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 the createxxxListener() 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
| 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 the |
class |
BasicComboBoxUI.PropertyChangeHandler This listener watches for bound properties that have changed in the combo box. |
protected JComboBox comboBox
protected boolean hasFocus
This protected field is implementation specific. Do not access directly or override.
protected JList listBox
protected CellRendererPane currentValuePane
protected ComboPopup popup
protected Component editor
protected JButton arrowButton
protected KeyListener keyListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.
createKeyListener()protected FocusListener focusListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.
createFocusListener()protected PropertyChangeListener propertyChangeListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.
createPropertyChangeListener()protected ItemListener itemListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.
createItemListener()protected MouseListener popupMouseListener
protected MouseMotionListener popupMouseMotionListener
protected KeyListener popupKeyListener
protected ListDataListener listDataListener
This protected field is implementation specific. Do not access directly or override. Override the listener construction method instead.
createListDataListener()protected boolean isMinimumSizeDirty
protected Dimension cachedMinimumSize
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.
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.
public BasicComboBoxUI()
public static ComponentUI createUI(JComponent c)
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 the ComponentUI 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:
LayoutManager on the component if necessary. PropertyChangeListener on the component in order to detect and respond to component property changes appropriately. installUI in class ComponentUI
c - the component where this UI delegate is being installedComponentUI.uninstallUI(javax.swing.JComponent), JComponent.setUI(javax.swing.plaf.ComponentUI), JComponent.updateUI()
public void uninstallUI(JComponent c)
Description copied from class: ComponentUI
Reverses configuration which was done on the specified component during installUI. This method is invoked when this UIComponent instance is being removed as the UI delegate for the specified component. This method should undo the configuration performed in installUI, being careful to leave the JComponent instance in a clean state (no extraneous listeners, look-and-feel-specific property objects, etc.). This should include the following:
uninstallUI in class ComponentUI
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 componentsComponentUI.installUI(javax.swing.JComponent), JComponent.updateUI()
protected void installDefaults()
Installs the default colors, default font, default renderer, and default editor into the JComboBox.
protected void installListeners()
Creates and installs listeners for the combo box and its model. This method is called when the UI is installed.
protected void uninstallDefaults()
Uninstalls the default colors, default font, default renderer, and default editor from the combo box.
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 in installListeners
protected ComboPopup createPopup()
Creates the popup portion of the combo box.
ComboPopup
ComboPopupprotected KeyListener createKeyListener()
Creates a KeyListener which will be added to the combo box. If this method returns null then it will not be added to the combo box.
KeyListener or nullprotected FocusListener createFocusListener()
Creates a FocusListener which will be added to the combo box. If this method returns null then it will not be added to the combo box.
FocusListener or nullprotected ListDataListener createListDataListener()
Creates a list data listener which will be added to the ComboBoxModel. If this method returns null then it will not be added to the combo box model.
ListDataListener or nullprotected ItemListener createItemListener()
Creates an ItemListener 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.
ItemListener or nullprotected PropertyChangeListener createPropertyChangeListener()
Creates a PropertyChangeListener which will be added to the combo box. If this method returns null then it will not be added to the combo box.
PropertyChangeListener or nullprotected LayoutManager createLayoutManager()
Creates a layout manager for managing the components which make up the combo box.
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 with setRenderer.
ListCellRender used for the combo boxJComboBox.setRenderer(javax.swing.ListCellRenderer<? super E>)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 with setEditor.
ComboBoxEditor used for the combo boxJComboBox.setEditor(javax.swing.ComboBoxEditor)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.
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.
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 custom ComboBoxEditor
public void removeEditor()
This public method is implementation specific and should be private. do not call or override.
addEditor()protected void configureEditor()
This protected method is implementation specific and should be private. do not call or override.
addEditor()protected void unconfigureEditor()
This protected method is implementation specific and should be private. Do not call or override.
addEditor()public void configureArrowButton()
This public method is implementation specific and should be private. Do not call or override.
createArrowButton()public void unconfigureArrowButton()
This public method is implementation specific and should be private. Do not call or override.
