Need help with inserting element into a grid

Question

Hi,
I'm trying to add an element in a 11x11 grid, but the program stop and give me 2 error (identified in the code) and I have no idea on what is wrong with those line. If anyone have any idea, suggestion or an other way to do this, I could use some help.
Thx
          for (int i = 0; i != NUMBER; ++i) {
                  int row = 2 + (int)(Math.random() * 10);
               int col = 2 + (int)(Math.random() * 10);
               int nb = 0 + (int)(Math.random() * 2);
               boolean horizontal = true;
               if (nb == 1)
                    horizontal = false;
               if (horizontal) {
                    if (row <= element.getDimension()) {  // error at this line
                         for (int j = 0; j != element[i].getDimension(); j++) {
                              grid[row + j][col]     = "X";
                    else {
                         for (int j = 0; j != element[i].getDimension(); j++) {
                              grid[row - j][col]     = "X";
               if (! horizontal) {
                    if (col <= element[i].getDimension()) { // error at this line
                         for (int j = 0; j != element[i].getDimension(); j++) {
                              grid[row][col + j]     = "X";
                    else {
                         for (int j = 0; j != element[i].getDimension(); j++) {
                              grid[row][col - j]     = "X";

Answer 1

My error is : Exception in thread "main" java.lang.NullPointerException
at Grid.<init><Grid.java:67>
at PrincTp1.main<PrincTp1.java:24>
That's my class element
public class Element {
// Attributs
     private int dimension;
     private boolean horizontal;
     private String name;
     private int row;
     private int col;
// Constructor
     public Element(int dimension_, String name_) {
          dimension = dimension_;
          name = name_;
     public Element() {
// getter/setter
     public void setDimension(int dimension_) {
          dimension = dimension_;
     public int getDimension() {
          return dimension;
     public void setHorizontal(boolean horizontal_) {
          horizontal = horizontal_;
     public boolean getHorizontal() {
          return horizontal;
     public void setNom(String name_) {
          name = name_;
     public String getName() {
          return name;
     public void setLigne(int row_) {
          row = row_;
     public int getRow() {
          return row;
     public void setCol(int col_) {
          col = col_;
     public int getCol() {
          return col;
     }