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package javax.swing;

import java.awt.Component;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.*;
import java.beans.JavaBean;
import java.beans.BeanProperty;
import java.beans.Transient;
import java.util.Vector;

import java.io.Serializable;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;

import javax.swing.plaf.*;
import javax.accessibility.*;

import sun.awt.SunToolkit;

An implementation of a menu bar. You add JMenu objects to the menu bar to construct a menu. When the user selects a JMenu object, its associated JPopupMenu is displayed, allowing the user to select one of the JMenuItems on it.

For information and examples of using menu bars see How to Use Menus, a section in The Java Tutorial.

Warning: Swing is not thread safe. For more information see Swing's Threading Policy.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans™ has been added to the java.beans package. Please see XMLEncoder.

Warning: By default, pressing the Tab key does not transfer focus from a JMenuBar which is added to a container together with other Swing components, because the focusTraversalKeysEnabled property of JMenuBar is set to false. To resolve this, you should call the JMenuBar.setFocusTraversalKeysEnabled(true) method.

Author:Georges Saab, David Karlton, Arnaud Weber
See Also:
Since:1.2
/** * An implementation of a menu bar. You add <code>JMenu</code> objects to the * menu bar to construct a menu. When the user selects a <code>JMenu</code> * object, its associated <code>JPopupMenu</code> is displayed, allowing the * user to select one of the <code>JMenuItems</code> on it. * <p> * For information and examples of using menu bars see * <a href="http://docs.oracle.com/javase/tutorial/uiswing/components/menu.html">How to Use Menus</a>, * a section in <em>The Java Tutorial.</em> * <p> * <strong>Warning:</strong> Swing is not thread safe. For more * information see <a * href="package-summary.html#threading">Swing's Threading * Policy</a>. * <p> * <strong>Warning:</strong> * Serialized objects of this class will not be compatible with * future Swing releases. The current serialization support is * appropriate for short term storage or RMI between applications running * the same version of Swing. As of 1.4, support for long term storage * of all JavaBeans&trade; * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. * <p> * <strong>Warning:</strong> * By default, pressing the Tab key does not transfer focus from a <code> * JMenuBar</code> which is added to a container together with other Swing * components, because the <code>focusTraversalKeysEnabled</code> property * of <code>JMenuBar</code> is set to <code>false</code>. To resolve this, * you should call the <code>JMenuBar.setFocusTraversalKeysEnabled(true)</code> * method. * * @author Georges Saab * @author David Karlton * @author Arnaud Weber * @see JMenu * @see JPopupMenu * @see JMenuItem * @since 1.2 */
@JavaBean(defaultProperty = "UI", description = "A container for holding and displaying menus.") @SwingContainer @SuppressWarnings("serial") public class JMenuBar extends JComponent implements Accessible,MenuElement {
See Also:
/** * @see #getUIClassID * @see #readObject */
private static final String uiClassID = "MenuBarUI"; /* * Model for the selected subcontrol. */ private transient SingleSelectionModel selectionModel; private boolean paintBorder = true; private Insets margin = null; /* diagnostic aids -- should be false for production builds. */ private static final boolean TRACE = false; // trace creates and disposes private static final boolean VERBOSE = false; // show reuse hits/misses private static final boolean DEBUG = false; // show bad params, misc.
Creates a new menu bar.
/** * Creates a new menu bar. */
public JMenuBar() { super(); setFocusTraversalKeysEnabled(false); setSelectionModel(new DefaultSingleSelectionModel()); updateUI(); }
Returns the menubar's current UI.
See Also:
Returns:a MenuBarUI which is the menubar's current L&F object
/** * Returns the menubar's current UI. * * @return a {@code MenuBarUI} which is the menubar's current L&amp;F object * @see #setUI */
public MenuBarUI getUI() { return (MenuBarUI)ui; }
Sets the L&F object that renders this component.
