java - NullPointerException when initialising a 2D array of BooleanProperty?

I have a very simple constructor where I initialise a 2D array of type BooleanProperty to all false. However, I am getting a NullPointerException at the line grid[i][j].set(false). I am not sure why this is the case, as grid is not null? I think I must be using BooleanProperty incorrectly, but I'm not sure why.

public class Game {
    private BooleanProperty[][] grid;

    public Game() {
        grid = new BooleanProperty[10][10];
        for (int i = 0; i < 10; i++) {
            for (int j = 0; j < 10; j++) {
                grid[i][j].set(false);
            }
        }
    }

    // other methods
}

Answer

Even though you have created the array of BooleanProperty references, you need to initialize each one. Try this:

public class Game {
    private BooleanProperty[][] grid;

    public Game() {
        grid = new BooleanProperty[10][10];
        for (int i = 0; i < 10; i++) {
            for (int j = 0; j < 10; j++) {
                BooleanProperty p = new SimpleBooleanProperty();
                p.set(false);
                grid[i][j] = p;
            }
        }
    }

    // other methods
}