JComponent unreachable by tabbing, but SHIFT-tab works??

Question

Hey all,
I have some weird behaviour happening with a JComboBox in the following JPanel code. The JPanel has several JLabels, JTextFields and JComboBoxes. All button one (the last one) of the JTextFields and JComboBoxes is reachable by pressing the TAB button. However, I can get to it if I press SHIFT+TAB and go through my focusable components backwards.
Either I'm missing something very simple, or maybe this is a bug. I would think it's me, not Java, that is causing this problem.
Any help is appreciated. Thanks.
* Created on Jul 20, 2006
* To change the template for this generated file go to
* Window>Preferences>Java>Code Generation>Code and Comments
package GUI;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import inputHandlers.DigitDocument;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.TitledBorder;
* @author Michael C. Freake
* To change the template for this generated type comment go to
* Window>Preferences>Java>Code Generation>Code and Comments
public class CurrCovgPanel extends JPanel implements FocusListener{
     private static int WIDTH, HEIGHT;
     private static Color BACKGROUND_COLOR, GREEN_COLOR = Color.GREEN, WHITE_COLOR = Color.WHITE;
     public CurrCovgPanel(Color bgColor, int width, int height){
          super(new FlowLayout(FlowLayout.LEADING,0,1));
          //BACKGROUND_COLOR = bgColor;
BACKGROUND_COLOR = Color.BLUE;
          WIDTH = width;
          HEIGHT = height;
          init();
          // TODO Create a 'load' method that would put actual buffer values in the components.
          // Otherwise we can default to blank/default values in all fields.
          // TODO May want to create and call validate method here that would indicate any errors
          // to the user on load.
          // OR Have the CovgApp call this validate method AFTER the screen has been loaded.
     public void init(){
          setBackground(BACKGROUND_COLOR);
          setPreferredSize(new Dimension(WIDTH,HEIGHT));
          setBorder(BorderFactory.createTitledBorder(
                                        BorderFactory.createLineBorder(Color.YELLOW),
                                        "CURRENT COVERAGE AND PREMIUMS",
                                        TitledBorder.CENTER, TitledBorder.TOP,
                                        null, Color.YELLOW));
          int labelHeight = 15;
          // The following components should be Globals to whatever class they end up in.
          // If they are globals, we can access their values and modify them in other methods.
          JTextField buildLimit1 = new JTextField(new DigitDocument(4),"0",0);
          buildLimit1.setPreferredSize(new Dimension(35,labelHeight));
          buildLimit1.setHorizontalAlignment(JTextField.RIGHT);
          buildLimit1.setForeground(Color.CYAN);
          buildLimit1.setBackground(BACKGROUND_COLOR);
          buildLimit1.setBorder(null);
          buildLimit1.addFocusListener(this);
          JTextField buildLimit2 = new JTextField(new DigitDocument(4),"0",0);
          buildLimit2.setPreferredSize(new Dimension(35,labelHeight));
          buildLimit2.setHorizontalAlignment(JTextField.RIGHT);
          buildLimit2.setForeground(Color.CYAN);
          buildLimit2.setBackground(BACKGROUND_COLOR);
          buildLimit2.setBorder(null);
          buildLimit2.addFocusListener(this);     
          JComboBox buildDed1 = new JComboBox();
          buildDed1.setPreferredSize(new Dimension(60, labelHeight));
          buildDed1.setForeground(Color.CYAN);
          JComboBox buildDed2 = new JComboBox();
          buildDed2.setPreferredSize(new Dimension(60, labelHeight));
          buildDed2.setForeground(Color.CYAN);
          JComboBox buildForm1 = new JComboBox();
          buildForm1.setPreferredSize(new Dimension(60, labelHeight));
          buildForm1.setForeground(Color.CYAN);
          JComboBox buildForm2 = new JComboBox();
          buildForm2.setPreferredSize(new Dimension(60, labelHeight));
          buildForm2.setForeground(Color.CYAN);
          JLabel buildPrem1 = new JLabel("1234",JLabel.RIGHT);
