-
- 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
public interface Action extends ActionListener
TheAction
interface provides a useful extension to theActionListener
interface in cases where the same functionality may be accessed by several controls.In addition to the
actionPerformed
method defined by theActionListener
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
). TheAction
object can then be added to multipleAction
-aware containers and connected toAction
-capable components. The GUI controls can then be activated or deactivated all at once by invoking theAction
object'ssetEnabled
method.Note that
Action
implementations tend to be more expensive in terms of storage than a typicalActionListener
, 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 useAction
s where their benefits are desired, and use simpleActionListener
s elsewhere.
Swing Components Supporting
Action
Many of Swing's components have an
Action
property. When anAction
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 supportActions
. In the table, button refers to anyAbstractButton
subclass, which includes not onlyJButton
but also classes such asJMenuItem
. Unless otherwise stated, anull
property value in anAction
(or aAction
that isnull
) results in the button's corresponding property being set tonull
.Component Property Components Action Key Notes enabled
All The isEnabled
methodtoolTipText
All SHORT_DESCRIPTION
actionCommand
All ACTION_COMMAND_KEY
mnemonic
All buttons MNEMONIC_KEY
A null
value orAction
results in the button'smnemonic
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 propertyhideActionText
totrue
. IfhideActionText
istrue
, setting theAction
changes the text of the button tonull
and any changes toNAME
are ignored.hideActionText
is useful for tool bar buttons that typically only show anIcon
.JToolBar.add(Action)
sets the property totrue
if theAction
has a non-null
value forLARGE_ICON_KEY
orSMALL_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. WhensetAction
is called, if the value from theAction
isnull
, the displayed mnemonic index is not updated. In any subsequent changes toDISPLAYED_MNEMONIC_INDEX_KEY
,null
is treated as -1.icon
All buttons except of JCheckBox
,JToggleButton
andJRadioButton
.either LARGE_ICON_KEY
orSMALL_ICON
The JMenuItem
subclasses only useSMALL_ICON
. All other buttons will useLARGE_ICON_KEY
; if the value isnull
they useSMALL_ICON
.accelerator
All JMenuItem
subclasses, with the exception ofJMenu
.ACCELERATOR_KEY
selected
JToggleButton
,JCheckBox
,JRadioButton
,JCheckBoxMenuItem
andJRadioButtonMenuItem
SELECTED_KEY
Components that honor this property only use the value if it is non-null
. For example, if you set anAction
that has anull
value forSELECTED_KEY
on aJToggleButton
, theJToggleButton
will not update it's selected state in any way. Similarly, any time theJToggleButton
's selected state changes it will only set the value back on theAction
if theAction
has anon-null
value forSELECTED_KEY
.
Components that honor this property keep their selected state in sync with this property. When the sameAction
is used with multiple components, all the components keep their selected state in sync with this property. Mutually exclusive buttons, such asJToggleButton
s in aButtonGroup
, force only one of the buttons to be selected. As such, do not use the sameAction
that defines a value for theSELECTED_KEY
property with multiple mutually exclusive buttons.JPopupMenu
,JToolBar
andJMenu
all provide convenience methods for creating a component and setting theAction
on the corresponding component. Refer to each of these classes for more information.Action
usesPropertyChangeListener
to inform listeners theAction
has changed. The beans specification indicates that anull
property name can be used to indicate multiple values have changed. By default Swing components that take anAction
do not handle such a change. To indicate that Swing should treatnull
according to the beans specification set the system propertyswing.actions.reconfigureOnNull
to theString
valuetrue
.- Since:
- 1.2
- See Also:
AbstractAction
-
-
Field Summary
Fields Modifier and Type Field Description static String
ACCELERATOR_KEY
The key used for storing aKeyStroke
to be used as the accelerator for the action.static String
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
.static String
DEFAULT
Not currently used.static String
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.static String
LARGE_ICON_KEY
The key used for storing anIcon
.static String
LONG_DESCRIPTION
The key used for storing a longerString
description for the action, could be used for context-sensitive help.static String
MNEMONIC_KEY
The key used for storing anInteger
that corresponds to one of theKeyEvent
key codes.static String
NAME
The key used for storing theString
name for the action, used for a menu or button.static String
SELECTED_KEY
The key used for storing aBoolean
that corresponds to the selected state.static String
SHORT_DESCRIPTION
The key used for storing a shortString
description for the action, used for tooltip text.static String
SMALL_ICON
The key used for storing a smallIcon
, such asImageIcon
.
-
Method Summary
All Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description default boolean
accept(Object sender)
Determines whether the action should be performed with the specified sender object.void
addPropertyChangeListener(PropertyChangeListener listener)
Adds aPropertyChange
listener.Object
getValue(String key)
Gets one of this object's properties using the associated key.boolean
isEnabled()
Returns the enabled state of theAction
.void
putValue(String key, Object value)
Sets one of this object's properties using the associated key.void
removePropertyChangeListener(PropertyChangeListener listener)
Removes aPropertyChange
listener.void
setEnabled(boolean b)
Sets the enabled state of theAction
.-
Methods inherited from interface java.awt.event.ActionListener
actionPerformed
-
-
-
-
Field Detail
-
DEFAULT
static final String DEFAULT
Not currently used.- See Also:
- Constant Field Values
-
NAME
static final String NAME
The key used for storing theString
name for the action, used for a menu or button.- See Also:
- Constant Field Values
-
SHORT_DESCRIPTION
static final String SHORT_DESCRIPTION
The key used for storing a shortString
description for the action, used for tooltip text.- See Also:
- Constant Field Values
-
LONG_DESCRIPTION
static final String LONG_DESCRIPTION
The key used for storing a longerString
description for the action, could be used for context-sensitive help.- See Also:
- Constant Field Values
-
SMALL_ICON
static final String 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:
- Constant Field Values
-
ACTION_COMMAND_KEY
static final String 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:
- Constant Field Values
-
ACCELERATOR_KEY
static final String ACCELERATOR_KEY
The key used for storing aKeyStroke
to be used as the accelerator for the action.- Since:
- 1.3
- See Also:
- Constant Field Values
-
MNEMONIC_KEY
static final String 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('?'))
sets the mnemonic ofmyAction
to Cyrillic letter "Ef".- Since:
- 1.3
- See Also:
- Constant Field Values
-
SELECTED_KEY
static final String 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:
- Constant Field Values
-
DISPLAYED_MNEMONIC_INDEX_KEY
static final String 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:
AbstractButton.setDisplayedMnemonicIndex(int)
, Constant Field Values
-
LARGE_ICON_KEY
static final String 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:
- Constant Field Values
-
-
Method Detail
-
getValue
Object getValue(String key)
Gets one of this object's properties using the associated key.- Parameters:
key
- aString
containing the key- Returns:
- the
Object
value - See Also:
putValue(java.lang.String, java.lang.Object)
-
putValue
void putValue(String key, Object value)
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:
accept(java.lang.Object)
-
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(java.lang.Object)
-
accept
default boolean accept(Object sender)
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:
isEnabled()
,setEnabled(boolean)
-
addPropertyChangeListener
void addPropertyChangeListener(PropertyChangeListener listener)
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
void removePropertyChangeListener(PropertyChangeListener listener)
Removes aPropertyChange
listener.- Parameters:
listener
- aPropertyChangeListener
object- See Also:
addPropertyChangeListener(java.beans.PropertyChangeListener)
-
-