JCardPane

<code=java> /*

* JCardPane.java
* wraps a JTabbedPane, hiding the tabs.
* The main method shows an example.
*/

import java.awt.*; import java.awt.event.*; import java.beans.*; import java.util.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.plaf.TabbedPaneUI; import javax.swing.plaf.basic.BasicTabbedPaneUI;

public class JCardPane extends JComponent {

   private JTabbedPane pane;
   private CardAction nextAction;
   private CardAction previousAction;
   private TabFocusHandler tabFocusHandler;
   private TabbedPaneUI uiNoTabs = new BasicTabbedPaneUI() {

       @Override
       protected int calculateTabAreaHeight(int tabPlacement,
               int horizRunCount, int maxTabHeight) {
           return 0;
       }

       @Override
       protected Insets getContentBorderInsets(int tabPlacement) {
           return new Insets(0, 0, 0, 0);
       }

       @Override
       protected MouseListener createMouseListener() {
           return null;
       }

       @Override
       protected void installKeyboardActions() {
       }

       @Override
       protected int calculateTabWidth(int tabPlacement, int tabIndex, FontMetrics metrics) {
           return 0;
       }
   };

   /**
    * Creates an empty cardpane
    */
   public JCardPane() {
       pane = new JTabbedPane();
       tabFocusHandler = new TabFocusHandler(pane);
       hideTabs();
       pane.addChangeListener(new ChangeListener() {

           public void stateChanged(ChangeEvent e) {
               if (nextAction != null) {
                   nextAction.setEnabled(hasNext());
               }
               if (previousAction != null) {
                   previousAction.setEnabled(hasPrevious());
               }
           }
       });
       setLayout(new BorderLayout());
       add(pane);
   }

   /**
    * Flips to the first card of the cardpane.
    * @return 0 if this cardpane has a card
    * or -1 if this cardpane has no card
    */
   public int first() {
       return show(0);
   }

   /**
    * Flips to the last card of the cardpane.
    * @return 0 if this cardpane has a card
    * or -1 if this cardpane has no card
    */
   public int last() {
       return show(-1);
   }

   /**
    * Flips to the next card of the cardpane.
    * If the currently visible card is the last one,
    * this method flips to the first card of the cardpane.
    * @return the index of the card
    * or -1 if this cardpane has no card
    */
   public int next() {
       return show(pane.getSelectedIndex() + 1);
   }

   /**
    * Flips to the previous card of the cardpane.
    * If the currently visible card is the first one,
    * this method flips to the last card of the cardpane.
    * @return the index of the card
    * or -1 if this cardpane has no card
    */
   public int previous() {
       return show(pane.getSelectedIndex() - 1);
   }

   /**
    * Flips to the card at the specified index.
    * If the index is positive but does not exist,
    * this method flips to the first card of the cardpane.
    * If the index is negative,
    * this method flips to the last card of the cardpane.
    * @return the index of the card
    * or -1 if this cardpane has no card
    */
   public int show(final int index) {
       if (pane.getTabCount() == 0) {
           return -1;
       }
       if (index >= pane.getTabCount()) {
           pane.setSelectedIndex(0);
           return 0;

       }
       if (index < 0) {
           pane.setSelectedIndex(pane.getTabCount() - 1);
           return pane.getTabCount() - 1;

       }
       pane.setSelectedIndex(index);
       return index;
   }

   /**
    * Flips to the card with the specified name.
    * If the name does not exist, nothing happens.
    * @return the index of the card
    * or -1 if the name does not exist
    */
   public int show(final String name) {
       int index = pane.indexOfTab(name);
       if (index >= 0) {
           pane.setSelectedIndex(index);
       }
       return index;
   }

   /**
    * Flips to the specified card.
    * If the card does not exist in the cardpane, it is added to it.
    * @return the index of the specified card
    */
   public int show(final JComponent card) {
       int index = pane.indexOfComponent(card);
       if (index < 0) {
           index = pane.getTabCount();
           pane.addTab(card.getName(), card);
       }
       pane.setSelectedIndex(index);
       return index;
   }

   /**
    * @return true if there is a card after the visible one
    */
   public boolean hasNext() {
       return pane.getSelectedIndex() < pane.getComponentCount() - 1;
   }

   /**
    * @return true if there is a card before the visible one
    */
   public boolean hasPrevious() {
       return pane.getSelectedIndex() > 0;
   }

   /**
    * @return the visible card
    */
   public Component getCurrent() {
       return pane.getSelectedComponent();
   }

   /**
    * Adds a ChangeListener to this cardpane.
    */
   public void addChangeListener(ChangeListener l) {
       pane.addChangeListener(l);
   }

   /**
    * Removes a ChangeListener from this cardpane.
    */
   public void removeChangeListener(ChangeListener l) {
       pane.removeChangeListener(l);
   }

   /**
    * gets the action to be used for a "Next" button
    */
   public Action getNextAction() {
       if (nextAction == null) {
           nextAction = new CardAction("Next", true);
           nextAction.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_N);
           nextAction.setEnabled(hasNext());
       }
       return nextAction;
   }

   /**
    * gets the action to be used for a "Previous" button
    */
   public Action getPreviousAction() {
       if (previousAction == null) {
           previousAction = new CardAction("Previous", false);
           previousAction.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_P);
           previousAction.setEnabled(hasPrevious());
       }
       return previousAction;
   }

