- Direct Known Subclasses:
MetalComboBoxUI,SynthComboBoxUI
The combo box is a compound component which means that it is an aggregate of many simpler components. This class creates and manages the listeners on the combo box and the combo box model. These listeners update the user interface in response to changes in the properties and state of the combo box.
All event handling is handled by listener classes created with the
createxxxListener() methods and internal classes.
You can change the behavior of this class by overriding the
createxxxListener() methods and supplying your own
event listeners or subclassing from the ones supplied in this class.
For adding specific actions,
override installKeyboardActions to add actions in response to
KeyStroke bindings. See the article How to Use Key Bindings
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionclassThis layout manager handles the 'standard' layout of combo boxes.classThis listener hides the popup when the focus is lost.classThis listener watches for changes to the selection in the combo box.classThis listener checks to see if the key event isn't a navigation key.classThis listener watches for changes in theComboBoxModel.classThis listener watches for bound properties that have changed in the combo box. -
Field Summary
FieldsModifier and TypeFieldDescriptionprotected JButtonThe arrow button that invokes the popup.protected DimensionThe cached minimum preferred size.The instance ofJComboBox.protected CellRendererPaneUsed to render the currently selected item in the combo box.protected ComponentThe Component that theComboBoxEditoruses for editing.protected FocusListenerThis protected field is implementation specific.protected booleanThis protected field is implementation specific.protected booleanThe flag for recalculating the minimum preferred size.protected ItemListenerThis protected field is implementation specific.protected KeyListenerThis protected field is implementation specific.This list is for drawing the current item in the combo box.protected ListDataListenerThis protected field is implementation specific.protected InsetsIf specified, these insets act as padding around the cell renderer when laying out and painting the "selected" item in the combo box.protected ComboPopupThe implementation ofComboPopupthat is used to show the popup.protected KeyListenerTheKeyListenerlistens to events.protected MouseListenerTheMouseListenerlistens to events.protected MouseMotionListenerTheMouseMotionListenerlistens to events.protected PropertyChangeListenerThis protected field is implementation specific.protected booleanIndicates whether or not the combo box button should be square. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoidThis public method is implementation specific and should be private.voidThis public method is implementation specific and should be private.protected voidThis protected method is implementation specific and should be private.protected JButtonCreates a button which will be used as the control to show or hide the popup portion of the combo box.protected ComboBoxEditorCreates the default editor that will be used in editable combo boxes.protected FocusListenerCreates aFocusListenerwhich will be added to the combo box.protected ItemListenerCreates anItemListenerwhich will be added to the combo box.protected KeyListenerCreates aKeyListenerwhich will be added to the combo box.protected LayoutManagerCreates a layout manager for managing the components which make up the combo box.protected ListDataListenerCreates a list data listener which will be added to theComboBoxModel.protected ComboPopupCreates the popup portion of the combo box.protected PropertyChangeListenerCreates aPropertyChangeListenerwhich will be added to the combo box.protected ListCellRenderer<Object> Creates the default renderer that will be used in a non-editiable combo box.static ComponentUIConstructs a new instance ofBasicComboBoxUI.intgetBaseline(JComponent c, int width, int height) Returns the baseline.Returns an enum indicating how the baseline of the component changes as the size changes.protected DimensionReturn the default size of an empty display area of the combo box using the current renderer and font.protected DimensionReturns the calculated size of the display area.protected InsetsGets the insets from the JComboBox.The minimum size is the size of the display area plus insets plus the button.protected DimensiongetSizeForComponent(Component comp) Returns the size a component would have if used as a cell renderer.protected voidCreates and initializes the components which make up the aggregate combo box.protected voidInstalls the default colors, default font, default renderer, and default editor into the JComboBox.protected voidAdds keyboard actions to the JComboBox.protected voidCreates and installs listeners for the combo box and its model.booleanisFocusTraversable(JComboBox<?> c) Determines if the JComboBox is focus traversable.protected booleanisNavigationKey(int keyCode) Returns whether or not the supplied keyCode maps to a key that is used for navigation.booleanisPopupVisible(JComboBox<?> c) Tells if the popup is visible or not.voidpaintCurrentValue(Graphics g, Rectangle bounds, boolean hasFocus) Paints the currently selected item.voidpaintCurrentValueBackground(Graphics g, Rectangle bounds, boolean hasFocus) Paints the background of the currently selected item.protected RectangleReturns the area that is reserved for drawing the currently selected item.voidThis public method is implementation specific and should be private.protected voidSelects the next item in the list.protected voidSelects the previous item in the list.voidsetPopupVisible(JComboBox<?