Java javax.swing Class JComboBox<E>（JDK8）

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Java™ Platform
Standard Ed. 8

All Classes

Summary:
Nested |
Field |
Constr |
Method

Detail:
Field |
Constr |
Method

java.lang.Object
- java.awt.Component
- - java.awt.Container
  - - javax.swing.JComponent
    - - javax.swing.JComboBox<E>

Type Parameters:

E - the type of the elements of this combo box

All Implemented Interfaces:

ActionListener, ImageObserver, ItemSelectable, MenuContainer, Serializable, EventListener, Accessible, ListDataListener
```
public class JComboBox<E>
extends JComponent
implements ItemSelectable, ListDataListener, ActionListener, Accessible
```
A component that combines a button or editable field and a drop-down list. The user can select a value from the drop-down list, which appears at the user's request. If you make the combo box editable, then the combo box includes an editable field into which the user can type a value.
Warning: Swing is not thread safe. For more information see Swing's Threading Policy.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans™ has been added to the java.beans package. Please see XMLEncoder.

See How to Use Combo Boxes in The Java Tutorial for further information.

See Also:

ComboBoxModel, DefaultComboBoxModel

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`protected class`	`JComboBox.AccessibleJComboBox` This class implements accessibility support for the `JComboBox` class.
`static interface`	`JComboBox.KeySelectionManager` The interface that defines a `KeySelectionManager`.

Nested classes/interfaces inherited from class javax.swing.JComponent
JComponent.AccessibleJComponent

Nested classes/interfaces inherited from class java.awt.Container
Container.AccessibleAWTContainer

Nested classes/interfaces inherited from class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy

Field Summary

Fields
Modifier and Type	Field and Description
`protected String`	`actionCommand` This protected field is implementation specific.
`protected ComboBoxModel<E>`	`dataModel` This protected field is implementation specific.
`protected ComboBoxEditor`	`editor` This protected field is implementation specific.
`protected boolean`	`isEditable` This protected field is implementation specific.
`protected JComboBox.KeySelectionManager`	`keySelectionManager` This protected field is implementation specific.
`protected boolean`	`lightWeightPopupEnabled` This protected field is implementation specific.
`protected int`	`maximumRowCount` This protected field is implementation specific.
`protected ListCellRenderer<? super E>`	`renderer` This protected field is implementation specific.
`protected Object`	`selectedItemReminder` This protected field is implementation specific.

Fields inherited from class javax.swing.JComponent
listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW

Fields inherited from class java.awt.Component
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