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.
public boolean isPopupVisible(JComboBox c)
Tells if the popup is visible or not.
isPopupVisible in class ComboBoxUI
public void setPopupVisible(JComboBox c,
boolean v) Hides the popup.
setPopupVisible in class ComboBoxUI
public boolean isFocusTraversable(JComboBox c)
Determines if the JComboBox is focus traversable. If the JComboBox is editable this returns false, otherwise it returns true.
isFocusTraversable in class ComboBoxUI
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 the ComponentUI.update method when the specified component is being painted. Subclasses should override this method and use the specified Graphics object to render the content of the component.
paint in class ComponentUI
g - the Graphics context in which to paintc - the component being painted; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple componentsComponentUI.update(java.awt.Graphics, javax.swing.JComponent)public Dimension getPreferredSize(JComponent c)
Description copied from class: ComponentUI
Returns the specified component's preferred size appropriate for the look and feel. If null 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 returns null.
getPreferredSize in class ComponentUI
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 componentsJComponent.getPreferredSize(), LayoutManager.preferredLayoutSize(java.awt.Container)
public Dimension getMinimumSize(JComponent c)
The minimum size is the size of the display area plus insets plus the button.
getMinimumSize in class ComponentUI
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 componentsDimension object or null
JComponent.getMinimumSize(), LayoutManager.minimumLayoutSize(java.awt.Container), ComponentUI.getPreferredSize(javax.swing.JComponent)
public Dimension getMaximumSize(JComponent c)
Description copied from class: ComponentUI
Returns the specified component's maximum size appropriate for the look and feel. If null 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 invokes getPreferredSize and returns that value.
getMaximumSize in class ComponentUI
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 componentsDimension object or null
JComponent.getMaximumSize(), LayoutManager2.maximumLayoutSize(java.awt.Container)
public int getBaseline(JComponent c,
int width,
int height) Returns the baseline.
getBaseline in class ComponentUI
c - JComponent baseline is being requested forwidth - the width to get the baseline forheight - the height to get the baseline forNullPointerException - if c is null
IllegalArgumentException - if width or height is < 0JComponent.getBaseline(int, int)public Component.BaselineResizeBehavior getBaselineResizeBehavior(JComponent c)
Returns an enum indicating how the baseline of the component changes as the size changes.
getBaselineResizeBehavior in class ComponentUI
c - JComponent to return baseline resize behavior forNullPointerException - if c is null
JComponent.getBaseline(int, int)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 implement Accessible, 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 call Component.AccessibleAWTComponent.getAccessibleChildrenCount() instead of this method.
getAccessibleChildrenCount in class ComponentUI
ComponentUI.getAccessibleChild(javax.swing.JComponent, int)public Accessible getAccessibleChild(JComponent c,
int i) Description copied from class: ComponentUI
Returns the ith Accessible 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.
getAccessibleChild in class ComponentUI
i - zero-based index of childith Accessible child of the objectComponentUI.getAccessibleChildrenCount(javax.swing.JComponent)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.
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.
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.
protected void toggleOpenClose()
Hides the popup if it is showing and shows the popup if it is hidden.
protected Rectangle rectangleForCurrentValue()
Returns the area that is reserved for drawing the currently selected item.
protected Insets getInsets()
Gets the insets from the JComboBox.
public void paintCurrentValue(Graphics g,
Rectangle bounds,
boolean hasFocus) Paints the currently selected item.
public void paintCurrentValueBackground(Graphics g,
Rectangle bounds,
boolean hasFocus) Paints the background of the currently selected item.
protected Dimension getDefaultSize()
Return the default size of an empty display area of the combo box using the current renderer and font.
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.
JComboBox.setPrototypeDisplayValue(E)protected Dimension getSizeForComponent(Component comp)
Returns the size a component would have if used as a cell renderer.
comp - a Component to checkprotected void installKeyboardActions()
Adds keyboard actions to the JComboBox. Actions on enter and esc are already supplied. Add more actions as you need them.
protected void uninstallKeyboardActions()
Removes the focus InputMap and ActionMap.
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