The English alphabet (both cases) and, digits (0 to 9) are considered as word characters. You can match them using the meta character “\w”.
Example 1
import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a String"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); String regex = "^\\w{5}"; //Compiling the regular expression Pattern pattern = Pattern.compile(regex); //Retrieving the matcher object Matcher matcher = pattern.matcher(input); if(matcher.find()) { System.out.println("Match occurred"); } else { System.out.println("Match not occurred"); } } }
Output 1
Enter a String hello Match occurred
Output 2
Enter a String #how Match not occurred
Example 2
import java.util.Scanner; public class RegexExample { public static void main( String args[] ) { //regular expression to accept word characters String regex = "\\w*"; System.out.println("Enter input value: "); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); boolean bool = input.matches(regex); if(bool) { System.out.println("match occurred"); } else { System.out.println("match not occurred"); } } }
Output
Enter input value: *##& match not occurred