Jaredson Fetiza

I see so I cant use the same key because it can only contain one value. I thought I was creating a new key with the same name. If I need to create new keys each it loops,is it even possible to loop student record creation using hashmap?
I will try to start from scratch and think of something.

Liutauras Vilda wrote:
So what I was thinking of (and that is purely to work on the structure you laid down with Map<String, Map<String, String>>):
Map<String, Map<String, String>> studentsDatabase = ...; while (something) {    Map<String, String> studentDetails = new HashMap<>();    studentDetails.put("key1", "value1");    studentDetails.put("key2", "value2");    ...    studentsDatabase.put("<student_id_*>", studentDetails);    /* In the next iteration an Id (key) and studentDetails (value) would be of different student */ }
But again, I'm not entirely sure what you can use in your assignment. It doesn't say that you are not allowed something, nor it does say what you are allowed. Only you said you are not allowed that and that. So I'm not sure.

Wait I don't get it. Isn't this what I am trying to do? Except that the main problem is I cant do what's in your comment.

Campbell Ritchie wrote:What sort of course is this?

Computer Science?

Liutauras Vilda wrote:Why? Could you give an example please.

Because I need to create a new one each time it loops?
String fullName1 = sc.next() + sc.nextLine(); student.put("Full Name", fullName1); - like this

Am I doing it right? What did you have in mind?
Honestly I am willing to start over from scratch cause I feel like it shouldn't be this complicated and there is a simpler approach of doing this haha

Overriding happens when you have the key you are about to add already added to a map.

For instance
Map<String, String> someMap = ... someMap.put("key1", "valueA"); someMap.put("key1", "valueB"); // this entry would override previous (above) someMap.put("key2", "valueC"); // this entry wouldn't override any other key, because there is no key with such name "key2"

Yeah but I cant create new keys and value with my approach (not that I know of) because it is a loop using the same hashmap. I am experimenting with the hashmaps methods rn like
clone(), keyset(), clear() or values to somehow see if I can get around that.

This is the instructions for the task if it helps.
Create a student database program that stores student records, which consist of:

Student ID
Full name
Age
Gender
Course
Year enrolled
The user will be asked whether they will enter a new student record or to search for a student record.

If they will search for a student then ask them for the student ID. If the student ID is found output the details of the student, if not then output not found.

If they will enter a new student record then allow the user to enter the students new details.

The program must also keep looping until the user inputs "quit".

We just covered:
- Arrays
- Arraylists
- For each loop
- Multidimensional Arrays
- Arraylist
- Hashset
- Hashmap

Are there no hashmap methods I can use to somehow do I want after line 24?

Liutauras Vilda wrote:Welcome to the Ranch and enjoy the stay. -Thanks

We have not really covered classes,methods or objects yet. Our professor evaluates us based on how we use what was taught in class.

I am creating a student database that
- Lets user create new student records
- Lets user find a student record by their student ID
- if the student is found, output their details
This is the code I made:
Scanner sc = new Scanner(System.in); // Sorry for this messy code btw especially for the scanner HashMap<String, String> student = new HashMap<>(); HashMap<String, HashMap<String, String>> database = new HashMap<>(); String input;        do {            System.out.println("Create a student record");            System.out.println("Enter your Student ID");            String studentID = sc.next();            System.out.println("Enter Full Name");            String fullName = sc.next() + sc.nextLine();            student.put("Full Name", fullName);            System.out.println("Enter Age");            String age = sc.next();            student.put("Age", age);            System.out.println("Enter Gender");            String gender = sc.next();            student.put("Gender", gender);            System.out.println("Enter Course");            String course = sc.next() + sc.nextLine();            student.put("Course", course);            System.out.println("Enter Year Enrolled");            String yearEnrolled = sc.next() + sc.nextLine();            student.put("Year Enrolled", yearEnrolled);            database.put(studentID,student); //I use the student ID as key and the hashmap as the value            System.out.println("Enter '1' to add a student record");            System.out.println("Enter '2' to search for a student in the database");            System.out.println("Enter 'Quit' to end the program");            input = sc.next();            if (input.equalsIgnoreCase("Quit")){                break;            }            else if (input.equals("2")){                System.out.println("Enter the Student ID of the student you want to find");                System.out.println(inputID);               if (database.containsKey(inputID)){                   System.out.println(database.get(inputID));                }               else {                   System.out.println("Student not found");               }            }        }        while (input.equals("1"));
After the first loop, if I choose to create a new student record it will to start to overwrite the previous one and I get two hashmaps with the same values inside my Hashmap<String, Hashmap<String, String>>:  
[2022-21547={Full Name=Jaredson Fetiza, Gender=Male, Year Enrolled=2022, Course=CS, Age=18}], [2022-21859={Full Name=Jaredson Fetiza, Gender=Male, Year Enrolled=2022, Course=CS, Age=18}]
How do I create new values for the same hashmap without overwriting the previous inputted hashmaps? I am not supposed any methods, classes or anything object related.

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.

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.

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

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?

I'm back. Been trying out some things for an hour and this is where I get stuck. We just received a hint that a loop is used and the loop only ends if "Quit" is entered.
also the Scanner is inside the loop. So while (userinput != "yes") at the very beginning?
package Main; import java.util.Scanner; public class TemperatureCheck {    public static void main(String[] args) {        System.out.println("Give three values of a temperature unit.");        Scanner sc = new Scanner(System.in);        int temp1 = sc.nextInt();        int temp2 = sc.nextInt();        int temp3 = sc.nextInt(); //the temperature at 3 instances.        System.out.println(temp1);        System.out.println(temp2);        System.out.println(temp3);        System.out.println("Which unit of temperature is it?"); //unit of temperature for the 3 inputs.        String tempUnit = sc.next();      System.out.println("Give a unit of temperature to convert it into."); //Unit of Temperature for Conversion      String tempTOConvertInto = sc.next();      int avgTemperature = temp1 + temp2 + temp3;      if (avgTemperature % 2 == 0) {          System.out.println(avgTemperature);          //Convert it to the chosen unit of measurement of their 3rd input              }

You are right. I guess my laziness got the better of me . I will try to do it as best as I can then come back again to ask for some help, is what I would like to say but I am sleepy as hell so I would most likely do it tomorrow. Oh and we have not covered OOP yet so we are expected to solve with only using what we covered.