Class SystemTray
- java.lang.Object
-
- java.awt.SystemTray
public class SystemTray extends Object
The SystemTray
class represents the system tray for a desktop. On Microsoft Windows it is referred to as the "Taskbar Status Area", on Gnome it is referred to as the "Notification Area", on KDE it is referred to as the "System Tray". The system tray is shared by all applications running on the desktop.
On some platforms the system tray may not be present or may not be supported, in this case getSystemTray()
throws UnsupportedOperationException
. To detect whether the system tray is supported, use isSupported()
.
The SystemTray
may contain one or more TrayIcons
, which are added to the tray using the add(java.awt.TrayIcon)
method, and removed when no longer needed, using the remove(java.awt.TrayIcon)
. TrayIcon
consists of an image, a popup menu and a set of associated listeners. Please see the TrayIcon
class for details.
Every Java application has a single SystemTray
instance that allows the app to interface with the system tray of the desktop while the app is running. The SystemTray
instance can be obtained from the getSystemTray()
method. An application may not create its own instance of SystemTray
.
The following code snippet demonstrates how to access and customize the system tray:
TrayIcon trayIcon = null; if (SystemTray.isSupported()) { // get the SystemTray instance SystemTray tray = SystemTray.getSystemTray(); // load an image Image image = Toolkit.getDefaultToolkit().getImage(...); // create a action listener to listen for default action executed on the tray icon ActionListener listener = new ActionListener() { public void actionPerformed(ActionEvent e) { // execute default action of the application // ... } }; // create a popup menu PopupMenu popup = new PopupMenu(); // create menu item for the default action MenuItem defaultItem = new MenuItem(...); defaultItem.addActionListener(listener); popup.add(defaultItem); /// ... add other items // construct a TrayIcon trayIcon = new TrayIcon(image, "Tray Demo", popup); // set the TrayIcon properties trayIcon.addActionListener(listener); // ... // add the tray image try { tray.add(trayIcon); } catch (AWTException e) { System.err.println(e); } // ... } else { // disable tray option in your application or // perform other actions ... } // ... // some time later // the application state has changed - update the image if (trayIcon != null) { trayIcon.setImage(updatedImage); } // ...
- Since:
- 1.6
- See Also:
TrayIcon
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | add(TrayIcon trayIcon) | Adds a |
void | addPropertyChangeListener(String propertyName,
PropertyChangeListener listener) | Adds a |
PropertyChangeListener[] | getPropertyChangeListeners(String propertyName) | Returns an array of all the listeners that have been associated with the named property. |
static SystemTray | getSystemTray() | Gets the |
TrayIcon[] | getTrayIcons() | Returns an array of all icons added to the tray by this application. |
Dimension | getTrayIconSize() | Returns the size, in pixels, of the space that a tray icon will occupy in the system tray. |
static boolean | isSupported() | Returns whether the system tray is supported on the current platform. |
void | remove(TrayIcon trayIcon) | Removes the specified |
void | removePropertyChangeListener(String propertyName,
PropertyChangeListener listener) | Removes a |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Method Detail
getSystemTray
public static SystemTray getSystemTray()
Gets the SystemTray
instance that represents the desktop's tray area. This always returns the same instance per application. On some platforms the system tray may not be supported. You may use the isSupported()
method to check if the system tray is supported.
If a SecurityManager is installed, the AWTPermission accessSystemTray
must be granted in order to get the SystemTray
instance. Otherwise this method will throw a SecurityException.
- Returns:
- the
SystemTray
instance that represents the desktop's tray area - Throws:
-
UnsupportedOperationException
- if the system tray isn't supported by the current platform -
HeadlessException
- ifGraphicsEnvironment.isHeadless()
returnstrue
-
SecurityException
- ifaccessSystemTray
permission is not granted - See Also:
-
add(TrayIcon)
,TrayIcon
,isSupported()
,SecurityManager.checkPermission(java.security.Permission)
,AWTPermission
isSupported
public static boolean isSupported()
Returns whether the system tray is supported on the current platform. In addition to displaying the tray icon, minimal system tray support includes either a popup menu (see TrayIcon.setPopupMenu(PopupMenu)
) or an action event (see TrayIcon.addActionListener(ActionListener)
).
Developers should not assume that all of the system tray functionality is supported. To guarantee that the tray icon's default action is always accessible, add the default action to both the action listener and the popup menu. See the example
for an example of how to do this.
Note: When implementing SystemTray
and TrayIcon
it is strongly recommended that you assign different gestures to the popup menu and an action event. Overloading a gesture for both purposes is confusing and may prevent the user from accessing one or the other.