          buildPrem1.setPreferredSize(new Dimension(30,labelHeight));
          buildPrem1.setForeground(Color.CYAN);
          JLabel buildPrem2 = new JLabel("5678",JLabel.RIGHT);
          buildPrem2.setPreferredSize(new Dimension(30,labelHeight));
          buildPrem2.setForeground(Color.CYAN);
          JTextField contLimit1 = new JTextField(new DigitDocument(4),"0",0);
          contLimit1.setPreferredSize(new Dimension(35,labelHeight));
          contLimit1.setHorizontalAlignment(JTextField.RIGHT);
          contLimit1.setForeground(Color.CYAN);
          contLimit1.setBackground(BACKGROUND_COLOR);
          contLimit1.setBorder(null);
          contLimit1.addFocusListener(this);     
          JTextField contLimit2 = new JTextField(new DigitDocument(4),"0",0);
          contLimit2.setPreferredSize(new Dimension(35,labelHeight));
          contLimit2.setHorizontalAlignment(JTextField.RIGHT);
          contLimit2.setForeground(Color.CYAN);
          contLimit2.setBackground(BACKGROUND_COLOR);
          contLimit2.setBorder(null);
          contLimit2.addFocusListener(this);
          JComboBox contDed1 = new JComboBox();
          contDed1.setPreferredSize(new Dimension(60, labelHeight));
          contDed1.setForeground(Color.CYAN);
          JComboBox contDed2 = new JComboBox();
          contDed2.setPreferredSize(new Dimension(60, labelHeight));
          contDed2.setForeground(Color.CYAN);
          JComboBox contForm1 = new JComboBox();
          contForm1.setPreferredSize(new Dimension(60,labelHeight));
          contForm1.setForeground(Color.CYAN);          
          JComboBox contForm2 = new JComboBox();
          contForm2.setPreferredSize(new Dimension(60,labelHeight));
          contForm2.setForeground(Color.CYAN);
          JLabel contPrem1 = new JLabel("4321",JLabel.RIGHT);
          contPrem1.setPreferredSize(new Dimension(30,labelHeight));
          contPrem1.setForeground(Color.CYAN);
          JLabel contPrem2 = new JLabel("8765",JLabel.RIGHT);
          contPrem2.setPreferredSize(new Dimension(30,labelHeight));
          contPrem2.setForeground(Color.CYAN);
          JComboBox liabLimit = new JComboBox();
          liabLimit.setPreferredSize(new Dimension(60,labelHeight));
          liabLimit.setForeground(Color.CYAN);
          JLabel liabPrem1 = new JLabel("7", JLabel.RIGHT);
          liabPrem1.setPreferredSize(new Dimension(30,labelHeight));
          liabPrem1.setForeground(Color.CYAN);
          JLabel liabPrem2 = new JLabel("7", JLabel.RIGHT);
          liabPrem2.setPreferredSize(new Dimension(30,labelHeight));
          liabPrem2.setForeground(Color.CYAN);
          JComboBox liabForm = new JComboBox();
          liabForm.setPreferredSize(new Dimension(60,labelHeight));
          liabForm.setForeground(Color.CYAN);
//          ********** THIS IS THE JCOMBOBOX THAT SHOULD TAB INTO THE glassLimit JCOMBOBOX          
          JComboBox medLimit = new JComboBox();
          medLimit.setPreferredSize(new Dimension(60,labelHeight));
          medLimit.setForeground(Color.CYAN);
          JLabel medPrem = new JLabel("12", JLabel.RIGHT);
          medPrem.setPreferredSize(new Dimension(30,labelHeight));
          medPrem.setForeground(Color.CYAN);
//          ********** THIS IS THE JCOMBOBOX THAT ISN"T ALLOWING FOCUS
          JComboBox glassLimit = new JComboBox();
          glassLimit.setPreferredSize(new Dimension(60,labelHeight));
          glassLimit.setForeground(Color.CYAN);
          JLabel glassPrem = new JLabel("5", JLabel.RIGHT);
          glassPrem.setPreferredSize(new Dimension(30,labelHeight));
          glassPrem.setForeground(Color.CYAN);
          JLabel grcYN = new JLabel("N", JLabel.LEFT);
          grcYN.setPreferredSize(new Dimension(30,labelHeight));
          grcYN.setForeground(WHITE_COLOR);
          JLabel subTotalPrem1 = new JLabel("539", JLabel.RIGHT);
          subTotalPrem1.setPreferredSize(new Dimension(30,labelHeight));
          subTotalPrem1.setForeground(WHITE_COLOR);
          JLabel subTotalPrem2 = new JLabel("554", JLabel.RIGHT);
