Character class: range - Java regular expressions

The character classes in Java regular expression is defined using the square brackets "[ ]", this subexpression matches a single character from the specified or, set of possible characters. For example, the regular expression [abc] matches a single character a or, b or, c.

The range variant of the character class allows you to use a range of characters i.e the expression [a-z] matches a single character from the alphabets a to z and the expression [^A-Z] matches a character which is not a capital letter.

Example 1

 Live Demo

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample1 {    public static void main(String[] args) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter input text: ");       String input = sc.nextLine();       String regex = "[a-z]";       //Creating a pattern object       Pattern pattern = Pattern.compile(regex);       //Matching the compiled pattern in the String       Matcher matcher = pattern.matcher(input);       int count =0;       while (matcher.find()) {          count++;       }       System.out.println("Number characters from the range (a-z): "+count);    } }

Output

Enter input text: sample data 5423 #@ %*& Number characters from the range (a-z): 10

Example 2

 Live Demo

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample3 {    public static void main(String[] args) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter input text: ");       String input = sc.nextLine();       String regex = "[^A-Z]";       //Creating a pattern object       Pattern pattern = Pattern.compile(regex);       //Matching the compiled pattern in the String       Matcher matcher = pattern.matcher(input);       int count =0;       if (matcher.find()) {          System.out.println("match occurred");       } else {          System.out.println("match not occurred");       }    } }

Output 1

Enter input text: sample data match occurred

Output 2

Enter input text: SAMPLEDATA match not occurred