Params:
  • ui – the new MenuBarUI L&F object
See Also:
/** * Sets the L&amp;F object that renders this component. * * @param ui the new MenuBarUI L&amp;F object * @see UIDefaults#getUI */
@BeanProperty(hidden = true, visualUpdate = true, description = "The UI object that implements the Component's LookAndFeel.") public void setUI(MenuBarUI ui) { super.setUI(ui); }
Resets the UI property with a value from the current look and feel.
See Also:
  • updateUI.updateUI
/** * Resets the UI property with a value from the current look and feel. * * @see JComponent#updateUI */
public void updateUI() { Toolkit tk = Toolkit.getDefaultToolkit(); if (tk instanceof SunToolkit) { ((SunToolkit)tk).updateScreenMenuBarUI(); } setUI((MenuBarUI)UIManager.getUI(this)); }
Returns the name of the L&F class that renders this component.
See Also:
Returns:the string "MenuBarUI"
/** * Returns the name of the L&amp;F class that renders this component. * * @return the string "MenuBarUI" * @see JComponent#getUIClassID * @see UIDefaults#getUI */
@BeanProperty(bound = false) public String getUIClassID() { return uiClassID; }
Returns the model object that handles single selections.
See Also:
Returns:the SingleSelectionModel property
/** * Returns the model object that handles single selections. * * @return the <code>SingleSelectionModel</code> property * @see SingleSelectionModel */
public SingleSelectionModel getSelectionModel() { return selectionModel; }
Sets the model object to handle single selections.
Params:
  • model – the SingleSelectionModel to use
See Also:
/** * Sets the model object to handle single selections. * * @param model the <code>SingleSelectionModel</code> to use * @see SingleSelectionModel */
@BeanProperty(description = "The selection model, recording which child is selected.") public void setSelectionModel(SingleSelectionModel model) { SingleSelectionModel oldValue = selectionModel; this.selectionModel = model; firePropertyChange("selectionModel", oldValue, selectionModel); }
Appends the specified menu to the end of the menu bar.
Params:
  • c – the JMenu component to add
Returns:the menu component
/** * Appends the specified menu to the end of the menu bar. * * @param c the <code>JMenu</code> component to add * @return the menu component */
public JMenu add(JMenu c) { super.add(c); return c; }
Returns the menu at the specified position in the menu bar.
Params:
  • index – an integer giving the position in the menu bar, where 0 is the first position
Returns:the JMenu at that position, or null if if there is no JMenu at that position (ie. if it is a JMenuItem)
/** * Returns the menu at the specified position in the menu bar. * * @param index an integer giving the position in the menu bar, where * 0 is the first position * @return the <code>JMenu</code> at that position, or <code>null</code> if * if there is no <code>JMenu</code> at that position (ie. if * it is a <code>JMenuItem</code>) */
public JMenu getMenu(int index) { Component c = getComponentAtIndex(index); if (c instanceof JMenu) return (JMenu) c; return null; }
Returns the number of items in the menu bar.
Returns:the number of items in the menu bar
/** * Returns the number of items in the menu bar. * * @return the number of items in the menu bar */
@BeanProperty(bound = false) public int getMenuCount() { return getComponentCount(); }
Sets the help menu that appears when the user selects the "help" option in the menu bar. This method is not yet implemented and will throw an exception.
Params:
  • menu – the JMenu that delivers help to the user
/** * Sets the help menu that appears when the user selects the * "help" option in the menu bar. This method is not yet implemented * and will throw an exception. * * @param menu the JMenu that delivers help to the user */
public void setHelpMenu(JMenu menu) { throw new Error("setHelpMenu() not yet implemented."); }
Gets the help menu for the menu bar. This method is not yet implemented and will throw an exception.
Returns:the JMenu that delivers help to the user
/** * Gets the help menu for the menu bar. This method is not yet * implemented and will throw an exception. * * @return the <code>JMenu</code> that delivers help to the user */
@Transient public JMenu getHelpMenu() { throw new Error("getHelpMenu() not yet implemented."); }
Returns the component at the specified index.
