How to reference a 2D array from a static context?

Question

Every time I call myGridin a method generateBoard, I get an error:

non-static variable myGridcannot refer to static context

As far as I understand, this should not happen, because I set the array to public and must be accessible from any other class. So I misconfigured the array?

import java.util.Random;

public class Zombies {
    private int Level = 1;
    private int MoveNo = 0;
    public int[][] myGrid = new int[12][12];

    public static void generateBoard() {
        Random rand = new Random();
        int i, j;
        for (i = 0; i < 12; i++) {
            for (j = 0; j < 12; j++) {
                if ( i == 6 && j == 6) {
                    myGrid[i][j] = 'P';
                }
                if (rand.nextInt(4) == 0) {
                    myGrid[i][j] = 'I';
                }
                myGrid[i][j] = 'x';
            }
        }
    }

    public static String printBoard() {
        int i, j;
        for (i = 0; i < 12; i++) {
            for (j = 0; j < 12; j++) {
                if (j == 0) {
                    System.out.print( "| " );
                }
                System.out.print( myGrid[i][j] + " " );
                if (j == 12) {
                    System.out.print( "|" );
                }
            }
        }
    }
}

Answer 1

myGrid variable - , . Zombies. , ( class, a.k.a. static, variables) , Zombies.

myGrid (int[][]) static.