Constructors
Constructor and Description
`JComboBox()` Creates a `JComboBox` with a default data model.
`JComboBox(ComboBoxModel<E> aModel)` Creates a `JComboBox` that takes its items from an existing `ComboBoxModel`.
`JComboBox(E[] items)` Creates a `JComboBox` that contains the elements in the specified array.
`JComboBox(Vector<E> items)` Creates a `JComboBox` that contains the elements in the specified Vector.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`actionPerformed(ActionEvent e)` This method is public as an implementation side effect.
`protected void`	`actionPropertyChanged(Action action, String propertyName)` Updates the combobox's state in response to property changes in associated action.
`void`	`addActionListener(ActionListener l)` Adds an `ActionListener`.
`void`	`addItem(E item)` Adds an item to the item list.
`void`	`addItemListener(ItemListener aListener)` Adds an `ItemListener`.
`void`	`addPopupMenuListener(PopupMenuListener l)` Adds a `PopupMenu` listener which will listen to notification messages from the popup portion of the combo box.
`void`	`configureEditor(ComboBoxEditor anEditor, Object anItem)` Initializes the editor with the specified item.
`protected void`	`configurePropertiesFromAction(Action a)` Sets the properties on this combobox to match those in the specified `Action`.
`void`	`contentsChanged(ListDataEvent e)` This method is public as an implementation side effect.
`protected PropertyChangeListener`	`createActionPropertyChangeListener(Action a)` Creates and returns a `PropertyChangeListener` that is responsible for listening for changes from the specified `Action` and updating the appropriate properties.
`protected JComboBox.KeySelectionManager`	`createDefaultKeySelectionManager()` Returns an instance of the default key-selection manager.
`protected void`	`fireActionEvent()` Notifies all listeners that have registered interest for notification on this event type.
`protected void`	`fireItemStateChanged(ItemEvent e)` Notifies all listeners that have registered interest for notification on this event type.
`void`	`firePopupMenuCanceled()` Notifies `PopupMenuListener`s that the popup portion of the combo box has been canceled.
`void`	`firePopupMenuWillBecomeInvisible()` Notifies `PopupMenuListener`s that the popup portion of the combo box has become invisible.
`void`	`firePopupMenuWillBecomeVisible()` Notifies `PopupMenuListener`s that the popup portion of the combo box will become visible.
`AccessibleContext`	`getAccessibleContext()` Gets the AccessibleContext associated with this JComboBox.
`Action`	`getAction()` Returns the currently set `Action` for this `ActionEvent` source, or `null` if no `Action` is set.
`String`	`getActionCommand()` Returns the action command that is included in the event sent to action listeners.
`ActionListener[]`	`getActionListeners()` Returns an array of all the `ActionListener`s added to this JComboBox with addActionListener().
`ComboBoxEditor`	`getEditor()` Returns the editor used to paint and edit the selected item in the `JComboBox` field.
`E`	`getItemAt(int index)` Returns the list item at the specified index.
`int`	`getItemCount()` Returns the number of items in the list.
`ItemListener[]`	`getItemListeners()` Returns an array of all the `ItemListener`s added to this JComboBox with addItemListener().
`JComboBox.KeySelectionManager`	`getKeySelectionManager()` Returns the list's key-selection manager.
`int`	`getMaximumRowCount()` Returns the maximum number of items the combo box can display without a scrollbar
`ComboBoxModel<E>`	`getModel()` Returns the data model currently used by the `JComboBox`.
`PopupMenuListener[]`	`getPopupMenuListeners()` Returns an array of all the `PopupMenuListener`s added to this JComboBox with addPopupMenuListener().
`E`	`getPrototypeDisplayValue()` Returns the "prototypical display" value - an Object used for the calculation of the display height and width.
`ListCellRenderer<? super E>`	`getRenderer()` Returns the renderer used to display the selected item in the `JComboBox` field.
`int`	`getSelectedIndex()` Returns the first item in the list that matches the given item.
`Object`	`getSelectedItem()` Returns the current selected item.
`Object[]`	`getSelectedObjects()` Returns an array containing the selected item.
`ComboBoxUI`	`getUI()` Returns the L&F object that renders this component.
`String`	`getUIClassID()` Returns the name of the L&F class that renders this component.
`void`	`hidePopup()` Causes the combo box to close its popup window.
`void`	`insertItemAt(E item, int index)` Inserts an item into the item list at a given index.
`protected void`	`installAncestorListener()`
`void`	`intervalAdded(ListDataEvent e)` This method is public as an implementation side effect.
`void`	`intervalRemoved(ListDataEvent e)` This method is public as an implementation side effect.
`boolean`	`isEditable()` Returns true if the `JComboBox` is editable.
`boolean`	`isLightWeightPopupEnabled()` Gets the value of the `lightWeightPopupEnabled` property.
`boolean`	`isPopupVisible()` Determines the visibility of the popup.
`protected String`	`paramString()` Returns a string representation of this `JComboBox`.
`protected boolean`	`processKeyBinding(KeyStroke ks, KeyEvent e, int condition, boolean pressed)` Invoked to process the key bindings for `ks` as the result of the `KeyEvent` `e`.
`void`	`processKeyEvent(KeyEvent e)` Handles `KeyEvent`s, looking for the Tab key.
`void`	`removeActionListener(ActionListener l)` Removes an `ActionListener`.
`void`	`removeAllItems()` Removes all items from the item list.
`void`	`removeItem(Object anObject)` Removes an item from the item list.
`void`	`removeItemAt(int anIndex)` Removes the item at `anIndex` This method works only if the `JComboBox` uses a mutable data model.
`void`	`removeItemListener(ItemListener aListener)` Removes an `ItemListener`.
`void`	`removePopupMenuListener(PopupMenuListener l)` Removes a `PopupMenuListener`.
`protected void`	`selectedItemChanged()` This protected method is implementation specific.
`boolean`	`selectWithKeyChar(char keyChar)` Selects the list item that corresponds to the specified keyboard character and returns true, if there is an item corresponding to that character.
`void`	`setAction(Action a)` Sets the `Action` for the `ActionEvent` source.
`void`	`setActionCommand(String aCommand)` Sets the action command that should be included in the event sent to action listeners.
`void`	`setEditable(boolean aFlag)` Determines whether the `JComboBox` field is editable.
`void`	`setEditor(ComboBoxEditor anEditor)` Sets the editor used to paint and edit the selected item in the `JComboBox` field.
`void`	`setEnabled(boolean b)` Enables the combo box so that items can be selected.
`void`	`setKeySelectionManager(JComboBox.KeySelectionManager aManager)` Sets the object that translates a keyboard character into a list selection.
`void`	`setLightWeightPopupEnabled(boolean aFlag)` Sets the `lightWeightPopupEnabled` property, which provides a hint as to whether or not a lightweight `Component` should be used to contain the `JComboBox`, versus a heavyweight `Component` such as a `Panel` or a `Window`.
`void`	`setMaximumRowCount(int count)` Sets the maximum number of rows the `JComboBox` displays.
`void`	`setModel(ComboBoxModel<E> aModel)` Sets the data model that the `JComboBox` uses to obtain the list of items.
`void`	`setPopupVisible(boolean v)` Sets the visibility of the popup.
`void`	`setPrototypeDisplayValue(E prototypeDisplayValue)` Sets the prototype display value used to calculate the size of the display for the UI portion.
`void`	`setRenderer(ListCellRenderer<? super E> aRenderer)` Sets the renderer that paints the list items and the item selected from the list in the JComboBox field.
`void`	`setSelectedIndex(int anIndex)` Selects the item at index `anIndex`.
`void`	`setSelectedItem(Object anObject)` Sets the selected item in the combo box display area to the object in the argument.
`void`	`setUI(ComboBoxUI ui)` Sets the L&F object that renders this component.
`void`	`showPopup()` Causes the combo box to display its popup window.
`void`	`updateUI()` Resets the UI property to a value from the current look and feel.

