Class BasicComboBoxUI
- java.lang.Object
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- javax.swing.plaf.ComponentUI
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- javax.swing.plaf.ComboBoxUI
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- javax.swing.plaf.basic.BasicComboBoxUI
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- Direct Known Subclasses:
- MetalComboBoxUI, SynthComboBoxUI
public class BasicComboBoxUI extends ComboBoxUI
Basic UI implementation for JComboBox.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 thecreatexxxListener()
methods and supplying your own event listeners or subclassing from the ones supplied in this class.For adding specific actions, overide
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 Classes Modifier and Type Class and Description class
BasicComboBoxUI.ComboBoxLayoutManager
This layout manager handles the 'standard' layout of combo boxes.class
BasicComboBoxUI.FocusHandler
This listener hides the popup when the focus is lost.class
BasicComboBoxUI.ItemHandler
This listener watches for changes to the selection in the combo box.class
BasicComboBoxUI.KeyHandler
This listener checks to see if the key event isn't a navigation key.class
BasicComboBoxUI.ListDataHandler
This listener watches for changes in theComboBoxModel
.class
BasicComboBoxUI.PropertyChangeHandler
This listener watches for bound properties that have changed in the combo box.
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Field Summary
Fields Modifier and Type Field and Description protected JButton
arrowButton
protected Dimension
cachedMinimumSize
protected JComboBox
comboBox
protected CellRendererPane
currentValuePane
protected Component
editor
protected FocusListener
focusListener
This protected field is implementation specific.protected boolean
hasFocus
This protected field is implementation specific.protected boolean
isMinimumSizeDirty
protected ItemListener
itemListener
This protected field is implementation specific.protected KeyListener
keyListener
This protected field is implementation specific.protected JList
listBox
protected ListDataListener
listDataListener
This protected field is implementation specific.protected Insets
padding
If specified, these insets act as padding around the cell renderer when laying out and painting the "selected" item in the combo box.protected ComboPopup
popup
protected KeyListener
popupKeyListener
protected MouseListener
popupMouseListener
protected MouseMotionListener
popupMouseMotionListener
protected PropertyChangeListener
propertyChangeListener
This protected field is implementation specific.protected boolean
squareButton
Indicates whether or not the combo box button should be square.
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Constructor Summary
Constructors Constructor and Description BasicComboBoxUI()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method and Description void
addEditor()
This public method is implementation specific and should be private.void
configureArrowButton()
This public method is implementation specific and should be private.protected void
configureEditor()
This protected method is implementation specific and should be private.protected JButton
createArrowButton()
Creates a button which will be used as the control to show or hide the popup portion of the combo box.protected ComboBoxEditor
createEditor()
Creates the default editor that will be used in editable combo boxes.protected FocusListener
createFocusListener()
Creates aFocusListener
which will be added to the combo box.protected ItemListener
createItemListener()
Creates anItemListener
which will be added to the combo box.protected KeyListener
createKeyListener()
Creates aKeyListener
which will be added to the combo box.protected LayoutManager
createLayoutManager()
Creates a layout manager for managing the components which make up the combo box.protected ListDataListener
createListDataListener()
Creates a list data listener which will be added to theComboBoxModel
.protected ComboPopup
createPopup()
Creates the popup portion of the combo box.protected PropertyChangeListener
createPropertyChangeListener()
Creates aPropertyChangeListener
which will be added to the combo box.protected ListCellRenderer
createRenderer()
Creates the default renderer that will be used in a non-editiable combo box.static ComponentUI
createUI(JComponent c)
Accessible
getAccessibleChild(JComponent c, int i)
Returns thei
thAccessible
child of the object.int
getAccessibleChildrenCount(JComponent c)
Returns the number of accessible children in the object.int
getBaseline(JComponent c, int width, int height)
Returns the baseline.Component.BaselineResizeBehavior
getBaselineResizeBehavior(JComponent c)
Returns an enum indicating how the baseline of the component changes as the size changes.protected Dimension
getDefaultSize()
Return the default size of an empty display area of the combo box using the current renderer and font.protected Dimension
getDisplaySize()
Returns the calculated size of the display area.protected Insets
getInsets()
Gets the insets from the JComboBox.Dimension
getMaximumSize(JComponent c)
Returns the specified component's maximum size appropriate for the look and feel.Dimension
getMinimumSize(JComponent c)
The minimum size is the size of the display area plus insets plus the button.Dimension
getPreferredSize(JComponent c)
Returns the specified component's preferred size appropriate for the look and feel.protected Dimension
getSizeForComponent(Component comp)
