Menu object is a pull-down menu component
* that is deployed from a menu bar.
* * A menu can optionally be a tear-off menu. A tear-off menu * can be opened and dragged away from its parent menu bar or menu. * It remains on the screen after the mouse button has been released. * The mechanism for tearing off a menu is platform dependent, since * the look and feel of the tear-off menu is determined by its peer. * On platforms that do not support tear-off menus, the tear-off * property is ignored. *
* Each item in a menu must belong to the MenuItem
* class. It can be an instance of MenuItem, a submenu
* (an instance of Menu), or a check box (an instance of
* CheckboxMenuItem).
*
* @author Sami Shaio
* @see java.awt.MenuItem
* @see java.awt.CheckboxMenuItem
* @since JDK1.0
*/
public class Menu extends MenuItem implements MenuContainer, Accessible {
static {
/* ensure that the necessary native libraries are loaded */
Toolkit.loadLibraries();
if (!GraphicsEnvironment.isHeadless()) {
initIDs();
}
AWTAccessor.setMenuAccessor(
new AWTAccessor.MenuAccessor() {
public Vector getItems(Menu menu) {
return menu.items;
}
});
}
/**
* A vector of the items that will be part of the Menu.
*
* @serial
* @see #countItems()
*/
Vector items = new Vector();
/**
* This field indicates whether the menu has the
* tear of property or not. It will be set to
* true if the menu has the tear off
* property and it will be set to false
* if it does not.
* A torn off menu can be deleted by a user when
* it is no longer needed.
*
* @serial
* @see #isTearOff()
*/
boolean tearOff;
/**
* This field will be set to true
* if the Menu in question is actually a help
* menu. Otherwise it will be set to
* false.
*
* @serial
*/
boolean isHelpMenu;
private static final String base = "menu";
private static int nameCounter = 0;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -8809584163345499784L;
/**
* Constructs a new menu with an empty label. This menu is not
* a tear-off menu.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
* @since JDK1.1
*/
public Menu() throws HeadlessException {
this("", false);
}
/**
* Constructs a new menu with the specified label. This menu is not
* a tear-off menu.
* @param label the menu's label in the menu bar, or in
* another menu of which this menu is a submenu.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public Menu(String label) throws HeadlessException {
this(label, false);
}
/**
* Constructs a new menu with the specified label,
* indicating whether the menu can be torn off.
*
* Tear-off functionality may not be supported by all
* implementations of AWT. If a particular implementation doesn't
* support tear-off menus, this value is silently ignored.
* @param label the menu's label in the menu bar, or in
* another menu of which this menu is a submenu.
* @param tearOff if true, the menu
* is a tear-off menu.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
* @since JDK1.0.
*/
public Menu(String label, boolean tearOff) throws HeadlessException {
super(label);
this.tearOff = tearOff;
}
/**
* Construct a name for this MenuComponent. Called by getName() when
* the name is null.
*/
String constructComponentName() {
synchronized (Menu.class) {
return base + nameCounter++;
}
}
/**
* Creates the menu's peer. The peer allows us to modify the
* appearance of the menu without changing its functionality.
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = Toolkit.getDefaultToolkit().createMenu(this);
int nitems = getItemCount();
for (int i = 0 ; i < nitems ; i++) {
MenuItem mi = getItem(i);
mi.parent = this;
mi.addNotify();
}
}
}
/**
* Removes the menu's peer. The peer allows us to modify the appearance
* of the menu without changing its functionality.
*/
public void removeNotify() {
synchronized (getTreeLock()) {
int nitems = getItemCount();
for (int i = 0 ; i < nitems ; i++) {
getItem(i).removeNotify();
}
super.removeNotify();
}
}
/**
* Indicates whether this menu is a tear-off menu.
*
* Tear-off functionality may not be supported by all
* implementations of AWT. If a particular implementation doesn't
* support tear-off menus, this value is silently ignored.
* @return true if this is a tear-off menu;
* false otherwise.
*/
public boolean isTearOff() {
return tearOff;
}
/**
* Get the number of items in this menu.
* @return the number of items in this menu.
* @since JDK1.1
*/
public int getItemCount() {
return countItems();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by getItemCount().
*/
@Deprecated
public int countItems() {
return countItemsImpl();
}
/*
* This is called by the native code, so client code can't
* be called on the toolkit thread.
*/
final int countItemsImpl() {
return items.size();
}
/**
* Gets the item located at the specified index of this menu.
* @param index the position of the item to be returned.
* @return the item located at the specified index.
