Java - wyrażenia regularne regex/maski

Przykładowa walidacja/maski za pomocą wyrażeń regularnych:

public class RegExTest {
    public static void main(String[] args) {
       
        System.out.print("\\a{5}\\d{15} ");
        String path = "abcde123456789012345";
        String regularExpression = "([A-Za-z]{5}+[0-9]{15})";
        Pattern pattern = Pattern.compile(regularExpression);
        System.out.print(pattern.matches(regularExpression, path));
        regularExpression = "([A-Za-z]{5}\\d{15})";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));
       
        System.out.print("\\a{2,} ");
        path = "ab";
        regularExpression = "[A-Za-z]{2,}";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));

        System.out.print("\\w{3,} ");
        path = "a0_";
        regularExpression = "[A-Za-z0-9_]{3,}";
        regularExpression = "\\w{3,}";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));
       
        System.out.print("\\d{11} ");
        path = "12345678901";
        regularExpression = "[0-9]{11}";
        pattern = Pattern.compile(regularExpression);
        System.out.print(pattern.matches(regularExpression, path)+"/");
       
        regularExpression = "\\d{11}";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));
       
        System.out.print("[tTnN]{1} ");
        path = "t";
        regularExpression = "[tTnN]{1}";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));
       
        System.out.print("[\\w\\d[:punct:]] ");
        path = "1";
        regularExpression = "[\\w\\d\\p{Punct}]{1,}";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));

        System.out.print("\\d{2}-\\d{3} ");
        path = "21-010";
        regularExpression = "\\d{2}-\\d{3}";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));
       
        System.out.print("\\w ");
        path = "gfasg4wer454351235Fw_";
        regularExpression = "[A-Za-z0-9_]{1,}";
        pattern = Pattern.compile(regularExpression);
        System.out.print(pattern.matches(regularExpression, path)+"/");
       
        regularExpression = "\\w{1,}";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));

        System.out.print("^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$ ");
        path = "konto@komena.pl";
        regularExpression = "^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$";
        pattern = Pattern.compile(regularExpression);
        System.out.println(pattern.matches(regularExpression, path));
       
        System.out.print("\\d{9} ");
        path = "123456789";
        regularExpression = "\\d{9}";
        pattern = Pattern.compile(regularExpression);
        System.out.println(": "+pattern.matches(regularExpression, path));

        String input = "linea\nlineb\nlinec";
        Pattern p = Pattern.compile("(?i)lineb", Pattern.DOTALL);
        Matcher m = p.matcher(input);
        boolean b = m.find();
        System.out.println("match found: " + b);
    }
}