Methods inherited from class javax.swing.JComponent
addAncestorListener, addNotify, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, firePropertyChange, firePropertyChange, firePropertyChange, fireVetoableChange, getActionForKeyStroke, getActionMap, getAlignmentX, getAlignmentY, getAncestorListeners, getAutoscrolls, getBaseline, getBaselineResizeBehavior, getBorder, getBounds, getClientProperty, getComponentGraphics, getComponentPopupMenu, getConditionForKeyStroke, getDebugGraphicsOptions, getDefaultLocale, getFontMetrics, getGraphics, getHeight, getInheritsPopupMenu, getInputMap, getInputMap, getInputVerifier, getInsets, getInsets, getListeners, getLocation, getMaximumSize, getMinimumSize, getNextFocusableComponent, getPopupLocation, getPreferredSize, getRegisteredKeyStrokes, getRootPane, getSize, getToolTipLocation, getToolTipText, getToolTipText, getTopLevelAncestor, getTransferHandler, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, hide, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isOptimizedDrawingEnabled, isPaintingForPrint, isPaintingOrigin, isPaintingTile, isRequestFocusEnabled, isValidateRoot, paint, paintBorder, paintChildren, paintComponent, paintImmediately, paintImmediately, print, printAll, printBorder, printChildren, printComponent, processComponentKeyEvent, processMouseEvent, processMouseMotionEvent, putClientProperty, registerKeyboardAction, registerKeyboardAction, removeAncestorListener, removeNotify, removeVetoableChangeListener, repaint, repaint, requestDefaultFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, resetKeyboardActions, reshape, revalidate, scrollRectToVisible, setActionMap, setAlignmentX, setAlignmentY, setAutoscrolls, setBackground, setBorder, setComponentPopupMenu, setDebugGraphicsOptions, setDefaultLocale, setDoubleBuffered, setFocusTraversalKeys, setFont, setForeground, setInheritsPopupMenu, setInputMap, setInputVerifier, setMaximumSize, setMinimumSize, setNextFocusableComponent, setOpaque, setPreferredSize, setRequestFocusEnabled, setToolTipText, setTransferHandler, setUI, setVerifyInputWhenFocusTarget, setVisible, unregisterKeyboardAction, update

Methods inherited from class java.awt.Container
add, add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getComponentZOrder, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getLayout, getMousePosition, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicyProvider, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, preferredSize, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, setComponentZOrder, setFocusCycleRoot, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setLayout, transferFocusDownCycle, validate, validateTree

Methods inherited from class java.awt.Component
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, createImage, createImage, createVolatileImage, createVolatileImage, disableEvents, dispatchEvent, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getForeground, getGraphicsConfiguration, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getToolkit, getTreeLock, gotFocus, handleEvent, hasFocus, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setFocusable, setFocusTraversalKeysEnabled, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, setSize, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - dataModel
```
protected ComboBoxModel<E> dataModel
```
    This protected field is implementation specific. Do not access directly or override. Use the accessor methods instead.
    
    See Also:
    
    getModel(), setModel(javax.swing.ComboBoxModel<E>)
  - renderer
```
protected ListCellRenderer<? super E> renderer
```
    This protected field is implementation specific. Do not access directly or override. Use the accessor methods instead.
    
    See Also:
    
    getRenderer(), setRenderer(javax.swing.ListCellRenderer<? super E>)
  - editor
```
protected ComboBoxEditor editor
```
    This protected field is implementation specific. Do not access directly or override. Use the accessor methods instead.
    
    See Also:
    
    getEditor(), setEditor(javax.swing.ComboBoxEditor)
  - maximumRowCount
```
protected int maximumRowCount
```
    This protected field is implementation specific. Do not access directly or override. Use the accessor methods instead.
    
    See Also:
    
    getMaximumRowCount(), setMaximumRowCount(int)
  - isEditable
```
protected boolean isEditable
```
    This protected field is implementation specific. Do not access directly or override. Use the accessor methods instead.
    
    See Also:
    
    isEditable, setEditable(boolean)
  - keySelectionManager
```
protected JComboBox.KeySelectionManager keySelectionManager
```
    This protected field is implementation specific. Do not access directly or override. Use the accessor methods instead.
    
    See Also:
    
    setKeySelectionManager(javax.swing.JComboBox.KeySelectionManager), getKeySelectionManager()
  - actionCommand
```
protected String actionCommand
```
    This protected field is implementation specific. Do not access directly or override. Use the accessor methods instead.
    
    See Also:
    
    setActionCommand(java.lang.String), getActionCommand()
  - lightWeightPopupEnabled
```
protected boolean lightWeightPopupEnabled
```
    This protected field is implementation specific. Do not access directly or override. Use the accessor methods instead.
    
    See Also:
    
    setLightWeightPopupEnabled(boolean), isLightWeightPopupEnabled()
  - selectedItemReminder
```
protected Object selectedItemReminder
```
    This protected field is implementation specific. Do not access directly or override.
- Constructor Detail
  - JComboBox
```
public JComboBox(ComboBoxModel<E> aModel)
```
    Creates a JComboBox that takes its items from an existing ComboBoxModel. Since the ComboBoxModel is provided, a combo box created using this constructor does not create a default combo box model and may impact how the insert, remove and add methods behave.
    
    Parameters:
    
    aModel - the ComboBoxModel that provides the displayed list of items
    
    See Also:
    
    DefaultComboBoxModel
  - JComboBox
```
public JComboBox(E[] items)
```
    Creates a JComboBox that contains the elements in the specified array. By default the first item in the array (and therefore the data model) becomes selected.
    
