JComboBox

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javax.swing
Class JComboBox

java.lang.Object
  java.awt.Component
      java.awt.Container
          javax.swing.JComponent
              javax.swing.JComboBox

All Implemented Interfaces:: javax.accessibility.Accessible, java.awt.event.ActionListener, java.util.EventListener, java.awt.image.ImageObserver, java.awt.ItemSelectable, javax.swing.event.ListDataListener, java.awt.MenuContainer, java.io.Serializable

public class JComboBox
extends JComponent
implements java.awt.ItemSelectable, javax.swing.event.ListDataListener, java.awt.event.ActionListener, javax.accessibility.Accessible

A component that allows a user to select any item in its list and displays the selected item to the user. JComboBox also can show/hide a popup menu containing its list of item whenever the mouse is pressed over it.

Nested Class Summary

protected class JComboBox.AccessibleJComboBox
          Accessibility support for JComboBox.

static interface JComboBox.KeySelectionManager
          Classes implementing this interface are responsible for matching key characters typed by the user with combo box's items.

Nested classes inherited from class javax.swing.JComponent

JComponent.AccessibleJComponent

Nested classes inherited from class java.awt.Container

java.awt.Container.AccessibleAWTContainer

Nested classes inherited from class java.awt.Component

java.awt.Component.AccessibleAWTComponent, java.awt.Component.BltBufferStrategy, java.awt.Component.FlipBufferStrategy

Field Summary

private Action action
          The action taken when new item is selected in the JComboBox

protected java.lang.String actionCommand
          This actionCommand is used in ActionEvent that is fired to JComboBox's ActionListeneres.

protected ComboBoxModel dataModel
          Data model used by JComboBox to keep track of its list data and currently selected element in the list.

private static int DEFAULT_MAXIMUM_ROW_COUNT
          Maximum number of rows that should be visible by default in the JComboBox's popup

protected ComboBoxEditor editor
          Editor that is responsible for editing an object in a combo box list.

protected boolean isEditable
          This field indicates if textfield of this JComboBox is editable or not.

protected JComboBox.KeySelectionManager keySelectionManager
          keySelectionManager

protected boolean lightWeightPopupEnabled
          This property indicates if heavyweight popup or lightweight popup will be used to diplay JComboBox's elements.

protected int maximumRowCount
          Number of rows that will be visible in the JComboBox's popup.

private java.lang.Object prototypeDisplayValue
          since 1.4 If this field is set then comboBox's display area for the selected item will be set by default to this value.

protected ListCellRenderer renderer
          Renderer renders(paints) every object in the combo box list in its associated list cell.

protected java.lang.Object selectedItemReminder
          This field is reference to the current selection of the combo box.

private static long serialVersionUID


Fields inherited from class javax.swing.JComponent

accessibleContext, alignmentX, alignmentY, autoscrolls, border, debugGraphicsOptions, doubleBuffered, isCompletelyDirty, isPaintingDoubleBuffered, listenerList, maximumSize, minimumSize, opaque, preferredSize, requestFocusEnabled, TOOL_TIP_TEXT_KEY, toolTipText, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW

Fields inherited from class java.awt.Container

Fields inherited from class java.awt.Component

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

JComboBox()
          Constructor.

JComboBox(ComboBoxModel model)
          Constructs JComboBox object with specified data model for it.

JComboBox(java.lang.Object[] itemArray)
          Constructs JComboBox with specified list of items.

JComboBox(java.util.Vector itemVector)
          Constructs JComboBox object with specified list of items.

Method Summary

void actionPerformed(java.awt.event.ActionEvent e)
          This method handles actionEvents fired by the ComboBoxEditor.

void addActionListener(java.awt.event.ActionListener listener)
          This methods adds specified ActionListener to this JComboBox.

void addItem(java.lang.Object element)
          This method adds given element to this JComboBox.

void addItemListener(java.awt.event.ItemListener listener)
          This method registers given ItemListener with this JComboBox

void addPopupMenuListener(javax.swing.event.PopupMenuListener listener)
          Adds PopupMenuListener to combo box to listen to the events fired by the combo box's popup menu containing its list of items

void configureEditor(ComboBoxEditor anEditor, java.lang.Object anItem)
          This method initializes specified ComboBoxEditor to display given item.

protected void configurePropertiesFromAction(Action a)
          Configure properties of the JComboBox by reading properties of specified action.

void contentsChanged(javax.swing.event.ListDataEvent event)
          The part of implementation of ListDataListener interface.

protected java.beans.PropertyChangeListener createActionPropertyChangeListener(Action action)
          Creates PropertyChangeListener to listen for the changes in comboBox's action properties.

protected JComboBox.KeySelectionManager createDefaultKeySelectionManager()
          createDefaultKeySelectionManager

protected void fireActionEvent()
          This method fires ActionEvent to this JComboBox's registered ActionListeners.

protected void fireItemStateChanged(java.awt.event.ItemEvent e)
          This method fires ItemEvent to this JComboBox's registered ItemListeners.

void firePopupMenuCanceled()
          Fires a popupMenuCanceled() event to all PopupMenuListeners.

void firePopupMenuWillBecomeInvisible()
          Fires a popupMenuWillBecomeInvisible() event to all PopupMenuListeners.

void firePopupMenuWillBecomeVisible()
          Fires a popupMenuWillBecomeVisible() event to all PopupMenuListeners.

javax.accessibility.AccessibleContext getAccessibleContext()
          Returns the object that provides accessibility features for this JComboBox component.

