I'm working on what I thought was a straightforward program to accept user inputs and store them in an ArrayList. I created a separate class containing an object and a constructor (first name, last name, and an integer).

In the main method, I prompt the user for input within a while loop and add a new Document object to the ArrayList on each iteration. When I print the array, the output isn't what I expected. The string elements of the last Document object entered print in every instance of the array, while the integer element of the Document object updates correctly. If anyone could point me in the right direction I would really appreciate the help! I'm stumped!

Main Method:

mport java.util.Scanner;
import java.util.ArrayList;


public class ExceptionDriver
{
    public static void main (String[] args)
    {
        Scanner scan = new Scanner(System.in);
        ArrayList<Document> someStuff = new ArrayList<Document>();
        char quit = 'Y';
        String firstname, lastname;
        int code;

            while (quit == 'Y')
            {
                System.out.print("\n First Name: ");
                firstname = scan.next();

                System.out.print(" Last Name: ");
                lastname = scan.next();

                System.out.print(" Document Code: ");
                code = scan.nextInt();

                someStuff.add (new Document(lastname, firstname, code));

                System.out.print(" Enter Another Record? (Y/N)");
                String word = scan.next();
                word = word.toUpperCase();
                quit= word.charAt(0);
            }


            for(Document stuff : someStuff)
            System.out.println(stuff);
    }

}

Constructor

public class Document
{
    public static String firstname, lastname;
    private int code;

    public Document (String Last, String First, int docCode)
    {
        firstname = First;
        lastname = Last;
        code = docCode;
    }

    public String toString ()
    {
        return "\n\n Name: " + lastname + ", " + firstname + "\n Document Code: " + code + "\n";
    }

    public boolean equals (Object other)
    {
        return (lastname.equals(((Document)other).getLast())&&
        firstname.equals(((Document)other).getFirst()));
    }

    public int compareTo (Object other)
    {

        int result;

        String otherFirst = ((Document)other).getFirst();
        String otherLast = ((Document)other).getLast();

        if (lastname.equals(otherLast))
            result = firstname.compareTo(otherFirst);
        else
            result = lastname.compareTo(otherLast);

        return result;
    }


    public String getFirst ()
    {
        return firstname;
    }

    public String getLast ()
    {
        return lastname;
    }
}

that's a logical error on your part.
remove the static keyword from the lastname and firstname variables.

static means: class scope, not instance scope. if you replace the value, you do it for the class itself, and for each and every instance made of that class.

also, you've got trouble if you're trying to input a firstname that consist out of more than one part (it'll take the second part as the lastname)
and for the lastname, you'll get an exception, since it's expecting a numerical value and you're entering a String.

Removing the static variable worked! Thanks, I understand what I did wrong now..

I just have started learning arraylist. Can you please tell me the benifit of using "new Document" in this line?

someStuff.add (new Document(lastname, firstname, code));

thank you.

This arraylist is a list of Document objects

ArrayList<Document> someStuff = new ArrayList<Document>();

The application prompts the user for lastname, firstname, code and then uses those values to create new Document object, which it then adds to the list.
It may be clearer if we break the statement down into smaller steps. It's equivalent to

Document d = new Document(lastname, firstname, code);
someStuff.add (d);
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