   /**
    * 
    * retain: if true, the component focused within a card will remain focused
    * each time it becomes visible, otherwise the first component of each card is focused
    */
   public void retainFocus(boolean retain) {
       int focusPolicy = TabFocusHandler.RESET_FOCUS;
       if (retain) {
           focusPolicy = TabFocusHandler.RETAIN_FOCUS;
       }
       tabFocusHandler.uninstall();
       tabFocusHandler = new TabFocusHandler(pane, focusPolicy);
   }

   private void hideTabs() {
       pane.setUI(uiNoTabs);
   }

   private class CardAction extends AbstractAction {

       private boolean isNext;

       public CardAction(String text, boolean isNext) {
           super(text);
           this.isNext = isNext;
           putValue(Action.SHORT_DESCRIPTION, getValue(Action.NAME));
       }

       public void actionPerformed(ActionEvent e) {
           if (isNext) {
               next();
           } else {
               previous();
           }
       }
   }

   /**
    *  Manage the focus when a new tab is selected. You can select a focus policy:
    *  a) Reset Focus - focus is reset to the first focusable component on the tab
    *  b) Retain Focus - focus returns to the last component with focus on the tab
    *
    *  In addition you add tabs that you want to exclude from the focus policy,
    *  in which case the other policy will be in effect.
    */
   private class TabFocusHandler implements ChangeListener, PropertyChangeListener {

       public final static int RESET_FOCUS = 0;
       public final static int RETAIN_FOCUS = 1;
       private HashMap<Component, Component> tabFocus = new HashMap<Component, Component>();
       private HashSet<Component> exceptions;
       private JTabbedPane tabbedPane;
       private int focusPolicy;
       private final KeyboardFocusManager focusManager;

       /**
        *  Create with the default Retain Focus policy
        */
       public TabFocusHandler(JTabbedPane tabbedPane) {
           this(tabbedPane, RETAIN_FOCUS);
       }

       /**
        *  Create using the specified focus policy
        */
       public TabFocusHandler(JTabbedPane tabbedPane, int focusPolicy) {
           if (focusPolicy != RESET_FOCUS && focusPolicy != RETAIN_FOCUS) {
               throw new IllegalArgumentException("Invalid focus policy");
           }
           this.tabbedPane = tabbedPane;
           this.focusPolicy = focusPolicy;
           //  Add listeners to manage a tab change
           tabbedPane.addChangeListener(this);
           focusManager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
           focusManager.addPropertyChangeListener("permanentFocusOwner", this);
       }

       public void uninstall() {
           tabbedPane.removeChangeListener(this);
           focusManager.removePropertyChangeListener(this);
       }

       /**
        *  Specify a tab with an exception to the focus policy rule
        */
       public void addException(int index) {
           if (exceptions == null) {
               exceptions = new HashSet<Component>();
           }
           Component key = tabbedPane.getComponentAt(index);
           exceptions.add(key);
       }

       /**
        * Tab has changed. Focus on saved component for the given tab.
        * When there is no saved component, focus on the first component.
        */
       public void stateChanged(ChangeEvent e) {
           Component key = tabbedPane.getComponentAt(tabbedPane.getSelectedIndex());
           if (key == null) {
               return;
           }
           Component value = tabFocus.get(key);
           //  First time selecting this tab or focus policy is RESET_FOCUS
           if (value == null) {
               key.transferFocus();
               tabFocus.put(key, value);
           } else //  Use the saved component for focusing
           {
               value.requestFocusInWindow();
           }
       }

       /**
        *  Track focus changes and update the current focus component
        *  for the current tab
        */
       public void propertyChange(PropertyChangeEvent e) {
           //  No need to track focus change
           if (exceptions == null && focusPolicy == RESET_FOCUS) {
               return;
           }
           //  Check for exceptions to the focus policy exist
           Component key = tabbedPane.getComponentAt(tabbedPane.getSelectedIndex());
           if (exceptions != null) {
               if (focusPolicy == RESET_FOCUS && !exceptions.contains(key)) {
                   return;
               }
               if (focusPolicy == RETAIN_FOCUS && exceptions.contains(key)) {
                   return;
               }
           }
           // Track focus changes for the tab
           Component value = (Component) e.getNewValue();
           if (value != null && SwingUtilities.isDescendingFrom(value, key)) {
               tabFocus.put(key, value);
           }
       }
   }

   //for testing only:
   public static void main(final String[] args) {
       try {
           UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
       } catch (Exception ex) {
           ex.printStackTrace();
       }
       Runnable gui = new Runnable() {

           @Override
           public void run() {
               final JFrame f = new JFrame("JCardPane Demo");
               f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               f.setSize(400, 150);
               f.setLocationRelativeTo(null);
               final JCardPane cardPane = new JCardPane();
               f.add(cardPane, BorderLayout.CENTER);
               class Card extends JPanel {

                   public Card(final String name) {
                       JTextField tf = new JTextField(20);
                       tf.setText(name);
                       add(tf);
                       tf = new JTextField(20);
                       tf.setText(name);
                       add(tf);
                       setName(name);
                   }
               }
               for (int i = 0; i < 5; i++) {
                   cardPane.show(new Card(String.valueOf(i + 1)));
               }
               cardPane.first();
               JPanel control = new JPanel();
               control.add(new JButton(cardPane.getPreviousAction()));
               control.add(new JButton(cardPane.getNextAction()));
               f.add(control, BorderLayout.SOUTH);
               f.setVisible(true);
           }
       };
       //GUI must start on EventDispatchThread:
       SwingUtilities.invokeLater(gui);
   }

} </code=java>