == 0)) { 
          //its a leap year 
          return day < 30; 
         } else { 
          return day < 29; 
         } 
        default: 
         break; 
        } 
       } 
      } 
      return false; 
     } 

     public String getRegex() { 
      return pattern.pattern(); 
     } 
    } 
} 

Alcune note utili:
- per attivare le asserzioni (affermare assegni) è necessario utilizzare - un argomento durante l'esecuzione del tester. (In eclissi ciò avviene modificando la configurazione Esegui/Debug -> Argomenti scheda -> Argomenti VM -> inserisci "-ea"
- la regex precedente è limitata agli anni 1800 a 2199
- non è necessario usa^all'inizio e $ alla fine per far corrispondere solo l'intera stringa di data.Il String.matches si prende cura di questo.
- assicurati di controllare i casi validi e non validi e modificali secondo le regole che hai.
- la versione "solo tutta la stringa" di ogni regex dà la stessa velocità della versione "normale" (quello senza^e $) Se si vede differenze di prestazioni questo è perché java "si abitua" per l'elaborazione delle stesse istruzioni così. il tempo si abbassa.Se si cambiano le linee in cui viene eseguita la versione "normale" e "solo tutta la stringa", lo si vedrà dimostrato.

Spero che questo aiuti qualcuno!
Cheers,
Despot

Answer 8

il modo corretto (e facile) per fare la convalida della data/ora usando Java 8+ è quello di utilizzare la classe java.time.format.DateTimeFormatter. L'uso di un'espressione regolare per la convalida non è davvero l'ideale per le date. Per il caso ad esempio in questa domanda:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd"); 

try { 
    LocalDate date = formatter.parse(text, LocalDate::from); 
} catch (DateTimeParseException e) { 
    // Thrown if text could not be parsed in the specified format 
} 

Questo codice analizzare il testo, convalidare che si tratta di una data valida, e anche restituire la data come oggetto LocalDate. Si noti che la classe DateTimeFormatter ha un numero di formati di data predefiniti statici che corrispondono agli standard ISO se il proprio caso d'uso corrisponde a uno di essi.