Hashmap - creating username and password.

[Jaredson Fetiza]

Create a program that allows users to:

1. Create new "users" with a username and password combination
2. "Log in" with any username and password combination.
You must store these username-password combinations in your program, and the program must notify the user if the login was successful or not
For the 1st condition I tried:

while (true) {
 hashmap.put(sc.nextLine(), sc.nextInt();
 String input =  sc.nextLine();
 if (input.equalsIgnoreCase("Yes")) {
                 break;  }

But I get InputMismatch the second time and I dont know why?
As for the 2nd condition:

System.out.println("Enter username");
if (hashmap.containsKey(sc.nextLine()){
System.out.println("Enter password")
if (hashmap.containsValue(sc.nextInt()){
System.out.println("Login Successful") }}

Here I get a hashmap.containsKey is always false.
I dont know why these errors appeared so I want to know what I did wrong exactly.
Do I have the right ideas?  How can I correct this?

[Jaredson Fetiza]

Woah this my first time using tags, its a mess.

[Liutauras Vilda]

Jaredson Fetiza wrote:Woah this my first time using tags, its a mess.

Agreed. Well, code formatting and indentation is as is.

[Carey Brown]

For the "password" I would not have expected you to use hashmap.containsValue(...) as the hashmap may contain duplicate values or the person my have inadvertently entered someone else's password. I expected to see hashmap.get( userename ) somewhere.

[Campbell Ritchie]

I also don't like while (true) ... I would suggest a do loop, reading while the input doesn't equal “Quit” or something like that.
I suspect you are falling into a little‑known pitfall with nextLine(). You have doubtless been told it reads the next line, and that is exactly what it doesn't do. Look in this old post of mine. When the loop runs the second time, you are using nextLine() after nextInt(), and the old post explains what can go wrong. Documentation link.

[Jaredson Fetiza]

Kinda late but I was able to do what I wanted with this:

public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        HashMap<String, Integer> hMap = new HashMap<>();
        int input;
        do {
            System.out.println("Create an account");
            System.out.println("Enter your username.");
            String username = sc.next();
            System.out.println("Enter your password.");
            int password = sc.nextInt();
            hMap.put(username, password);
            System.out.println("Account created successfully.");
            System.out.println("Enter the number 7 to stop account creation otherwise, enter any number to continue. ");
            input = sc.nextInt();
        }
        while (input == 7); {
            int input1;
            do {
                System.out.println("Login to your account");
                System.out.println("Enter your username");
                String username1 = sc.next();
                if (hMap.containsKey(username1)) {
                    System.out.println("Enter your password");
                    int password1 = sc.nextInt();
                    if (hMap.get(username1) == password1) {
                        System.out.println("Login Successful");
                        break;
                    } else {
                        System.out.println("Password is incorrect");
                    }
                } else {
                    System.out.println("Incorrect Username");
                }
                System.out.println("Do you want to try again?");
                System.out.println("Enter the number 7 to try again, enter any number to quit");
                input1 = sc.nextInt();
            }
            while (input1 == 7);
        }
    }

Thanks for the help      
Feel free to tell me if there was a better way I could have gone doing it.

[Norm Radder]

The { on line 16 (paired with } on line 39) is confusing.  I don't think it does anything.
The message to user:  Enter the number 7 to stop
does not agree with the logic in the while on line 16 which will continue with a 7

Then the next loop uses different logic, it asks user to enter a 7 to continue.
The confusion is the first loop says enter 7 to stop, the second loop says enter 7 to continue.

[Jaredson Fetiza]

Yeah sorry about that, the curly brackets on line 16 and 39 is something I forgot to delete when I finished the code.
And I understand that the enter 7 can be confusing so I'll try to make it clear next time.

[Junilu Lacar]

That first loop - do { ... } while (input == 7) will continue to execute until you enter something other than 7. However, your instruction is "Enter the number 7 to stop account creation otherwise, enter any number to continue."

So unless you somehow missed this in your testing, somebody else using your program will be led astray by the contradiction between the instructions and what the code is actually doing.

[Junilu Lacar]

Formatted properly, your code would look like this:

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    HashMap<String, Integer> hMap = new HashMap<>();
    int input;

    do {
        System.out.println("Create an account");
        System.out.println("Enter your username.");
        String username = sc.next();
        System.out.println("Enter your password.");
        int password = sc.nextInt();
        hMap.put(username, password);
        System.out.println("Account created successfully.");
        System.out.println("Enter the number 7 to stop account creation otherwise, enter any number to continue. ");
        input = sc.nextInt();
    }
    while (input == 7);

    {
        int input1;
        do {
            System.out.println("Login to your account");
            System.out.println("Enter your username");
            String username1 = sc.next();
            if (hMap.containsKey(username1)) {
                System.out.println("Enter your password");
                int password1 = sc.nextInt();
                if (hMap.get(username1) == password1) {
                    System.out.println("Login Successful");
                    break;
                } else {
                    System.out.println("Password is incorrect");
                }
            } else {
                System.out.println("Incorrect Username");
            }
            System.out.println("Do you want to try again?");
            System.out.println("Enter the number 7 to try again, enter any number to quit");
            input1 = sc.nextInt();
        }
        while (input1 == 7);
    }
}

The block from 19-42 is probably unintentional but it saved you from having to deal with a compile time error where you try to re-declare the input variable. If you try deleting lines 19 and 42 to remove the block, which is what you'd normally have, you'll see the error when you try to compile.

EDIT: I just noticed that you used a different name, input1 instead of input so no compiler error would have occurred if you deleted lines 19 and 42.