e427. greedy and nongreedy matching in a regular expression.txt

这里面包含了一百多个JAVA源文件

By default, pattern matching is greedy, which means that the matcher returns the longest match possible. For example, applying the pattern A.*c to AbcAbcA matches AbcAbc rather than the shorter Abc. To do nongreedy matching, a question mark must be added to the quantifier. For example, the pattern A.*?c will 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;
    }