Action getAction()
          This method returns Action that is invoked when selected item is changed in the JComboBox.

java.lang.String getActionCommand()
          Returns actionCommand associated with the ActionEvent fired by the JComboBox to its registered ActionListeners.

java.awt.event.ActionListener[] getActionListeners()
          This method returns array of ActionListeners that are registered with this JComboBox.

ComboBoxEditor getEditor()
          Returns editor component that is responsible for displaying/editing selected item in the combo box.

java.lang.Object getItemAt(int index)
          Returns elements located in the combo box at the given index.

int getItemCount()
          This method returns number of elements in this JComboBox

java.awt.event.ItemListener[] getItemListeners()
          This method returns array of ItemListeners that are registered with this JComboBox.

JComboBox.KeySelectionManager getKeySelectionManager()
          getKeySelectionManager

int getMaximumRowCount()
          This method returns number of rows visible in the JComboBox's list of items.

ComboBoxModel getModel()
          This method returns data model for this comboBox.

javax.swing.event.PopupMenuListener[] getPopupMenuListeners()
          Returns array of PopupMenuListeners that are registered with combo box.

java.lang.Object getPrototypeDisplayValue()
          Returns an object that is used as the display value when calculating the preferred size for the combo box.

ListCellRenderer getRenderer()
          This method returns renderer responsible for rendering selected item in the combo box

int getSelectedIndex()
          Returns index of the item that is currently selected in the combo box.

java.lang.Object getSelectedItem()
          Returns currently selected item in the combo box.

java.lang.Object[] getSelectedObjects()
          Returns Object array of size 1 containing currently selected element in the JComboBox.

javax.swing.plaf.ComboBoxUI getUI()
          This method returns the UI used to display the JComboBox.

java.lang.String getUIClassID()
          This method returns the String identifier for the UI class to the used with the JComboBox.

void hidePopup()
          This method hides popup containing list of combo box's items

void insertItemAt(java.lang.Object element, int index)
          Inserts given element at the specified index to this JComboBox.

protected void installAncestorListener()


void intervalAdded(javax.swing.event.ListDataEvent event)
          The part of implementation of ListDataListener interface.

void intervalRemoved(javax.swing.event.ListDataEvent event)
          The part of implementation of ListDataListener interface.

boolean isEditable()
          This method returns true JComboBox is editable and false otherwise

boolean isLightWeightPopupEnabled()
          This method returns whether popup menu that is used to display list of combo box's item is lightWeight or not.

boolean isPopupVisible()
          Checks if popup is currently visible on the screen.

protected java.lang.String paramString()
          Returns an implementation-dependent string describing the attributes of this JComboBox.

void processKeyEvent(java.awt.event.KeyEvent e)
          This method hides combo box's popup whenever TAB key is pressed.

void removeActionListener(java.awt.event.ActionListener listener)
          This method removes specified ActionListener from this JComboBox.

void removeAllItems()
          This method removes all elements from this JComboBox.

void removeItem(java.lang.Object element)
          This method removes given element from this JComboBox.

void removeItemAt(int index)
          This method remove element location in the specified index in the JComboBox.

void removeItemListener(java.awt.event.ItemListener listener)
          This method unregisters given ItemListener from this JComboBox

void removePopupMenuListener(javax.swing.event.PopupMenuListener listener)
          Removes PopupMenuListener to combo box to listen to the events fired by the combo box's popup menu containing its list of items

protected void selectedItemChanged()
          This method is invoked whenever selected item changes in the combo box's data model.

boolean selectWithKeyChar(char keyChar)
          This method selects item in this combo box that matches specified specified keyChar and returns true if such item is found.

void setAction(Action a)
          setAction

void setActionCommand(java.lang.String aCommand)
          This method sets actionCommand to the specified string.

void setEditable(boolean editable)
          This method sets editability of the combo box.

void setEditor(ComboBoxEditor newEditor)
          Sets editor for this JComboBox

void setEnabled(boolean enabled)
          This method disables or enables JComboBox.

