Question

I’m new to java, and I’m currently programming a pacman as a class project. The game is played on an array[8][8]; I’ve got to read a .txt file that includes walls, ghosts and their position in the array, and show them there. I’ve used Scanner, StringTokenizer and nextInt. When I compile the file, it doesn’t give any errors, but when running it, java.lang.ArrayIndexOutOfBoundsException: 8 shows up; by the error name I can infer there’s some object outside the array, but I can’t seem to identify which one. Here’s the code:

public class JuegoPacman
{
     private Elemento _mat[][];



    public JuegoPacman()
    {

    }



    public void Escanear() throws FileNotFoundException
    {
        Scanner sc=new Scanner(new File("inicio.txt"));
        while(sc.hasNext())
        {
            String token = sc.next();

            if (token.equals("Pared"))
            {
                int i=sc.nextInt() -1;
                int j=sc.nextInt() -1;

                _mat[i][j] = new Pared(i,j);
            }

            else if(token.equals("Fantasma"))
            {
                int i=sc.nextInt();
                int j=sc.nextInt();

                _mat[i][j]= new Fantasma(i,j);
            }
        }
    }

    public void crearMatriz()
    {
        for (int i=0; i<_mat.length;i++)
        {
            for (int j=0;i<_mat[i].length;j++)
            {
                System.out.print(_mat[i][j]);
            }
        }
    }

    public void jugar() throws FileNotFoundException
    {
        _mat=new Elemento[8][8];
        Escanear();
        crearMatriz();
    }
}

This is the main class:

public class Aplicacion {


    public Aplicacion()
    {
    }


    public static void main(String[] args) throws FileNotFoundException
    {
       JuegoPacman juego = new JuegoPacman();
       juego.jugar();
    }
}

And here’s the .txt i’m trying to read:

Pared 2 2 
Pared 3 2 
Pared 4 2 
Pared 6 2 
Pared 7 2 
Pared 5 4 
Pared 2 5 
Pared 4 5 
Pared 6 5 
Pared 2 6 
Pared 4 6 
Pared 6 6 
Pared 2 7 
Pared 5 7 
Fantasma 1 3
Fantasma 1 8
Fantasma 8 8

In advance, Thank you very much.

EDIT:

Substracting 1 of each of the location numbers still gives me the same error.

ERROR:
nullnullFantasma@a31e1bnullnullnullnullFantasma@10da5ebException in thread “main” java.lang.ArrayIndexOutOfBoundsException: 8
at JuegoPacman.crearMatriz(JuegoPacman.java:58)
at JuegoPacman.jugar(JuegoPacman.java:67)
at Aplicacion.main(Aplicacion.java:22)

Answer 1

The numbering arrangements in java start from zero. If you create an array of 8 positions, then the positions will be from 0 to 7. If you try to find position 8, it will give you that error.

what to do to fix your code is

             int i = sc.nextInt () - 1;
             int j = sc.nextInt () - 1;

must be replaced on both sides

public void Escanear() throws FileNotFoundException
{
    Scanner sc=new Scanner(new File("inicio.txt"));
    while(sc.hasNext())
    {
        String token = sc.next();

        if (token.equals("Pared"))
        {
            int i=sc.nextInt() -1;
            int j=sc.nextInt() -1;

            _mat[i][j] = new Pared(i,j);
        }

        else if(token.equals("Fantasma"))
        {
            int i=sc.nextInt() - 1;
            int j=sc.nextInt() - 1;

            _mat[i][j]= new Fantasma(i,j);
        }
    }
}