java - 密码检查、验证和要求

Question

我遇到一个问题，需要至少 2 个大写字母、至少 2 个小写字母和 2 个数字。

具体问题如下:

Write an application that prompts the user for a password that contains at least two uppercase letters, at least two lowercase letters, and at least two digits. After a password is entered, display a message indicating whether the user was successful or the reason the user was not successful.

For example, if the user enters "Password" your program should output: Your password was invalid for the following reasons: uppercase letters digits

If a user enters "P4SSw0rd", your program should output: valid password

这是到目前为止我的编码，我遇到了包含输出行的问题。例如，如果某人没有 2 个大写字母并且没有 2 个字母。当写入 1 个字母时，输出中不会包含两次失败。

import java.util.Scanner;
public class ValidatePassword {
  public static void main(String[] args) {
    String inputPassword;
    Scanner input = new Scanner(System.in);
    System.out.print("Password: ");
    inputPassword = input.next();
    System.out.println(PassCheck(inputPassword));
    System.out.println("");
  }

  public static String PassCheck(String Password) {
    String result = "Valid Password";
    int length = 0;
    int numCount = 0;
    int capCount = 0;
    for (int x = 0; x < Password.length(); x++) {
      if ((Password.charAt(x) >= 47 && Password.charAt(x) <= 58) || (Password.charAt(x) >= 64 && Password.charAt(x) <= 91) ||
        (Password.charAt(x) >= 97 && Password.charAt(x) <= 122)) {
      } else {
        result = "Password Contains Invalid Character!";
      }
      if ((Password.charAt(x) > 47 && Password.charAt(x) < 58)) {
        numCount++;
      }
      if ((Password.charAt(x) > 64 && Password.charAt(x) < 91)) {
        capCount++;
      }
      length = (x + 1);
    }
    if (numCount < 2) {
      result = "Not Enough Numbers in Password!";
    }
    if (capCount < 2) {
      result = "Not Enough Capital Letters in Password!";
    }
    if (length < 2) {
      result = "Password is Too Short!";
    }
    return (result);
  }
}

Answer 1

如果我理解正确的话，你想要做的就是当你输入“密码”时，你没有 2 个大写字母和 2 个数字，所以你的输出应该如下所示:“密码中的数字不足!密码中的大写字母不足!”。我建议两种解决方案:

1. 如果要将一个字符串添加到另一个字符串，请使用 +，因为您会用另一个结果值覆盖第一个结果值。但这不是最好的解决方案，因为每次向字符串添加值时，都会在字符串池上创建新的字符串。更多信息请点击这里: https://stackoverflow.com/a/1553110/6003541

   result += "Password is Too Short!";
   

   或

   result = result + "Password is Too Short!";
   

2. 我建议使用StringBuilder。使用“append”方法添加结果，最后返回 StringBuilder 对象的 toString() 值。

   StringBuilder sb = new StringBuilder(); 
   if (numCount < 2) {
     sb.append("Not Enough Numbers in Password!");
     sb.append(System.getProperty("line.separator"));
   }
   if (capCount < 2) {
     sb.append("Not Enough Capital Letters in Password!");
     sb.append(System.getProperty("line.separator"));
   }
   if (length < 2) {
     sb.append("Password is Too Short!");
   }
   
   return sb.toString();