    Parameters:
    
    items - an array of objects to insert into the combo box
    
    See Also:
    
    DefaultComboBoxModel
  - JComboBox
```
public JComboBox(Vector<E> items)
```
    Creates a JComboBox that contains the elements in the specified Vector. By default the first item in the vector (and therefore the data model) becomes selected.
    
    Parameters:
    
    items - an array of vectors to insert into the combo box
    
    See Also:
    
    DefaultComboBoxModel
  - JComboBox
```
public JComboBox()
```
    Creates a JComboBox with a default data model. The default data model is an empty list of objects. Use addItem to add items. By default the first item in the data model becomes selected.
    
    See Also:
    
    DefaultComboBoxModel
- Method Detail
  - installAncestorListener
```
protected void installAncestorListener()
```
  - setUI
```
public void setUI(ComboBoxUI ui)
```
    Sets the L&F object that renders this component.
    
    Parameters:
    
    ui - the ComboBoxUI L&F object
    
    See Also:
    
    UIDefaults.getUI(javax.swing.JComponent)
  - updateUI
```
public void updateUI()
```
    Resets the UI property to a value from the current look and feel.
    
    Overrides:
    
    updateUI in class JComponent
    
    See Also:
    
    JComponent.updateUI()
  - getUIClassID
```
public String getUIClassID()
```
    Returns the name of the L&F class that renders this component.
    
    Overrides:
    
    getUIClassID in class JComponent
    
    Returns:
    
    the string "ComboBoxUI"
    
    See Also:
    
    JComponent.getUIClassID(), UIDefaults.getUI(javax.swing.JComponent)
  - getUI
```
public ComboBoxUI getUI()
```
    Returns the L&F object that renders this component.
    
    Returns:
    
    the ComboBoxUI object that renders this component
  - setModel
```
public void setModel(ComboBoxModel<E> aModel)
```
    Sets the data model that the JComboBox uses to obtain the list of items.
    
    Parameters:
    
    aModel - the ComboBoxModel that provides the displayed list of items
  - getModel
```
public ComboBoxModel<E> getModel()
```
    Returns the data model currently used by the JComboBox.
    
    Returns:
    
    the ComboBoxModel that provides the displayed list of items
  - setLightWeightPopupEnabled
```
public void setLightWeightPopupEnabled(boolean aFlag)
```
    Sets the lightWeightPopupEnabled property, which provides a hint as to whether or not a lightweight Component should be used to contain the JComboBox, versus a heavyweight Component such as a Panel or a Window. The decision of lightweight versus heavyweight is ultimately up to the JComboBox. Lightweight windows are more efficient than heavyweight windows, but lightweight and heavyweight components do not mix well in a GUI. If your application mixes lightweight and heavyweight components, you should disable lightweight popups. The default value for the lightWeightPopupEnabled property is true, unless otherwise specified by the look and feel. Some look and feels always use heavyweight popups, no matter what the value of this property.
    See the article Mixing Heavy and Light Components This method fires a property changed event.
    
    Parameters:
    
    aFlag - if true, lightweight popups are desired
  - isLightWeightPopupEnabled
```
public boolean isLightWeightPopupEnabled()
```
    Gets the value of the lightWeightPopupEnabled property.
    
    Returns:
    
    the value of the lightWeightPopupEnabled property
    
    See Also:
    
    setLightWeightPopupEnabled(boolean)
  - setEditable
```
public void setEditable(boolean aFlag)
```
    Determines whether the JComboBox field is editable. An editable JComboBox allows the user to type into the field or selected an item from the list to initialize the field, after which it can be edited. (The editing affects only the field, the list item remains intact.) A non editable JComboBox displays the selected item in the field, but the selection cannot be modified.
    
    Parameters:
    
    aFlag - a boolean value, where true indicates that the field is editable
  - isEditable
```
public boolean isEditable()
```
    Returns true if the JComboBox is editable. By default, a combo box is not editable.
    
    Returns:
    
    true if the JComboBox is editable, else false
  - setMaximumRowCount
```
public void setMaximumRowCount(int count)
```
    Sets the maximum number of rows the JComboBox displays. If the number of objects in the model is greater than count, the combo box uses a scrollbar.
    
    Parameters:
    
    count - an integer specifying the maximum number of items to display in the list before using a scrollbar
  - getMaximumRowCount
```
public int getMaximumRowCount()
```
    Returns the maximum number of items the combo box can display without a scrollbar
    
    Returns:
    
    an integer specifying the maximum number of items that are displayed in the list before using a scrollbar
  - setRenderer
```
public void setRenderer(ListCellRenderer<? super E> aRenderer)
```
    Sets the renderer that paints the list items and the item selected from the list in the JComboBox field. The renderer is used if the JComboBox is not editable. If it is editable, the editor is used to render and edit the selected item.
    The default renderer displays a string or an icon. Other renderers can handle graphic images and composite items.
    
    To display the selected item, aRenderer.getListCellRendererComponent is called, passing the list object and an index of -1.
    
    Parameters:
    
    aRenderer - the ListCellRenderer that displays the selected item
    
    See Also:
    
    setEditor(javax.swing.ComboBoxEditor)
  - getRenderer
```
public ListCellRenderer<? super E> getRenderer()
```
    Returns the renderer used to display the selected item in the JComboBox field.
    