Params:
  • i – an integer specifying the position, where 0 is first
Returns:the Component at the position, or null for an invalid index
Deprecated:replaced by getComponent(int i)
/** * Returns the component at the specified index. * * @param i an integer specifying the position, where 0 is first * @return the <code>Component</code> at the position, * or <code>null</code> for an invalid index * @deprecated replaced by <code>getComponent(int i)</code> */
@Deprecated public Component getComponentAtIndex(int i) { if(i < 0 || i >= getComponentCount()) { return null; } return getComponent(i); }
Returns the index of the specified component.
Params:
  • c – the Component to find
Returns:an integer giving the component's position, where 0 is first; or -1 if it can't be found
/** * Returns the index of the specified component. * * @param c the <code>Component</code> to find * @return an integer giving the component's position, where 0 is first; * or -1 if it can't be found */
public int getComponentIndex(Component c) { int ncomponents = this.getComponentCount(); Component[] component = this.getComponents(); for (int i = 0 ; i < ncomponents ; i++) { Component comp = component[i]; if (comp == c) return i; } return -1; }
Sets the currently selected component, producing a a change to the selection model.
Params:
  • sel – the Component to select
/** * Sets the currently selected component, producing a * a change to the selection model. * * @param sel the <code>Component</code> to select */
public void setSelected(Component sel) { SingleSelectionModel model = getSelectionModel(); int index = getComponentIndex(sel); model.setSelectedIndex(index); }
Returns true if the menu bar currently has a component selected.
Returns:true if a selection has been made, else false
/** * Returns true if the menu bar currently has a component selected. * * @return true if a selection has been made, else false */
@BeanProperty(bound = false) public boolean isSelected() { return selectionModel.isSelected(); }
Returns true if the menu bars border should be painted.
Returns: true if the border should be painted, else false
/** * Returns true if the menu bars border should be painted. * * @return true if the border should be painted, else false */
public boolean isBorderPainted() { return paintBorder; }
Sets whether the border should be painted.
Params:
  • b – if true and border property is not null, the border is painted.
See Also:
/** * Sets whether the border should be painted. * * @param b if true and border property is not <code>null</code>, * the border is painted. * @see #isBorderPainted */
@BeanProperty(visualUpdate = true, description = "Whether the border should be painted.") public void setBorderPainted(boolean b) { boolean oldValue = paintBorder; paintBorder = b; firePropertyChange("borderPainted", oldValue, paintBorder); if (b != oldValue) { revalidate(); repaint(); } }
Paints the menubar's border if BorderPainted property is true.
Params:
  • g – the Graphics context to use for painting
See Also:
/** * Paints the menubar's border if <code>BorderPainted</code> * property is true. * * @param g the <code>Graphics</code> context to use for painting * @see JComponent#paint * @see JComponent#setBorder */
protected void paintBorder(Graphics g) { if (isBorderPainted()) { super.paintBorder(g); } }
Sets the margin between the menubar's border and its menus. Setting to null will cause the menubar to use the default margins.
Params:
  • m – an Insets object containing the margin values
See Also:
/** * Sets the margin between the menubar's border and * its menus. Setting to <code>null</code> will cause the menubar to * use the default margins. * * @param m an Insets object containing the margin values * @see Insets */
@BeanProperty(visualUpdate = true, description = "The space between the menubar's border and its contents") public void setMargin(Insets m) { Insets old = margin; this.margin = m; firePropertyChange("margin", old, m); if (old == null || !old.equals(m)) { revalidate(); repaint(); } }
Returns the margin between the menubar's border and its menus. If there is no previous margin, it will create a default margin with zero size.
See Also:
Returns:an Insets object containing the margin values
/** * Returns the margin between the menubar's border and * its menus. If there is no previous margin, it will create * a default margin with zero size. * * @return an <code>Insets</code> object containing the margin values * @see Insets */
public Insets getMargin() { if(margin == null) { return new Insets(0,0,0,0); } else { return margin; } }
Implemented to be a MenuElement -- does nothing.
