Thread: Password program for school

Here is what the command prompt outputs when I enter the password wrong. It will re prompt until the length is right, but for the other conditions, it will simply get stuck reprinting the requirement statement, never moving on even when the conditions are met. In this example, adding capital letters doesn't have the program move on to the next test. I feel like it needs to re run through the for loop that increments the character counters but there is no way to have it go back to a certain line, and repeating that for loop would have to be done infinitely if someone never puts in the correct conditions.

Program run first with too short a password then with no capitals, then with all capitals it won't move out of that while loop.

Enter a password. Must have
at least two uppercase letters,
at least three lowercase letters
and at least one digit.
Enter your password:
1
The password you entered is 1
The password length is 1
Your password is too short, please enter password:
123456
Password must contain at least 2 upper case letters!
Please enter a new password:
AA123456
Password must contain at least 2 upper case letters!
Please enter a new password:
AAAAAA
Password must contain at least 2 upper case letters!
Please enter a new password:

Here is the error messages:

ValidatePassword.java:93: error: cannot find symbol
while (passwordLength < 6) //makes sure that password isn't too short
^
symbol: variable passwordLength
location: class ValidatePassword
ValidatePassword.java:96: error: cannot find symbol
password = stdin.nextLine();
^
symbol: variable password
location: class ValidatePassword
ValidatePassword.java:96: error: cannot find symbol
password = stdin.nextLine();
^
symbol: variable stdin
location: class ValidatePassword
ValidatePassword.java:97: error: cannot find symbol
passwordLength = password.length();
^
symbol: variable passwordLength
location: class ValidatePassword
ValidatePassword.java:97: error: cannot find symbol
passwordLength = password.length();
^
symbol: variable password
location: class ValidatePassword
ValidatePassword.java:104: error: cannot find symbol
for(i = 0; i < passwordLength; i++)
^
symbol: variable i
location: class ValidatePassword
ValidatePassword.java:104: error: cannot find symbol
for(i = 0; i < passwordLength; i++)
^
symbol: variable i
location: class ValidatePassword
ValidatePassword.java:104: error: cannot find symbol
for(i = 0; i < passwordLength; i++)
^
symbol: variable passwordLength
location: class ValidatePassword
ValidatePassword.java:104: error: cannot find symbol
for(i = 0; i < passwordLength; i++)
^
symbol: variable i
location: class ValidatePassword
ValidatePassword.java:106: error: cannot find symbol
c = password.charAt(i);
^
symbol: variable c
location: class ValidatePassword
ValidatePassword.java:106: error: cannot find symbol
c = password.charAt(i);
^
symbol: variable i
location: class ValidatePassword
ValidatePassword.java:106: error: cannot find symbol
c = password.charAt(i);
^
symbol: variable password
location: class ValidatePassword
ValidatePassword.java:107: error: cannot find symbol
if(Character.isUpperCase(c))
^
symbol: variable c
location: class ValidatePassword
ValidatePassword.java:109: error: cannot find symbol
upperCount++;
^
symbol: variable upperCount
location: class ValidatePassword
ValidatePassword.java:111: error: cannot find symbol
else if(Character.isLowerCase(c))
^
symbol: variable c
location: class ValidatePassword
ValidatePassword.java:113: error: cannot find symbol
lowerCount++;
^
symbol: variable lowerCount
location: class ValidatePassword
ValidatePassword.java:115: error: cannot find symbol
else if(Character.isDigit(c))
^
symbol: variable c
location: class ValidatePassword
ValidatePassword.java:117: error: cannot find symbol
digitCount++;
^
symbol: variable digitCount
location: class ValidatePassword
18 errors



And here is the code. There were nested methods, they have been moved, but the variables seem to be unable to be used outside of the main method.

