正则表达式的贪婪匹配和非贪婪匹配

By default,pattern matching is greedy,which means that the matcher returns the longest match possible. For example,applying the patternA.*ctoAbcAbcAmatchesAbcAbcrather than the shorterAbc. To do nongreedy matching,a question mark must be added to the quantifier. For example,the patternA.*?cwill find the shortest match possible.

    // Greedy quantifiers
    String match = find("A.*c","AbcAbc");  // AbcAbc
    match = find("A.+","AbcAbc");          // AbcAbc
    
    // Nongreedy quantifiers
    match = find("A.*?c","AbcAbc");        // Abc
    match = find("A.+?","AbcAbc");         // Abc
    
    // Returns the first substring in input that matches the pattern.
    // Returns null if no match found.
    public static String find(String patternStr,CharSequence input) {
        Pattern pattern = Pattern.compile(patternStr);
        Matcher matcher = pattern.matcher(input);
        if (matcher.find()) {
            return matcher.group();
        }
        return null;
    }

注：本文转载自：http://www.zsm8.com/book/java_Exa/java.util.regex/Greedy.html

（编辑：李大同）

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