    Returns:
    
    the ListCellRenderer that displays the selected item.
  - setEditor
```
public void setEditor(ComboBoxEditor anEditor)
```
    Sets the editor used to paint and edit the selected item in the JComboBox field. The editor is used only if the receiving JComboBox is editable. If not editable, the combo box uses the renderer to paint the selected item.
    
    Parameters:
    
    anEditor - the ComboBoxEditor that displays the selected item
    
    See Also:
    
    setRenderer(javax.swing.ListCellRenderer<? super E>)
  - getEditor
```
public ComboBoxEditor getEditor()
```
    Returns the editor used to paint and edit the selected item in the JComboBox field.
    
    Returns:
    
    the ComboBoxEditor that displays the selected item
  - setSelectedItem
```
public void setSelectedItem(Object anObject)
```
    Sets the selected item in the combo box display area to the object in the argument. If anObject is in the list, the display area shows anObject selected.
    If anObject is not in the list and the combo box is uneditable, it will not change the current selection. For editable combo boxes, the selection will change to anObject.
    
    If this constitutes a change in the selected item, ItemListeners added to the combo box will be notified with one or two ItemEvents. If there is a current selected item, an ItemEvent will be fired and the state change will be ItemEvent.DESELECTED. If anObject is in the list and is not currently selected then an ItemEvent will be fired and the state change will be ItemEvent.SELECTED.
    
    ActionListeners added to the combo box will be notified with an ActionEvent when this method is called.
    
    Parameters:
    
    anObject - the list object to select; use null to clear the selection
  - getSelectedItem
```
public Object getSelectedItem()
```
    Returns the current selected item.
    If the combo box is editable, then this value may not have been added to the combo box with addItem, insertItemAt or the data constructors.
    
    Returns:
    
    the current selected Object
    
    See Also:
    
    setSelectedItem(java.lang.Object)
  - setSelectedIndex
```
public void setSelectedIndex(int anIndex)
```
    Selects the item at index anIndex.
    
    Parameters:
    
    anIndex - an integer specifying the list item to select, where 0 specifies the first item in the list and -1 indicates no selection
    
    Throws:
    
    IllegalArgumentException - if anIndex < -1 or anIndex is greater than or equal to size
  - getSelectedIndex
```
public int getSelectedIndex()
```
    Returns the first item in the list that matches the given item. The result is not always defined if the JComboBox allows selected items that are not in the list. Returns -1 if there is no selected item or if the user specified an item which is not in the list.
    
    Returns:
    
    an integer specifying the currently selected list item, where 0 specifies the first item in the list; or -1 if no item is selected or if the currently selected item is not in the list
  - getPrototypeDisplayValue
```
public E getPrototypeDisplayValue()
```
    Returns the "prototypical display" value - an Object used for the calculation of the display height and width.
    
    Returns:
    
    the value of the prototypeDisplayValue property
    
    Since:
    
    1.4
    
    See Also:
    
    setPrototypeDisplayValue(E)
  - setPrototypeDisplayValue
```
public void setPrototypeDisplayValue(E prototypeDisplayValue)
```
    Sets the prototype display value used to calculate the size of the display for the UI portion.
    If a prototype display value is specified, the preferred size of the combo box is calculated by configuring the renderer with the prototype display value and obtaining its preferred size. Specifying the preferred display value is often useful when the combo box will be displaying large amounts of data. If no prototype display value has been specified, the renderer must be configured for each value from the model and its preferred size obtained, which can be relatively expensive.
    
    Parameters:
    
    prototypeDisplayValue -
    
    Since:
    
    1.4
    
    See Also:
    
    getPrototypeDisplayValue()
  - addItem
```
public void addItem(E item)
```
    Adds an item to the item list. This method works only if the JComboBox uses a mutable data model.
    Warning: Focus and keyboard navigation problems may arise if you add duplicate String objects. A workaround is to add new objects instead of String objects and make sure that the toString() method is defined. For example:
```
   comboBox.addItem(makeObj("Item 1"));
   comboBox.addItem(makeObj("Item 1"));
   ...
   private Object makeObj(final String item)  {
     return new Object() { public String toString() { return item; } };
   }
 
```
    Parameters:
    
    item - the item to add to the list
    
    See Also:
    
    MutableComboBoxModel
  - insertItemAt
```
public void insertItemAt(E item,
                         int index)
```
    Inserts an item into the item list at a given index. This method works only if the JComboBox uses a mutable data model.
    
    Parameters:
    
    item - the item to add to the list
    
    index - an integer specifying the position at which to add the item
    
    See Also:
    
    MutableComboBoxModel
  - removeItem
```
public void removeItem(Object anObject)
```
    Removes an item from the item list. This method works only if the JComboBox uses a mutable data model.
    
    Parameters:
    
    anObject - the object to remove from the item list
    
    See Also:
    
    MutableComboBoxModel
  - removeItemAt
```
public void removeItemAt(int anIndex)
```
    Removes the item at anIndex This method works only if the JComboBox uses a mutable data model.
    
    Parameters:
    
    anIndex - an int specifying the index of the item to remove, where 0 indicates the first item in the list
    
    See Also:
    
    MutableComboBoxModel
  - removeAllItems
```
public void removeAllItems()
```
    Removes all items from the item list.
  - showPopup
```
public void showPopup()
```
    Causes the combo box to display its popup window.
    