See Also:
  • getSubElements
/** * Implemented to be a <code>MenuElement</code> -- does nothing. * * @see #getSubElements */
public void processMouseEvent(MouseEvent event,MenuElement path[],MenuSelectionManager manager) { }
Implemented to be a MenuElement -- does nothing.
See Also:
  • getSubElements
/** * Implemented to be a <code>MenuElement</code> -- does nothing. * * @see #getSubElements */
public void processKeyEvent(KeyEvent e,MenuElement path[],MenuSelectionManager manager) { }
Implemented to be a MenuElement -- does nothing.
See Also:
  • getSubElements
/** * Implemented to be a <code>MenuElement</code> -- does nothing. * * @see #getSubElements */
public void menuSelectionChanged(boolean isIncluded) { }
Implemented to be a MenuElement -- returns the menus in this menu bar. This is the reason for implementing the MenuElement interface -- so that the menu bar can be treated the same as other menu elements.
Returns:an array of menu items in the menu bar.
/** * Implemented to be a <code>MenuElement</code> -- returns the * menus in this menu bar. * This is the reason for implementing the <code>MenuElement</code> * interface -- so that the menu bar can be treated the same as * other menu elements. * @return an array of menu items in the menu bar. */
@BeanProperty(bound = false) public MenuElement[] getSubElements() { MenuElement result[]; Vector<MenuElement> tmp = new Vector<MenuElement>(); int c = getComponentCount(); int i; Component m; for(i=0 ; i < c ; i++) { m = getComponent(i); if(m instanceof MenuElement) tmp.addElement((MenuElement) m); } result = new MenuElement[tmp.size()]; for(i=0,c=tmp.size() ; i < c ; i++) result[i] = tmp.elementAt(i); return result; }
Implemented to be a MenuElement. Returns this object.
See Also:
Returns:the current Component (this)
/** * Implemented to be a <code>MenuElement</code>. Returns this object. * * @return the current <code>Component</code> (this) * @see #getSubElements */
public Component getComponent() { return this; }
Returns a string representation of this JMenuBar. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null.
Returns: a string representation of this JMenuBar
/** * Returns a string representation of this <code>JMenuBar</code>. * This method * is intended to be used only for debugging purposes, and the * content and format of the returned string may vary between * implementations. The returned string may be empty but may not * be <code>null</code>. * * @return a string representation of this <code>JMenuBar</code> */
protected String paramString() { String paintBorderString = (paintBorder ? "true" : "false"); String marginString = (margin != null ? margin.toString() : ""); return super.paramString() + ",margin=" + marginString + ",paintBorder=" + paintBorderString; } ///////////////// // Accessibility support ////////////////
Gets the AccessibleContext associated with this JMenuBar. For JMenuBars, the AccessibleContext takes the form of an AccessibleJMenuBar. A new AccessibleJMenuBar instance is created if necessary.
Returns:an AccessibleJMenuBar that serves as the AccessibleContext of this JMenuBar
/** * Gets the AccessibleContext associated with this JMenuBar. * For JMenuBars, the AccessibleContext takes the form of an * AccessibleJMenuBar. * A new AccessibleJMenuBar instance is created if necessary. * * @return an AccessibleJMenuBar that serves as the * AccessibleContext of this JMenuBar */
@BeanProperty(bound = false) public AccessibleContext getAccessibleContext() { if (accessibleContext == null) { accessibleContext = new AccessibleJMenuBar(); } return accessibleContext; }
This class implements accessibility support for the JMenuBar class. It provides an implementation of the Java Accessibility API appropriate to menu bar user-interface elements.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans™ has been added to the java.beans package. Please see XMLEncoder.

/** * This class implements accessibility support for the * <code>JMenuBar</code> class. It provides an implementation of the * Java Accessibility API appropriate to menu bar user-interface * elements. * <p> * <strong>Warning:</strong> * Serialized objects of this class will not be compatible with * future Swing releases. The current serialization support is * appropriate for short term storage or RMI between applications running * the same version of Swing. As of 1.4, support for long term storage * of all JavaBeans&trade; * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. */
@SuppressWarnings("serial") protected class AccessibleJMenuBar extends AccessibleJComponent implements AccessibleSelection {
Get the accessible state set of this object.
