How do I write negated character class regex?

A negation class is a character class that begins with a "^" metacharacter which will exclude a set of defined characters within a square brackets. For example the negation class h[^ao]t in the example below match only the word hit and exclude the words hat and hot.

package org.kodejava.example.util.regex;

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

public class CharacterClassesNegationClassDemo {
    public static void main(String[] args) {
        //
        // Defines a regular expression that will search all
        // sequences of string that begin with 'h' and end with 't'
        // and have a middle letter except those appearing to the
        // right of the ^ character within the square brackets
        // ('a' and 'o')
        //
        String regex = "h[^ao]t";

        //
        // Compiles the pattern and obtains the matcher object.
        //
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher =
                pattern.matcher("Wow, that hot hat will make a hit");

        //
        // Find every matches and prints it.
        //
        while (matcher.find()) {
            System.out.format("Text "%s" found at %d to %d.%n",
                    matcher.group(), matcher.start(), matcher.end());
        }
    }
}

The program output the following result:

Text "hit" found at 30 to 33.

Wayan

Programmer, runner, recreational diver, live in the island of Bali, Indonesia. Mostly programming in Java, Spring Framework, Hibernate / JPA. Support me by donating.

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