使用正则表达式判断字符串中是否存在重复字符

.*(.)+.*
.*

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

public class DuplicateCharacterChecker {

    public static boolean hasDuplicateCharacters(String str) {
        // 用于匹配包含重复字符的正则表达式
        String regex = ".*(.)+.*\1.*";
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(str);

        return matcher.matches();
    }

    public static void main(String[] args) {
        String a = "abcdefgz";
        String b = "aacdefgz";
        String c = "abcdefghz";

        System.out.println(a + " has duplicate characters: " + hasDuplicateCharacters(a)); // Output: false
        System.out.println(b + " has duplicate characters: " + hasDuplicateCharacters(b)); // Output: true
        System.out.println(c + " has duplicate characters: " + hasDuplicateCharacters(c)); // Output: false

        String d = "abcdeffa";
        System.out.println(d + " has duplicate characters: " + hasDuplicateCharacters(d)); // Output: true

    }
}

public class DuplicateCharacterChecker {

    public static boolean isValidString(String str) {
        // 检查字符串长度是否为8
        if (str.length() != 8) {
            return false;
        }

        // 检查字符串是否包含重复字符
        String regex = ".*(.)+.*\1.*";
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(str);

        //如果包含重复字符，则返回false, 否则返回true
        return !matcher.matches();
    }

    public static void main(String[] args) {
        String a = "abcdefgz";
        String b = "aacdefgz";
        String c = "abcdefgh";
        String d = "abcdefghz";


        System.out.println(a + " is valid: " + isValidString(a)); // Output: true
        System.out.println(b + " is valid: " + isValidString(b)); // Output: false
        System.out.println(c + " is valid: " + isValidString(c)); // Output: true
        System.out.println(d + " is valid: " + isValidString(d)); // Output: false
    }
}