          subTotalPrem2.setPreferredSize(new Dimension(30,labelHeight));
          subTotalPrem2.setForeground(WHITE_COLOR);
          // Setting up and adding Location 1 & 2 headers
          JLabel loc1 = new JLabel("Location 1", JLabel.RIGHT);
          loc1.setPreferredSize(new Dimension(60,labelHeight));
          loc1.setForeground(Color.YELLOW);
          JLabel loc2 = new JLabel("Location 2", JLabel.RIGHT);
          loc2.setPreferredSize(new Dimension(60,labelHeight));
          loc2.setForeground(Color.YELLOW);
          JLabel prem1 = new JLabel("Premium", JLabel.RIGHT);
          prem1.setPreferredSize(new Dimension(60,labelHeight));
          prem1.setForeground(Color.YELLOW);
          JLabel prem2 = new JLabel("Premium", JLabel.RIGHT);
          prem2.setPreferredSize(new Dimension(60,labelHeight));
          prem2.setForeground(Color.YELLOW);
          add(loc1);
          add(Box.createHorizontalStrut(155));
          add(prem1);
          add(Box.createHorizontalStrut(30));
          add(loc2);
          add(Box.createHorizontalStrut(155));
          add(prem2);
          // Setting up static JLabels for viewing on the screen
          JLabel build = new JLabel("BUILD", JLabel.RIGHT);
          build.setPreferredSize(new Dimension(40,labelHeight));
          build.setForeground(GREEN_COLOR);
          JLabel cont = new JLabel("CONT", JLabel.RIGHT);
          cont.setPreferredSize(new Dimension(40, labelHeight));
          cont.setForeground(GREEN_COLOR);
          JLabel liab = new JLabel("LIAB", JLabel.RIGHT);
          liab.setPreferredSize(new Dimension(40, labelHeight));
          liab.setForeground(GREEN_COLOR);
          JLabel med = new JLabel("MED", JLabel.RIGHT);
          med.setPreferredSize(new Dimension(40, labelHeight));
          med.setForeground(GREEN_COLOR);
          JLabel glass = new JLabel("GLASS", JLabel.RIGHT);
          glass.setPreferredSize(new Dimension(40,labelHeight));
          glass.setForeground(GREEN_COLOR);
          JLabel grc = new JLabel("GRC", JLabel.RIGHT);
          grc.setPreferredSize(new Dimension(40,labelHeight));
          grc.setForeground(GREEN_COLOR);
          JLabel subTotal = new JLabel("SUB TOTAL", JLabel.LEFT);
          subTotal.setPreferredSize(new Dimension(70,labelHeight));
          subTotal.setForeground(GREEN_COLOR);
          JLabel ded1 = new JLabel("ded", JLabel.RIGHT);
          ded1.setPreferredSize(new Dimension(40, labelHeight));
          ded1.setForeground(WHITE_COLOR);
          JLabel ded2 = new JLabel("ded", JLabel.RIGHT);
          ded2.setPreferredSize(new Dimension(40,labelHeight));
          ded2.setForeground(WHITE_COLOR);
          JLabel form1 = new JLabel("form", JLabel.RIGHT);
          form1.setPreferredSize(new Dimension(40, labelHeight));
          form1.setForeground(WHITE_COLOR);
          JLabel form2 = new JLabel("form", JLabel.RIGHT);
          form2.setPreferredSize(new Dimension(40, labelHeight));
          form2.setForeground(WHITE_COLOR);
          JLabel form3 = new JLabel("form", JLabel.RIGHT);
          form3.setPreferredSize(new Dimension(40, labelHeight));
          form3.setForeground(WHITE_COLOR);
          // Load the coverage JPanel to the Window
          // Line 1 - BUILD
          add(build);
          add(Box.createHorizontalStrut(5));
          add(buildLimit1);
          add(Box.createHorizontalStrut(230));
          add(buildLimit2);
          add(Box.createHorizontalStrut(210));
          // Line 2 - BUILD Deductible
          add(ded1);
          add(Box.createHorizontalStrut(5));
          add(buildDed1);
          add(Box.createHorizontalStrut(200));
          add(buildDed2);
          add(Box.createHorizontalStrut(180));
          // Line 3 - BUILD Form
          add(form1);
          add(Box.createHorizontalStrut(5));
          add(buildForm1);
          add(Box.createHorizontalStrut(140));
          add(buildPrem1);
          add(Box.createHorizontalStrut(30));
          add(buildForm2);
          add(Box.createHorizontalStrut(180));
          add(buildPrem2);
          // Line 4 - CONT
          add(cont);
          add(Box.createHorizontalStrut(5));
