Highlighting problems

Question

Hi,
i have created a specific JTextField that, among other things, only can take in numbers. To do this I have modified the Document of the textfield.
My problem is that the user can toggle between two different textfields using a combo box. One textfield of this kind and one standard JTextField. When the user toggles the focus should be on the text field, and if there is text in the textfield it should be highlighted. This works fine for the standard JTextField using requestFocus() on the textfield, and a FocusListener that does a selectAll() when the text field recieves focus. But my "enhanced" textfield gets a null pointer exception when the selectAll() occurs. Any ideas?
The TextFields new Document
protected Document createDefaultModel() {
return new FaTkTaxNrDocument();
protected class FaTkTaxNrDocument extends PlainDocument
public void insertString(int offs, String str, AttributeSet a)
throws BadLocationException
char[] source = str.toCharArray();
int size = source.length;
char[] result = new char[size];
int j = 0;
boolean dashSet = false;
// Ska endast f� plats 7 tecken
if(this.getLength() > 7) {
return;
for (int i = 0; i < result.length; i++) {
if (Character.isDigit(source)) {
result[j++] = source[i];
if (offs+i == 6) {
dashSet = true;
else if (offs == 6 && Character.isSpaceChar(source[i])) {
result[j++] = '-';
else {
// System.err.println("insertString: " + source[i]);
if(dashSet) {
super.insertString(offs, new String(result, 0, j), a);
super.insertString(offs, "-", null);
else
super.insertString(offs, new String(result, 0, j), a);
The focus listener
public class FaTkInputListener implements FocusListener
public void focusGained(FocusEvent arg0)
     selectAll();
The null pointer exception
Exception occurred during event dispatching:
java.lang.NullPointerException
     at javax.swing.plaf.basic.BasicTextUI.damageRange(Unknown Source)
     at javax.swing.plaf.basic.BasicTextUI.damageRange(Unknown Source)
     at javax.swing.text.DefaultHighlighter.addHighlight(Unknown Source)
     at javax.swing.text.DefaultCaret.moveDot(Unknown Source)
     at javax.swing.text.DefaultCaret.moveDot(Unknown Source)
     at javax.swing.text.JTextComponent.moveCaretPosition(Unknown Source)
     at javax.swing.text.JTextComponent.selectAll(Unknown Source)
     at se.rsv.fa.tk.client.view.FaTkInputField$FaTkInputListener.focusGained(FaTkInputField.java:124)
     at java.awt.AWTEventMulticaster.focusGained(Unknown Source)
     at java.awt.Component.processFocusEvent(Unknown Source)
     at javax.swing.JComponent.processFocusEvent(Unknown Source)
     at java.awt.Component.processEvent(Unknown Source)
     at java.awt.Container.processEvent(Unknown Source)
     at java.awt.Component.dispatchEventImpl(Unknown Source)
     at java.awt.Container.dispatchEventImpl(Unknown Source)
     at java.awt.Component.dispatchEvent(Unknown Source)
     at java.awt.LightweightDispatcher.setFocusRequest(Unknown Source)
     at java.awt.Container.proxyRequestFocus(Unknown Source)
     at java.awt.Container.proxyRequestFocus(Unknown Source)
     at java.awt.Container.proxyRequestFocus(Unknown Source)
     at java.awt.Container.proxyRequestFocus(Unknown Source)
     at java.awt.Container.proxyRequestFocus(Unknown Source)
     at java.awt.Container.proxyRequestFocus(Unknown Source)
     at java.awt.Component.requestFocus(Unknown Source)
     at javax.swing.JComponent.grabFocus(Unknown Source)
     at javax.swing.JComponent.requestFocus(Unknown Source)
     at se.rsv.fa.tk.client.application.view.FaTkSearchBar.updateData(FaTkSearchBar.java:161)
     at se.rsv.fa.tk.client.control.FaTkModelListener.modelChanged(FaTkModelListener.java:54)
     at se.rsv.fa.tk.client.model.FaTkModel.fireChangedEvent(FaTkModel.java:78)
     at se.rsv.fa.tk.client.model.FaTkModel.setData(FaTkModel.java:110)
     at se.rsv.fa.tk.client.model.FaTkModel.runUpdate(FaTkModel.java:57)
     at se.rsv.fa.tk.client.view.FaTkSelectBox.fireDataEvent(FaTkSelectBox.java:89)
at se.rsv.fa.tk.client.view.FaTkSelectBox$FaTkSelectionListener.itemStateChanged(FaTkSelectBox.java:109)
     at javax.swing.JComboBox.fireItemStateChanged(Unknown Source)
     at javax.swing.JComboBox.selectedItemChanged(Unknown Source)
     at javax.swing.JComboBox.contentsChanged(Unknown Source)
     at javax.swing.AbstractListModel.fireContentsChanged(Unknown Source)
     at javax.swing.DefaultComboBoxModel.setSelectedItem(Unknown Source)
     at javax.swing.JComboBox.setSelectedItem(Unknown Source)
     at javax.swing.JComboBox.setSelectedIndex(Unknown Source)
     at javax.swing.plaf.basic.BasicComboBoxUI.selectPreviousPossibleValue(Unknown Source)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI.selectPreviousPossibleValue(Unknown Source)
     at com.sun.java.swing.plaf.windows.WindowsComboBoxUI$UpAction.actionPerformed(Unknown Source)
     at javax.swing.SwingUtilities.notifyAction(Unknown Source)
     at javax.swing.JComponent.processKeyBinding(Unknown Source)
     at javax.swing.JComponent.processKeyBindings(Unknown Source)
     at javax.swing.JComponent.processKeyEvent(Unknown Source)
     at javax.swing.JComboBox.processKeyEvent(Unknown Source)
     at java.awt.Component.processEvent(Unknown Source)
     at java.awt.Container.processEvent(Unknown Source)
     at java.awt.Component.dispatchEventImpl(Unknown Source)
     at java.awt.Container.dispatchEventImpl(Unknown Source)
     at java.awt.Component.dispatchEvent(Unknown Source)
     at java.awt.LightweightDispatcher.processKeyEvent(Unknown Source)
     at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
     at java.awt.Container.dispatchEventImpl(Unknown Source)
     at java.awt.Window.dispatchEventImpl(Unknown Source)
     at java.awt.Component.dispatchEvent(Unknown Source)
     at java.awt.EventQueue.dispatchEvent(Unknown Source)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