Returns the size a component would have if used as a cell renderer.protected void
installComponents()
Creates and initializes the components which make up the aggregate combo box.protected void
installDefaults()
Installs the default colors, default font, default renderer, and default editor into the JComboBox.protected void
installKeyboardActions()
Adds keyboard actions to the JComboBox.protected void
installListeners()
Creates and installs listeners for the combo box and its model.void
installUI(JComponent c)
Configures the specified component appropriately for the look and feel.boolean
isFocusTraversable(JComboBox c)
Determines if the JComboBox is focus traversable.protected boolean
isNavigationKey(int keyCode)
Returns whether or not the supplied keyCode maps to a key that is used for navigation.boolean
isPopupVisible(JComboBox c)
Tells if the popup is visible or not.void
paint(Graphics g, JComponent c)
Paints the specified component appropriately for the look and feel.void
paintCurrentValue(Graphics g, Rectangle bounds, boolean hasFocus)
Paints the currently selected item.void
paintCurrentValueBackground(Graphics g, Rectangle bounds, boolean hasFocus)
Paints the background of the currently selected item.protected Rectangle
rectangleForCurrentValue()
Returns the area that is reserved for drawing the currently selected item.void
removeEditor()
This public method is implementation specific and should be private.protected void
selectNextPossibleValue()
Selects the next item in the list.protected void
selectPreviousPossibleValue()
Selects the previous item in the list.void
setPopupVisible(JComboBox c, boolean v)
Hides the popup.protected void
toggleOpenClose()
Hides the popup if it is showing and shows the popup if it is hidden.void
unconfigureArrowButton()
This public method is implementation specific and should be private.protected void
unconfigureEditor()
This protected method is implementation specific and should be private.protected void
uninstallComponents()
The aggregate components which comprise the combo box are unregistered and uninitialized.protected void
uninstallDefaults()
Uninstalls the default colors, default font, default renderer, and default editor from the combo box.protected void
uninstallKeyboardActions()
Removes the focus InputMap and ActionMap.protected void
uninstallListeners()
Removes the installed listeners from the combo box and its model.void
uninstallUI(JComponent c)
Reverses configuration which was done on the specified component duringinstallUI
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Methods inherited from class javax.swing.plaf.ComponentUI
contains, update
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Field Detail
comboBox
protected JComboBox comboBox
hasFocus
protected boolean hasFocus
This protected field is implementation specific. Do not access directly or override.
listBox
protected JList listBox
currentValuePane
protected CellRendererPane currentValuePane
popup
protected ComboPopup popup
editor
protected Component editor
arrowButton
protected JButton arrowButton
keyListener
protected KeyListener 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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createKeyListener()
focusListener
protected FocusListener 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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createFocusListener()
propertyChangeListener
protected PropertyChangeListener 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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createPropertyChangeListener()
itemListener
protected ItemListener 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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createItemListener()
popupMouseListener
protected MouseListener popupMouseListener
popupMouseMotionListener
protected MouseMotionListener popupMouseMotionListener
popupKeyListener
protected KeyListener popupKeyListener
listDataListener
protected ListDataListener 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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createListDataListener()
isMinimumSizeDirty
protected boolean isMinimumSizeDirty
cachedMinimumSize
protected Dimension cachedMinimumSize
squareButton
protected boolean squareButton
Indicates 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
padding
protected Insets 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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Method Detail
createUI
public static ComponentUI createUI(JComponent c)
installUI
public void installUI(JComponent c)
Description copied from class:ComponentUI
Configures the specified component appropriately for the look and feel. This method is invoked when theComponentUI
instance is being installed as the UI delegate on the specified component. This method should completely configure the component for the look and feel, including the following:- Install default property values for color, fonts, borders, icons, opacity, etc. on the component. Whenever possible, property values initialized by the client program should not be overridden.
- Install a
LayoutManager
on the component if necessary. - Create/add any required sub-components to the component.
- Create/install event listeners on the component.
- Create/install a
PropertyChangeListener
on the component in order to detect and respond to component property changes appropriately. - Install keyboard UI (mnemonics, traversal, etc.) on the component.
- Initialize any appropriate instance data.
