Java Scrollable Popup Menu

SCROLLABLE JPOPUPMENU

Java Swing Tutorial Explaining the Scrollable Popup Menu Component. Scrollable JPopupMenu can be used in
any of the Java Applications.
I developed this as the popup menu can have so many menuitems that, they exceed the screen visible area
and would not be visible.
I needed a way to scroll through the menu items of the pop up menu to avoid this visibility problem.

SCROLLABLE POPUPMENU SOURCE CODE

Custom JButtons are placed on a JPanel. This JPanel is placed on JScrollPane which has a scrollbar.
These custom JButtons are nothing but menuitems. These menuitems can be checked and unchecked similar to JCheckBoxMenuItems.

My scrollable jpopupmenu source code contains 5 files.

1. JFramePopupMenu.java (Mainframe containing the button to invoke Scrollable popup menu)

2. XCheckedButton.java (Custom JButton which acts like a JCheckBoxMenuItem for the pop up menu.
This class provides a JCheckBoxMenuItrem Functionality, optionally working like a JMenuItem, primarily
used with XJPopupMenu. Rationale for development of this component was the inability of a JMenuItem to work
in a Scrollable Popup menu as in XJPopupMenu)

3. XJPopupMenu.java (This is the heart of Scrollable JPopupMenu code)

4. XConstant.java (Interface containing commonly used constants)

5. check.gif

6. menu_spacer.gif

Here is a source code showing, how to create a java swing JPopupMenu with a vertical scrollbar:

1. JFramePopupMenu.java

import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class JFramePopupMenu extends JFrame  {
 private JPanel jContentPane = null;
 private JButton jbnPopup = null;
 private JTextField jtfNumOfMenus = null;
 private JLabel lblNumElem = null;

    private XJPopupMenu scrollablePopupMenu = new XJPopupMenu(this);
    private JButton getBtnPopup() {

        if (jbnPopup == null) {
            jbnPopup = new JButton();
            jbnPopup.setText("View Scrollable popup menu ");
            int n = Integer.parseInt(getTxtNumElem().getText());

            for (int i=0;i&lt;n;i++){
             XCheckedButton xx = new XCheckedButton(" JMenuItem  " + (i+1));
                xx.addActionListener(new ActionListener(){
                    public void actionPerformed(ActionEvent e) {
                        System.out.println( e );
                        scrollablePopupMenu.hidemenu();
                    }

                });

                // Add Custom JSeperator after 2nd and 7th MenuItem.
                if(i == 2 || i == 7){
                 scrollablePopupMenu.addSeparator();
                }
                scrollablePopupMenu.add(xx);
            }

            jbnPopup.addMouseListener(new MouseAdapter() {
                public void mousePressed(MouseEvent e) {
                 Component source = (Component) e.getSource();
                 scrollablePopupMenu.show(source, e.getX(), e.getY());
    }
            });
        }

        return jbnPopup;
    }

 private JTextField getTxtNumElem() {
  if (jtfNumOfMenus == null) {
   jtfNumOfMenus = new JTextField();
   jtfNumOfMenus.setColumns(3);
   jtfNumOfMenus.setText("60");
  }
  return jtfNumOfMenus;
 }

 public static void main(String[] args) {
  SwingUtilities.invokeLater(new Runnable() {
   public void run() {
      JFramePopupMenu thisClass = new JFramePopupMenu();
                thisClass.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       thisClass.setVisible(true);
   }
  });
 }

 public JFramePopupMenu() {
  super();
  initialize();
 }

 private void initialize() {
  this.setSize(274, 109);
  this.setContentPane(getJContentPane());
  this.setTitle(" Scrollable JPopupMenu ");
 }

 private JPanel getJContentPane() {
  if (jContentPane == null) {
   lblNumElem = new JLabel();
   FlowLayout flowLayout = new FlowLayout();
   flowLayout.setHgap(8);
   flowLayout.setVgap(8);
   jContentPane = new JPanel();
   jContentPane.setLayout(flowLayout);
   jContentPane.add(getBtnPopup(), null);
   jContentPane.add(lblNumElem, null);
   jContentPane.add(getTxtNumElem(), null);
  }

  return jContentPane;
 }
}

2. XCheckedButton.java

import java.awt.Color;
import java.awt.event.ItemEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.Action;
import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JToggleButton;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.basic.BasicButtonUI;
/**
 * @author balajihe
 *
 */

public class XCheckedButton extends JButton {
 // Icon to be used to for the Checked Icon of the Button
 private static ImageIcon checkedIcon;
 