> c, boolean v) Hides the popup.protected voidHides the popup if it is showing and shows the popup if it is hidden.voidThis public method is implementation specific and should be private.protected voidThis protected method is implementation specific and should be private.protected voidThe aggregate components which comprise the combo box are unregistered and uninitialized.protected voidUninstalls the default colors, default font, default renderer, and default editor from the combo box.protected voidRemoves the focus InputMap and ActionMap.protected voidRemoves the installed listeners from the combo box and its model.Methods declared in class javax.swing.plaf.ComponentUI
contains, getAccessibleChild, getAccessibleChildrenCount, getMaximumSize, getPreferredSize, installUI, paint, uninstallUI, update
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Field Details
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comboBox
The instance ofJComboBox. -
hasFocus
protected boolean hasFocusThis protected field is implementation specific. Do not access directly or override. -
listBox
This list is for drawing the current item in the combo box. -
currentValuePane
Used to render the currently selected item in the combo box. It doesn't have anything to do with the popup's rendering. -
popup
The implementation ofComboPopupthat is used to show the popup. -
editor
The Component that theComboBoxEditoruses for editing. -
arrowButton
The arrow button that invokes the popup. -
keyListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.- See Also:
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focusListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.- See Also:
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propertyChangeListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.- See Also:
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itemListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.- See Also:
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popupMouseListener
TheMouseListenerlistens to events. -
popupMouseMotionListener
TheMouseMotionListenerlistens to events. -
popupKeyListener
TheKeyListenerlistens to events. -
listDataListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.- See Also:
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isMinimumSizeDirty
protected boolean isMinimumSizeDirtyThe flag for recalculating the minimum preferred size. -
cachedMinimumSize
The cached minimum preferred size. -
squareButton
protected boolean squareButtonIndicates whether or not the combo box button should be square. If square, then the width and height are equal, and are both set to the height of the combo minus appropriate insets.- Since:
- 1.7
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padding
If specified, these insets act as padding around the cell renderer when laying out and painting the "selected" item in the combo box. These insets add to those specified by the cell renderer.- Since:
- 1.7
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Constructor Details
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BasicComboBoxUI
public BasicComboBoxUI()Constructs aBasicComboBoxUI.
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Method Details
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createUI
Constructs a new instance ofBasicComboBoxUI.- Parameters:
c- a component- Returns:
- a new instance of
BasicComboBoxUI
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installDefaults
protected void installDefaults()Installs the default colors, default font, default renderer, and default editor into the JComboBox. -
installListeners
protected void installListeners()Creates and installs listeners for the combo box and its model. This method is called when the UI is installed. -
uninstallDefaults
protected void uninstallDefaults()Uninstalls the default colors, default font, default renderer, and default editor from the combo box. -
uninstallListeners
protected void uninstallListeners()Removes the installed listeners from the combo box and its model. The number and types of listeners removed and in this method should be the same that was added ininstallListeners -
createPopup
Creates the popup portion of the combo box.- Returns:
- an instance of
ComboPopup - See Also:
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createKeyListener
Creates aKeyListenerwhich will be added to the combo box. If this method returns null then it will not be added to the combo box.- Returns:
- an instance
KeyListeneror null
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createFocusListener
Creates aFocusListenerwhich will be added to the combo box. If this method returns null then it will not be added to the combo box.- Returns:
- an instance of a
FocusListeneror null
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createListDataListener
Creates a list data listener which will be added to theComboBoxModel. If this method returns null then it will not be added to the combo box model.- Returns:
- an instance of a
ListDataListeneror null
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createItemListener
Creates anItemListenerwhich will be added to the combo box. If this method returns null then it will not be added to the combo box.Subclasses may override this method to return instances of their own ItemEvent handlers.
