Interface Action
- 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 Actions where their benefits
 are desired, and use simple ActionListeners 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 Actionis added as anActionListenerto the component.
- The component configures some of its properties to match the
      Action.
- The component installs a PropertyChangeListeneron theActionso 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 isEnabledmethod | |
| toolTipText | All | SHORT_DESCRIPTION | |
| actionCommand | All | ACTION_COMMAND_KEY | |
| mnemonic | All buttons | MNEMONIC_KEY | A nullvalue orActionresults in the button'smnemonicproperty 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 propertyhideActionTexttotrue.
    IfhideActionTextistrue, setting theActionchanges the text of the button tonulland any changes toNAMEare ignored.hideActionTextis useful for tool bar
    buttons that typically only show anIcon.JToolBar.add(Action)sets the property totrueif theActionhas a non-nullvalue forLARGE_ICON_KEYorSMALL_ICON. | 
| displayedMnemonicIndex | All buttons | DISPLAYED_MNEMONIC_INDEX_KEY | If the value of DISPLAYED_MNEMONIC_INDEX_KEYis beyond the
    bounds of the text, it is ignored. WhensetActionis called, if
    the value from theActionisnull, the displayed mnemonic
    index is not updated. In any subsequent changes toDISPLAYED_MNEMONIC_INDEX_KEY,nullis treated as -1. | 
| icon | All buttons except of JCheckBox,JToggleButtonandJRadioButton. | either LARGE_ICON_KEYorSMALL_ICON | The JMenuItemsubclasses only useSMALL_ICON. All
    other buttons will useLARGE_ICON_KEY; if the value isnullthey useSMALL_ICON. | 
| accelerator | All JMenuItemsubclasses, with the exception ofJMenu. | ACCELERATOR_KEY | |
| selected | JToggleButton,JCheckBox,JRadioButton,JCheckBoxMenuItemandJRadioButtonMenuItem | SELECTED_KEY | Components that honor this property only use the value if it is non-null. For example, if you set anActionthat has anullvalue forSELECTED_KEYon aJToggleButton,
    theJToggleButtonwill 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 theActionif theActionhas anon-nullvalue forSELECTED_KEY.Components that honor this property keep their selected state in sync with this property. When the same Actionis used with multiple
    components, all the components keep their selected state in sync with this
    property. Mutually exclusive buttons, such asJToggleButtons in aButtonGroup, force only one of the buttons to be selected. As
    such, do not use the sameActionthat defines a value for theSELECTED_KEYproperty 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 SummaryFieldsModifier and TypeFieldDescriptionstatic final StringThe key used for storing aKeyStroketo be used as the accelerator for the action.static final StringThe key used to determine the commandStringfor theActionEventthat will be created when anActionis going to be notified as the result of residing in aKeymapassociated with aJComponent.static final StringNot currently used.static final StringThe key used for storing anIntegerthat corresponds to the index in the text (identified by theNAMEproperty) that the decoration for a mnemonic should be rendered at.static final StringThe key used for storing anIcon.static final StringThe key used for storing a longerStringdescription for the action, could be used for context-sensitive help.static final StringThe key used for storing anIntegerthat corresponds to one of theKeyEventkey codes.static final StringThe key used for storing theStringname for the action, used for a menu or button.static final StringThe key used for storing aBooleanthat corresponds to the selected state.static final StringThe key used for storing a shortStringdescription for the action, used for tooltip text.static final StringThe key used for storing a smallIcon, such asImageIcon.
- 
Method SummaryModifier and TypeMethodDescriptiondefault booleanDetermines whether the action should be performed with the specified sender object.voidAdds aPropertyChangelistener.Gets one of this object's properties using the associated key.booleanReturns the enabled state of theAction.voidSets one of this object's properties using the associated key.voidRemoves aPropertyChangelistener.voidsetEnabled(boolean b) Sets the enabled state of theAction.Methods declared in interface java.awt.event.ActionListeneractionPerformed
- 
Field Details- 
DEFAULT
- 
NAMEThe key used for storing theStringname for the action, used for a menu or button.- See Also:
 
- 
SHORT_DESCRIPTIONThe key used for storing a shortStringdescription for the action, used for tooltip text.- See Also:
 
- 
LONG_DESCRIPTIONThe key used for storing a longerStringdescription for the action, could be used for context-sensitive help.- See Also:
 
- 
SMALL_ICONThe key used for storing a smallIcon, such asImageIcon. This is typically used with menus such asJMenuItem.If the same Actionis used with menus and buttons you'll typically specify both aSMALL_ICONand aLARGE_ICON_KEY. The menu will use theSMALL_ICONand the button will use theLARGE_ICON_KEY.- See Also:
 
- 
ACTION_COMMAND_KEYThe key used to determine the commandStringfor theActionEventthat will be created when anActionis going to be notified as the result of residing in aKeymapassociated with aJComponent.- See Also:
 
- 
ACCELERATOR_KEYThe key used for storing aKeyStroketo be used as the accelerator for the action.- Since:
- 1.3
- See Also:
 
- 
MNEMONIC_KEYThe key used for storing anIntegerthat corresponds to one of theKeyEventkey codes. The value is commonly used to specify a mnemonic. For example:myAction.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_A)sets the mnemonic ofmyActionto 'a', whilemyAction.putValue(Action.MNEMONIC_KEY, KeyEvent.getExtendedKeyCodeForChar('ф'))sets the mnemonic ofmyActionto Cyrillic letter "Ef".- Since:
- 1.3
- See Also:
 
- 
SELECTED_KEYThe key used for storing aBooleanthat corresponds to the selected state. This is typically used only for components that have a meaningful selection state. For example,JRadioButtonandJCheckBoxmake use of this but instances ofJMenudon'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 Actionis attached to aJCheckBoxthe selected state of theJCheckBoxwill be set from that of theAction. If the user clicks on theJCheckBoxthe selected state of theJCheckBoxand theActionwill 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_KEYThe key used for storing anIntegerthat corresponds to the index in the text (identified by theNAMEproperty) 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_KEYThe key used for storing anIcon. This is typically used by buttons, such asJButtonandJToggleButton.If the same Actionis used with menus and buttons you'll typically specify both aSMALL_ICONand aLARGE_ICON_KEY. The menu will use theSMALL_ICONand 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
- 
putValue
- 
setEnabledvoid 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'sactionPerformedmethod. If the value has changed, aPropertyChangeEventis sent to listeners.- Parameters:
- b- true to enable this- Action, false to disable it
- See Also:
 
- 
isEnabledboolean isEnabled()Returns the enabled state of theAction. When enabled, any component associated with this object is active and able to fire this object'sactionPerformedmethod.- Returns:
- true if this Actionis enabled
- See Also:
 
- 
acceptDetermines whether the action should be performed with the specified sender object. Thesendercan benull. The method must return false if the action is disabled.- Parameters:
- sender- the object to check, can be null
- Returns:
- trueif the action should be performed with the sender object, must be false if the action is disabled.
- See Also:
 
- 
addPropertyChangeListenerAdds aPropertyChangelistener. Containers and attached components use these methods to register interest in thisActionobject. When its enabled state or other property changes, the registered listeners are informed of the change.- Parameters:
- listener- a- PropertyChangeListenerobject
 
- 
removePropertyChangeListenerRemoves aPropertyChangelistener.- Parameters:
- listener- a- PropertyChangeListenerobject
- See Also:
 
 
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