public Tableau(int x_default, int y_default){
        this.x = x_default;
        this.y = y_default;
        this.tab = new Case[x][y];
        for (int width = 0; width < this.y; width++) {
            for (int length = 0; length < this.x; length++) {
                this.tab[length][width] = new Case(Etat.vide);
            }
        }
    }