How do I compile character classes with quantifier?

By Wayan in Regex 0 Comment

This example show you how to attach quantifier to character classes or capturing group in regular expressions.

package org.kodejava.example.regex;

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

public class CombineWithQuantifier {
    public static void main(String[] args) {
        // [abc]{3} --> apply quantifier in character class.
        // Find 'a' or 'b' or 'c', three times in a row.
        //
        // (abc){3} --> apply quantifier in capturing group.
        // Find 'abc', three times in a row.
        //
        // abc{3} --> apply quantifier in character class.
        // Find character 'c', three times in a row.
        String[] regexs = {"[abc]{3}", "(abc){3}", "abc{3}"};
        String text = "abcabcabcabcaba";

        for (String regex : regexs) {
            Pattern pattern = Pattern.compile(regex);
            Matcher matcher = pattern.matcher(text);

            // Find every match and print it
            System.out.format("Regex:  %s %n", regex);
            while (matcher.find()) {
                System.out.format("Text \"%s\" found at %d to %d.%n",
                    matcher.group(), matcher.start(),
                    matcher.end());
            }
            System.out.println("------------------------------");
        }
    }
}

This program will print the following output:

Regex:  [abc]{3} 
Text "abc" found at 0 to 3.
Text "abc" found at 3 to 6.
Text "abc" found at 6 to 9.
Text "abc" found at 9 to 12.
Text "aba" found at 12 to 15.
------------------------------
Regex:  (abc){3} 
Text "abcabcabc" found at 0 to 9.
------------------------------
Regex:  abc{3} 
------------------------------
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