java - 在Java中使用字符串来接受基于特定要求的密码

Question

该程序应该接受字符串输入，即密码。然后，程序会检查以确保密码长度至少为 8 个字符，至少包含 2 位数字，并且仅包含字母和数字。我似乎无法找到计算至少 2 位数字的正确方法，尽管从我所见这个方法应该可行。

这是我收到的错误线程“main”中的异常 java.lang.StringIndexOutOfBoundsException:字符串索引超出范围:10 在 java.lang.String.charAt(String.java:658) 在Password.main(Password.java:35)

import java.util.*;


public class Password{
    public static void main(String[] args){
    Scanner input = new Scanner(System.in);
    String s;
    int numbers = 0;

    System.out.println("Enter a password (Must contain only letters and numbers, ");
    System.out.print("minimum of 8 characters with atleast two numbers): ");    
    s = input.nextLine();

    while(1==1){
    if (s.length() < 8){
        System.out.println("Password is too short");
        System.out.println("Enter correctly formatted password");
        s = input.nextLine();
        continue;
        }

    if (s.matches("^[a-zA-Z0-9_]+$")){  
    }
    else{
        System.out.println("Password may only contain Letters and Digits");
        System.out.println("Enter correctly formatted password");
        s = input.nextLine();
        continue;
        }



    int i;
    for (i = 0; i <= s.length(); i++){
        if (Character.isDigit(s.charAt(i))){
            numbers++;
            }
            }

    if (numbers < 2){
        System.out.println("Password must contain atleast 2 digits");
        System.out.println("Enter correctly formatted password");
        s = input.nextLine();
        continue;
        }
        break;
        }


    while (0==0){   
    System.out.println("Reenter Password to see if it matches");
        String a = input.nextLine();

    if (s.equals(a)){
        System.out.println("Password matches!");
        break;
        }
    else{
        System.out.println("Password does not match");
        continue;
    }
    }
    }
    }

Answer 1

在 for 循环中，不应允许 i 等于 s.length()

for (i = 0; i <= s.length(); i++)

当您尝试访问s[s.length()]时会引发ArrayIndexOutOfBoundsException。