Runtime Error in JTable with JTableModel Implementation

Question

Hi,
I tried to do a JTable (named "table) in my program, with an implementation of JTableModel, called DataContent (obj named "dc"). Now if I try to change dc's data and refresh the table in the window by doing a "table.setModel(dc);", my programm gives me just runtime errors.
class MyFrame extends JFrame implements ActionListener{
// This is the class of the JFrame which contains the table
// globally defined vars:
private DataContent dc;
private final JTable table;
// in someMethod(){
public MyFrame(){
// creates, inits and draws the table into the window - this works !
     JPanel jpPreview = new JPanel(new GridLayout(1,0));
     dc = new DataContent();
        table = new JTable(dc.getTableData(), dc.getCol());
        table.setPreferredScrollableViewportSize(new Dimension(500, 40));
        table.setBorder(borderPanel);
        jpPreview.add(table);
     jpSeparator.add(jpPreview);
public void actionPerformed(ActionEvent ae) {
// in the same class
          if(ae.getSource() == butLoadPath){
               // choose a path by clicking on a button "butLoadPath"
               szPath = sg.readPath();
               labelLoadPath.setText(szPath);
               dc.setPath(szPath);
               dc.setContent(szToken);
          }else if(ae.getSource() == butSeparator){
               // choose a different separator token by JRadioButtons
               // when someone clicks on the button butSeparator,
               // the table should be refreshed, with this function:
               setPreview();
          }else...
private void setPreview(){
          // reads out which option was chosen by the radiobuttons - this works
          // refreshes the Object[][] oData in dc - this works, too
          dc.setContent(szToken);
          // this should refresh the table obj in the JFrame,
          // this gives me some Null.pointer.exception - why ?
          table.setModel(dc);// ??? P R O B L E M ???
     }I have implemented the Interface DataContent like this:
public class DataContent implements TableModel{
     // vars
     private int iRow,iCol;
     private String szInputData = "";
     char cToken, cLineLimiter;
     private Object[][] oData;
     // ctor
     public DataContent(){
          reset(); // set Elements...
     public void setPath( String szPath){          
          // read line from file obj...
     private void reset(){
          // set up an epmty set of data in the table...
     public void setContent( String szToken){          
          // separate content of szInputData by szToken and set oData...
     public Object[][] getTableData(){
          // return oData...
     public String[] getCol(){
          // gives some name for each column...
////////////////////////////////// automatic generated for the implementation of the interface JTableModel /////////////////
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#getRowCount()
     public int getRowCount() {
          // TODO Auto-generated method stub
          return iRow;
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#getColumnCount()
     public int getColumnCount() {
          // TODO Auto-generated method stub
          return iCol;
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#getColumnName(int)
     public String getColumnName(int columnIndex) {
          // TODO Auto-generated method stub
          String[] szColumnName = getCol();
          return szColumnName[columnIndex];
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#getColumnClass(int)
     public Class getColumnClass(int columnIndex) {
          // TODO Auto-generated method stub
          return null;
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#isCellEditable(int, int)
     public boolean isCellEditable(int rowIndex, int columnIndex) {
          // TODO Auto-generated method stub
          return false;
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#getValueAt(int, int)
     public Object getValueAt(int rowIndex, int columnIndex) {
          // TODO Auto-generated method stub
          return oData[rowIndex][columnIndex];
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#setValueAt(java.lang.Object, int, int)
     public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
          // TODO Auto-generated method stub
          // NO editing !
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#addTableModelListener(javax.swing.event.TableModelListener)
     public void addTableModelListener(TableModelListener l) {
          // TODO Auto-generated method stub
     /* (non-Javadoc)
      * @see javax.swing.table.TableModel#removeTableModelListener(javax.swing.event.TableModelListener)
     public void removeTableModelListener(TableModelListener l) {
          // TODO Auto-generated method stub
}I tried to implement some of the automatic generated methods, without success, still the same problem. What can I do, that...
table.setModel(dc);
...works without probs ???
Is there a better way to do this - the table should not even be editable, just to be shown in the window, to give an impression ??
THX

Answer 1

Why are you creating you own TableModel. Use the DefaultTableModel its easier. If you don't want you cells to be editable then you just do this:
JTable table = new JTable(...)
     public boolean isCellEditable(int row, int column)
          return false;
};