- Returns:
- an instance of an
ItemListeneror null
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createPropertyChangeListener
Creates aPropertyChangeListenerwhich will be added to the combo box. If this method returns null then it will not be added to the combo box.- Returns:
- an instance of a
PropertyChangeListeneror null
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createLayoutManager
Creates a layout manager for managing the components which make up the combo box.- Returns:
- an instance of a layout manager
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createRenderer
Creates the default renderer that will be used in a non-editiable combo box. A default renderer will used only if a renderer has not been explicitly set withsetRenderer.- Returns:
- a
ListCellRenderused for the combo box - See Also:
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createEditor
Creates the default editor that will be used in editable combo boxes. A default editor will be used only if an editor has not been explicitly set withsetEditor.- Returns:
- a
ComboBoxEditorused for the combo box - See Also:
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installComponents
protected void installComponents()Creates and initializes the components which make up the aggregate combo box. This method is called as part of the UI installation process. -
uninstallComponents
protected void uninstallComponents()The aggregate components which comprise the combo box are unregistered and uninitialized. This method is called as part of the UI uninstallation process. -
addEditor
public void addEditor()This public method is implementation specific and should be private. do not call or override. To implement a specific editor create a customComboBoxEditor- See Also:
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removeEditor
public void removeEditor()This public method is implementation specific and should be private. do not call or override.- See Also:
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configureEditor
protected void configureEditor()This protected method is implementation specific and should be private. do not call or override.- See Also:
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unconfigureEditor
protected void unconfigureEditor()This protected method is implementation specific and should be private. Do not call or override.- See Also:
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configureArrowButton
public void configureArrowButton()This public method is implementation specific and should be private. Do not call or override.- See Also:
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unconfigureArrowButton
public void unconfigureArrowButton()This public method is implementation specific and should be private. Do not call or override.- See Also:
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createArrowButton
Creates a button which will be used as the control to show or hide the popup portion of the combo box.- Returns:
- a button which represents the popup control
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isPopupVisible
Tells if the popup is visible or not.- Specified by:
isPopupVisiblein classComboBoxUI- Parameters:
c- aJComboBox- Returns:
- true if popup of the
JComboBoxis visible
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setPopupVisible
Hides the popup.- Specified by:
setPopupVisiblein classComboBoxUI- Parameters:
c- aJComboBoxv- abooleandetermining the visibility of the popup
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isFocusTraversable
Determines if the JComboBox is focus traversable. If the JComboBox is editable this returns false, otherwise it returns true.- Specified by:
isFocusTraversablein classComboBoxUI- Parameters:
c- aJComboBox- Returns:
- true if the given
JComboBoxis traversable
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getMinimumSize
The minimum size is the size of the display area plus insets plus the button.- Overrides:
getMinimumSizein classComponentUI- Parameters:
c- the component whose minimum size is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components- Returns:
- a
Dimensionobject ornull - See Also:
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getBaseline
Returns the baseline.- Overrides:
getBaselinein classComponentUI- Parameters:
c-JComponentbaseline is being requested forwidth- the width to get the baseline forheight- the height to get the baseline for- Returns:
- baseline or a value < 0 indicating there is no reasonable baseline
- Throws:
NullPointerException- ifcisnullIllegalArgumentException- if width or height is < 0- Since:
- 1.6
- See Also:
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getBaselineResizeBehavior
Returns an enum indicating how the baseline of the component changes as the size changes.- Overrides:
getBaselineResizeBehaviorin classComponentUI- Parameters:
c-JComponentto return baseline resize behavior for- Returns:
- an enum indicating how the baseline changes as the component size changes
- Throws:
NullPointerException- ifcisnull- Since:
- 1.6
- See Also:
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selectNextPossibleValue
protected void selectNextPossibleValue()Selects the next item in the list. It won't change the selection if the currently selected item is already the last item. -
selectPreviousPossibleValue
protected void selectPreviousPossibleValue()Selects the previous item in the list. It won't change the selection if the currently selected item is already the first item. -
toggleOpenClose
protected void toggleOpenClose()Hides the popup if it is showing and shows the popup if it is hidden. -
rectangleForCurrentValue
Returns the area that is reserved for drawing the currently selected item.- Returns:
- the area that is reserved for drawing the currently selected item
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getInsets
Gets the insets from the JComboBox.- Returns:
- the insets
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paintCurrentValue
Paints the currently selected item.- Parameters:
g- an instance ofGraphicsbounds- a bounding rectangle to render tohasFocus- is focused
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paintCurrentValueBackground
Paints the background of the currently selected item.- Parameters:
g- an instance ofGraphicsbounds- a bounding rectangle to render tohasFocus- is focused
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getDefaultSize
Return the default size of an empty display area of the combo box using the current renderer and font.- Returns:
- the size of an empty display area
- See Also:
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getDisplaySize
Returns the calculated size of the display area. The display area is the portion of the combo box in which the selected item is displayed. This method will use the prototype display value if it has been set.For combo boxes with a non trivial number of items, it is recommended to use a prototype display value to significantly speed up the display size calculation.
- Returns:
- the size of the display area calculated from the combo box items
- See Also:
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getSizeForComponent
Returns the size a component would have if used as a cell renderer.- Parameters:
comp- aComponentto check- Returns:
- size of the component
- Since:
- 1.7
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installKeyboardActions
protected void installKeyboardActions()Adds keyboard actions to the JComboBox. Actions on enter and esc are already supplied. Add more actions as you need them. -
uninstallKeyboardActions
protected void uninstallKeyboardActions()Removes the focus InputMap and ActionMap.
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