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Character class: Negation - 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. Similarly, "[a-z]" matches a single character from a to z.
Similarly, the negation variant of the character class is defined as "[^ ]" (with ^ within the square braces), it matches a single character which is not in the specified or set of possible characters.
For example the regular expression [^abc] matches a single character except a or, b or, c. Similarly, "[^a-z]" matches a character excepts alphabets from a to z.
Example 1
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 = "[^aeiou]";
//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 of non-vowel characters : "+count);
}
}Output
Enter input text: sample data Number of non-vowel characters : 7
Updated on: 13-Jan-2020
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