Returns:an instance of AccessibleState containing the current state of the object
/** * Get the accessible state set of this object. * * @return an instance of AccessibleState containing the current state * of the object */
public AccessibleStateSet getAccessibleStateSet() { AccessibleStateSet states = super.getAccessibleStateSet(); return states; }
Get the role of this object.
Returns:an instance of AccessibleRole describing the role of the object
/** * Get the role of this object. * * @return an instance of AccessibleRole describing the role of the * object */
public AccessibleRole getAccessibleRole() { return AccessibleRole.MENU_BAR; }
Get the AccessibleSelection associated with this object. In the implementation of the Java Accessibility API for this class, return this object, which is responsible for implementing the AccessibleSelection interface on behalf of itself.
Returns:this object
/** * Get the AccessibleSelection associated with this object. In the * implementation of the Java Accessibility API for this class, * return this object, which is responsible for implementing the * AccessibleSelection interface on behalf of itself. * * @return this object */
public AccessibleSelection getAccessibleSelection() { return this; }
Returns 1 if a menu is currently selected in this menu bar.
Returns:1 if a menu is currently selected, else 0
/** * Returns 1 if a menu is currently selected in this menu bar. * * @return 1 if a menu is currently selected, else 0 */
public int getAccessibleSelectionCount() { if (isSelected()) { return 1; } else { return 0; } }
Returns the currently selected menu if one is selected, otherwise null.
/** * Returns the currently selected menu if one is selected, * otherwise null. */
public Accessible getAccessibleSelection(int i) { if (isSelected()) { if (i != 0) { // single selection model for JMenuBar return null; } int j = getSelectionModel().getSelectedIndex(); if (getComponentAtIndex(j) instanceof Accessible) { return (Accessible) getComponentAtIndex(j); } } return null; }
Returns true if the current child of this object is selected.
Params:
  • i – the zero-based index of the child in this Accessible object.
See Also:
/** * Returns true if the current child of this object is selected. * * @param i the zero-based index of the child in this Accessible * object. * @see AccessibleContext#getAccessibleChild */
public boolean isAccessibleChildSelected(int i) { return (i == getSelectionModel().getSelectedIndex()); }
Selects the nth menu in the menu bar, forcing it to pop up. If another menu is popped up, this will force it to close. If the nth menu is already selected, this method has no effect.
Params:
  • i – the zero-based index of selectable items
See Also:
/** * Selects the nth menu in the menu bar, forcing it to * pop up. If another menu is popped up, this will force * it to close. If the nth menu is already selected, this * method has no effect. * * @param i the zero-based index of selectable items * @see #getAccessibleStateSet */
public void addAccessibleSelection(int i) { // first close up any open menu int j = getSelectionModel().getSelectedIndex(); if (i == j) { return; } if (j >= 0 && j < getMenuCount()) { JMenu menu = getMenu(j); if (menu != null) { MenuSelectionManager.defaultManager().setSelectedPath(null); // menu.setPopupMenuVisible(false); } } // now popup the new menu getSelectionModel().setSelectedIndex(i); JMenu menu = getMenu(i); if (menu != null) { MenuElement me[] = new MenuElement[3]; me[0] = JMenuBar.this; me[1] = menu; me[2] = menu.getPopupMenu(); MenuSelectionManager.defaultManager().setSelectedPath(me); // menu.setPopupMenuVisible(true); } }
Removes the nth selected item in the object from the object's selection. If the nth item isn't currently selected, this method has no effect. Otherwise, it closes the popup menu.