*/
public MenuItem getItem(int index) {
return getItemImpl(index);
}
/*
* This is called by the native code, so client code can't
* be called on the toolkit thread.
*/
final MenuItem getItemImpl(int index) {
return (MenuItem)items.elementAt(index);
}
/**
* Adds the specified menu item to this menu. If the
* menu item has been part of another menu, removes it
* from that menu.
*
* @param mi the menu item to be added
* @return the menu item added
* @see java.awt.Menu#insert(java.lang.String, int)
* @see java.awt.Menu#insert(java.awt.MenuItem, int)
*/
public MenuItem add(MenuItem mi) {
synchronized (getTreeLock()) {
if (mi.parent != null) {
mi.parent.remove(mi);
}
items.addElement(mi);
mi.parent = this;
MenuPeer peer = (MenuPeer)this.peer;
if (peer != null) {
mi.addNotify();
peer.addItem(mi);
}
return mi;
}
}
/**
* Adds an item with the specified label to this menu.
*
* @param label the text on the item
* @see java.awt.Menu#insert(java.lang.String, int)
* @see java.awt.Menu#insert(java.awt.MenuItem, int)
*/
public void add(String label) {
add(new MenuItem(label));
}
/**
* Inserts a menu item into this menu
* at the specified position.
*
* @param menuitem the menu item to be inserted.
* @param index the position at which the menu
* item should be inserted.
* @see java.awt.Menu#add(java.lang.String)
* @see java.awt.Menu#add(java.awt.MenuItem)
* @exception IllegalArgumentException if the value of
* index is less than zero
* @since JDK1.1
*/
public void insert(MenuItem menuitem, int index) {
synchronized (getTreeLock()) {
if (index < 0) {
throw new IllegalArgumentException("index less than zero.");
}
int nitems = getItemCount();
Vector tempItems = new Vector();
/* Remove the item at index, nitems-index times
storing them in a temporary vector in the
order they appear on the menu.
*/
for (int i = index ; i < nitems; i++) {
tempItems.addElement(getItem(index));
remove(index);
}
add(menuitem);
/* Add the removed items back to the menu, they are
already in the correct order in the temp vector.
*/
for (int i = 0; i < tempItems.size() ; i++) {
add((MenuItem)tempItems.elementAt(i));
}
}
}
/**
* Inserts a menu item with the specified label into this menu
* at the specified position. This is a convenience method for
* insert(menuItem, index).
*
* @param label the text on the item
* @param index the position at which the menu item
* should be inserted
* @see java.awt.Menu#add(java.lang.String)
* @see java.awt.Menu#add(java.awt.MenuItem)
* @exception IllegalArgumentException if the value of
* index is less than zero
* @since JDK1.1
*/
public void insert(String label, int index) {
insert(new MenuItem(label), index);
}
/**
* Adds a separator line, or a hypen, to the menu at the current position.
* @see java.awt.Menu#insertSeparator(int)
*/
public void addSeparator() {
add("-");
}
/**
* Inserts a separator at the specified position.
* @param index the position at which the
* menu separator should be inserted.
* @exception IllegalArgumentException if the value of
* index is less than 0.
* @see java.awt.Menu#addSeparator
* @since JDK1.1
*/
public void insertSeparator(int index) {
synchronized (getTreeLock()) {
if (index < 0) {
throw new IllegalArgumentException("index less than zero.");
}
int nitems = getItemCount();
Vector tempItems = new Vector();
/* Remove the item at index, nitems-index times
storing them in a temporary vector in the
order they appear on the menu.
*/
for (int i = index ; i < nitems; i++) {
tempItems.addElement(getItem(index));
remove(index);
}
addSeparator();
/* Add the removed items back to the menu, they are
already in the correct order in the temp vector.
*/
for (int i = 0; i < tempItems.size() ; i++) {
add((MenuItem)tempItems.elementAt(i));
}
}
}
/**
* Removes the menu item at the specified index from this menu.
* @param index the position of the item to be removed.
*/
public void remove(int index) {
synchronized (getTreeLock()) {
MenuItem mi = getItem(index);
items.removeElementAt(index);
MenuPeer peer = (MenuPeer)this.peer;
if (peer != null) {
mi.removeNotify();
mi.parent = null;
peer.delItem(index);
}
}
}
/**
* Removes the specified menu item from this menu.
* @param item the item to be removed from the menu.
* If item is null
* or is not in this menu, this method does
* nothing.
*/
public void remove(MenuComponent item) {
synchronized (getTreeLock()) {
int index = items.indexOf(item);
if (index >= 0) {
remove(index);
}
}
}
/**
* Removes all items from this menu.
