Regex date format validation on Java
Use the following regular expression:
^\d{4}-\d{2}-\d{2}$
as in
if (str.matches("\\d{4}-\\d{2}-\\d{2}")) {
...
}
With the matches method, the anchors ^ and $ (beginning and end of string, respectively) are present implicitly.
The pattern above checks conformance with the general “shape” of a date, but it will accept more invalid than valid dates. You may be surprised to learn that checking for valid dates — including leap years! — is possible using a regular expression, but not advisable. Borrowing from an answer elsewhere by Kuldeep, we can all find amusement and admiration for persistence in
((18|19|20)[0-9]{2}[\-.](0[13578]|1[02])[\-.](0[1-9]|[12][0-9]|3[01]))|(18|19|20)[0-9]{2}[\-.](0[469]|11)[\-.](0[1-9]|[12][0-9]|30)|(18|19|20)[0-9]{2}[\-.](02)[\-.](0[1-9]|1[0-9]|2[0-8])|(((18|19|20)(04|08|[2468][048]|[13579][26]))|2000)[\-.](02)[\-.]29
In a production context, your colleagues will appreciate a more straightforward implementation. Remember, the first rule of optimization is Don’t!
Java Regex to check for date and time
Why you don't use SimpleDateFormat instead of regex :
try{
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:SS");
format.parse("55555");
System.out.println("Correct date");
}catch(ParseException e){
System.out.println("Incorrect date");
}
If you want to use multiple you can use an Array which store your formats, for example :
String[] patterns = {"yyyy-MM-dd HH", "yyyy-MM-dd HH:mm", ...};//<<---your formats
for (String pattern : patterns) {
try {
new SimpleDateFormat(pattern).parse("your date");
System.out.println("Correct date");
break;//if your date is correct break your look
} catch (ParseException e) {
System.out.println("Incorrect date");
}
}
Java 8 or Java 9
But I prefers to use the java.time from Java 8 or Java 9, so you can solve your problem like this :
String[] patterns = {"yyyy-MM-dd HH:mm", "yyyy-MM-dd HH"};
String date = "2018-02-02 11:50";
boolean check = Arrays.asList(patterns).stream()
.anyMatch(pattern -> {
try {
LocalDateTime.parse(date, DateTimeFormatter.ofPattern(pattern));
System.out.println("Correct");
return true;
} catch (Exception e) {
System.out.println("Not Correct");
return false;
}
});
Regex to Capture next line Date/Time YYYY/MM/DD HH:mm or YYYY/M/D H:m
Here it is...
\d{4}\/([1-9]{1}|0[1-9]|1[0-2])\/([1-9]{1}|[0-2]{1}[1-9]{1}|3[0-1])\s+([0-9]{1}|[0-1]{1}[0-9]{1}|2[0-4]):([0-9]{1}|[0-5]{1}[0-9]{1})\s+
This may seems overwhelming, so here is a walkthrough the expression.
This expression will not only take find the date and time but also ingnore the unrealistic date-time such as 2001/44/44 or 2344/44444/999. It checks for valid date-time only. Invalid date-time will be ignored.Also it will not just check date-time at beginning of line but anywhere in the string wheter the string the single line or multiple lines.
Explanation
1st 4 digits will be year....
\d{4}
followed by '/'...
\d{4}\/
Now, month can be in single digit like 1-9
\d{4}\/( [1-9]{1} )
or in double digits 01, 02, 03, 09 ( remember here if a month start with 0,then its 2nd digit cannot be greater than 9.)
\d{4}\/( [1-9]{1} | 0[1-9]{1} )
or 10, 11, 12 but cannot be greater than 12.
\d{4}\/( [1-9]{1} | 0[1-9]{1} | 1[0-2]{1} )
followed by a '/'
\d{4}\/( [1-9]{1} | 0[1-9]{1} | 1[0-2]{1} ) \/
Now comes days, it can be single digit 1-9
\d{4}\/( [1-9]{1} | 0[1-9]{1} | 1[0-2]{1} ) \/( [1-9]{1} )
or double digit 01, 02, 03, 09, 19 , 29.