Params:
  • i – the zero-based index of selectable items
/** * Removes the nth selected item in the object from the object's * selection. If the nth item isn't currently selected, this * method has no effect. Otherwise, it closes the popup menu. * * @param i the zero-based index of selectable items */
public void removeAccessibleSelection(int i) { if (i >= 0 && i < getMenuCount()) { JMenu menu = getMenu(i); if (menu != null) { MenuSelectionManager.defaultManager().setSelectedPath(null); // menu.setPopupMenuVisible(false); } getSelectionModel().setSelectedIndex(-1); } }
Clears the selection in the object, so that nothing in the object is selected. This will close any open menu.
/** * Clears the selection in the object, so that nothing in the * object is selected. This will close any open menu. */
public void clearAccessibleSelection() { int i = getSelectionModel().getSelectedIndex(); if (i >= 0 && i < getMenuCount()) { JMenu menu = getMenu(i); if (menu != null) { MenuSelectionManager.defaultManager().setSelectedPath(null); // menu.setPopupMenuVisible(false); } } getSelectionModel().setSelectedIndex(-1); }
Normally causes every selected item in the object to be selected if the object supports multiple selections. This method makes no sense in a menu bar, and so does nothing.
/** * Normally causes every selected item in the object to be selected * if the object supports multiple selections. This method * makes no sense in a menu bar, and so does nothing. */
public void selectAllAccessibleSelection() { } } // internal class AccessibleJMenuBar
Subclassed to check all the child menus.
Since:1.3
/** * Subclassed to check all the child menus. * @since 1.3 */
protected boolean processKeyBinding(KeyStroke ks, KeyEvent e, int condition, boolean pressed) { // See if we have a local binding. boolean retValue = super.processKeyBinding(ks, e, condition, pressed); if (!retValue) { MenuElement[] subElements = getSubElements(); for (MenuElement subElement : subElements) { if (processBindingForKeyStrokeRecursive( subElement, ks, e, condition, pressed)) { return true; } } } return retValue; } static boolean processBindingForKeyStrokeRecursive(MenuElement elem, KeyStroke ks, KeyEvent e, int condition, boolean pressed) { if (elem == null) { return false; } Component c = elem.getComponent(); if ( !(c.isVisible() || (c instanceof JPopupMenu)) || !c.isEnabled() ) { return false; } if (c != null && c instanceof JComponent && ((JComponent)c).processKeyBinding(ks, e, condition, pressed)) { return true; } MenuElement[] subElements = elem.getSubElements(); for (MenuElement subElement : subElements) { if (processBindingForKeyStrokeRecursive(subElement, ks, e, condition, pressed)) { return true; // We don't, pass along to children JMenu's } } return false; }
Overrides JComponent.addNotify to register this menu bar with the current keyboard manager.
/** * Overrides <code>JComponent.addNotify</code> to register this * menu bar with the current keyboard manager. */
public void addNotify() { super.addNotify(); KeyboardManager.getCurrentManager().registerMenuBar(this); }
Overrides JComponent.removeNotify to unregister this menu bar with the current keyboard manager.
/** * Overrides <code>JComponent.removeNotify</code> to unregister this * menu bar with the current keyboard manager. */
public void removeNotify() { super.removeNotify(); KeyboardManager.getCurrentManager().unregisterMenuBar(this); } private void writeObject(ObjectOutputStream s) throws IOException { s.defaultWriteObject(); if (getUIClassID().equals(uiClassID)) { byte count = JComponent.getWriteObjCounter(this); JComponent.setWriteObjCounter(this, --count); if (count == 0 && ui != null) { ui.installUI(this); } } Object[] kvData = new Object[4]; int n = 0; if (selectionModel instanceof Serializable) { kvData[n++] = "selectionModel"; kvData[n++] = selectionModel; } s.writeObject(kvData); }
See JComponent.readObject() for information about serialization in Swing.
/** * See JComponent.readObject() for information about serialization * in Swing. */
private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException { s.defaultReadObject(); Object[] kvData = (Object[])(s.readObject()); for(int i = 0; i < kvData.length; i += 2) { if (kvData[i] == null) { break; } else if (kvData[i].equals("selectionModel")) { selectionModel = (SingleSelectionModel)kvData[i + 1]; } } } }