What does java.util.InputMismatchException mean

Question

I am a noob programmer on JAVA and i'm trying to do one of my first programs and needless to say it's not going great. I have gotten rid of several error of the same type as this one, but i can't seem to be able to fix this. Without further ado here is what i need help with:

error:

Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at Main.createGame(Main.java:67)
at Main.processCommand(Main.java:116)
at Main.main(Main.java:40)`
`Exception in thread "main"` 

code:

import java.util.Scanner;

public class Main{

private static final String SAI = "SAI"; 
private static final String AJUDA = "AJUDA";
private static final String NOVO = "NOVO";
private static final String MAPA = "MAPA";
private static final String KNIGHT = "CAVALEIRO";
private static final String SWORDSMAN = "ESPADACHIM";
private static final String SPEARMAN = "LANCEIRO";
private static final String NORTH = "NORTE";
private static final String SOUTH = "SUL";
private static final String WEST = "OESTE";
private static final String EAST = "ESTE";
private static final String SAIR = "Obrigado por jogar. Ate a proxima.";

public static void main(String[] args) 
    {
          Scanner in = new Scanner(System.in);

          Game g1 = new Game();

          Units u1 = new Units();

          String command = "";

          String movement = "";


        System.out.println("novo - Novo jogo");
        System.out.println("ajuda - Mostra a ajuda");
        System.out.println("sai - Termina a execucao do programa");
        System.out.print("> ");

          while(!command.equals(SAI))
            {
                command = readCommand(in);
                movement = readMovement(in);
                processCommand(command, movement, g1, u1, in);
            }

          in.close();
    }

private static String readCommand(Scanner in)
{
    String command;

    command = in.next().toUpperCase();

    return command;
}

private static String readMovement(Scanner in)
{
    String movement;

    movement = in.next().toUpperCase();

    return movement;
}

private static void createGame(Game g1, Scanner in)
{
    int x = in.nextInt();
    int y = in.nextInt();
    String team1 = in.next();
    int f1x = in.nextInt();
    int f1y = in.nextInt();
    String team2 = in.next();
    int f2x = in.nextInt();
    int f2y = in.nextInt();
    in.nextLine();
    g1.createGame(x, y, f1x, f1y, f2x, f2y, team1, team2);
}

private static void processCommand(String command, String movement, Game g1, Units u1, Scanner in)
    {
      int tempflag = 0;

     switch (command)
        {
            case AJUDA:
                if(g1.on() == false)
                {
                in.nextLine();
                System.out.println("novo - Novo jogo");
                System.out.println("ajuda - Mostra a ajuda");
                System.out.println("sai - Termina a execucao do programa");
                System.out.print("> ");
                }
                else
                {
                    in.nextLine();
                    System.out.println("novo - Novo jogo");
                    System.out.println("mapa - Mostra o mapa do jogo");
                    System.out.println("cavaleiro - Move o cavaleiro");
                    System.out.println("espadachim - Move o espadachim");
                    System.out.println("lanceiro - Move o lanceiro");
                    System.out.println("ajuda - Mostra a ajuda");
                    System.out.println("sai - Termina a execucao do programa");
                    if((g1.turns()%2) == 0)
                    {
                        System.out.println(g1.Team1() + "> ");
                    }
                    else
                    {
                        System.out.println(g1.Team2() + "> ");
                    }
                }
                break;

            case NOVO:
                  g1.stop();
                  createGame(g1, in);
                  tempflag = (Math.abs(g1.flag1X() - g1.flag2X()) + Math.abs(g1.flag1Y() - g1.flag2Y()));
                  if(g1.altura() < 10 || g1.largura() < 10)
                  {
                      System.out.println("Mapa pequeno demais para o jogo");
                  }
                  if(g1.flag1X() < 2 || g1.flag1Y() < 2)
                  {
                      System.out.println(g1.Team1() + " bandeira em posicao invalida " + g1.flag1X() + g1.flag1Y());
                  }
                  if(g1.flag2X() < 2 || g1.flag2Y() < 2 || tempflag < 5)
                  {
                      System.out.printf(g1.Team2() + " bandeira em posicao invalida " + g1.flag2X() + g1.flag2Y());
                  }
                  if(g1.Team1() == g1.Team2())
                  {
                      System.out.println("As equipas nao podem ter o mesmo nome");
                  }
                  else
                  {
                      g1.start();
                      u1.knightAlive1();
                      u1.swordsmanAlive1();
                      u1.spearmanAlive1();
                      u1.knightAlive2();
                      u1.swordsmanAlive2();
                      u1.spearmanAlive2();
                      System.out.println("Jogo iniciado com sucesso, comeca a equipa " + g1.Team1());
                      System.out.print(g1.Team1() + "> ");
                  }
                  break;

Answer 1

You should always ensure that your Scanner Object has the nextXXX(type) before calling attempting to get the desired type.

Your stack trace is very telling, "at java.util.Scanner.nextInt(Unknown Source) " is stating that it got something other than the expected type of int when it attempted to read. This occurs inside of your createGame() method, which looks like is called because the command "NOVO" was passed.

To avoid this error use the Scanners hasNextInt() method before attempting to get the next int within the stream. I.E if(hasNextInt()){....}