\d{4}\/( [1-9]{1} | 0[1-9]{1} | 1[0-2]{1} ) \/( [1-9]{1} | [0-2]{1}[1-9]{1} )
or it can be 30 or 31 but not greater than that.
\d{4}\/( [1-9]{1} | 0[1-9]{1} | 1[0-2]{1} ) \/( [1-9]{1} | [0-2]{1}[1-9]{1} | 3[0-1] )
Now the date part is done. Some space between date and time.
\d{4}\/( [1-9]{1} | 0[1-9]{1} | 1[0-2]{1} ) \/( [1-9]{1} | [0-2]{1}[1-9]{1} | 3[0-1] ) \s+
Now let focus on time part.
Assuming time is based on 24hr format.
Hour can be single digit like 0, 1, 2, 9
( [0-9]{1} )
or double digit like 01, 02, 09, 11, 19
( [0-9]{1} | [0-1]{1}[0-9]{1} )
or 20, 21, 22, 23, 24 but not greater than 24.
( [0-9]{1} | [0-1]{1}[0-9]{1} | 2[0-4]{1} )
followed by ':'
( [0-9]{1} | [0-1]{1}[0-9]{1} | 2[0-4]{1} ) :
Minutes can be in single digit like 0, 1, 2, 9...
( [0-9]{1} | [0-1]{1}[0-9]{1} | 2[0-4]{1} ) : ( [0-9]{1} )
or double digit like 01, 02, 03, 23, 44, 59 (not 60).
( [0-9]{1} | [0-1]{1}[0-9]{1} | 2[0-4]{1} ) : ( [0-9]{1} | [0-5]{1}[0-9]{1} )
followed by some space
( [0-9]{1} | [0-1]{1}[0-9]{1} | 2[0-4]{1} ) : ( [0-9]{1} | [0-5]{1}[0-9]{1} )
\s+
Now combine your Date Regex and Time Regex and you will get
\d{4}\/([1-9]{1}|0[1-9]|1[0-2])\/([1-9]{1}|[0-2]{1}[1-9]{1}|3[0-1])\s+([0-9]{1}|[0-1]{1}[0-9]{1}|2[0-4]):([0-9]{1}|[0-5]{1}[0-9]{1})\s+
NOTE: During the explanation, i have added extra space in the Regex just for better readability.
How to validate the DateTime string format 2018-01-22T18:23:00.000Z in Java?
2018-01-22T18:23:00.000Z is the ISO 8601 format for an instant. So you may just use Instant.parse("2018-01-22T18:23:00.000Z"). Catch a DateTimeParseException from the case where the string isn’t valid, either because it’s in the wrong format or the date and time is not valid (like month 13 or hour 25). It will accept 2018-01-22T18:23Z and 2018-01-22T18:23:00.000000000Z too. This should be OK for most purposes since it is still allowed within the ISO 8601 standard.
You may want to add a range check. Probably instants that are too far into the past or the future should be considered invalid for your application. Use Instant.isBefore() and/or Instant.isAfter().
Don’t use a regular expression. It will be complicated to write and very, very complicated to read for those maintaining your code. If you do need more detailed syntax validation, use a DateTimeFormatter as already mentioned in Akshay Batra’s answer.
RegEx for validating correct ISO8601 date string
Using capturing groups, you can simply design an expression to capture anything that you wish from your input. For example this expression,
(\d{4}-\d{2}-\d{2})[A-Z]+(\d{2}:\d{2}:\d{2}).([0-9+-:]+)
divides your input into three capturing groups and you can simply call them using $1-$3.
You can also add any char that you may want to in [].
