How can I add to or change a label on a JMenuItem?

Question

I need to add a label on the right hand side of a JMenuItem, like the labels shown below:

I have an application that uses Ctrl++ and Ctrl+- to zoom into an image. However, the + key by default (without Shift) is the = key. When I try adding accelerators for these menu items, the Ctrl+- shortcut label displays as "Ctrl+Minus" (I would prefer "Ctrl -") and the Ctrl++ shortcut label displays as "Ctrl+Equals" (even worse - in the interest of user experience, I would prefer "Ctrl +"):

menuBar_view_zoomIn.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_EQUALS, ActionEvent.CTRL_MASK));

I want Ctrl++ to display as "Ctrl +" and Ctrl+- to display as "Ctrl -". How can this be done?

Answer 1

not an answer, you need to search for

• paint() to heavy, paintComponent() for lightweight JPopup, JMenu (for custom painting can be switch to isHeavyWeight...)

• overlay JLabel into container (few question about JTable by @Guillaume Polet and @Robin)

• create own JMenu/JPopup (see my comment to your question)

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.Icon;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.border.EtchedBorder;
import javax.swing.border.TitledBorder;
import javax.swing.plaf.basic.BasicArrowButton;

public class ComboBoxMenuExample extends JFrame {

    public ComboBoxMenuExample() {
        super("ComboBoxMenu Example");
        String[] itemStr = {"name", "Red", "Blue", "number", "255,0,0", "0,0,255",
            /*separator*/ "system", "control", "controlHighlight", "controlShadow", "text"};
        JMenuItem[] menuItems = new JMenuItem[7];
        menuItems[0] = new JMenuItem(itemStr[1]);
        menuItems[1] = new JMenuItem(itemStr[2]);
        menuItems[2] = new JMenuItem(itemStr[4]);
        menuItems[3] = new JMenuItem(itemStr[5]);
        menuItems[4] = new JMenuItem(itemStr[8]);
        menuItems[5] = new JMenuItem(itemStr[9]);
        menuItems[6] = new JMenuItem(itemStr[10]);
        JMenu[] menus = new JMenu[4];
        menus[0] = new JMenu(itemStr[0]);
        menus[1] = new JMenu(itemStr[3]);
        menus[2] = new JMenu(itemStr[6]);
        menus[3] = new JMenu(itemStr[7]);
        menus[0].add(menuItems[0]);
        menus[0].add(menuItems[1]);
        menus[1].add(menuItems[2]);
        menus[1].add(menuItems[3]);
        menus[3].add(menuItems[4]);
        menus[3].add(menuItems[5]);
        menus[2].add(menus[3]);
        menus[2].add(menuItems[6]);
        JMenu menu = ComboMenuBar.createMenu(menuItems[0].getText());
        menu.add(menus[0]);
        menu.add(menus[1]);
        menu.addSeparator();
        menu.add(menus[2]);
        ComboMenuBar comboMenu = new ComboMenuBar(menu);
        JComboBox combo = new JComboBox();
        combo.addItem(itemStr[1]);
        combo.addItem(itemStr[2]);
        combo.addItem(itemStr[4]);
        combo.addItem(itemStr[5]);
        combo.addItem(itemStr[8]);
        combo.addItem(itemStr[9]);
        combo.addItem(itemStr[10]);
        getContentPane().setLayout(new FlowLayout());
        getContentPane().add(new ComboPanel("Fake ComboBox", comboMenu));
        getContentPane().add(new ComboPanel("ComboBox", combo));
    }

    class ComboPanel extends JPanel {

        ComboPanel(String title, JComponent c) {
            setLayout(new FlowLayout());
            setBorder(new TitledBorder(title));
            add(c);
        }
    }

    public static void main(String args[]) {
        try {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
        } catch (Exception evt) {
        }
        ComboBoxMenuExample frame = new ComboBoxMenuExample();
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        frame.setSize(370, 100);
        frame.setVisible(true);
    }
}

class ComboMenuBar extends JMenuBar {

    JMenu menu;
    Dimension preferredSize;

    public ComboMenuBar(JMenu menu) {
        this.menu = menu;
        Color color = UIManager.getColor("Menu.selectionBackground");
        UIManager.put("Menu.selectionBackground", UIManager.getColor("Menu.background"));
        UIManager.put("Menu.selectionBackground", color);
        menu.updateUI();
        MenuItemListener listener = new MenuItemListener();
        setListener(menu, listener);
        add(menu);
    }

    class MenuItemListener implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            JMenuItem item = (JMenuItem) e.getSource();
            menu.setText(item.getText());
            menu.requestFocus();
        }
    }

    private void setListener(JMenuItem item, ActionListener listener) {
        if (item instanceof JMenu) {
            JMenu menu1 = (JMenu) item;
            int n = menu1.getItemCount();
            for (int i = 0; i < n; i++) {
                setListener(menu1.getItem(i), listener);
            }
        } else if (item != null) { // null means separator
            item.addActionListener(listener);
        }
    }

    public String getSelectedItem() {
        return menu.getText();
    }

    @Override
    public void setPreferredSize(Dimension size) {
        preferredSize = size;
    }

