Trouble with command intepreter

Question

Evening guys, I'm doing a project for uni and I find myself in kind of a fuss. I'm having trouble with my command interpreter. I can get the code to run, but unfortunately it's not reading my input right. Could someone point me in the right direction towards approaching the error ? The code follows below, ignore the comments and the instances of other supporting classes. Any help would be appreciated. Thanks in advance !

import java.util.Scanner;


public class Main {
    //Constantes que definem os comandos
     public static final String REGISTER     = "register";
     public static final String LISTUSERS    = "listusers";
     public static final String UPLOAD       = "upload";
     public static final String READ         = "read";
     public static final String WRITE        = "write";
     public static final String GRANT        = "grant";
     public static final String REVOKE       = "revoke";
     public static final String USERDOCS     = "userdocs";
     public static final String TOPLEAKED    = "topleaked";
     public static final String TOPGRANTERS  = "topgranters";
     public static final String HELP         = "help";
     public static final String EXIT         = "exit";

     //Constantes que definem as mensagens para o utilizador
     public static final String EXIT_COMM           = "Bye!";
     public static final String REGISTER_COMM       = " was registered.";
     public static final String ALREADY_REG_ERROR   = " is already assigned to another user.";
     public static final String NO_LIST_USERS       = "There are no registered users.";
     public static final String DOC_UPLOADED        = " was uploaded.";
     public static final String OFFICIAL_DOC        = "Contact upda1ted.";
     public static final String TOPSECRET_DOC       = "Contact book empty.";
     public static final String CONFIDENTIAL_DOC    = "Phone number does not exist.";
     public static final String CONTACT_SHARE_PHONE = "There are contacts that share phone numbers.";
     public static final String HELP_COMM           = "register - registers a new user /n";

     public static void main(String[] args) {   
         System.out.println("Welcome!");
        //WeKeepSecrets app = new WeKeepSecretsClass();     
        Scanner in  = new Scanner(System.in);
        String comm = getCommand(in);


             while (!comm.equals(EXIT)){
                 switch (comm) {
                 case HELP:
                    System.out.println(HELP);
                 default:
                     System.out.println("ERRO");
                     break;
                 }
                 comm = getCommand(in);
             }
             System.out.println(EXIT_COMM);
             in.close();
     }

     private static String getCommand(Scanner in) {
            String input;

            input = in.nextLine().toUpperCase();
            return input;
        }
}

Answer 1

1. break is missing in case for HELP. Note that you do not need break in the last case which is default.
2. The value in case should match the value of string constants, therefore, remove toUpperCase() from returned string.
3. Also, use do...while to avoid using comm = getCommand(in); twice.

Given below is the corrected code:

import java.util.Scanner;

public class Main {
    // Constantes que definem os comandos
    public static final String REGISTER = "register";
    public static final String LISTUSERS = "listusers";
    public static final String UPLOAD = "upload";
    public static final String READ = "read";
    public static final String WRITE = "write";
    public static final String GRANT = "grant";
    public static final String REVOKE = "revoke";
    public static final String USERDOCS = "userdocs";
    public static final String TOPLEAKED = "topleaked";
    public static final String TOPGRANTERS = "topgranters";
    public static final String HELP = "help";
    public static final String EXIT = "exit";

    // Constantes que definem as mensagens para o utilizador
    public static final String EXIT_COMM = "Bye!";
    public static final String REGISTER_COMM = " was registered.";
    public static final String ALREADY_REG_ERROR = " is already assigned to another user.";
    public static final String NO_LIST_USERS = "There are no registered users.";
    public static final String DOC_UPLOADED = " was uploaded.";
    public static final String OFFICIAL_DOC = "Contact upda1ted.";
    public static final String TOPSECRET_DOC = "Contact book empty.";
    public static final String CONFIDENTIAL_DOC = "Phone number does not exist.";
    public static final String CONTACT_SHARE_PHONE = "There are contacts that share phone numbers.";
    public static final String HELP_COMM = "register - registers a new user /n";

    public static void main(String[] args) {
        System.out.println("Welcome!");
        // WeKeepSecrets app = new WeKeepSecretsClass();
        Scanner in = new Scanner(System.in);
        String comm;

        do {
            System.out.print("Enter command: ");
            comm = getCommand(in);
            switch (comm) {
            case HELP:
                System.out.println(HELP);
                break;
            default:
                if (!comm.equals(EXIT)) {
                    System.out.println("ERRO");
                }
            }
        } while (!comm.equals(EXIT));
        System.out.println(EXIT_COMM);
    }

    private static String getCommand(Scanner in) {
        String input;
        input = in.nextLine();
        return input;
    }
}

A sample run:

Welcome!
Enter command: help
help
Enter command: abc
ERRO
Enter command: exit
Bye!

Answer 2

Your commands are all lower case, but you're transforming the user input into upper case. Transform into lower case instead.

input = in.nextLine().toLowerCase();

You may also want to add break to the HELP command:

             case HELP:
                System.out.println(HELP);
                break;