* @since JDK1.0.
*/
public void removeAll() {
synchronized (getTreeLock()) {
int nitems = getItemCount();
for (int i = nitems-1 ; i >= 0 ; i--) {
remove(i);
}
}
}
/*
* Post an ActionEvent to the target of the MenuPeer
* associated with the specified keyboard event (on
* keydown). Returns true if there is an associated
* keyboard event.
*/
boolean handleShortcut(KeyEvent e) {
int nitems = getItemCount();
for (int i = 0 ; i < nitems ; i++) {
MenuItem mi = getItem(i);
if (mi.handleShortcut(e)) {
return true;
}
}
return false;
}
MenuItem getShortcutMenuItem(MenuShortcut s) {
int nitems = getItemCount();
for (int i = 0 ; i < nitems ; i++) {
MenuItem mi = getItem(i).getShortcutMenuItem(s);
if (mi != null) {
return mi;
}
}
return null;
}
synchronized Enumeration shortcuts() {
Vector shortcuts = new Vector();
int nitems = getItemCount();
for (int i = 0 ; i < nitems ; i++) {
MenuItem mi = getItem(i);
if (mi instanceof Menu) {
Enumeration e = ((Menu)mi).shortcuts();
while (e.hasMoreElements()) {
shortcuts.addElement(e.nextElement());
}
} else {
MenuShortcut ms = mi.getShortcut();
if (ms != null) {
shortcuts.addElement(ms);
}
}
}
return shortcuts.elements();
}
void deleteShortcut(MenuShortcut s) {
int nitems = getItemCount();
for (int i = 0 ; i < nitems ; i++) {
getItem(i).deleteShortcut(s);
}
}
/* Serialization support. A MenuContainer is responsible for
* restoring the parent fields of its children.
*/
/**
* The menu serialized Data Version.
*
* @serial
*/
private int menuSerializedDataVersion = 1;
/**
* Writes default serializable fields to stream.
*
* @param s the ObjectOutputStream to write
* @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
* @see #readObject(ObjectInputStream)
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException
{
s.defaultWriteObject();
}
/**
* Reads the ObjectInputStream.
* Unrecognized keys or values will be ignored.
*
* @param s the ObjectInputStream to read
* @exception HeadlessException if
* GraphicsEnvironment.isHeadless returns
* true
* @see java.awt.GraphicsEnvironment#isHeadless
* @see #writeObject(ObjectOutputStream)
*/
private void readObject(ObjectInputStream s)
throws IOException, ClassNotFoundException, HeadlessException
{
// HeadlessException will be thrown from MenuComponent's readObject
s.defaultReadObject();
for(int i = 0; i < items.size(); i++) {
MenuItem item = (MenuItem)items.elementAt(i);
item.parent = this;
}
}
/**
* Returns a string representing the state of this Menu.
* 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.
*
* @return the parameter string of this menu
*/
public String paramString() {
String str = ",tearOff=" + tearOff+",isHelpMenu=" + isHelpMenu;
return super.paramString() + str;
}
/**
* Initialize JNI field and method IDs
*/
private static native void initIDs();
/////////////////
// Accessibility support
////////////////
/**
* Gets the AccessibleContext associated with this Menu.
* For menus, the AccessibleContext takes the form of an
* AccessibleAWTMenu.
* A new AccessibleAWTMenu instance is created if necessary.
*
* @return an AccessibleAWTMenu that serves as the
* AccessibleContext of this Menu
* @since 1.3
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleAWTMenu();
}
return accessibleContext;
}
/**
* Defined in MenuComponent. Overridden here.
*/
int getAccessibleChildIndex(MenuComponent child) {
return items.indexOf(child);
}
/**
* Inner class of Menu used to provide default support for
* accessibility. This class is not meant to be used directly by
* application developers, but is instead meant only to be
* subclassed by menu component developers.
*
* This class implements accessibility support for the
* Menu class. It provides an implementation of the
* Java Accessibility API appropriate to menu user-interface elements.
* @since 1.3
*/
protected class AccessibleAWTMenu extends AccessibleAWTMenuItem
{
/*
* JDK 1.3 serialVersionUID
*/
private static final long serialVersionUID = 5228160894980069094L;
/**
* Get the role of this object.
*
* @return an instance of AccessibleRole describing the role of the
* object
*/
public AccessibleRole getAccessibleRole() {
return AccessibleRole.MENU;
}
} // class AccessibleAWTMenu
}