Trying to understand the concept of collecting multiple users inputs

[JonP Lee]

Hi, my name is Jon. Hope everyone is doing well during these times. Still learning Java, but it feels like every concept takes a very long time to sink in.

If it's no trouble, I wanted to try to understand getting inputs from different users to print them all afterward. It's for an assignment, and just curious if I could get sent to the right path. Not trying to get it solved, I'm just not sure how to go about it or the thought process.

I only understand how to take, store and print for 1 user, but lost on how to add 2 more.

Apologies for the trouble and hopefully this makes sense.

[Carey Brown]

Welcome to the Code Ranch Jon.

We need some more info to go on. Is your program interface web based, text based, or GUI based? What are you currently using to save the user responses: a text file, a database, or something else?

[JonP Lee]

Ah, sorry Carey. I'm just using NetBeans if that's what you mean. Not sure if this clears it up.

       

System.out.println("Enter employee ID:");
        int i = input.nextInt();
        String id = Integer.toString(i);
        
        System.out.println("Enter employee name:");
        String name = input.next();
        
        System.out.println("Enter years of employment:");
        int numOfYears = input.nextInt();
        
        System.out.println("Enter monthly salary:");
        double monthlySalary= input.nextDouble();
        
        System.out.println("In management? True/False");
        boolean manager = input.nextBoolean();

[Norm Radder]

Do you know how to define and use your own classes?  Your program could define a class to hold all the input from a user and then save each instance of that class with a user's data in a list.
After getting the input from all the users, the program could go through the list and print out the data for each user.

[Carey Brown]

If you are going to accept spaces in the name then for the name you'll have to call nextLine() instead. Unfortunately when you do that you will run into one of the infamous Scanner gotchas, the left over new-line from nextInt() which would cause name to be empty. Here's how to fix that problem.
       

        System.out.println("Enter employee ID:");
        int i = input.nextInt();
        input.nextLine(); // read left over new-line and throw away
        String id = Integer.toString(i);
        
        System.out.println("Enter employee name:");
        String name = input.nextLine(); // allow spaces in name
        
        System.out.println("Enter years of employment:");
        int numOfYears = input.nextInt();
        
        System.out.println("Enter monthly salary:");
        double monthlySalary= input.nextDouble();
        
        System.out.println("In management? True/False");
        boolean manager = input.nextBoolean();

[JonP Lee]

Norm Radder wrote:Do you know how to define and use your own classes?  Your program could define a class to hold all the input from a user and then save each instance of that class with a user's data in a list.
After getting the input from all the users, the program could go through the list and print out the data for each user.

Sorry, do you mean creating a new class? Would I create an array to store the data?

[JonP Lee]

Ah.. Thanks Carey. I completely overlooked that part about the nextLine.

Carey Brown wrote:If you are going to accept spaces in the name then for the name you'll have to call nextLine() instead. Unfortunately when you do that you will run into one of the infamous Scanner gotchas, the left over new-line from nextInt() which would cause name to be empty. Here's how to fix that problem.
       

        System.out.println("Enter employee ID:");
        int i = input.nextInt();
        input.nextLine(); // read left over new-line and throw away
        String id = Integer.toString(i);
        
        System.out.println("Enter employee name:");
        String name = input.nextLine(); // allow spaces in name
        
        System.out.println("Enter years of employment:");
        int numOfYears = input.nextInt();
        
        System.out.println("Enter monthly salary:");
        double monthlySalary= input.nextDouble();
        
        System.out.println("In management? True/False");
        boolean manager = input.nextBoolean();

[Carey Brown]

More likely that you'd use a List instead of an array because a List can keep track of its own size and expand and contract as needed.

List<Employee> employees = new ArrayList<>(); // for example

[JonP Lee]

Carey Brown wrote:More likely that you'd use a List instead of an array because a List can keep track of its own size and expand and contract as needed.

List<Employee> employees = new ArrayList<>(); // for example

Thank you very much Carey. Hope my post wasn't too vague.

[Carey Brown]

Jon, when replying to a post don't use Quote unless you are trying to point out something specific in the message that you're replying to. Using Quote all the time just fills the thread with redundant information. Thanks.

[Edit:]To reply to the last post, look below the last post, just to the left, and you should see a "Post Reply" button.

[Campbell Ritchie]

Welcome to the Ranch

The reason for that problem is that the nextLine() method isn't well named and so many of the book authors believe its name reflects its functionality; this API link tells you what it actually does. Please tell us what your book says it does.
What happens after nextInt()‑<line‑terminator> is that the Scanner reads the remainder of the line, which in this case contains no useful information, and after that all your inputs are out of sequence, just like what Carey said. It is only a matter of time before you can't match an input, and suffer an exception. I used to call nextLine() twice, but have since hit on a better solution: create a utility class. You can now write KeyboardInputs.nextLine() and even use Scanner's ability to read ahead. The following code will happily handle input like this:-

123 JonP Lee

int id = KeyboardInputs.nextInt();
String name = KeyboardInputs.nextLine().strip();

/* alternative version */ String id = String.valueOf(KeyboardInputs.nextInt()); /* There are many ways to turn any datatype into a String */ String name = KeyboardInputs.nextLine().strip();...and this is an example of how you can write a nextLine() method:-/** don't forget the documentation comments */ public static String nextLine(String message) {   System.out.print(message);   String line;   do   {      line = scanner.nextLine().strip();   } while (line.isEmpty());   return line; }Pre-Java11 code used trim() instead of strip(). The message would read something like, “Please write name‑<enter>: ” Remember that unlike many Scanner methods, nextLine() is dependent on a line end sequence being used and its input depends on the location of that line end.

[Carey Brown]

Campbell, I'm uncomfortable with your approach to handling extraneous new-lines in nextLine(). What if an empty String is actually a valid input? In Jon's case your approach may be acceptable but I'd hate to adopt it as the universal answer.

[Campbell Ritchie]

Good point. My utility class misses out certain functionality. For example it doesn't provide any technique for changing the delimiter on the Scanner. It never occurred to me to accept an empty line as a valid input. As you imply, that would require a different approach.