RegEx Descriptive Graph
This graph shows how the expression would work and you can visualize other expressions in this link:
Java Test
import java.util.regex.Matcher;
import java.util.regex.Pattern;
final String regex = "(\\d{4}-\\d{2}-\\d{2})[A-Z]+(\\d{2}:\\d{2}:\\d{2}).([0-9+-:]+)";
final String string = "2013-08-11T17:22:04.51+01:00";
final String subst = "\\1 \\2 \\3";
final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
final Matcher matcher = pattern.matcher(string);
// The substituted value will be contained in the result variable
final String result = matcher.replaceAll(subst);
System.out.println("Substitution result: " + result);
JavaScript Demo
const regex = /(\d{4}-\d{2}-\d{2})[A-Z]+(\d{2}:\d{2}:\d{2}).([0-9+-:]+)/gm;const str = `2013-08-11T17:22:04.51+01:00`;const subst = `\nGroup 1: $1\nGroup 2: $2\nGroup 3: $3\n`;
// The substituted value will be contained in the result variableconst result = str.replace(regex, subst);
console.log('Substitution result: ', result);Dynamically creating a regex from a DateFormat
Since you're doing getDateInstance(SHORT, locale), with emphasis on Date and SHORT, the patterns are fairly limited, so the following code will do:
public static String dateFormatToRegex(Locale locale) {
StringBuilder regex = new StringBuilder();
String fmt = ((SimpleDateFormat) DateFormat.getDateInstance(DateFormat.SHORT, locale)).toPattern();
for (Matcher m = Pattern.compile("[^a-zA-Z]+|([a-zA-Z])\\1*").matcher(fmt); m.find(); ) {
String part = m.group();
if (m.start(1) == -1) { // Not letter(s): Literal text
regex.append(Pattern.quote(part));
} else {
switch (part.charAt(0)) {
case 'G': // Era designator
regex.append("\\p{L}+");
break;
case 'y': // Year
regex.append("\\d{1,4}");
break;
case 'M': // Month in year
if (part.length() > 2)
throw new UnsupportedOperationException("Date format part: " + part);
regex.append("(?:1[0-2]|0?[1-9])");
break;
case 'd': // Day in month
regex.append("(?:3[01]|[12][0-9]|0?[1-9])");
break;
default:
throw new UnsupportedOperationException("Date format part: " + part);
}
}
}
return regex.toString();
}
To see what regex's you'll get for various locales:
Locale[] locales = Locale.getAvailableLocales();
Arrays.sort(locales, Comparator.comparing(Locale::toLanguageTag));
Map<String, List<String>> fmtLocales = new TreeMap<>();
for (Locale locale : locales) {
String fmt = ((SimpleDateFormat) DateFormat.getDateInstance(DateFormat.SHORT, locale)).toPattern();
fmtLocales.computeIfAbsent(fmt, k -> new ArrayList<>()).add(locale.toLanguageTag());
}