    See Also:
    
    setPopupVisible(boolean)
  - hidePopup
```
public void hidePopup()
```
    Causes the combo box to close its popup window.
    
    See Also:
    
    setPopupVisible(boolean)
  - setPopupVisible
```
public void setPopupVisible(boolean v)
```
    Sets the visibility of the popup.
  - isPopupVisible
```
public boolean isPopupVisible()
```
    Determines the visibility of the popup.
    
    Returns:
    
    true if the popup is visible, otherwise returns false
  - addItemListener
```
public void addItemListener(ItemListener aListener)
```
    Adds an ItemListener.
    aListener will receive one or two ItemEvents when the selected item changes.
    
    Specified by:
    
    addItemListener in interface ItemSelectable
    
    Parameters:
    
    aListener - the ItemListener that is to be notified
    
    See Also:
    
    setSelectedItem(java.lang.Object)
  - removeItemListener
```
public void removeItemListener(ItemListener aListener)
```
    Removes an ItemListener.
    
    Specified by:
    
    removeItemListener in interface ItemSelectable
    
    Parameters:
    
    aListener - the ItemListener to remove
    
    See Also:
    
    ItemEvent
  - getItemListeners
```
public ItemListener[] getItemListeners()
```
    Returns an array of all the ItemListeners added to this JComboBox with addItemListener().
    
    Returns:
    
    all of the ItemListeners added or an empty array if no listeners have been added
    
    Since:
    
    1.4
  - addActionListener
```
public void addActionListener(ActionListener l)
```
    Adds an ActionListener.
    The ActionListener will receive an ActionEvent when a selection has been made. If the combo box is editable, then an ActionEvent will be fired when editing has stopped.
    
    Parameters:
    
    l - the ActionListener that is to be notified
    
    See Also:
    
    setSelectedItem(java.lang.Object)
  - removeActionListener
```
public void removeActionListener(ActionListener l)
```
    Removes an ActionListener.
    
    Parameters:
    
    l - the ActionListener to remove
  - getActionListeners
```
public ActionListener[] getActionListeners()
```
    Returns an array of all the ActionListeners added to this JComboBox with addActionListener().
    
    Returns:
    
    all of the ActionListeners added or an empty array if no listeners have been added
    
    Since:
    
    1.4
  - addPopupMenuListener
```
public void addPopupMenuListener(PopupMenuListener l)
```
    Adds a PopupMenu listener which will listen to notification messages from the popup portion of the combo box.
    For all standard look and feels shipped with Java, the popup list portion of combo box is implemented as a JPopupMenu. A custom look and feel may not implement it this way and will therefore not receive the notification.
    
    Parameters:
    
    l - the PopupMenuListener to add
    
    Since:
    
    1.4
  - removePopupMenuListener
```
public void removePopupMenuListener(PopupMenuListener l)
```
    Removes a PopupMenuListener.
    
    Parameters:
    
    l - the PopupMenuListener to remove
    
    Since:
    
    1.4
    
    See Also:
    
    addPopupMenuListener(javax.swing.event.PopupMenuListener)
  - getPopupMenuListeners
```
public PopupMenuListener[] getPopupMenuListeners()
```
    Returns an array of all the PopupMenuListeners added to this JComboBox with addPopupMenuListener().
    
    Returns:
    
    all of the PopupMenuListeners added or an empty array if no listeners have been added
    
    Since:
    
    1.4
  - firePopupMenuWillBecomeVisible
```
public void firePopupMenuWillBecomeVisible()
```
    Notifies PopupMenuListeners that the popup portion of the combo box will become visible.
    This method is public but should not be called by anything other than the UI delegate.
    
    Since:
    
    1.4
    
    See Also:
    
    addPopupMenuListener(javax.swing.event.PopupMenuListener)
  - firePopupMenuWillBecomeInvisible
```
public void firePopupMenuWillBecomeInvisible()
```
    Notifies PopupMenuListeners that the popup portion of the combo box has become invisible.
    This method is public but should not be called by anything other than the UI delegate.
    
    Since:
    
    1.4
    
    See Also:
    
    addPopupMenuListener(javax.swing.event.PopupMenuListener)
  - firePopupMenuCanceled
```
public void firePopupMenuCanceled()
```
    Notifies PopupMenuListeners that the popup portion of the combo box has been canceled.
    This method is public but should not be called by anything other than the UI delegate.
    
    Since:
    
    1.4
    
    See Also:
    
    addPopupMenuListener(javax.swing.event.PopupMenuListener)
  - setActionCommand
```
public void setActionCommand(String aCommand)
```
    Sets the action command that should be included in the event sent to action listeners.
    
    Parameters:
    
    aCommand - a string containing the "command" that is sent to action listeners; the same listener can then do different things depending on the command it receives
  - getActionCommand
```
public String getActionCommand()
```
    Returns the action command that is included in the event sent to action listeners.
    
    Returns:
    
    the string containing the "command" that is sent to action listeners.
  - setAction
```
public void setAction(Action a)
```
    Sets the Action for the ActionEvent source. The new Action replaces any previously set Action but does not affect ActionListeners independently added with addActionListener. If the Action is already a registered ActionListener for the ActionEvent source, it is not re-registered.
    Setting the Action results in immediately changing all the properties described in Swing Components Supporting Action. Subsequently, the combobox's properties are automatically updated as the Action's properties change.
    
