使用 Java 检查密码中的重复字符

Question

我是 CIS 的学生，正在攻读 Java class（希望成为一名程序员）。无论如何，我有一项任务是创建一个程序来检查密码的有效性。如果密码无效，则打印一条消息。如果密码有效，用户将重新输入密码。如果两者匹配，则打印消息接受。如果不匹配，则打印消息。密码要求是：

长度必须至少为 8 个字符
1. 必须包含一个数字
2. 必须包含一个字母
3. 必须包含一个特殊字符
4. 不能有 3 个或更多相同的字符
5. 不能包含空格
6. 不能以 !或者？

我正在使用 netbeans。

package pass1;

import java.util.Scanner;

public class Pass1 {

//Main method asks for pasword from user and calls upon methods to verify                                 password requirements and password 1 and 2 match
public static void main(String[] args) {
    //declare variables
    String pass1;
    String pass2;
    boolean passvalid;
    boolean passmatch;


//initialize new instance of scanner
Scanner kb = new Scanner(System.in);
//get password
System.out.println("Please input password. (Must be at least 8 characters,  contain a number, letter, and special character");
pass1 = kb.nextLine();
//initialize instance of passisvalid to check password for requirements
passvalid = passisvalid(pass1);
//if pass is valid, allow user to reinsert password 
if (passvalid){
System.out.println("Please reinsert password:");
pass2 = kb.nextLine();
//initialize instance of passismatch to check passwords match
passmatch = passismatch(pass1, pass2);
//if passwords do not match, print message
if (!passmatch)
{
System.out.println("Passwords do not match.");
}
//if passwords match, print message
else if (passmatch)
{
    System.out.println("Password set.");
}
}
//if password is not valid, print message         
else
{
    System.out.println("Password is not valid:");
}


}

     /*************************************************************************************/   

//this method check that user inputted password meets requirements, and         returns boolean value 
public static boolean passisvalid(String password) {
//declare variables
boolean letter;
boolean digit;
boolean space;
boolean length;
boolean start1;
boolean start2;
boolean valid;
boolean special;
//initialize variables
valid=false;
letter=false;
digit=false;
space=false;
special=false;
length = false;
start1=false;
start2=false;

//initialize count 
for(int i=0;i<password.length();i++)
{
char s=password.charAt(i);
//check for letter in password
if(Character.isLetter(s))
{
letter = true;
}
//check for number in password
if(Character.isDigit(s))
{
digit = true;
}
//check for spaces in password
if(Character.isSpaceChar(s))
{
space=true;
}
//check for special characters in password
if(!Character.isDigit(s) && !Character.isLetter(s))
{
special=true;
}
}
//check password length
if (password.length() > 8) 
{  
length=true;
} 
//check password start with ? or !
else if (password.startsWith("?"))
{
start1=true;
}
else if (password.startsWith("!"))
{
start1=true;
}
//requirements of password for boolean true
if(letter && digit && special && length)
{
valid = true;
}
//return boolean false if detect start with ? or !, or spaces in password
if(start1||start2||space)
{
valid = false;
}

return valid;

}

/**********************************************************************************/

//this method checks that both user entered passwords match       
public static boolean passismatch(String password1, String password2){
//declare variables
boolean match;
//initialize variables
match=false;

//compare password strings   
if (password1.equals(password2))
{
match= true;
}

return match;

}

}

所以除了确保没有连续的重复字符外，我已经能够计算出所有内容。我真的不知道从哪里开始。我在几个论坛上搜索了几个小时，试图找到一个解决方案并将它们放在一起，但没有看到一个例子，或者只是我一生都无法弄清楚的东西。任何帮助将不胜感激。

Answer 1

可以获取密码到字符串数组，比较每个字符串和后面两个字符串是否相同。

public static boolean hasConsecutiveCharacters(String pwd){
        String[] letter = pwd.split(""); // here you get each letter in to a string array

        for(int i=0; i<letter.length-2; i++){
            if(letter[i].equals(letter[i+1]) && letter[i+1].equals(letter[i+2])){
                return true; //return true as it has 3 consecutive same character
            }
        }
        return false; //If you reach here that means there are no 3 consecutive characters therefore return false.
    }

Answer 2

package filehandling;

import java.util.Scanner;

public class PasswordValidation {

    public static void main(String[] args) {

        String enterPassword ;
        String reEnterPassword ;

        boolean passValid ;
        boolean isPassMatch ;

        Scanner password = new Scanner(System.in);
        System.out.println("Enter Your Password:");
        System.out.println("(Must be at least 8 characters,  contain a number, letter, and special character");
        enterPassword = password.nextLine();

        passValid = checkPassIsValid(enterPassword);

        if(passValid) {
            System.out.println("Re-Enter Your Password: ");
            reEnterPassword = password.nextLine();
            isPassMatch = checkPasswordMatching(enterPassword,reEnterPassword);

            if(!isPassMatch)
                System.out.println("Password do Not Match: ");
            else if (isPassMatch)
                System.out.println("Password Set.");

        }
        else
            System.out.println("Password is Not Valid.");

    }

    private static boolean checkPassIsValid(String enterPassword) {

        boolean length = false;
        boolean letter = false;
        boolean digit = false;
        boolean space = false;
        boolean startSpace = false;
        boolean special = false;
        boolean start1 = false;
        boolean start2 = false;
        boolean valid = false;

        for(int i = 0; i < enterPassword.length(); i++) {
            char c = enterPassword.charAt(i);

            if(enterPassword.length() >= 8)
                length = true;
            if(Character.isDigit(c))
                digit = true;
            if(Character.isLetter(c))
                letter = true;
            if(Character.isSpaceChar(c))
                space = true;
            if( (!Character.isDigit(c)) && (!Character.isLetter(c)) )
                special = true;
            if(enterPassword.startsWith(" "))
                startSpace = true;
            else if(enterPassword.startsWith("?"))
                start1 = true;
            else if(enterPassword.startsWith("!"))
                start2 = true;
            if(letter && digit && special && length)
                valid = true;
            if(start1 || start2 || startSpace)
                valid = false;
        }
        return valid;

    }

    private static boolean checkPasswordMatching(String enterPassword,String reEnterPassword) {

        if(enterPassword.equals(reEnterPassword))
            return true;        
        return false;
    }

}

使用 Java 检查密码中的重复字符

Checking for repeated characters in password using Java

java

validation

passwords

character