如何用Java检测文本行是否包含指定双括号日期字符串模式？

Let’s work through fixing your regex and completing the date detection functionality step by step.

Issues with Your Current Regex #

Your existing regex "(?s)(\\[)(\\[)[0-9]+(\\s)[abc]+(\\])(\\])(?s)" has a few critical problems:

• [abc]+ only matches lowercase a/b/c characters, which won’t work for month names like "Februari" (it includes uppercase letters and other characters).
• It only targets a single [[...]] segment, but you need to detect paired segments like [[19 Februari]] [[1942]].
• The (?s) flags are unnecessary here—they enable dotall mode, but you aren’t using the dot (.) metacharacter in your pattern.

Improved Regex #

To match date pairs in the format [[DD Month]] [[YYYY]], use this refined regex:

String datePairRegex = "\\[\\[(\\d+ \\p{L}+)\\]\\] \\[\\[(\\d{4})\\]\\]";

Pattern Breakdown: #

• \\[\\[: Matches the opening double brackets (escaped for Java string syntax).
• (\\d+ \\p{L}+): Captures the day and month (one or more digits, a space, then one or more Unicode letters to support non-English months like "Februari").
• \\]\\]: Matches the closing double brackets.
• : Matches the space between the two date components.
• \\[\\[(\\d{4})\\]\\]: Captures the 4-digit year inside double brackets.

If you need a more flexible pattern to match any two double-bracket segments separated by a space (not just day-month + year), use:

String flexibleRegex = "\\[\\[([^\\]]+)\\]\\] \\[\\[([^\\]]+)\\]\\]";

Complete Java Code #

Here’s the finished method that detects and extracts all valid date pairs from your input string:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class DateDetector {
    public static void dumpDateTagger(String inputString) {
        // Check for date range separators
        if (inputString.contains("–") || inputString.contains("-")) {
            // Compile the regex pattern
            Pattern pattern = Pattern.compile("\\[\\[(\\d+ \\p{L}+)\\]\\] \\[\\[(\\d{4})\\]\\]");
            Matcher matcher = pattern.matcher(inputString);
            
            // Iterate through all matches
            while (matcher.find()) {
                String fullDatePair = matcher.group(0); // Entire matched pair (e.g., [[19 Februari]] [[1942]])
                String dayMonth = matcher.group(1); // e.g., 19 Februari
                String year = matcher.group(2); // e.g., 1942
                
                System.out.println("Detected date pair: " + fullDatePair);
                System.out.println("Day & Month: " + dayMonth);
                System.out.println("Year: " + year);
                System.out.println("---");
            }
        } else {
            System.out.println("No date range separator found in the input string.");
        }
    }

    public static void main(String[] args) {
        String testInput = "|date=[[19 Februari]] [[1942]] – [[10 Februari]] [[1943]]";
        dumpDateTagger(testInput);
    }
}

Sample Output: #

Detected date pair: [[19 Februari]] [[1942]]
Day & Month: 19 Februari
Year: 1942
---
Detected date pair: [[10 Februari]] [[1943]]
Day & Month: 10 Februari
Year: 1943
---

Key Notes #

• Use \\p{L} instead of [a-zA-Z] to support Unicode letters, which is essential for non-English month names.
• The while (matcher.find()) loop ensures all date pairs in the string are detected, not just the first occurrence.
• If you need to handle optional spaces between segments, add \\s* (zero or more spaces) to the regex (e.g., \\[\\[(\\d+ \\p{L}+)\\]\\]\\s*\\[\\[(\\d{4})\\]\\]).

内容的提问来源于stack exchange，提问作者Acantya