实例：使用Java正则表达式匹配邮箱和手机号码

String emailRegex = "\w+@(\w+\.)+[a-zA-Z]{2,4}";

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

public class EmailValidator {
    private static final String EMAIL_REGEX = "\w+@(\w+\.)+[a-zA-Z]{2,4}";

    public static boolean isValidEmail(String email) {
        Pattern pattern = Pattern.compile(EMAIL_REGEX);
        Matcher matcher = pattern.matcher(email);
        return matcher.matches();
    }

    public static void main(String[] args) {
        String email = "test123@example.com";
        if (isValidEmail(email)) {
            System.out.println(email + "是一个有效的邮箱地址");
        } else {
            System.out.println(email + "不是一个有效的邮箱地址");
        }
    }
}

test123@example.com是一个有效的邮箱地址

String phoneRegex = "1[3-9]\d{9}";

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

public class PhoneValidator {
    private static final String PHONE_REGEX = "1[3-9]\d{9}";

    public static boolean isValidPhone(String phone) {
        Pattern pattern = Pattern.compile(PHONE_REGEX);
        Matcher matcher = pattern.matcher(phone);
        return matcher.matches();
    }

    public static void main(String[] args) {
        String phone = "13812345678";
        if (isValidPhone(phone)) {
            System.out.println(phone + "是一个有效的手机号码");
        } else {
            System.out.println(phone + "不是一个有效的手机号码");
        }
    }
}

13812345678是一个有效的手机号码