Re: Problem with JTable and DefaultCellEditor
michael.o'connor@bluescopesteel.com wrote:
I have a JTable with editable columns, some of which should accept only
numbers. To do this, I have added a DefaultCellEditor to the numeric
columns, with a JTextField to accept user input, and a KeyListener to
filter out non-numeric keystrokes from the JTextField.
The user can start editing by mouse-clicking in a cell and typing, or
by navigating around the table using the arrow keys, then type in a
cell, without using the mouse.
All this works well, except in the second case when the user types in a
cell without first selecting it with the mouse. The problem here is
that the KeyListener does not see the first keystroke, but does see
subsequent ones. That means one non-numeric character can be entered
into the cell. However, the KeyListener always works if the user first
selects the cell with a mouse-click. Below is some code showing this
behaviour. What am I missing? How can I capture that first keystroke? I
am using Java 1.5.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
public class Test extends JFrame {
public Test() {
JTable table = new JTable(new Object[][] { {"a",1,2},{"b",3,4} },
{"a",1,2},{"b",3,4} - ??
new String[] {"Text", "Num 1", "Num 2"});
table.setRowSelectionAllowed(false);
table.setSurrendersFocusOnKeystroke(true);
TableColumnModel cm = table.getColumnModel();
cm.getColumn(1).setCellEditor(new MyCellEditor());
cm.getColumn(2).setCellEditor(new MyCellEditor());
JScrollPane scrollPane = new JScrollPane(table);
getContentPane().add(scrollPane);
}
private class MyCellEditor extends DefaultCellEditor {
private final JTextField tf;
public MyCellEditor() {
super(new JTextField());
tf = (JTextField) getComponent();
tf.addKeyListener(new MyKeyListener ());
setClickCountToStart(1);
}
public Component getTableCellEditorComponent(JTable table,
Object value, boolean isSelected, int row, int column) {
tf.setText(value.toString());
return tf;
}
public Object getCellEditorValue() {
return tf.getText();
}
}
private class MyKeyListener implements KeyListener {
public void keyPressed(KeyEvent e) {}
public void keyReleased(KeyEvent e) {}
public void keyTyped(KeyEvent e) {
if ( ! Character.isDigit(e.getKeyChar()) ) {
Toolkit.getDefaultToolkit().beep();
e.consume();
}
}
}
public static void main(String[] args) {
Test frame = new Test();
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
Mike
You don't need custom editor and KeyListener
(but if you want you'd better to use JFormattedTextField which
you may pass to a constructor of DefaultCellEditor).
You may create your own TableModel where you need to override
getColumnClass and your table will know what to do.
Your class back (different name) with custom table model.
import java.awt.Component;
import java.awt.Toolkit;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.DefaultCellEditor;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableColumnModel;
import javax.swing.table.TableModel;
public class NumericColumnTester extends JFrame {
public NumericColumnTester() {
// JTable table = new JTable(new Object[][] {
// { "a", new Integer(1), "2" }, { "b", new Integer(3), "4" } },
// new String[] { "Text", "Num 1", "Num 2" });
String[]header = { "Text", "Num 1", "Num 2" };
List data = new ArrayList();
data.add(new Object[]{ "a", new Integer(1), "2" });
data.add(new Object[]{ "b", new Integer(3), "4" });
TableModel model = new TblModel(data, header);
JTable table = new JTable(model);
table.setRowSelectionAllowed(false);
table.setSurrendersFocusOnKeystroke(true);
// TableColumnModel cm = table.getColumnModel();
// cm.getColumn(1).setCellEditor(new MyCellEditor());
// cm.getColumn(2).setCellEditor(new MyCellEditor());
JScrollPane scrollPane = new JScrollPane(table);
getContentPane().add(scrollPane);
}
private class MyCellEditor extends DefaultCellEditor {
private final JTextField tf;
public MyCellEditor() {
super(new JTextField());
tf = (JTextField) getComponent();
tf.addKeyListener(new MyKeyListener());
setClickCountToStart(1);
}
public Component getTableCellEditorComponent(JTable table,
Object value, boolean isSelected, int row, int column) {
tf.setText(value.toString());
return tf;
}
public Object getCellEditorValue() {
return tf.getText();
}
}
class TblModel extends AbstractTableModel {
private List data;
private String[] header;
public TblModel(List data, String[] header) {
this.data = data;
this.header = header;
}
public boolean isCellEditable(int rowIndex, int columnIndex) {
return columnIndex == 1;
}
public int getColumnCount() {
return header == null ? 0 : header.length;
}
public int getRowCount() {
return data == null ? 0 : data.size();
}
public Object getValueAt(int rowIndex, int columnIndex) {
Object[] row = (Object[]) data.get(rowIndex);
return row[columnIndex];
}
public Class getColumnClass(int columnIndex) {
if (data == null) {
return Object.class;
}
Object[] row = (Object[]) data.get(0);
return row[columnIndex] == null ? Object.class :
row[columnIndex].getClass();
}
public String getColumnName(int column) {
return header[column];
}
public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
Object[] row = (Object[]) data.get(rowIndex);
row[columnIndex] = aValue;
super.fireTableCellUpdated(rowIndex, columnIndex);
}
}
private class MyKeyListener implements KeyListener {
public void keyPressed(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
}
public void keyTyped(KeyEvent e) {
if (!Character.isDigit(e.getKeyChar())) {
Toolkit.getDefaultToolkit().beep();
e.consume();
}
}
}
public static void main(String[] args) {
JFrame frame = new NumericColumnTester();
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}