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Mastering Regular Expressions in Java

Pattern Matching Using Character Classes

Learn how to create pattern objects using character classes and search for the given pattern within any text.

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Character classes

A character class is a group of characters that represent patterns. It is made up of brackets followed by a series of characters, e.g. [aeiou], This would match any vowel within your string.

You can specify multiple options in one character class, e.g. [a-zA-Z0-9] will match upper and lower case letters and numbers within your string.

Below are few examples of simple character classes:

The character class [abc]

The character class [abc] will match any one character from the set {a, b, c}. Execute the code below to see this in action.

Java
import java.util.regex.*;
class Main {
    public static void main( String args[] ) {
        System.out.println(Pattern.matches("[abc]", "xyz")); // false 
        System.out.println(Pattern.matches("[abc]", "a")); // true 
        System.out.println(Pattern.matches("[abc]", "aabbcc")); //false
    }
}

Explanation:

  1. false - “xyz” is not matched with the character class [abc] as the string does not contain any
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