         /**
  * These colors are required in order to simulate the JMenuItem's L&amp;F
  */

 public static final Color MENU_HIGHLIGHT_BG_COLOR = UIManager.getColor
             ("MenuItem.selectionBackground");
 public static final Color MENU_HIGHLIGHT_FG_COLOR = UIManager.getColor
              ("MenuItem.selectionForeground");
 public static final Color MENUITEM_BG_COLOR = UIManager.getColor
              ("MenuItem.background");
 public static final Color MENUITEM_FG_COLOR = UIManager.getColor
              ("MenuItem.foreground");

 //  This property if set to false, will result in the checked Icon not being 
        //   displayed  when the button is selected
    private boolean displayCheck = true;
    public XCheckedButton() {
  super();
  init();
 }

 public XCheckedButton(Action a) {
  super(a);
  init();
 }

 public XCheckedButton(Icon icon) {
  super(icon);
  init();
 }

 public XCheckedButton(String text, Icon icon) {
  super(text, icon);
  init();
 }

 public XCheckedButton(String text) {
  super(text);
  init();
 }
 /**
  * Initialize component LAF and add Listeners
  */

 private void init() {
  MouseAdapter mouseAdapter = getMouseAdapter();
  // Basically JGoodies LAF UI for JButton does not allow
                   Background color to be set.
  
  // So we need to set the default UI, 

  ComponentUI ui = BasicButtonUI.createUI(this);
  this.setUI(ui);
  setBorder(BorderFactory.createEmptyBorder(3, 0, 3, 2));

  setMenuItemDefaultColors();

  // setContentAreaFilled(false);
  setHorizontalTextPosition(SwingConstants.RIGHT);
  setHorizontalAlignment(SwingConstants.LEFT);

  //  setModel(new JToggleButton.ToggleButtonModel());
  setModel(new XCheckedButtonModel());
  setSelected(false);
  this.addMouseListener(mouseAdapter);
 }

 private void setMenuItemDefaultColors() {
  XCheckedButton.this.setBackground(MENUITEM_BG_COLOR);
  XCheckedButton.this.setForeground(MENUITEM_FG_COLOR);
 }

 /**
  * @return
  */

 private MouseAdapter getMouseAdapter() {
  return new MouseAdapter() {

        // For static menuitems, the background color remains the highlighted color,
           if this is not overridden

   public void mousePressed(MouseEvent e) {
    setMenuItemDefaultColors();
   }

   public void mouseEntered(MouseEvent e) {
    XCheckedButton.this.setBackground(MENU_HIGHLIGHT_BG_COLOR);
    XCheckedButton.this.setForeground(MENU_HIGHLIGHT_FG_COLOR);
   }

   public void mouseExited(MouseEvent e) {
    setMenuItemDefaultColors();
   }
  };
 }

 /**  * @param checkedFlag

  */

 public void displayIcon(boolean checkedFlag) {
  if (checkedFlag &amp;&amp; isDisplayCheck()) {
   if (checkedIcon == null) {
    checkedIcon = new ImageIcon("check.gif");
   }
   this.setIcon(checkedIcon);
  } else {
   this.setIcon(XConstant.EMPTY_IMAGE_ICON);
  }
  this.repaint();
 }
 private class XCheckedButtonModel extends JToggleButton.ToggleButtonModel {
  /*
   * Need to Override keeping the super code, else the check mark won't come  
   */

  public void setSelected(boolean b) {
   ButtonGroup group = getGroup();
   if (group != null) {
    // use the group model instead
    group.setSelected(this, b);
    b = group.isSelected(this);
   }
   if (isSelected() == b) {
    return;
   }

   if (b) {
    stateMask |= SELECTED;
   } else {
    stateMask &amp;= ~SELECTED;
   }

   // Send ChangeEvent
   fireStateChanged();
   // Send ItemEvent
   fireItemStateChanged(new ItemEvent(this, ItemEvent.ITEM_STATE_CHANGED, 
                          this,this.isSelected() ? ItemEvent.SELECTED : ItemEvent.DESELECTED));
   XCheckedButton.this.displayIcon(b);
  }
 }