fmtLocales.forEach((k, v) -> System.out.println(dateFormatToRegex(Locale.forLanguageTag(v.get(0))) + " " + v));
Output
\p{L}+\d{1,4}\Q.\E(?:0[1-9]|1[0-2])\Q.\E(?:0[1-9]|[12][0-9]|3[01]) [ja-JP-u-ca-japanese-x-lvariant-JP]
(?:0[1-9]|1[0-2])\Q/\E(?:0[1-9]|[12][0-9]|3[01])\Q/\E\d{1,4} [brx, brx-IN, chr, chr-US, ee, ee-GH, ee-TG, en, en-AS, en-BI, en-GU, en-MH, en-MP, en-PR, en-UM, en-US, en-US-POSIX, en-VI, fil, fil-PH, ks, ks-IN, ug, ug-CN, zu, zu-ZA]
(?:0[1-9]|1[0-2])\Q/\E(?:0[1-9]|[12][0-9]|3[01])\Q/\E\d{1,4} [es-PA, es-PR]
(?:0[1-9]|[12][0-9]|3[01])\Q-\E(?:0[1-9]|1[0-2])\Q-\E\d{1,4} [or, or-IN]
(?:0[1-9]|[12][0-9]|3[01])\Q. \E(?:0[1-9]|1[0-2])\Q. \E\d{1,4} [ksh, ksh-DE]
(?:0[1-9]|[12][0-9]|3[01])\Q. \E(?:0[1-9]|1[0-2])\Q. \E\d{1,4} [sl, sl-SI]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4} [fi, fi-FI, he, he-IL, is, is-IS]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4} [be, be-BY, dsb, dsb-DE, hsb, hsb-DE, sk, sk-SK, sq, sq-AL, sq-MK, sq-XK]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4}\Q.\E [bs-Cyrl, bs-Cyrl-BA, sr, sr-CS, sr-Cyrl, sr-Cyrl-BA, sr-Cyrl-ME, sr-Cyrl-RS, sr-Cyrl-XK, sr-Latn, sr-Latn-BA, sr-Latn-ME, sr-Latn-RS, sr-Latn-XK, sr-ME, sr-RS]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4} [tr, tr-CY, tr-TR]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4}\Q 'г'.\E [bg, bg-BG]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q/\E\d{1,4} [agq, agq-CM, bas, bas-CM, bm, bm-ML, dje, dje-NE, dua, dua-CM, dyo, dyo-SN, en-HK, en-ZW, ewo, ewo-CM, ff, ff-CM, ff-GN, ff-MR, ff-SN, kab, kab-DZ, kea, kea-CV, khq, khq-ML, ksf, ksf-CM, ln, ln-AO, ln-CD, ln-CF, ln-CG, lo, lo-LA, lu, lu-CD, mfe, mfe-MU, mg, mg-MG, mua, mua-CM, nmg, nmg-CM, rn, rn-BI, seh, seh-MZ, ses, ses-ML, sg, sg-CF, shi, shi-Latn, shi-Latn-MA, shi-MA, shi-Tfng, shi-Tfng-MA, sw-CD, twq, twq-NE, yav, yav-CM, zgh, zgh-MA, zh-HK, zh-Hant-HK, zh-Hant-MO]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q/\E\d{1,4} [ast, ast-ES, bn, bn-BD, bn-IN, ca, ca-AD, ca-ES, ca-ES-VALENCIA, ca-FR, ca-IT, el, el-CY, el-GR, en-AU, en-SG, es, es-419, es-AR, es-BO, es-BR, es-CR, es-CU, es-DO, es-EA, es-EC, es-ES, es-GQ, es-HN, es-IC, es-NI, es-PH, es-PY, es-SV, es-US, es-UY, es-VE, gu, gu-IN, ha, ha-GH, ha-NE, ha-NG, haw, haw-US, hi, hi-IN, km, km-KH, kn, kn-IN, ml, ml-IN, mr, mr-IN, pa, pa-Guru, pa-Guru-IN, pa-IN, pa-PK, ta, ta-IN, ta-LK, ta-MY, ta-SG, th, th-TH, to, to-TO, ur, ur-IN, ur-PK, zh-Hans-HK, zh-Hans-MO]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q/\E\d{1,4} [th-TH-u-nu-thai-x-lvariant-TH]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q/\E\d{1,4} [nus, nus-SS]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q/\E\d{1,4} [en-NZ, es-CO, es-GT, es-PE, fr-BE, ms, ms-BN, ms-MY, ms-SG, nl-BE]