    This method uses three other methods to set and help track the Action's property values. It uses the configurePropertiesFromAction method to immediately change the combobox's properties. To track changes in the Action's property values, this method registers the PropertyChangeListener returned by createActionPropertyChangeListener. The default PropertyChangeListener invokes the actionPropertyChanged method when a property in the Action changes.
    
    Parameters:
    
    a - the Action for the JComboBox, or null.
    
    Since:
    
    1.3
    
    See Also:
    
    Action, getAction(), configurePropertiesFromAction(javax.swing.Action), createActionPropertyChangeListener(javax.swing.Action), actionPropertyChanged(javax.swing.Action, java.lang.String)
  - getAction
```
public Action getAction()
```
    Returns the currently set Action for this ActionEvent source, or null if no Action is set.
    
    Returns:
    
    the Action for this ActionEvent source; or null
    
    Since:
    
    1.3
    
    See Also:
    
    Action, setAction(javax.swing.Action)
  - configurePropertiesFromAction
```
protected void configurePropertiesFromAction(Action a)
```
    Sets the properties on this combobox to match those in the specified Action. Refer to Swing Components Supporting Action for more details as to which properties this sets.
    
    Parameters:
    
    a - the Action from which to get the properties, or null
    
    Since:
    
    1.3
    
    See Also:
    
    Action, setAction(javax.swing.Action)
  - createActionPropertyChangeListener
```
protected PropertyChangeListener createActionPropertyChangeListener(Action a)
```
    Creates and returns a PropertyChangeListener that is responsible for listening for changes from the specified Action and updating the appropriate properties.
    Warning: If you subclass this do not create an anonymous inner class. If you do the lifetime of the combobox will be tied to that of the Action.
    
    Parameters:
    
    a - the combobox's action
    
    Since:
    
    1.3
    
    See Also:
    
    Action, setAction(javax.swing.Action)
  - actionPropertyChanged
```
protected void actionPropertyChanged(Action action,
                                     String propertyName)
```
    Updates the combobox's state in response to property changes in associated action. This method is invoked from the PropertyChangeListener returned from createActionPropertyChangeListener. Subclasses do not normally need to invoke this. Subclasses that support additional Action properties should override this and configurePropertiesFromAction.
    Refer to the table at Swing Components Supporting Action for a list of the properties this method sets.
    
    Parameters:
    
    action - the Action associated with this combobox
    
    propertyName - the name of the property that changed
    
    Since:
    
    1.6
    
    See Also:
    
    Action, configurePropertiesFromAction(javax.swing.Action)
  - fireItemStateChanged
```
protected void fireItemStateChanged(ItemEvent e)
```
    Notifies all listeners that have registered interest for notification on this event type.
    
    Parameters:
    
    e - the event of interest
    
    See Also:
    
    EventListenerList
  - fireActionEvent
```
protected void fireActionEvent()
```
    Notifies all listeners that have registered interest for notification on this event type.
    
    See Also:
    
    EventListenerList
  - selectedItemChanged
```
protected void selectedItemChanged()
```
    This protected method is implementation specific. Do not access directly or override.
  - getSelectedObjects
```
public Object[] getSelectedObjects()
```
    Returns an array containing the selected item. This method is implemented for compatibility with ItemSelectable.
    
    Specified by:
    
    getSelectedObjects in interface ItemSelectable
    
    Returns:
    
    an array of Objects containing one element -- the selected item
  - actionPerformed
```
public void actionPerformed(ActionEvent e)
```
    This method is public as an implementation side effect. do not call or override.
    
    Specified by:
    
    actionPerformed in interface ActionListener
  - contentsChanged
```
public void contentsChanged(ListDataEvent e)
```
    This method is public as an implementation side effect. do not call or override.
    
    Specified by:
    
    contentsChanged in interface ListDataListener
    
    Parameters:
    
    e - a ListDataEvent encapsulating the event information
  - intervalAdded
```
public void intervalAdded(ListDataEvent e)
```
    This method is public as an implementation side effect. do not call or override.
    
    Specified by:
    
    intervalAdded in interface ListDataListener
    
    Parameters:
    
    e - a ListDataEvent encapsulating the event information
  - intervalRemoved
```
public void intervalRemoved(ListDataEvent e)
```
    This method is public as an implementation side effect. do not call or override.
    
    Specified by:
    
    intervalRemoved in interface ListDataListener
    
    Parameters:
    
    e - a ListDataEvent encapsulating the event information
  - selectWithKeyChar
```
public boolean selectWithKeyChar(char keyChar)
```
    Selects the list item that corresponds to the specified keyboard character and returns true, if there is an item corresponding to that character. Otherwise, returns false.
    
    Parameters:
    
    keyChar - a char, typically this is a keyboard key typed by the user
  - setEnabled
```
public void setEnabled(boolean b)
```
    Enables the combo box so that items can be selected. When the combo box is disabled, items cannot be selected and values cannot be typed into its field (if it is editable).
    
    Overrides:
    
    setEnabled in class JComponent
    
    Parameters:
    
    b - a boolean value, where true enables the component and false disables it
    
    See Also:
    
    Component.isEnabled(), Component.isLightweight()
  - configureEditor
```
public void configureEditor(ComboBoxEditor anEditor,
                            Object anItem)
```
    Initializes the editor with the specified item.
    
