Regular Expression  Metacharacter in Java

The subexpression/metacharacter “\b” matches the word boundaries when outside the brackets. Matches the backspace (0x08) when inside the brackets.

Example 1

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "\bbecause\b";       Scanner sc = new Scanner(System.in);       System.out.println("Enter a string: ");       String input = sc.nextLine();       Pattern p = Pattern.compile(regex);       Matcher m = p.matcher(input);       int count = 0;       while(m.find()) {          count ++;       }       System.out.println("Number of matches: "+count);    } }

Output

Enter a string: A sentence doesn't end with because because, because is a conjunction Number of matches: 3

Example 2

The following Java example reads a string value from the user and prints the number of word boundaries.

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example {    public static void main( String args[] ) {       System.out.println("Enter input string: ");       Scanner sc = new Scanner(System.in);       String input = sc.nextLine();       String regex = "\b";       //Compiling the regular expression       Pattern pattern = Pattern.compile(regex);       //Retrieving the matcher object       Matcher matcher = pattern.matcher(input);       int count =0;       while(matcher.find()) {          count ++;       }       System.out.println(count);    } }

Output

Enter input string: Hello how are you welcome to Tutorialspoint 14