 
/** A program to have a user enter a password with
 * specified requirements, and have the user re-enter
 * a password until those requirements are met.*/
 
import java.util.Scanner; //allows keyboard input
 
public class ValidatePassword
{
	public static void main(String[] args) 
	{
	   String passwordRequirements ="Enter a password. Must have \n" //String describing password requiremts
	   + "at least two uppercase letters, \n"
	   + "at least three lowercase letters \n"
	   + "and at least one digit.";
	   String password;                         //String that holds the users password
	   Scanner stdin = new Scanner(System.in);  //Scanner class that allows user input
	   int passwordLength;                      //integer storing password length
 
	   /*These next lines get the inital user password after defining the
	   password requirements and then parrots back the password and stores
	   and shows the length*/
 
	   System.out.println(passwordRequirements);
	   System.out.println("Enter your password: ");
	   password = stdin.nextLine();
	   passwordLength = password.length();
	   System.out.println("The password you entered is " + password);   //These are for
	   System.out.println("The password length is " + passwordLength);  //testing only
 
	   int i;               //integer of position of character in the string
	   char c;              //character used to determine upper/lower case
	   int lowerCount = 0;  //integer of how many lower case characters there are
	   int upperCount = 0;  //integer of how many upper case characters there are
	   int digitCount = 0;
	   final int MIN_LOWER = 3; //min number of lower case letters needed
	   final int MIN_UPPER = 2; //min number of upper case letters needed
	   final int MIN_DIG = 1;    //min number of numeric digits needed
 
 
	   /*This section tests the password entered and has the user correct
	   any wrong elements*/
 
 
		if(upperCount >= MIN_UPPER && lowerCount >= MIN_LOWER && digitCount >= MIN_DIG)
		{
		    System.out.println("Password accepted!");
		}
 
		else if(upperCount != MIN_UPPER)
		  {
		    while(upperCount < MIN_UPPER)
		    {
		    System.out.println("Password must contain at least 2 upper case letters!");
		    System.out.println("Please enter a new password: ");
		    password = stdin.nextLine();
		    passwordLength = password.length();
		    lengthTest();
		    counter();
		    }
		  }
 
		  else if(lowerCount != MIN_LOWER)
		  {
		    while(lowerCount < MIN_LOWER)
		    {
		    System.out.println("Password must contain at least 3 lower case letters!");
		    System.out.println("Please enter a new password: ");
		    password = stdin.nextLine();
		    passwordLength = password.length();
		    lengthTest();
		    counter();
		    }
		  }
 
		  else if(digitCount != MIN_DIG)
		  {
		    while(digitCount < MIN_DIG)
		    {
		    System.out.println("Password must contain at least 1 digit!");
		    System.out.println("Please enter a new password: ");
		    password = stdin.nextLine();
		    passwordLength = password.length();
		    lengthTest();
		    counter();
		    }
		  }
	}
 
	    public static void lengthTest()
	    {    
 
	        while (passwordLength < 6) //makes sure that password isn't too short
	        {
	            System.out.println("Your password is too short, please enter password: ");
		        password = stdin.nextLine();
		        passwordLength = password.length();
	        }
	    }
 
	   public static void counter()
	   {
 
	        for(i = 0; i < passwordLength; i++)
	        {
		        c = password.charAt(i);
		        if(Character.isUpperCase(c))
		        {
		            upperCount++;
		        }
		         else if(Character.isLowerCase(c))
		        {
		            lowerCount++;
		        }
		        else if(Character.isDigit(c))
		        {
		            digitCount++;
		        }
		    }
	   }
 
}

Norm, thank you for the help. I suppose I still have a lot to learn in terms of constructors and what can and cannot be in or out of a class and where it can be used. I did get it working by making them all static variables and separate method calls. It seems to be quirky in how it counts digits and where that takes it but it is overall working in terms of prompting until the password is useable. Here is the updated code.

