- All Superinterfaces:
ActionListener
,EventListener
- All Known Implementing Classes:
AbstractAction
,BasicDesktopPaneUI.CloseAction
,BasicDesktopPaneUI.MaximizeAction
,BasicDesktopPaneUI.MinimizeAction
,BasicDesktopPaneUI.NavigateAction
,BasicDesktopPaneUI.OpenAction
,BasicFileChooserUI.ApproveSelectionAction
,BasicFileChooserUI.CancelSelectionAction
,BasicFileChooserUI.ChangeToParentDirectoryAction
,BasicFileChooserUI.GoHomeAction
,BasicFileChooserUI.NewFolderAction
,BasicFileChooserUI.UpdateAction
,BasicInternalFrameTitlePane.CloseAction
,BasicInternalFrameTitlePane.IconifyAction
,BasicInternalFrameTitlePane.MaximizeAction
,BasicInternalFrameTitlePane.MoveAction
,BasicInternalFrameTitlePane.RestoreAction
,BasicInternalFrameTitlePane.SizeAction
,BasicSliderUI.ActionScroller
,BasicTreeUI.TreeCancelEditingAction
,BasicTreeUI.TreeHomeAction
,BasicTreeUI.TreeIncrementAction
,BasicTreeUI.TreePageAction
,BasicTreeUI.TreeToggleAction
,BasicTreeUI.TreeTraverseAction
,DefaultEditorKit.BeepAction
,DefaultEditorKit.CopyAction
,DefaultEditorKit.CutAction
,DefaultEditorKit.DefaultKeyTypedAction
,DefaultEditorKit.InsertBreakAction
,DefaultEditorKit.InsertContentAction
,DefaultEditorKit.InsertTabAction
,DefaultEditorKit.PasteAction
,HTMLEditorKit.HTMLTextAction
,HTMLEditorKit.InsertHTMLTextAction
,MetalFileChooserUI.DirectoryComboBoxAction
,StyledEditorKit.AlignmentAction
,StyledEditorKit.BoldAction
,StyledEditorKit.FontFamilyAction
,StyledEditorKit.FontSizeAction
,StyledEditorKit.ForegroundAction
,StyledEditorKit.ItalicAction
,StyledEditorKit.StyledTextAction
,StyledEditorKit.UnderlineAction
,TextAction
Action
interface provides a useful extension to the
ActionListener
interface in cases where the same functionality may be accessed by
several controls.
In addition to the actionPerformed
method defined by the
ActionListener
interface, this interface allows the
application to define, in a single place:
- One or more text strings that describe the function. These strings can be used, for example, to display the flyover text for a button or to set the text in a menu item.
- One or more icons that depict the function. These icons can be used for the images in a menu control, or for composite entries in a more sophisticated user interface.
- The enabled/disabled state of the functionality. Instead of having to separately disable the menu item and the toolbar button, the application can disable the function that implements this interface. All components which are registered as listeners for the state change then know to disable event generation for that item and to modify the display accordingly.
This interface can be added to an existing class or used to create an
adapter (typically, by subclassing AbstractAction
).
The Action
object
can then be added to multiple Action
-aware containers
and connected to Action
-capable
components. The GUI controls can then be activated or
deactivated all at once by invoking the Action
object's
setEnabled
method.
Note that Action
implementations tend to be more expensive
in terms of storage than a typical ActionListener
,
which does not offer the benefits of centralized control of
functionality and broadcast of property changes. For this reason,
you should take care to only use Action
s where their benefits
are desired, and use simple ActionListener
s elsewhere.
Swing Components Supporting Action
Many of Swing's components have an Action
property. When
an Action
is set on a component, the following things
happen:
- The
Action
is added as anActionListener
to the component. - The component configures some of its properties to match the
Action
. - The component installs a
PropertyChangeListener
on theAction
so that the component can change its properties to reflect changes in theAction
's properties.
The following table describes the properties used by
Swing
components that support Actions
.
In the table, button refers to any
AbstractButton
subclass, which includes not only
JButton
but also classes such as
JMenuItem
. Unless otherwise stated, a
null
property value in an Action
(or a
Action
that is null
) results in the
button's corresponding property being set to null
.
Component Property | Components | Action Key | Notes |
---|---|---|---|
enabled
| All | The isEnabled method
| |
toolTipText
| All | SHORT_DESCRIPTION
| |
actionCommand
| All | ACTION_COMMAND_KEY
| |
mnemonic
| All buttons | MNEMONIC_KEY
| A null value or Action results in the button's
mnemonic property being set to '\0' .
|
text
| All buttons | NAME
| If you do not want the text of the button to mirror that of the
Action , set the property hideActionText to true .