(?:0[1-9]|[12][0-9]|3[01])\Q-\E(?:0[1-9]|1[0-2])\Q-\E\d{1,4} [sv-FI]
(?:0[1-9]|[12][0-9]|3[01])\Q-\E(?:0[1-9]|1[0-2])\Q-\E\d{1,4} [es-CL, fy, fy-NL, my, my-MM, nl, nl-AW, nl-BQ, nl-CW, nl-NL, nl-SR, nl-SX, rm, rm-CH, te, te-IN]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4} [mk, mk-MK]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4} [nb, nb-NO, nb-SJ, nn, nn-NO, nn-NO, no, no-NO, pl, pl-PL, ro, ro-MD, ro-RO, tk, tk-TM]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4}\Q.\E [hr, hr-BA, hr-HR]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4} [az, az-AZ, az-Cyrl, az-Cyrl-AZ, az-Latn, az-Latn-AZ, cs, cs-CZ, de, de-AT, de-BE, de-CH, de-DE, de-LI, de-LU, et, et-EE, fo, fo-DK, fo-FO, fr-CH, gsw, gsw-CH, gsw-FR, gsw-LI, hy, hy-AM, it-CH, ka, ka-GE, kk, kk-KZ, ky, ky-KG, lb, lb-LU, lv, lv-LV, os, os-GE, os-RU, ru, ru-BY, ru-KG, ru-KZ, ru-MD, ru-RU, ru-UA, uk, uk-UA]
(?:0[1-9]|[12][0-9]|3[01])\Q.\E(?:0[1-9]|1[0-2])\Q.\E\d{1,4}\Q.\E [bs, bs-BA, bs-Latn, bs-Latn-BA]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q \E\d{1,4} [kkj, kkj-CM]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q/\E\d{1,4} [am, am-ET, asa, asa-TZ, bem, bem-ZM, bez, bez-TZ, cgg, cgg-UG, da, da-DK, da-GL, dav, dav-KE, ebu, ebu-KE, en-001, en-150, en-AG, en-AI, en-AT, en-BB, en-BM, en-BS, en-CC, en-CH, en-CK, en-CM, en-CX, en-CY, en-DE, en-DG, en-DK, en-DM, en-ER, en-FI, en-FJ, en-FK, en-FM, en-GB, en-GD, en-GG, en-GH, en-GI, en-GM, en-GY, en-IE, en-IL, en-IM, en-IO, en-JE, en-JM, en-KE, en-KI, en-KN, en-KY, en-LC, en-LR, en-LS, en-MG, en-MO, en-MS, en-MT, en-MU, en-MW, en-MY, en-NA, en-NF, en-NG, en-NL, en-NR, en-NU, en-PG, en-PH, en-PK, en-PN, en-PW, en-RW, en-SB, en-SC, en-SD, en-SH, en-SI, en-SL, en-SS, en-SX, en-SZ, en-TC, en-TK, en-TO, en-TT, en-TV, en-TZ, en-UG, en-VC, en-VG, en-VU, en-WS, en-ZM, fr, fr-BF, fr-BI, fr-BJ, fr-BL, fr-CD, fr-CF, fr-CG, fr-CI, fr-CM, fr-DJ, fr-DZ, fr-FR, fr-GA, fr-GF, fr-GN, fr-GP, fr-GQ, fr-HT, fr-KM, fr-LU, fr-MA, fr-MC, fr-MF, fr-MG, fr-ML, fr-MQ, fr-MR, fr-MU, fr-NC, fr-NE, fr-PF, fr-PM, fr-RE, fr-RW, fr-SC, fr-SN, fr-SY, fr-TD, fr-TG, fr-TN, fr-VU, fr-WF, fr-YT, ga, ga-IE, gd, gd-GB, guz, guz-KE, ig, ig-NG, jmc, jmc-TZ, kam, kam-KE, kde, kde-TZ, ki, ki-KE, kln, kln-KE, ksb, ksb-TZ, lag, lag-TZ, lg, lg-UG, luo, luo-KE, luy, luy-KE, mas, mas-KE, mas-TZ, mer, mer-KE, mgh, mgh-MZ, mt, mt-MT, naq, naq-NA, nd, nd-ZW, nyn, nyn-UG, pa-Arab, pa-Arab-PK, qu, qu-BO, qu-EC, qu-PE, rof, rof-TZ, rwk, rwk-TZ, saq, saq-KE, sbp, sbp-TZ, sn, sn-ZW, sw, sw-KE, sw-TZ, sw-UG, teo, teo-KE, teo-UG, tzm, tzm-MA, vai, vai-LR, vai-Latn, vai-Latn-LR, vai-Vaii, vai-Vaii-LR, vi, vi-VN, vun, vun-TZ, xog, xog-UG, yo, yo-BJ, yo-NG]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q/\E\d{1,4} [cy, cy-GB, en-BE, en-BW, en-BZ, en-IN, es-MX, fur, fur-IT, gl, gl-ES, id, id-ID, it, it-IT, it-SM, nnh, nnh-CM, om, om-ET, om-KE, pt, pt-AO, pt-BR, pt-CH, pt-CV, pt-GQ, pt-GW, pt-LU, pt-MO, pt-MZ, pt-PT, pt-ST, pt-TL, so, so-DJ, so-ET, so-KE, so-SO, ti, ti-ER, ti-ET, uz, uz-AF, uz-Cyrl, uz-Cyrl-UZ, uz-Latn, uz-Latn-UZ, uz-UZ, yi, yi-001, zh-Hans-SG, zh-SG]
(?:0[1-9]|[12][0-9]|3[01])\Q/\E(?:0[1-9]|1[0-2])\Q/\E\d{1,4} [ar, ar-001, ar-AE, ar-BH, ar-DJ, ar-DZ, ar-EG, ar-EH, ar-ER, ar-IL, ar-IQ, ar-JO, ar-KM, ar-KW, ar-LB, ar-LY, ar-MA, ar-MR, ar-OM, ar-PS, ar-QA, ar-SA, ar-SD, ar-SO, ar-SS, ar-SY, ar-TD, ar-TN, ar-YE]
\d{1,4}\Q-\E(?:0[1-9]|1[0-2])\Q-\E(?:0[1-9]|[12][0-9]|3[01]) [af, af-NA, af-ZA, as, as-IN, bo, bo-CN, bo-IN, br, br-FR, ce, ce-RU, ckb, ckb-IQ, ckb-IR, cu, cu-RU, dz, dz-BT, en-CA, en-SE, gv, gv-IM, ii, ii-CN, jgo, jgo-CM, kl, kl-GL, kok, kok-IN, kw, kw-GB, lkt, lkt-US, lrc, lrc-IQ, lrc-IR, lt, lt-LT, mgo, mgo-CM, mn, mn-MN, mzn, mzn-IR, ne, ne-IN, ne-NP, prg, prg-001, se, se-FI, se-NO, se-SE, si, si-LK, smn, smn-FI, sv, sv-AX, sv-SE, und, uz-Arab, uz-Arab-AF, vo, vo-001, wae, wae-CH]
\d{1,4}\Q. \E(?:0[1-9]|1[0-2])\Q. \E(?:0[1-9]|[12][0-9]|3[01])\Q.\E [hu, hu-HU]
\d{1,4}\Q/\E(?:0[1-9]|1[0-2])\Q/\E(?:0[1-9]|[12][0-9]|3[01]) [fa, fa-AF, fa-IR, ps, ps-AF, yue, yue-HK, zh, zh-CN, zh-Hans, zh-Hans-CN, zh-Hant, zh-Hant-TW, zh-TW]
\d{1,4}\Q/\E(?:0[1-9]|1[0-2])\Q/\E(?:0[1-9]|[12][0-9]|3[01]) [en-ZA, eu, eu-ES, ja, ja-JP]
\d{1,4}\Q-\E(?:0[1-9]|1[0-2])\Q-\E(?:0[1-9]|[12][0-9]|3[01]) [eo, eo-001, fr-CA, sr-BA]
\d{1,4}\Q. \E(?:0[1-9]|1[0-2])\Q. \E(?:0[1-9]|[12][0-9]|3[01])\Q.\E [ko, ko-KP, ko-KR]
\d{1,4}\Q/\E(?:0[1-9]|1[0-2])\Q/\E(?:0[1-9]|[12][0-9]|3[01]) [sah, sah-RU]
\d{1,4}\Q/\E(?:0[1-9]|1[0-2])\Q/\E(?:0[1-9]|[12][0-9]|3[01]) [ak, ak-GH, rw, rw-RW]
Regex pattern for date format yyyy/MM/dd
I have found the answer:
((?:19|20)\\d\\d)/(0?[1-9]|1[012])/([12][0-9]|3[01]|0?[1-9])
Regex to match date formats DD-MM-YYYY and DD/MM/YYYY
This pattern will work for your conditon. Strictly not allowed month to date and vice versa.
^([0]?[1-9]|[1|2][0-9]|[3][0|1])[./-]([0]?[1-9]|[1][0-2])[./-]([0-9]{4}|[0-9]{2})$
This pattern will match these formats: (Date, Month, Year)
25.04.2017
02.04.2017
2.4.2017
25/04/2017
5/12/2017
15/2/2017
25-04-2017
6-10-2017
16-5-2017
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