 
/** A program to have a user enter a password with
 * specified requirements, and have the user re-enter
 * a password until those requirements are met.*/
 
import java.util.Scanner;		//allows keyboard input
 
public class ValidatePassword
{
  static String password;		//String that holds the users password
  static Scanner stdin = new Scanner (System.in);	//Scanner class that allows user input
  static int passwordLength;	//integer storing password length
 
  static int i;					//integer of position of character in the string
  static char c;				//character used to determine upper/lower case
  static int lowerCount = 0;	//integer of how many lower case characters
  static int upperCount = 0;	//integer of how many upper case characters
  static int digitCount = 0;    //integer of how many digits
  static final int MIN_LOWER = 3;	//min number of lower case letters needed
  static final int MIN_UPPER = 2;	//min number of upper case letters needed
  static final int MIN_DIG = 1;	//min number of numeric digits needed
 
 
  public static void main (String[]args)
  {
	String passwordRequirements = "Enter a password. Must have \n"	//String describing password requiremts
	  + "at least two uppercase letters, \n"
	  + "at least three lowercase letters \n" + "and at least one digit.";
 
	/*These next lines get the inital user password after displaying
	   password requirements*/
 
	  System.out.println (passwordRequirements);
	  System.out.println ("Enter your password: ");
	  password = stdin.nextLine ();
	  passwordLength = password.length ();
 
	/*This section tests the password entered and has the user correct
	 any wrong elements */
 
 
	  lengthTest ();
	  counter ();
	  upperLetters ();
	  lowerLetters ();
	  digits ();
 
	  System.out.println("Digits are: " + digitCount);
  }
 
  public static void lengthTest () //makes sure that password isn't too short
  {
	while (passwordLength < 6)	
	  {
		System.out.println ("Your password is too short, please enter a new password: ");
		password = stdin.nextLine ();
		passwordLength = password.length ();
	  }
  }
 
  public static void counter () //counts uppercase, lowercase and digits
  {
 
	for (i = 0; i < passwordLength; i++)
	  {
		c = password.charAt (i);
		if (Character.isUpperCase (c))
		  {
			upperCount++;
		  }
		else if (Character.isLowerCase (c))
		  {
			lowerCount++;
		  }
		else if (Character.isDigit (c))
		  {
			digitCount++;
		  }
	  }
 
	    if (upperCount >= MIN_UPPER && lowerCount >= MIN_LOWER
		    && digitCount >= MIN_DIG)
	    {
		    System.out.println ("Password accepted!");
	    }
  }
 
  public static void upperLetters () //ensures the correct amount of uppercase letters.
  {
	while (upperCount < MIN_UPPER)
	  {
		System.out.println ("Password must contain at least 2 upper case letters!");
		System.out.println ("Please enter a new password: ");
		password = stdin.nextLine ();
		passwordLength = password.length ();
		lengthTest ();
		counter ();
	  }
  }
 
  public static void lowerLetters () //ensure the right amount of lowercase letters
  {
	while (lowerCount < MIN_LOWER)
	  {
		System.out.println ("Password must contain at least 3 lower case letters!");
		System.out.println ("Please enter a new password: ");
		password = stdin.nextLine ();
		passwordLength = password.length ();
		lengthTest ();
		counter ();
	  }
  }
 
  public static void digits ()
  {
	while (digitCount < MIN_DIG)
	  {
		System.out.println ("Password must contain at least 1 digit!");
		System.out.println ("Please enter a new password: ");
		password = stdin.nextLine ();
		passwordLength = password.length ();
		lengthTest ();
		counter ();
	  }
  }
 
}

It's quirky in that it seems never to recount anything but the length test. As long as at some point the conditions were met, even if the current password entered is wrong, it will accept it and say it is valid even though it is not. Those three inputs you listed are one of a few examples I was able to do, where it will call it a valid password even though it is not.

For checking password if it has required number of uppercase, lowercase,special characters, numbers etc. you can go for regular expression, which will check if your entered password follows the required constraints.

Second you want to check if your re-entered password is same as the first one and until it doesn't match , you will be prompted to re-enter the password. For this I am assuming you dont have any fixed number of retries constraint, So you can go for while or do-while loop. Inside the loop you can check if the first and second password(i.e re-entered password) is same or not. If same you can break from the loop or else give a prompt that the re-entered password is wrong and ask to enter the password again.

Hope this helps and All the Best!!!