    @Override
    public Dimension getPreferredSize() {
        if (preferredSize == null) {
            Dimension sd = super.getPreferredSize();
            Dimension menuD = getItemSize(menu);
            Insets margin = menu.getMargin();
            Dimension retD = new Dimension(menuD.width, margin.top
                    + margin.bottom + menuD.height);
            menu.setPreferredSize(retD);
            preferredSize = retD;
        }
        return preferredSize;
    }

    private Dimension getItemSize(JMenu menu) {
        Dimension d = new Dimension(0, 0);
        int n = menu.getItemCount();
        for (int i = 0; i < n; i++) {
            Dimension itemD;
            JMenuItem item = menu.getItem(i);
            if (item instanceof JMenu) {
                itemD = getItemSize((JMenu) item);
            } else if (item != null) {
                itemD = item.getPreferredSize();
            } else {
                itemD = new Dimension(0, 0); // separator
            }
            d.width = Math.max(d.width, itemD.width);
            d.height = Math.max(d.height, itemD.height);
        }
        return d;
    }

    public static class ComboMenu extends JMenu {

        ArrowIcon iconRenderer;

        public ComboMenu(String label) {
            super(label);
            iconRenderer = new ArrowIcon(SwingConstants.SOUTH, true);
            setBorder(new EtchedBorder());
            setIcon(new BlankIcon(null, 11));
            setHorizontalTextPosition(JButton.LEFT);
            setFocusPainted(true);
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            Dimension d = this.getPreferredSize();
            int x = Math.max(0, d.width - iconRenderer.getIconWidth() - 3);
            int y = Math.max(0,
                    (d.height - iconRenderer.getIconHeight()) / 2 - 2);
            iconRenderer.paintIcon(this, g, x, y);
        }
    }

    public static JMenu createMenu(String label) {
        return new ComboMenu(label);
    }
}

class ArrowIcon implements Icon, SwingConstants {

    private static final int DEFAULT_SIZE = 11;
    //private static final int DEFAULT_SIZE = 5;
    private int size;
    private int iconSize;
    private int direction;
    private boolean isEnabled;
    private BasicArrowButton iconRenderer;

    public ArrowIcon(int direction, boolean isPressedView) {
        this(DEFAULT_SIZE, direction, isPressedView);
    }

    public ArrowIcon(int iconSize, int direction, boolean isEnabled) {
        this.size = iconSize / 2;
        this.iconSize = iconSize;
        this.direction = direction;
        this.isEnabled = isEnabled;
        iconRenderer = new BasicArrowButton(direction);
    }

    @Override
    public void paintIcon(Component c, Graphics g, int x, int y) {
        iconRenderer.paintTriangle(g, x, y, size, direction, isEnabled);
    }

    @Override
    public int getIconWidth() {
        //int retCode;
        switch (direction) {
            case NORTH:
            case SOUTH:
                return iconSize;
            case EAST:
            case WEST:
                return size;
        }
        return iconSize;
    }

    @Override
    public int getIconHeight() {
        switch (direction) {
            case NORTH:
            case SOUTH:
                return size;
            case EAST:
            case WEST:
                return iconSize;
        }
        return size;
    }
}

class BlankIcon implements Icon {

    private Color fillColor;
    private int size;

    public BlankIcon() {
        this(null, 11);
    }

    public BlankIcon(Color color, int size) {
        //UIManager.getColor("control")
        //UIManager.getColor("controlShadow")
        fillColor = color;
        this.size = size;
    }

    @Override
    public void paintIcon(Component c, Graphics g, int x, int y) {
        if (fillColor != null) {
            g.setColor(fillColor);
            g.drawRect(x, y, size - 1, size - 1);
        }
    }

    @Override
    public int getIconWidth() {
        return size;
    }

    @Override
    public int getIconHeight() {
        return size;
    }
}