Facing troubles with "requestFocus()"

Question

Hi
Can anyone help me telling what is wrong with my code?. I hv 2 JTextFields and both will hv their values checked when losing focus. My problem is that a MessageDialog is showed telling what's wrong for the user, but then when ok button is clicked, the same messagedialog appears but with no button or message and everything freezes.
Here's my code
public void focusGained(FocusEvent e)
public void focusLost(FocusEvent e)
if (e.getSource().equals(edtCityCode))
//check if CityCode is valid or not               
if (!valid)
JOptionPane.showMessageDialog(null, "This code is not valid. Type another");
edtCityCode.requestFocus();
else if (e.getSource().equals(edtCityName))
if (edtCityName.getText().equalsIgnoreCase(""))
JOptionPane.showMessageDialog(null, "You must type field = cityname");
edtCityName.requestFocus();
Thanks in advance.

Answer 1

After reading all over Sun/Google/Yahoo about this bug and the workarounds posted for this problem I finally got to get it to work as per my requirements.
Following were some of the constraints that I had:-
1) All screens are already developed and buttons are already coded so I cannot go back and
substitute extended JButton instance with has altered behaviour regarding focus events.
So the one possible workaround that for this problem which involved extending JButton was ruled out.
2) I want to make the IV generic so that it can read from some property file the rules to validate this.
(I did not include this stuff in the implementation below but if you need that you can ask via email.
3) I did not liked the idea of altering the basic plaf which was another way how people have worked out their ways from this problem.
So here is my solution.
1: Assign an extended verifier SCAInputVerifier to the JTextField/JTextArea. Pass the Container that contains the text field to the constructor of SCAInputVerifier.
2: First time when the verify() method is called it creates a SCAJFocusListner as listed below. It validates and keeps the result in SCAInputVerifier but always returns true.
3: As soon as the focus is about to loose to the next component the SCAJFocusListner comes into picture
and displays the message via JOptionPane.showMessageDialog().
(Before clicking the Ok button on this error message dialog if the user clicks on any AbstractButton it showed random behaviour.
This is addressed in point 5)
(Optional)
4: As a general rule I we have all Cancel button or Close button closing the JDialog and their name starts with Cancel.
If the user clicks cancel or close button on the screen user is allowed to go exit.
5: Now the main problem:If the focus was going to a AbstractButton it was showing weired behaviour.
It was getting pressed as soon as mouse was over that button.
This problem is fixed in focusLost() method of SCAFocusListener.
6: The focus is requested back into the text field.
* SCAFocusListener.java
* Created on August 14, 2003, 7:01 PM
package walgreens.sca.system;
import java.awt.event.*;
import javax.swing.*;
* @author Yogesh Gadge
public class SCAFocusListener extends FocusAdapter{
private SCAInputVerifier iv = null;
public SCAFocusListener(SCAInputVerifier iv) {
super();
this.iv=iv;
public void focusLost(FocusEvent fe) {
if ( (! iv.isGood()) && iv.getParentPane()!= null && iv.getParentPane().isVisible()) {
java.awt.Component opp = fe.getOppositeComponent();
//if cancel or close button
if (opp instanceof AbstractButton) {
AbstractButton aBut = (AbstractButton)opp;
String name = aBut.getText();
if(name != null && (name.trim().toLowerCase().startsWith("cancel") || name.trim().toLowerCase().startsWith("close"))) {
return;
//workaround for bug in JDK 1.4.1 bugID 4342333
ButtonModel mod = aBut.getModel();
aBut.revalidate();
if (mod.isArmed())
mod.setArmed(false);
if (mod.isPressed())
mod.setPressed(false);
JOptionPane.showMessageDialog(iv.getParentPane(),"Input is invalid.");
java.awt.Component c = fe.getComponent();
//fe.consume();
c.requestFocusInWindow();//InWindow();
} else
super.focusLost(fe);
import javax.swing.*;
import java.awt.event.*;
* @author Yogesh Gadge
public class SCAInputVerifier extends javax.swing.InputVerifier {
private java.awt.Container parentPane=null;
private boolean good = false;
private FocusListener focusListener = null;
/** Creates a new instance of SCAInputVerifier */
public SCAInputVerifier(java.awt.Container parentPane) {
this.parentPane=parentPane;
public boolean verify(javax.swing.JComponent comp) {
if (focusListener == null)
comp.addFocusListener(createFocusListener());
this.good=true;
if (comp instanceof javax.swing.text.JTextComponent) {
javax.swing.text.JTextComponent field = (javax.swing.text.JTextComponent) comp;
String input = field.getText();
System.out.println(input);
try {
//lets say it is convergence factor
double d = Double.parseDouble(input);
if (d < 0.0 || d >=1.0 )
good=false;
} catch(Exception e) {
good=false;
return true;
public boolean isGood() {
return this.good;
protected FocusListener createFocusListener() {
FocusListener f = new SCAFocusListener(this);
System.out.println(f);
this.focusListener=f;
return f ;
/** Setter for property good.
* @param good New value of property good.
public void setGood(boolean good) {
this.good = good;
/** Getter for property focusListener.
* @return Value of property focusListener.
public java.awt.event.FocusListener getFocusListener() {
return focusListener;
/** Setter for property focusListener.
* @param focusListener New value of property focusListener.
public void setFocusListener(java.awt.event.FocusListener focusListener) {
this.focusListener = focusListener;
/** Getter for property parentPane.
* @return Value of property parentPane.
public java.awt.Container getParentPane() {
return parentPane;
/** Setter for property parentPane.
* @param parentPane New value of property parentPane.
public void setParentPane(java.awt.Container parentPane) {
this.parentPane = parentPane;