    Parameters:
    
    anEditor - the ComboBoxEditor that displays the list item in the combo box field and allows it to be edited
    
    anItem - the object to display and edit in the field
  - processKeyEvent
```
public void processKeyEvent(KeyEvent e)
```
    Handles KeyEvents, looking for the Tab key. If the Tab key is found, the popup window is closed.
    
    Overrides:
    
    processKeyEvent in class JComponent
    
    Parameters:
    
    e - the KeyEvent containing the keyboard key that was pressed
    
    See Also:
    
    KeyEvent, KeyListener, KeyboardFocusManager, DefaultKeyboardFocusManager, Component.processEvent(java.awt.AWTEvent), Component.dispatchEvent(java.awt.AWTEvent), Component.addKeyListener(java.awt.event.KeyListener), Component.enableEvents(long), Component.isShowing()
  - processKeyBinding
```
protected boolean processKeyBinding(KeyStroke ks,
                                    KeyEvent e,
                                    int condition,
                                    boolean pressed)
```
    Invoked to process the key bindings for ks as the result of the KeyEvent e. This obtains the appropriate InputMap, gets the binding, gets the action from the ActionMap, and then (if the action is found and the component is enabled) invokes notifyAction to notify the action.
    Overrides:
    
    processKeyBinding in class JComponent
    
    Parameters:
    
    ks - the KeyStroke queried
    
    e - the KeyEvent
    condition - one of the following values:
    
    JComponent.WHEN_FOCUSED
    
    JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
    
    JComponent.WHEN_IN_FOCUSED_WINDOW
    pressed - true if the key is pressed
    
    Returns:
    
    true if there was a binding to an action, and the action was enabled
  - setKeySelectionManager
```
public void setKeySelectionManager(JComboBox.KeySelectionManager aManager)
```
    Sets the object that translates a keyboard character into a list selection. Typically, the first selection with a matching first character becomes the selected item.
  - getKeySelectionManager
```
public JComboBox.KeySelectionManager getKeySelectionManager()
```
    Returns the list's key-selection manager.
    
    Returns:
    
    the KeySelectionManager currently in use
  - getItemCount
```
public int getItemCount()
```
    Returns the number of items in the list.
    
    Returns:
    
    an integer equal to the number of items in the list
  - getItemAt
```
public E getItemAt(int index)
```
    Returns the list item at the specified index. If index is out of range (less than zero or greater than or equal to size) it will return null.
    
    Parameters:
    
    index - an integer indicating the list position, where the first item starts at zero
    
    Returns:
    
    the item at that list position; or null if out of range
  - createDefaultKeySelectionManager
```
protected JComboBox.KeySelectionManager createDefaultKeySelectionManager()
```
    Returns an instance of the default key-selection manager.
    
    Returns:
    
    the KeySelectionManager currently used by the list
    
    See Also:
    
    setKeySelectionManager(javax.swing.JComboBox.KeySelectionManager)
  - paramString
```
protected String paramString()
```
    Returns a string representation of this JComboBox. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null.
    
    Overrides:
    
    paramString in class JComponent
    
    Returns:
    
    a string representation of this JComboBox
  - getAccessibleContext
```
public AccessibleContext getAccessibleContext()
```
    Gets the AccessibleContext associated with this JComboBox. For combo boxes, the AccessibleContext takes the form of an AccessibleJComboBox. A new AccessibleJComboBox instance is created if necessary.
    
    Specified by:
    
    getAccessibleContext in interface Accessible
    
    Overrides:
    
    getAccessibleContext in class Component
    
    Returns:
    
    an AccessibleJComboBox that serves as the AccessibleContext of this JComboBox

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Java javax.swing Class JComboBox<E>（JDK8）

Class JComboBox<E>

Nested Class Summary

Nested classes/interfaces inherited from class javax.swing.JComponent

Nested classes/interfaces inherited from class java.awt.Container

Nested classes/interfaces inherited from class java.awt.Component

Field Summary

Fields inherited from class javax.swing.JComponent

Fields inherited from class java.awt.Component

Fields inherited from interface java.awt.image.ImageObserver

Constructor Summary

Method Summary

Methods inherited from class javax.swing.JComponent

Methods inherited from class java.awt.Container

Methods inherited from class java.awt.Component

Methods inherited from class java.lang.Object

Field Detail

dataModel

renderer

editor

maximumRowCount

isEditable

keySelectionManager

actionCommand

lightWeightPopupEnabled

selectedItemReminder

Constructor Detail

JComboBox

JComboBox

JComboBox

JComboBox

Method Detail

installAncestorListener

setUI

updateUI

getUIClassID

getUI

setModel

getModel

setLightWeightPopupEnabled

isLightWeightPopupEnabled

setEditable

isEditable

setMaximumRowCount

getMaximumRowCount

setRenderer

getRenderer

setEditor

getEditor

setSelectedItem

getSelectedItem

setSelectedIndex

getSelectedIndex

getPrototypeDisplayValue

setPrototypeDisplayValue

addItem

insertItemAt

removeItem

removeItemAt

removeAllItems

showPopup

hidePopup

setPopupVisible

isPopupVisible

addItemListener

removeItemListener

getItemListeners

addActionListener

removeActionListener

getActionListeners

addPopupMenuListener

removePopupMenuListener

getPopupMenuListeners

firePopupMenuWillBecomeVisible

firePopupMenuWillBecomeInvisible

firePopupMenuCanceled

setActionCommand

getActionCommand

setAction

getAction