Event problem with JComboBox

Hi, javamen.
I ve gotten a little problem when working with Itemlistener interface. My combo has 4 options, in which the first one always appears when the applet starts up. Whenever the user DOESNT change it and submit the applet form, throught a button click, the applet gets a NullPointerException. But, if the user changes the option, i always get it, throught my interface' methods(ItemStateChanged). Of course, i know its because there was no combobox event, just a button event (click). So, how can i deal with this situation, since i need to get the combobox option content.
Regards, Euclides.

But, this is the question! I dont know how to initialize the combobox' first option. Help me, please! I am using the addItem method as follow:
MakeJCombo ( JComboBox ComboObj) {
ComboObj.addItem ("option1");
ComboObj.addItem ("option2");
ComboObj.addItem ("option3");
then:
public void itemStateChange(ItemEvent ie) ...
Object origem = ie.getSource()...
if (origem == ComboObj) ...

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I try to put JComboBox in JTableCell,
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import javax.swing.table.*;
import javax.swing.*;
import java.awt.Component;
import java.awt.event.MouseEvent;
import java.util.EventObject;
import de.falcom.table.*;
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 protected JComboBox mComboBox;
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 mComboBox = new JComboBox();
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 if(value instanceof AnswerChoices){
 AnswerChoices a = (AnswerChoices)value;
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 mComboBox.addItem(c);
 mComboBox.setSelectedIndex(a.getAnswer());
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 int nchoices = mComboBox.getItemCount();
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 c[i] = mComboBox.getItemAt(i).toString();
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import javax.swing.table.TableCellRenderer;
import javax.swing.*;
import java.awt.Component;
public class AnswerChoicesCellRenderer extends JComboBox implements TableCellRenderer {
 private Object curValue;
/** Creates new AnswerChoiceCellRenderer */
public AnswerChoicesCellRenderer() {
setEditable(false);
public Component getTableCellRendererComponent(JTable table,Object value,boolean isSelected,boolean hasFocus,int row,int column) {
if (value instanceof AnswerChoices) {
AnswerChoices nl = (AnswerChoices)value;
String[] tList = nl.getChoices();
if (tList != null) {
removeAllItems();
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if (table != null)
if (table.isCellEditable(row, column))
setForeground(CellRendererConstants.EDITABLE_COLOR);
else
setForeground(CellRendererConstants.UNEDITABLE_COLOR);
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 static int ans = 0;
 String[] choices ;
public AnswerChoices(String[]c,int a){
 choices = c;
 ans = a;
public AnswerChoices(String[] c){
 this(c,0);
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import java.awt.Color;
import javax.swing.JTable;
import javax.swing.ListSelectionModel;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellEditor;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableColumn;
import javax.swing.table.TableModel;
import javax.swing.*;
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/** Creates new FAL_Table */
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super(dtm);
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setColumnSelectionAllowed(false);
setBackground(java.awt.Color.white);
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 setDefaultCellEditorRenderer(JComboBox.class, new ComboBoxCellEditor( ),new ComboBoxRenderer());
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 setDefaultCellEditorRenderer(java.math.BigDecimal.class,new NumberCellEditor(), new NumberCellRenderer());
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 setDefaultCellEditorRenderer(String.class,new StringCellEditor(), new StringCellRenderer());
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 setDefaultCellEditorRenderer(Color.class,new ColorCellEditor(), new ColorCellRenderer());
 setDefaultCellEditorRenderer(AnswerChoices.class, new AnswerChoicesCellEditor(), new AnswerChoicesCellRenderer());
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TableModel model = getModel();
if (model instanceof FAL_TableModel) {
FAL_TableModel ptm = (FAL_TableModel)model;
return ptm.getCellClass(row,convertColumnIndexToModel(col));
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TableColumn tableColumn = getColumnModel().getColumn(column);
TableCellRenderer renderer = tableColumn.getCellRenderer();
if (renderer == null) {
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TableColumn tableColumn = getColumnModel().getColumn(column);
TableCellEditor editor = tableColumn.getCellEditor();
if (editor == null) {
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import java.util.Vector;
import java.awt.event.MouseEvent;
import java.util.EventObject;
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public FAL_TableModel() {
this((Vector)null, 0);
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setDataVector(data, columnNames);
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if (col != 1){
return false;
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Object obj = getValueAt(row,col);
if (obj != null)
 return obj.getClass();
 else
 return Object.class;
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Object obj = getValueAt(row,col);
 return obj;
my problem is, when i select an item from one of the comboBox in the table the value of the other cells changes too and i have the same problem with JSpinner.
please help i am stuck
Gebi

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