Reading values from JTable

Question

I have som problems reading the values from JTable. the user enters a number in the table, but some cells are empty. I want to store the values in an int array, and if the user has not filled a cell it is supposed to be set as zero. Now I cant seam to get it right.
I get the error message: Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: null
It is for the code. Integer intObj = new Integer(str);[/u
int[] tmp = new int[brettStorelse * brettStorelse];
for (int i = 0; i < brettStorelse; i++) {
     for (int j = 0; j < brettStorelse;j++) {
          String k = String.valueOf(j+i);
          int l = Integer.parseInt(k);
          if (sudokuTabell.getValueAt(i, j) != null) {
               String str = (String) sudokuTabell.getValueAt(i+1, j+1);
               Integer intObj = new Integer(str);
               tmp[l] = intObj.intValue();
               System.out.println(tmp[l]);
          } else {
               tmp[l] = 0;

Answer 1

What are you doing to prevent the user from entering values in the table that are not parseable? Seems like you should be doing the below.
int[] tmp = new int[brettStorelse * brettStorelse];
for (int i = 0; i < brettStorelse; i++) {
     for (int j = 0; j < brettStorelse;j++) {
          String k = String.valueOf(j+i);
          int l = Integer.parseInt(k);
          if (sudokuTabell.getValueAt(i, j) != null) {
               String str = (String) sudokuTabell.getValueAt(i+1, j+1);
                        try {
                            tmp[l] = Integer.parseInt (str);
                        catch (NumberFormatException e){
                             tmp[l] = 0;
               System.out.println(tmp[l]);
          } else {
               tmp[l] = 0;
}