          add(contLimit1);
          add(Box.createHorizontalStrut(230));
          add(contLimit2);
          add(Box.createHorizontalStrut(210));
          // Line 5 - CONT Deductible
          add(ded2);
          add(Box.createHorizontalStrut(5));
          add(contDed1);
          add(Box.createHorizontalStrut(200));
          add(contDed2);
          add(Box.createHorizontalStrut(180));
          // Line 6 - CONT Form
          add(form2);
          add(Box.createHorizontalStrut(5));
          add(contForm1);
          add(Box.createHorizontalStrut(140));
          add(contPrem1);
          add(Box.createHorizontalStrut(30));
          add(contForm2);
          add(Box.createHorizontalStrut(180));
          add(contPrem2);
          // Line 7 - LIAB
          add(liab);
          add(Box.createHorizontalStrut(5));
          add(liabLimit);
          add(Box.createHorizontalStrut(140));
          add(liabPrem1);
          add(Box.createHorizontalStrut(270));
          add(liabPrem2);
          // Line 8 - LIAB Form
          add(form3);
          add(Box.createHorizontalStrut(5));
          add(liabForm);
          add(Box.createHorizontalStrut(460));
          // Line 9 - MED
          add(med);
          add(Box.createHorizontalStrut(5));
          add(medLimit);
          add(Box.createHorizontalStrut(140));
          add(medPrem);
          add(Box.createHorizontalStrut(270));
          // Line 10 - GLASS
          add(glass);
          add(Box.createHorizontalStrut(5));
          add(glassLimit);
          add(Box.createHorizontalStrut(140));
          add(glassPrem);
          add(Box.createHorizontalStrut(280));
          // Line 11 - GRC
          add(grc);
          add(Box.createHorizontalStrut(5));
          add(grcYN);
          add(Box.createHorizontalStrut(440));
          // Line 12 - SUB TOTAL
          add(subTotal);
          add(Box.createHorizontalStrut(175));
          add(subTotalPrem1);
          add(Box.createHorizontalStrut(270));
          add(subTotalPrem2);
     /* (non-Javadoc)
      * @see java.awt.event.FocusListener#focusGained(java.awt.event.FocusEvent)
     public void focusGained(FocusEvent e) {
          // TODO Could adjust color here to look better.
          JComponent theComp = (JComponent) e.getSource();
          if (theComp instanceof JTextField){
               theComp.setBackground(Color.WHITE);
          System.out.println("theComp = " + theComp);
     /* (non-Javadoc)
      * @see java.awt.event.FocusListener#focusLost(java.awt.event.FocusEvent)
     public void focusLost(FocusEvent e) {
          // TODO Could perform validation checks and do call to rating here.
          JComponent theComp = (JComponent) e.getSource();
          if (theComp instanceof JTextField){
               theComp.setBackground(BACKGROUND_COLOR);
          System.out.println("theComp = " + theComp);
}

Answer 1

Here some code to help anyone run and view my panel:
Main:
package GUI;
import java.awt.Color;
import javax.swing.JFrame;
public class ShowPanel extends JFrame{
     public ShowPanel(){
          super();
          setTitle("MY Example");
          getContentPane().add(new CurrCovgPanel(Color.BLUE, 590,240));
          pack();
          setResizable(false);
          setVisible(true);
     public static void main(String[] args){
          ShowPanel a = new ShowPanel();
}Another need component:
package inputHandlers;
import java.awt.Toolkit;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
public class DigitDocument extends PlainDocument{
     private int maxChars;
     public DigitDocument(int maxChars){
          super();
          this.maxChars = maxChars;
     public void insertString(int offs, String str, AttributeSet a) throws BadLocationException, NumberFormatException{
       try{
          if(this.getLength()+str.length() > maxChars) throw new NumberFormatException();//<----
          int i = Integer.parseInt(str);
          super.insertString(offs, str, a);
       catch(NumberFormatException e){
          // do nothing because a user input was not a digit
          Toolkit.getDefaultToolkit().beep();
}