The Java Developers Almanac 1.4


Order this book from Amazon.

   
Home > List of Packages > java.util.regex  [26 examples]

e427. Greedy and Nongreedy Matching in a Regular Expression

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;
    }

 Related Examples
e423. Quintessential Regular Expression Search Program
e424. Determining If a String Matches a Pattern Exactly
e425. Applying Regular Expressions on the Contents of a File
e426. Removing Duplicate Whitespace in a String
e428. Escaping Special Characters in a Pattern

See also: Flags    Groups    Lines    Paragraphs    Searching and Replacing    Tokenizing   


© 2002 Addison-Wesley.