       // Returns true if Button will display Checked Icon on Click. Default Behaviour is 
       // to display a Checked Icon  

 public boolean isDisplayCheck() {
  return displayCheck;
 }

 /**
  * Sets the property which determines whether a checked Icon should be displayed or not
  * Setting to false, makes this button display like a normal button 
  * @param displayCheck
  */

 public void setDisplayCheck(boolean displayCheck) {
  this.displayCheck = displayCheck;
 }
}

3. XJPopupMenu.java


 this.getToolkit().getScreenSize().height
 - this.getToolkit().getScreenInsets(jframe.getGraphicsConfiguration()).top
 - this.getToolkit().getScreenInsets(jframe.getGraphicsConfiguration()).bottom - 4));
 super.add(scroll, BorderLayout.CENTER);

 //  super.add(scroll);
 }

 public void show(Component invoker, int x, int y) {
  init(jframe);
  //   this.pack();
  panelMenus.validate();
  int maxsize = scroll.getMaximumSize().height;
  int realsize = panelMenus.getPreferredSize().height;
  int sizescroll = 0;
  if (maxsize &lt; realsize) {
   sizescroll = scroll.getVerticalScrollBar().getPreferredSize().width;
  }

                Scroll.setPreferredSize(new Dimension(scroll.getPreferredSize().width + 
                   sizescroll + 20, scroll.getPreferredSize().height));
  this.pack();
  this.setInvoker(invoker);
  if (sizescroll != 0) {
   //Set popup size only if scrollbar is visible

         this.setPopupSize(new Dimension(scroll.getPreferredSize().width + 20,   
                      scroll.getMaximumSize().height - 20));
 
  }

  //   this.setMaximumSize(scroll.getMaximumSize());
  Point invokerOrigin = invoker.getLocationOnScreen()
  this.setLocation((int) invokerOrigin.getX() + x, (int) invokerOrigin.getY() + y);
  this.setVisible(true);
 }

 public void hidemenu() {
  if (this.isVisible()) {
   this.setVisible(false);
  }
 }

 public void add(AbstractButton menuItem) {
  //  menuItem.setMargin(new Insets(0, 20, 0 , 0));
  if (menuItem == null) {
   return;
  }

  panelMenus.add(menuItem);
  menuItem.removeActionListener(this);
  menuItem.addActionListener(this);
  if (menuItem.getIcon() == null) {
   menuItem.setIcon(EMPTY_IMAGE_ICON);
  }

  if (!(menuItem instanceof XCheckedButton)) {
   System.out.println(menuItem.getName());
  }
 }

 public void addSeparator() {
  panelMenus.add(new XSeperator());
 }

 public void actionPerformed(ActionEvent e) {
  this.hidemenu();
 }

 public Component[] getComponents() {
  return panelMenus.getComponents();
 }

 private static class XSeperator extends JSeparator {
  XSeperator() {
   ComponentUI ui = XBasicSeparatorUI.createUI(this);
   XSeperator.this.setUI(ui);
  }

  private static class XBasicSeparatorUI extends BasicSeparatorUI {
   public static ComponentUI createUI(JComponent c) {
    return new XBasicSeparatorUI();
   }

   public void paint(Graphics g, JComponent c) {
    Dimension s = c.getSize();
    if (((JSeparator) c).getOrientation() == JSeparator.VERTICAL) {
     g.setColor(c.getForeground());
     g.drawLine(0, 0, 0, s.height);
     g.setColor(c.getBackground());
     g.drawLine(1, 0, 1, s.height);
    } else // HORIZONTAL
    {
     g.setColor(c.getForeground());
     g.drawLine(0, 7, s.width, 7);
     g.setColor(c.getBackground());
     g.drawLine(0, 8, s.width, 8);
    }
   }
  }
 }
}

4. XConstant.java

import javax.swing.Icon;
import javax.swing.ImageIcon;
public interface XConstant {

 public static final Icon EMPTY_IMAGE_ICON = new ImageIcon("menu_spacer.gif");
}

Note: Please use the 2 jgoodies jars present in the zip file for the jgoodies look and feel

Download Scrollable JPopupMenu Source Code

Karthik Alapati's Blog

HOME