If hideActionText is true , setting the Action
changes the text of the button to null and any changes to
NAME are ignored. hideActionText is useful for tool bar
buttons that typically only show an Icon .
JToolBar.add(Action) sets the property to true if the
Action has a non-null value for LARGE_ICON_KEY or
SMALL_ICON .
|
displayedMnemonicIndex
| All buttons | DISPLAYED_MNEMONIC_INDEX_KEY
| If the value of DISPLAYED_MNEMONIC_INDEX_KEY is beyond the
bounds of the text, it is ignored. When setAction is called, if
the value from the Action is null , the displayed mnemonic
index is not updated. In any subsequent changes to
DISPLAYED_MNEMONIC_INDEX_KEY , null is treated as -1.
|
icon
| All buttons except of JCheckBox , JToggleButton and
JRadioButton .
| either LARGE_ICON_KEY or SMALL_ICON
| The JMenuItem subclasses only use SMALL_ICON . All
other buttons will use LARGE_ICON_KEY ; if the value is
null they use SMALL_ICON .
|
accelerator
| All JMenuItem subclasses, with the exception of JMenu .
| ACCELERATOR_KEY
| |
selected
| JToggleButton , JCheckBox , JRadioButton ,
JCheckBoxMenuItem and JRadioButtonMenuItem
| SELECTED_KEY
| Components that honor this property only use the value if it is
non-null . For example, if you set an Action that has a
null value for SELECTED_KEY on a JToggleButton ,
the JToggleButton will not update it's selected state in any way.
Similarly, any time the JToggleButton 's selected state changes it
will only set the value back on the Action if the Action
has a non-null value for SELECTED_KEY .
Components that honor this property keep their selected state in sync with this property. When the same Action is used with multiple
components, all the components keep their selected state in sync with this
property. Mutually exclusive buttons, such as JToggleButton s in a
ButtonGroup , force only one of the buttons to be selected. As
such, do not use the same Action that defines a value for the
SELECTED_KEY property with multiple mutually exclusive buttons.
|
JPopupMenu
, JToolBar
and JMenu
all provide convenience methods for creating a component and setting the
Action
on the corresponding component. Refer to each of
these classes for more information.
Action
uses PropertyChangeListener
to
inform listeners the Action
has changed. The beans
specification indicates that a null
property name can
be used to indicate multiple values have changed. By default Swing
components that take an Action
do not handle such a
change. To indicate that Swing should treat null
according to the beans specification set the system property
swing.actions.reconfigureOnNull
to the String
value true
.
- Since:
- 1.2
- See Also:
-
Field Summary
Modifier and TypeFieldDescriptionstatic final String
The key used for storing aKeyStroke
to be used as the accelerator for the action.static final String
The key used to determine the commandString
for theActionEvent
that will be created when anAction
is going to be notified as the result of residing in aKeymap
associated with aJComponent
.static final String
Not currently used.static final String
The key used for storing anInteger
that corresponds to the index in the text (identified by theNAME
property) that the decoration for a mnemonic should be rendered at.static final String
The key used for storing anIcon
.static final String
The key used for storing a longerString
description for the action, could be used for context-sensitive help.static final String
The key used for storing anInteger
that corresponds to one of theKeyEvent
key codes.static final String
The key used for storing theString
name for the action, used for a menu or button.static final String
The key used for storing aBoolean
that corresponds to the selected state.static final String
The key used for storing a shortString
description for the action, used for tooltip text.static final String
The key used for storing a smallIcon
, such asImageIcon
. -
Method Summary
Modifier and TypeMethodDescriptiondefault boolean
Determines whether the action should be performed with the specified sender object.void
Adds aPropertyChange
listener.Gets one of this object's properties using the associated key.boolean
Returns the enabled state of theAction
.void
Sets one of this object's properties using the associated key.void
Removes aPropertyChange
listener.void
setEnabled
(boolean b) Sets the enabled state of theAction
.Methods declared in interface java.awt.event.ActionListener
actionPerformed
-
Field Details
-
DEFAULT
Not currently used.- See Also:
-
NAME
The key used for storing theString
name for the action, used for a menu or button.- See Also:
-
SHORT_DESCRIPTION
The key used for storing a shortString
