Predefined Character classes in Regular Expression

package demo.example3;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @author Tyson
 *
 *         Search for chracters which already have special meaning in Java Regex
 */
public class Demo3 {
	public static void main(String[] args) {
		// add \ before\s for escape because \ is a escape character
		printMatch("\\s", "a7b k@9", "Search for Space");
		printMatch("\\S", "a7b k@9", "Search for anything Except Space");
		printMatch("\\d", "a7b k@9", "Search for only digit");
		printMatch("\\D", "a7b k@9", "Search for aything except digit");
		printMatch("\\w", "a7b k@9", "Search for alphanumeric character");
		printMatch("\\W", "a7b k@9", "Search for Special Character");
		printMatch(".", "a7b k@9", "Search for Any Character");
	}

	public static void printMatch(String regularExpression, String targetString, String comment) {
		Pattern p = Pattern.compile(regularExpression);
		Matcher m = p.matcher(targetString);
		System.out.println("===" + regularExpression + "===in===" + targetString + "=== " + comment);
		while (m.find()) {
			System.out.println(m.start() + "..." + m.group());
		}
		System.out.println("\n");
	}
}

Output :