Read from File, Load arrays

Question

I'm trying to implement Banker's Algorithm in Java, but I'm having trouble loading my arrays. Here is the code I'm working with

public static void main(String[] args) throws FileNotFoundException {
    String filename = null;
    int need[][];
    int allocate[][];
    int max[][];
    int available[][];
    int n = 0;
    int m = 0;
    int lineCount = 0;
    Scanner in = new Scanner(System.in);

    System.out.println("Enter the file name.");
    filename = in.nextLine();

    File textFile = new File(filename);
    Scanner input = new Scanner(textFile);

    max = new int[n][m];
    allocate = new int[n][m];
    need = new int[n][m];
    available = new int[1][m];

    n = input.nextInt();
    m = input.nextInt();
    System.out.print("Number of Processes: " + n);
    System.out.print("\nNumber of Processes: " + m);

    max = new int[n][m];
    allocate = new int[n][m];
    need = new int[n][m];
    available = new int[1][m];

    String line = input.nextLine();

    while (line != null && lineCount < n) {

        String[] temp = line.split(" ");
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                allocate[i][j] = Integer.parseInt(line);
                System.out.println("here");
            }
            line = input.nextLine();
            lineCount++;
        }
    }
}

My sample file contains this data.

5

4

0 0 1 2 1 0 0 0 1 3 5 4 0 6 3 2 0 0 1 4

0 0 1 2 1 7 5 0 2 3 5 6 0 6 5 2 0 6 5 6

1 5 2 0

1:0 4 2 0

So, I've had a number of different errors while trying to do this. Right now I'm getting an NumberFormatException: For input string "" error. Any help is much appreciated.

Answer 1

You have a bunch of really small arrays, and you never increase the sizes of them:

int n = 0;
int m = 0;
...
max = new int[n][m];       // 0x0 array, unused
allocate = new int[n][m];  // 0x0 array, likely the culprit
need = new int[n][m];      // 0x0 array, unused
available = new int[1][m]; // 1x0 array, unused

Of these arrays, only allocate is used, and you are using it later in a for loop:

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            // OutOfBounds is probably here:
            allocate[i][j] = Integer.parseInt(line);
            System.out.println("here");
        }
        line = input.nextLine();
        lineCount++;
    }

Also, you are running Integer.parseInt(line) which is attempting to parse the whole line. You should just parse a single token at a time which would be Integer.parseInt(temp[someindex]).