Hi everyone, I have changed nick from mbr1799 to Mr. Brodd
Ok guys, here is a program that reproduces the exception.
Copy, compile and run!
import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.event.*;
import javax.swing.*;
public class ClipTest extends JFrame
implements ActionListener, KeyListener, FocusListener
JTextField tf = new JTextField(20);
JTextField tf2 = new JTextField(20);
JComboBox cb = null;
JComboBox cb2 = null;
JButton b = null;
JLabel l1 = new JLabel("Kommun");
JLabel l2 = new JLabel("Taxenhet");
Box toolBox = new Box(BoxLayout.X_AXIS);
String keys = null;
public ClipTest() {
String lookAndFeel = "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
try {
UIManager.setLookAndFeel(lookAndFeel);
catch (ClassNotFoundException e) {
System.out.println("Couldn't find class for specified look and feel:" + lookAndFeel);
System.out.println("Did you include the L&F library in the class path?");
System.out.println("Using the default look and feel.");
catch (UnsupportedLookAndFeelException e) {
System.out.println("Can't use the specified look and feel ("+ lookAndFeel + ") on this platform.");
System.out.println("Using the default look and feel.");
catch (Exception e) {
System.out.println("Couldn't get specified look and feel ("+ lookAndFeel+ "), for some reason.");
System.out.println("Using the default look and feel.");
//e.printStackTrace();
init();
public static void main(String[] args) {
ClipTest ct = new ClipTest();
public void init() {
button.setBackground(Color.blue);
Box topBox = new Box(BoxLayout.Y_AXIS);
String[] listExamples = {"kommun", "taxenhet"};
cb2 = new JComboBox(listExamples);
cb2.addActionListener(this);
tf.addFocusListener(this);
tf2.addFocusListener(this);
fixBox();
this.getContentPane().add(toolBox);
this.pack();
setVisible(true);
private void fixBox()
toolBox.add(Box.createHorizontalStrut(5));
toolBox.add(cb2);
toolBox.add(Box.createHorizontalStrut(5));
toolBox.add(l1);
toolBox.add(tf);
toolBox.add(Box.createHorizontalStrut(5));
toolBox.add(l2);
toolBox.add(tf2);
l2.setVisible(false);
tf2.setVisible(false);
private void fixBoxKommun() {
l1.setVisible(true);
tf.setVisible(true);
l2.setVisible(false);
tf2.setVisible(false);
tf.requestFocus();
private void fixBoxTax() {
l1.setVisible(false);
tf.setVisible(false);
l2.setVisible(true);
tf2.setVisible(true);
tf2.requestFocus();
public void actionPerformed(ActionEvent e) {
System.out.println("Action " + e.toString());
String selected = (String)cb2.getSelectedItem();
if(selected.equals("kommun"))
fixBoxKommun();
else if(selected.equals("taxenhet"))
fixBoxTax();
else
System.out.println("Huh??");
public void keyPressed(KeyEvent ke) {
public void keyReleased(KeyEvent ke) {
public void keyTyped(KeyEvent ke) {
public void lostOwnership(Clipboard cb, Transferable tr)
public void focusGained(FocusEvent fe) {
if(tf.isVisible())
tf.selectAll();
else if(tf2.isVisible())
tf2.selectAll();
public void focusLost(FocusEvent fe) {
}