- Returns:
-
false
if no system tray access is supported; this method returnstrue
if the minimal system tray access is supported but does not guarantee that all system tray functionality is supported for the current platform - See Also:
getSystemTray()
add
public void add(TrayIcon trayIcon) throws AWTException
Adds a TrayIcon
to the SystemTray
. The tray icon becomes visible in the system tray once it is added. The order in which icons are displayed in a tray is not specified - it is platform and implementation-dependent.
All icons added by the application are automatically removed from the SystemTray
upon application exit and also when the desktop system tray becomes unavailable.
- Parameters:
-
trayIcon
- theTrayIcon
to be added - Throws:
-
NullPointerException
- iftrayIcon
isnull
-
IllegalArgumentException
- if the same instance of aTrayIcon
is added more than once -
AWTException
- if the desktop system tray is missing - See Also:
-
remove(TrayIcon)
,getSystemTray()
,TrayIcon
,Image
remove
public void remove(TrayIcon trayIcon)
Removes the specified TrayIcon
from the SystemTray
.
All icons added by the application are automatically removed from the SystemTray
upon application exit and also when the desktop system tray becomes unavailable.
If trayIcon
is null
or was not added to the system tray, no exception is thrown and no action is performed.
- Parameters:
-
trayIcon
- theTrayIcon
to be removed - See Also:
-
add(TrayIcon)
,TrayIcon
getTrayIcons
public TrayIcon[] getTrayIcons()
Returns an array of all icons added to the tray by this application. You can't access the icons added by another application. Some browsers partition applets in different code bases into separate contexts, and establish walls between these contexts. In such a scenario, only the tray icons added from this context will be returned.
The returned array is a copy of the actual array and may be modified in any way without affecting the system tray. To remove a TrayIcon
from the SystemTray
, use the remove(TrayIcon)
method.
- Returns:
- an array of all tray icons added to this tray, or an empty array if none has been added
- See Also:
-
add(TrayIcon)
,TrayIcon
getTrayIconSize
public Dimension getTrayIconSize()
Returns the size, in pixels, of the space that a tray icon will occupy in the system tray. Developers may use this methods to acquire the preferred size for the image property of a tray icon before it is created. For convenience, there is a similar method TrayIcon.getSize()
in the TrayIcon
class.
- Returns:
- the default size of a tray icon, in pixels
- See Also:
-
TrayIcon.setImageAutoSize(boolean)
,Image
,TrayIcon.getSize()
addPropertyChangeListener
public void addPropertyChangeListener(String propertyName, PropertyChangeListener listener)
Adds a PropertyChangeListener
to the list of listeners for the specific property. The following properties are currently supported:
Property | Description |
---|---|
trayIcons |
The SystemTray 's array of TrayIcon objects. The array is accessed via the getTrayIcons() method. This property is changed when a tray icon is added to (or removed from) the system tray. For example, this property is changed when the system tray becomes unavailable on the desktop and the tray icons are automatically removed. |
systemTray |
This property contains SystemTray instance when the system tray is available or null otherwise. This property is changed when the system tray becomes available or unavailable on the desktop. The property is accessed by the getSystemTray() method. |
The listener
listens to property changes only in this context.
If listener
is null
, no exception is thrown and no action is performed.
- Parameters:
-
propertyName
- the specified property -
listener
- the property change listener to be added - See Also:
-
removePropertyChangeListener(java.lang.String, java.beans.PropertyChangeListener)
,getPropertyChangeListeners(java.lang.String)
removePropertyChangeListener
public void removePropertyChangeListener(String propertyName, PropertyChangeListener listener)
Removes a PropertyChangeListener
from the listener list for a specific property.
The PropertyChangeListener
must be from this context.
If propertyName
or listener
is null
or invalid, no exception is thrown and no action is taken.
- Parameters:
-
propertyName
- the specified property -
listener
- the PropertyChangeListener to be removed - See Also:
-
addPropertyChangeListener(java.lang.String, java.beans.PropertyChangeListener)
,getPropertyChangeListeners(java.lang.String)
getPropertyChangeListeners
public PropertyChangeListener[] getPropertyChangeListeners(String propertyName)
Returns an array of all the listeners that have been associated with the named property.
Only the listeners in this context are returned.
- Parameters:
-
propertyName
- the specified property - Returns:
- all of the
PropertyChangeListener
s associated with the named property; if no such listeners have been added or ifpropertyName
isnull
or invalid, an empty array is returned - See Also:
-
addPropertyChangeListener(java.lang.String, java.beans.PropertyChangeListener)
,removePropertyChangeListener(java.lang.String, java.beans.PropertyChangeListener)