- Overrides:
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installUI
in classComponentUI
- Parameters:
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c
- the component where this UI delegate is being installed - See Also:
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ComponentUI.uninstallUI(javax.swing.JComponent)
,JComponent.setUI(javax.swing.plaf.ComponentUI)
,JComponent.updateUI()
uninstallUI
public void uninstallUI(JComponent c)
Description copied from class:ComponentUI
Reverses configuration which was done on the specified component duringinstallUI
. This method is invoked when thisUIComponent
instance is being removed as the UI delegate for the specified component. This method should undo the configuration performed ininstallUI
, being careful to leave theJComponent
instance in a clean state (no extraneous listeners, look-and-feel-specific property objects, etc.). This should include the following:- Remove any UI-set borders from the component.
- Remove any UI-set layout managers on the component.
- Remove any UI-added sub-components from the component.
- Remove any UI-added event/property listeners from the component.
- Remove any UI-installed keyboard UI from the component.
- Nullify any allocated instance data objects to allow for GC.
- Overrides:
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uninstallUI
in classComponentUI
- Parameters:
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c
- the component from which this UI delegate is being removed; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components - See Also:
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ComponentUI.installUI(javax.swing.JComponent)
,JComponent.updateUI()
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
protected ComboPopup createPopup()
Creates the popup portion of the combo box.- Returns:
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an instance of
ComboPopup
- See Also:
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ComboPopup
createKeyListener
protected KeyListener createKeyListener()
Creates aKeyListener
which will be added to the combo box. If this method returns null then it will not be added to the combo box.- Returns:
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an instance
KeyListener
or null
createFocusListener
protected FocusListener createFocusListener()
Creates aFocusListener
which will be added to the combo box. If this method returns null then it will not be added to the combo box.- Returns:
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an instance of a
FocusListener
or null
createListDataListener
protected ListDataListener 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:
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an instance of a
ListDataListener
or null
createItemListener
protected ItemListener createItemListener()
Creates anItemListener
which 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:
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an instance of an
ItemListener
or null
createPropertyChangeListener
protected PropertyChangeListener createPropertyChangeListener()
Creates aPropertyChangeListener
which will be added to the combo box. If this method returns null then it will not be added to the combo box.- Returns:
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an instance of a
PropertyChangeListener
or null
createLayoutManager
protected LayoutManager createLayoutManager()
Creates a layout manager for managing the components which make up the combo box.- Returns:
- an instance of a layout manager
createRenderer
protected ListCellRenderer 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:
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a
ListCellRender
used for the combo box - See Also:
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JComboBox.setRenderer(javax.swing.ListCellRenderer<? super E>)
createEditor
protected ComboBoxEditor 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:
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a
ComboBoxEditor
used for the combo box - See Also:
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JComboBox.setEditor(javax.swing.ComboBoxEditor)
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
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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addEditor()
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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addEditor()
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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addEditor()
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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createArrowButton()
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()
createArrowButton
protected JButton 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
isPopupVisible
public boolean isPopupVisible(JComboBox c)
Tells if the popup is visible or not.- Specified by:
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isPopupVisible
in classComboBoxUI
setPopupVisible
public void setPopupVisible(JComboBox c, boolean v)
Hides the popup.- Specified by:
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setPopupVisible
in classComboBoxUI
isFocusTraversable
public boolean isFocusTraversable(JComboBox c)
Determines if the JComboBox is focus traversable. If the JComboBox is editable this returns false, otherwise it returns true.- Specified by:
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isFocusTraversable
in classComboBoxUI
paint
public void paint(Graphics g, JComponent c)
Description copied from class:ComponentUI
Paints the specified component appropriately for the look and feel. This method is invoked from theComponentUI.update
method when the specified component is being painted. Subclasses should override this method and use the specifiedGraphics
object to render the content of the component.- Overrides:
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paint
in classComponentUI
- Parameters:
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g
- theGraphics
context in which to paint -
c
- the component being painted; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components - See Also:
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ComponentUI.update(java.awt.Graphics, javax.swing.JComponent)
getPreferredSize
public Dimension getPreferredSize(JComponent c)
Description copied from class:ComponentUI
Returns the specified component's preferred size appropriate for the look and feel. Ifnull
is returned, the preferred size will be calculated by the component's layout manager instead (this is the preferred approach for any component with a specific layout manager installed). The default implementation of this method returnsnull
.- Overrides:
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getPreferredSize
in classComponentUI
- Parameters:
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c
- the component whose preferred size is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components - See Also:
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JComponent.getPreferredSize()
,LayoutManager.preferredLayoutSize(java.awt.Container)
getMinimumSize
public Dimension getMinimumSize(JComponent c)
The minimum size is the size of the display area plus insets plus the button.- Overrides:
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getMinimumSize
in classComponentUI
- Parameters:
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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:
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a
Dimension
object ornull
- See Also:
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JComponent.getMinimumSize()
,LayoutManager.minimumLayoutSize(java.awt.Container)
,ComponentUI.getPreferredSize(javax.swing.JComponent)
getMaximumSize
public Dimension getMaximumSize(JComponent c)
Description copied from class:ComponentUI
Returns the specified component's maximum size appropriate for the look and feel. Ifnull
is returned, the maximum size will be calculated by the component's layout manager instead (this is the preferred approach for any component with a specific layout manager installed). The default implementation of this method invokesgetPreferredSize
and returns that value.- Overrides:
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getMaximumSize
in classComponentUI
- Parameters:
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c
- the component whose maximum 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
Dimension
object ornull
- See Also:
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JComponent.getMaximumSize()
,LayoutManager2.maximumLayoutSize(java.awt.Container)
getBaseline
public int getBaseline(JComponent c, int width, int height)
Returns the baseline.- Overrides:
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getBaseline
in classComponentUI
- Parameters:
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c
-JComponent
baseline is being requested for -
width
- the width to get the baseline for -
height
- the height to get the baseline for - Returns:
- baseline or a value < 0 indicating there is no reasonable baseline
- Throws:
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NullPointerException
- ifc
isnull
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IllegalArgumentException
- if width or height is < 0 - Since:
- 1.6
- See Also:
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JComponent.getBaseline(int, int)
getBaselineResizeBehavior
public Component.BaselineResizeBehavior getBaselineResizeBehavior(JComponent c)
Returns an enum indicating how the baseline of the component changes as the size changes.- Overrides:
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getBaselineResizeBehavior
in classComponentUI
- Parameters:
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c
-JComponent
to return baseline resize behavior for - Returns:
- an enum indicating how the baseline changes as the component size changes
- Throws:
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NullPointerException
- ifc
isnull
- Since:
- 1.6
- See Also:
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JComponent.getBaseline(int, int)
getAccessibleChildrenCount
public int getAccessibleChildrenCount(JComponent c)
Description copied from class:ComponentUI
Returns the number of accessible children in the object. If all of the children of this object implementAccessible
, this method should return the number of children of this object. UIs might wish to override this if they present areas on the screen that can be viewed as components, but actual components are not used for presenting those areas. Note: As of v1.3, it is recommended that developers callComponent.AccessibleAWTComponent.getAccessibleChildrenCount()
instead of this method.- Overrides:
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getAccessibleChildrenCount
in classComponentUI
- Returns:
- the number of accessible children in the object
- See Also:
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ComponentUI.getAccessibleChild(javax.swing.JComponent, int)
getAccessibleChild
public Accessible getAccessibleChild(JComponent c, int i)
Description copied from class:ComponentUI
Returns thei
thAccessible
child of the object. UIs might need to override this if they present areas on the screen that can be viewed as components, but actual components are not used for presenting those areas.Note: As of v1.3, it is recommended that developers call
Component.AccessibleAWTComponent.getAccessibleChild()
instead of this method.- Overrides:
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getAccessibleChild
in classComponentUI
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i
- zero-based index of child - Returns:
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the
i
thAccessible
child of the object - See Also:
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ComponentUI.getAccessibleChildrenCount(javax.swing.JComponent)
isNavigationKey
protected boolean isNavigationKey(int keyCode)
Returns whether or not the supplied keyCode maps to a key that is used for navigation. This is used for optimizing key input by only passing non- navigation keys to the type-ahead mechanism. Subclasses should override this if they change the navigation keys.
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
protected Rectangle rectangleForCurrentValue()
Returns the area that is reserved for drawing the currently selected item.
getInsets
protected Insets getInsets()
Gets the insets from the JComboBox.
paintCurrentValue
public void paintCurrentValue(Graphics g, Rectangle bounds, boolean hasFocus)
Paints the currently selected item.
paintCurrentValueBackground
public void paintCurrentValueBackground(Graphics g, Rectangle bounds, boolean hasFocus)
Paints the background of the currently selected item.
getDefaultSize
protected Dimension 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()
getDisplaySize
protected Dimension 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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JComboBox.setPrototypeDisplayValue(E)
getSizeForComponent
protected Dimension getSizeForComponent(Component comp)
Returns the size a component would have if used as a cell renderer.- Parameters:
-
comp
- aComponent
to check - Returns:
- size of the component
- Since:
- 1.7
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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Submit a bug or feature
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