import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
public static void main(String[] args) {
final String regex = "(?(DEFINE)\n"
+ " (?# Date )\n"
+ " (?# Day ranges )\n"
+ " (?<d_day28>0[1-9]|1\\d|2[0-8]|[1-9])\n"
+ " (?<d_day29>0[1-9]|1\\d|2\\d|[1-9])\n"
+ " (?<d_day30>0[1-9]|1\\d|2\\d|30|[1-9])\n"
+ " (?<d_day31>0[1-9]|1\\d|2\\d|3[01]|[1-9])\n"
+ " (?# Month specifications )\n"
+ " (?<d_month28>0?2)\n"
+ " (?<d_month29>0?2)\n"
+ " (?<d_month30>0?[469]|11)\n"
+ " (?<d_month31>0?[13578]|1[02])\n"
+ " (?# Year specifications )\n"
+ " (?<d_year>\\d+)\n"
+ " (?<d_yearLeap>(?:\\d*?(?:(?:0[48]|[13579][26]|[2468][048])|(?:(?:[02468][048]|[13579][26])00))|[48]00|[48])(?=\\D|\\b))\n"
+ " (?# Valid date formats )\n"
+ " (?<d_format>\n"
+ " (?&d_day28)-(?&d_month28)-(?&d_year)|\n"
+ " (?&d_day29)-(?&d_month29)-(?&d_yearLeap)|\n"
+ " (?&d_day30)-(?&d_month30)-(?&d_year)|\n"
+ " (?&d_day31)-(?&d_month31)-(?&d_year)\n"
+ " )\n"
+ ")\n"
+ "\\b(?&d_format)\\b";
final String string = "29-02-2016 - valid\n"
+ "29-02-2017 - invalid (not leap year)\n"
+ "30-03-2016 - valid\n"
+ "29-2-2017 - invalid (not leap year)\n"
+ "28-2-2017 - valid\n"
+ "2-2-2017 - valid\n"
+ "31-11-2017 - invalid (November has 30 days)\n"
+ "30-11-2017 - valid";
final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.COMMENTS);
final Matcher matcher = pattern.matcher(string);
while (matcher.find()) {
System.out.println("Full match: " + matcher.group(0));
for (int i = 1; i <= matcher.groupCount(); i++) {
System.out.println("Group " + i + ": " + matcher.group(i));
}
}
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html