java.lang.Objectjava.awt.Component
java.awt.Container
javax.swing.JComponent
javax.swing.JComboBox
public class JComboBox
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 TM has been added to the java.beans package. Please see XMLEncoder .
See How to Use Combo Boxes in The Java Tutorial for further information.
Nested Class Summary | |
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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 |
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JComponent.AccessibleJComponent |
Nested classes/interfaces inherited from class java.awt. Container |
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Container.AccessibleAWTContainer |
Nested classes/interfaces inherited from class java.awt. Component |
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Component.AccessibleAWTComponent , Component.BaselineResizeBehavior , Component.BltBufferStrategy , Component.FlipBufferStrategy |
Field Summary | |
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protected String |
actionCommand
This protected field is implementation specific. |
protected ComboBoxModel |
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 |
renderer
This protected field is implementation specific. |
protected Object |
selectedItemReminder
This protected field is implementation specific. |
Fields inherited from class javax.swing. JComponent |
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accessibleContext , 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 |
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BOTTOM_ALIGNMENT , CENTER_ALIGNMENT , LEFT_ALIGNMENT , RIGHT_ALIGNMENT , TOP_ALIGNMENT |
Fields inherited from interface java.awt.image. ImageObserver |
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ABORT , ALLBITS , ERROR , FRAMEBITS , HEIGHT , PROPERTIES , SOMEBITS , WIDTH |
Constructor Summary | |
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JComboBox
() Creates a JComboBox with a default data model. |
|
JComboBox
(
ComboBoxModel
Creates a JComboBox that takes ![]() ![]() |
|
JComboBox
(
Object
[] items) Creates a JComboBox that contains the elements in the specified array. |
|
JComboBox
(
Vector
<?> items) Creates a JComboBox that contains the elements in the specified Vector. |
Method Summary | |
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void |
actionPerformed
(
ActionEvent
e) This method is public as an implementation side effect. |
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![]() ![]() ![]() ![]() ![]() ![]() |
void |
addActionListener
(
ActionListener
l) Adds an ActionListener. |
void |
addItem
(
Object
anObject) 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 PopupMenuListeners that the popup portion of the combo box has been canceled. |
void |
firePopupMenuWillBecomeInvisible
() Notifies PopupMenuListeners that the popup portion of the combo box has become invisible. |
void |
firePopupMenuWillBecomeVisible
() Notifies PopupMenuListeners 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 ActionListeners added to this JComboBox with addActionListener(). |
ComboBoxEditor |
getEditor
() Returns the editor used to paint and edit the selected item in the JComboBox field. |
Object |
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 ItemListeners 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 |
getModel
() Returns the data model currently used by the JComboBox. |
PopupMenuListener [] |
getPopupMenuListeners
() Returns an array of all the PopupMenuListeners added to this JComboBox with addPopupMenuListener(). |
Object |
getPrototypeDisplayValue
() Returns the "prototypical display" value - an Object used for the calculation of the display height and width. |
ListCellRenderer |
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
(
Object
anObject, 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. |
void |
processKeyEvent
(
KeyEvent
e) Handles KeyEvents, 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
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
(
Object
prototypeDisplayValue) Sets the prototype display value used to calculate the size of the display for the UI portion. |
void |
setRenderer
(
ListCellRenderer
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 java.lang. Object |
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clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait |
Field Detail |
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protected ComboBoxModel dataModel
protected ListCellRenderer renderer
protected ComboBoxEditor editor
protected int maximumRowCount
protected boolean isEditable
protected JComboBox.KeySelectionManager keySelectionManager
protected String actionCommand
protected boolean lightWeightPopupEnabled
protected Object selectedItemReminder
Constructor Detail |
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public JComboBox(ComboBoxModel aModel)
public JComboBox(Object[] items)
public JComboBox(Vector<?> items)
public JComboBox()
Method Detail |
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protected void installAncestorListener()
public void setUI(ComboBoxUI ui)
public void updateUI()
public String getUIClassID()
public ComboBoxUI getUI()
public void setModel(ComboBoxModel aModel)
public ComboBoxModel getModel()
public void setLightWeightPopupEnabled(boolean aFlag)
See the article Mixing Heavy and Light Components on The Swing Connection This method fires a property changed event.
public boolean isLightWeightPopupEnabled()
public void setEditable(boolean aFlag)
public boolean isEditable()
public void setMaximumRowCount(int count)
public int getMaximumRowCount()
public void setRenderer(ListCellRenderer aRenderer)
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.
public ListCellRenderer getRenderer()
public void setEditor(ComboBoxEditor anEditor)
public ComboBoxEditor getEditor()
public void setSelectedItem(Object anObject)
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.
public Object getSelectedItem()
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.
public void setSelectedIndex(int anIndex)
public int getSelectedIndex()
public Object getPrototypeDisplayValue()
public void setPrototypeDisplayValue(Object prototypeDisplayValue)
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.
public void addItem(Object anObject)
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; } }; }
public void insertItemAt(Object anObject, int index)
public void removeItem(Object anObject)
public void removeItemAt(int anIndex)
public void removeAllItems()
public void showPopup()
public void hidePopup()
public void setPopupVisible(boolean v)
public boolean isPopupVisible()
public void addItemListener(ItemListener aListener)
aListener will receive one or two ItemEvents when the selected item changes.
public void removeItemListener(ItemListener aListener)
public ItemListener[] getItemListeners()
public void addActionListener(ActionListener l)
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.
public void removeActionListener(ActionListener l)
public ActionListener[] getActionListeners()
public void addPopupMenuListener(PopupMenuListener l)
For all standard look and feels shipped with
Java,
Java 2,
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.
public void removePopupMenuListener(PopupMenuListener l)
public PopupMenuListener[] getPopupMenuListeners()
public void firePopupMenuWillBecomeVisible()
This method is public but should not be called by anything other than the UI delegate.
public void firePopupMenuWillBecomeInvisible()
This method is public but should not be called by anything other than the UI delegate.
public void firePopupMenuCanceled()
This method is public but should not be called by anything other than the UI delegate.
public void setActionCommand(String aCommand)
public String getActionCommand()
public void setAction(Action a)
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
two
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.
public Action getAction()
protected void configurePropertiesFromAction(Action a)
protected PropertyChangeListener createActionPropertyChangeListener(Action a)
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.
protected void
actionPropertyChanged
(
Action
action,
String
propertyName)
Refer to the table at
Swing Components Supporting Action
for a list of the properties this method sets.
protected void fireItemStateChanged(ItemEvent e)
protected void fireActionEvent()
protected void selectedItemChanged()
public Object[] getSelectedObjects()
public void actionPerformed(ActionEvent e)
public void contentsChanged(ListDataEvent e)
public void intervalAdded(ListDataEvent e)
public void intervalRemoved(ListDataEvent e)
public boolean selectWithKeyChar(char keyChar)
public void setEnabled(boolean b)
public void configureEditor(ComboBoxEditor anEditor, Object anItem)
public void processKeyEvent(KeyEvent e)
public void setKeySelectionManager(JComboBox.KeySelectionManager aManager)
public JComboBox.KeySelectionManager getKeySelectionManager()
public int getItemCount()
public Object getItemAt(int index)
protected JComboBox.KeySelectionManager createDefaultKeySelectionManager()
protected String paramString()
public AccessibleContext getAccessibleContext()