Win a copy of Java Concurrency Live Lessons this week in the Threads forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic

Why I can't catch NumberFormatException in the tableModel  RSS feed

Renee Zhang
Ranch Hand
Posts: 72
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Here is some source code from swing tutorial. ( I find it can't catch the NumberFormatException at column[3]. When I enter a String into column[3], the cell's border turns red and the table is dead. Can anyone tell me why? Any consideration will be greatly appreciated!
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableColumn;
import javax.swing.DefaultCellEditor;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.JScrollPane;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.JOptionPane;
import java.awt.*;
import java.awt.event.*;
public class TableRenderDemo extends JFrame {
private boolean DEBUG = true;
public TableRenderDemo() {
MyTableModel myModel = new MyTableModel();
JTable table = new JTable(myModel);
table.setPreferredScrollableViewportSize(new Dimension(500, 70));
//Create the scroll pane and add the table to it.
JScrollPane scrollPane = new JScrollPane(table);
//Set up column sizes.
initColumnSizes(table, myModel);
//Fiddle with the Sport column's cell editors/renderers.
//Add the scroll pane to this window.
getContentPane().add(scrollPane, BorderLayout.CENTER);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
* This method picks good column sizes.
* If all column heads are wider than the column's cells'
* contents, then you can just use column.sizeWidthToFit().
private void initColumnSizes(JTable table, MyTableModel model) {
TableColumn column = null;
Component comp = null;
int headerWidth = 0;
int cellWidth = 0;
Object[] longValues = model.longValues;
for (int i = 0; i < 5; i++) {
column = table.getColumnModel().getColumn(i);
try {
comp = column.getHeaderRenderer().
null, column.getHeaderValue(),
false, false, 0, 0);
headerWidth = comp.getPreferredSize().width;
} catch (NullPointerException e) {
System.err.println("Null pointer exception!");
System.err.println(" getHeaderRenderer returns null in 1.3.");
System.err.println(" The replacement is getDefaultRenderer.");
comp = table.getDefaultRenderer(model.getColumnClass(i)).
table, longValues[i],
false, false, 0, i);
cellWidth = comp.getPreferredSize().width;
if (DEBUG) {
System.out.println("Initializing width of column "
+ i + ". "
+ "headerWidth = " + headerWidth
+ "; cellWidth = " + cellWidth);
//XXX: Before Swing 1.1 Beta 2, use setMinWidth instead.
column.setPreferredWidth(Math.max(headerWidth, cellWidth));
public void setUpSportColumn(TableColumn sportColumn) {
//Set up the editor for the sport cells.
JComboBox comboBox = new JComboBox();
comboBox.addItem("Chasing toddlers");
comboBox.addItem("Speed reading");
comboBox.addItem("Teaching high school");
sportColumn.setCellEditor(new DefaultCellEditor(comboBox));
//Set up tool tips for the sport cells.
DefaultTableCellRenderer renderer =
new DefaultTableCellRenderer();
renderer.setToolTipText("Click for combo box");
//Set up tool tip for the sport column header.
TableCellRenderer headerRenderer = sportColumn.getHeaderRenderer();
if (headerRenderer instanceof DefaultTableCellRenderer) {
"Click the sport to see a list of choices");
class MyTableModel extends AbstractTableModel {
final String[] columnNames = {"First Name",
"Last Name",
"# of Years",
final Object[][] data = {
{"Mary", "Campione",
"Snowboarding", new Integer(5), new Boolean(false)},
{"Alison", "Huml",
"Rowing", new Integer(3), new Boolean(true)},
{"Kathy", "Walrath",
"Chasing toddlers", new Integer(2), new Boolean(false)},
{"Mark", "Andrews",
"Speed reading", new Integer(20), new Boolean(true)},
{"Angela", "Lih",
"Teaching high school", new Integer(4), new Boolean(false)}
public final Object[] longValues = {"Angela", "Andrews",
"Teaching high school",
new Integer(20), Boolean.TRUE};
public int getColumnCount() {
return columnNames.length;
public int getRowCount() {
return data.length;
public String getColumnName(int col) {
return columnNames[col];
public Object getValueAt(int row, int col) {
return data[row][col];
* JTable uses this method to determine the default renderer/
* editor for each cell. If we didn't implement this method,
* then the last column would contain text ("true"/"false"),
* rather than a check box.
public Class getColumnClass(int c) {
return getValueAt(0, c).getClass();
* Don't need to implement this method unless your table's
* editable.
public boolean isCellEditable(int row, int col) {
//Note that the data/cell address is constant,
//no matter where the cell appears onscreen.
if (col < 2) {
return false;
} else {
return true;
* Don't need to implement this method unless your table's
* data can change.
public void setValueAt(Object value, int row, int col) {
if (DEBUG) {
System.out.println("Setting value at " + row + "," + col
+ " to " + value
+ " (an instance of "
+ value.getClass() + ")");
if (data[0][col] instanceof Integer
&& !(value instanceof Integer)) {
//With JFC/Swing 1.1 and JDK 1.2, we need to create
//an Integer from the value; otherwise, the column
//switches to contain Strings. Starting with v 1.3,
//the table automatically converts value to an Integer,
//so you only need the code in the 'else' part of this
//'if' block.
try {
data[row][col] = new Integer(value.toString());
fireTableCellUpdated(row, col);
} catch (NumberFormatException e) {
"The \"" + getColumnName(col)
+ "\" column accepts only integer values.");
} else {
data[row][col] = value;
fireTableCellUpdated(row, col);
if (DEBUG) {
System.out.println("New value of data:");
private void printDebugData() {
int numRows = getRowCount();
int numCols = getColumnCount();
for (int i=0; i < numRows; i++) {
System.out.print(" row " + i + ":");
for (int j=0; j < numCols; j++) {
System.out.print(" " + data[i][j]);
public static void main(String[] args) {
TableRenderDemo frame = new TableRenderDemo();
Paul Stevens
Ranch Hand
Posts: 2823
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
This is just a preference of mine. I would create an editor and not allow invalid data in the first place.

ps When posting code, use the code tags.
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!