description for the action, used for tooltip text.- See Also:
-
LONG_DESCRIPTION
The key used for storing a longerString
description for the action, could be used for context-sensitive help.- See Also:
-
SMALL_ICON
The key used for storing a smallIcon
, such asImageIcon
. This is typically used with menus such asJMenuItem
.If the same
Action
is used with menus and buttons you'll typically specify both aSMALL_ICON
and aLARGE_ICON_KEY
. The menu will use theSMALL_ICON
and the button will use theLARGE_ICON_KEY
.- See Also:
-
ACTION_COMMAND_KEY
The key used to determine the commandString
for theActionEvent
that will be created when anAction
is going to be notified as the result of residing in aKeymap
associated with aJComponent
.- See Also:
-
ACCELERATOR_KEY
The key used for storing aKeyStroke
to be used as the accelerator for the action.- Since:
- 1.3
- See Also:
-
MNEMONIC_KEY
The key used for storing anInteger
that corresponds to one of theKeyEvent
key codes. The value is commonly used to specify a mnemonic. For example:myAction.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_A)
sets the mnemonic ofmyAction
to 'a', whilemyAction.putValue(Action.MNEMONIC_KEY, KeyEvent.getExtendedKeyCodeForChar('ф'))
sets the mnemonic ofmyAction
to Cyrillic letter "Ef".- Since:
- 1.3
- See Also:
-
SELECTED_KEY
The key used for storing aBoolean
that corresponds to the selected state. This is typically used only for components that have a meaningful selection state. For example,JRadioButton
andJCheckBox
make use of this but instances ofJMenu
don't.This property differs from the others in that it is both read by the component and set by the component. For example, if an
Action
is attached to aJCheckBox
the selected state of theJCheckBox
will be set from that of theAction
. If the user clicks on theJCheckBox
the selected state of theJCheckBox
and theAction
will both be updated.Note: the value of this field is prefixed with 'Swing' to avoid possible collisions with existing
Actions
.- Since:
- 1.6
- See Also:
-
DISPLAYED_MNEMONIC_INDEX_KEY
The key used for storing anInteger
that corresponds to the index in the text (identified by theNAME
property) that the decoration for a mnemonic should be rendered at. If the value of this property is greater than or equal to the length of the text, it will treated as -1.Note: the value of this field is prefixed with 'Swing' to avoid possible collisions with existing
Actions
.- Since:
- 1.6
- See Also:
-
LARGE_ICON_KEY
The key used for storing anIcon
. This is typically used by buttons, such asJButton
andJToggleButton
.If the same
Action
is used with menus and buttons you'll typically specify both aSMALL_ICON
and aLARGE_ICON_KEY
. The menu will use theSMALL_ICON
and the button theLARGE_ICON_KEY
.Note: the value of this field is prefixed with 'Swing' to avoid possible collisions with existing
Actions
.- Since:
- 1.6
- See Also:
-
-
Method Details
-
getValue
Gets one of this object's properties using the associated key.- Parameters:
key
- aString
containing the key- Returns:
- the
Object
value - See Also:
-
putValue
Sets one of this object's properties using the associated key. If the value has changed, aPropertyChangeEvent
is sent to listeners.- Parameters:
key
- aString
containing the keyvalue
- anObject
value
-
setEnabled
void setEnabled(boolean b) Sets the enabled state of theAction
. When enabled, any component associated with this object is active and able to fire this object'sactionPerformed
method. If the value has changed, aPropertyChangeEvent
is sent to listeners.- Parameters:
b
- true to enable thisAction
, false to disable it- See Also:
-
isEnabled
boolean isEnabled()Returns the enabled state of theAction
. When enabled, any component associated with this object is active and able to fire this object'sactionPerformed
method.- Returns:
- true if this
Action
is enabled - See Also:
-
accept
Determines whether the action should be performed with the specified sender object. Thesender
can benull
. The method must return false if the action is disabled.- Parameters:
sender
- the object to check, can be null- Returns:
true
if the action should be performed with the sender object, must be false if the action is disabled.- See Also:
-
addPropertyChangeListener
Adds aPropertyChange
listener. Containers and attached components use these methods to register interest in thisAction
object. When its enabled state or other property changes, the registered listeners are informed of the change.- Parameters:
listener
- aPropertyChangeListener
object
-
removePropertyChangeListener
Removes aPropertyChange
listener.- Parameters:
listener
- aPropertyChangeListener
object- See Also:
-