void setKeySelectionManager(JComboBox.KeySelectionManager aManager)
          setKeySelectionManager

void setLightWeightPopupEnabled(boolean enabled)
          This method sets JComboBox's popup to be either lightweight or heavyweight.

void setMaximumRowCount(int rowCount)
          Sets number of rows that should be visible in this JComboBox's popup.

void setModel(ComboBoxModel newDataModel)
          Set the data model for this JComboBox.

void setPopupVisible(boolean visible)
          This method either displayes or hides the popup containing list of combo box's items.

void setPrototypeDisplayValue(java.lang.Object value)
          Sets the object that is assumed to be the displayed item when calculating the preferred size for the combo box.

void setRenderer(ListCellRenderer aRenderer)
          This method sets cell renderer for this JComboBox that will be used to paint combo box's items.

void setSelectedIndex(int index)
          Forces JComboBox to select component located in the given index in the combo box.

void setSelectedItem(java.lang.Object item)
          Forces combo box to select given item

void setUI(javax.swing.plaf.ComboBoxUI ui)
          Set the "UI" property of the combo box, which is a look and feel class responsible for handling comboBox's input events and painting it.

void showPopup()
          This method displays popup with list of combo box's items on the screen

void updateUI()
          This method sets this comboBox's UI to the UIManager's default for the current look and feel.

Methods inherited from class javax.swing.JComponent

addAncestorListener, addNotify, addPropertyChangeListener, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, fireAncestorEvent, firePropertyChange, firePropertyChange, firePropertyChange, fireVetoableChange, getActionForKeyStroke, getActionMap, getAlignmentX, getAlignmentY, getAncestorListeners, getAutoscrolls, getBorder, getBounds, getClientProperty, getComponentGraphics, getConditionForKeyStroke, getDebugGraphicsOptions, getDefaultLocale, getGraphics, getHeight, getInputMap, getInputMap, getInputVerifier, getInsets, getInsets, getListeners, getLocation, getMaximumSize, getMinimumSize, getNextFocusableComponent, getPreferredSize, getRegisteredKeyStrokes, getRootPane, getSize, getToolTipLocation, getToolTipText, getToolTipText, getTopLevelAncestor, getTransferHandler, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, isDoubleBuffered, isLightweightComponent, isManagingFocus, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isOptimizedDrawingEnabled, isPaintingTile, isPreferredSizeSet, isRequestFocusEnabled, isValidateRoot, paint, paintBorder, paintChildren, paintComponent, paintImmediately, paintImmediately, paintImmediately2, paintSimple, print, printAll, printBorder, printChildren, printComponent, processComponentKeyEvent, processKeyBinding, processMouseMotionEvent, putClientProperty, registerKeyboardAction, registerKeyboardAction, removeAncestorListener, removeNotify, removeVetoableChangeListener, repaint, repaint, requestDefaultFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, resetKeyboardActions, reshape, revalidate, scrollRectToVisible, setActionMap, setAlignmentX, setAlignmentY, setAutoscrolls, setBackground, setBorder, setDebugGraphicsOptions, setDefaultLocale, setDoubleBuffered, setFont, setForeground, setInputMap, setInputVerifier, setMaximumSize, setMinimumSize, setNextFocusableComponent, setOpaque, setPreferredSize, setRequestFocusEnabled, setToolTipText, setTransferHandler, setUI, setUIProperty, setVerifyInputWhenFocusTarget, setVisible, unregisterKeyboardAction, update, updateComponentInputMap

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getComponentZOrder, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getLayout, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, preferredSize, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, setComponentZOrder, setFocusCycleRoot, setFocusTraversalKeys, setFocusTraversalPolicy, 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, getFontMetrics, getForeground, getGraphicsConfiguration, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getToolkit, getTreeLock, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, 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, processMouseEvent, 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

serialVersionUID

private static final long serialVersionUID

See Also:: Constant Field Values

DEFAULT_MAXIMUM_ROW_COUNT

private static final int DEFAULT_MAXIMUM_ROW_COUNT

Maximum number of rows that should be visible by default in the JComboBox's popup

See Also:: Constant Field Values

dataModel

protected ComboBoxModel dataModel

Data model used by JComboBox to keep track of its list data and currently selected element in the list.

renderer

protected ListCellRenderer renderer

Renderer renders(paints) every object in the combo box list in its associated list cell. This ListCellRenderer is used only when this JComboBox is uneditable.

editor

protected ComboBoxEditor editor

Editor that is responsible for editing an object in a combo box list.

maximumRowCount

protected int maximumRowCount

Number of rows that will be visible in the JComboBox's popup.

isEditable

protected boolean isEditable

This field indicates if textfield of this JComboBox is editable or not.

selectedItemReminder

protected java.lang.Object selectedItemReminder

This field is reference to the current selection of the combo box.

keySelectionManager

protected JComboBox.KeySelectionManager keySelectionManager

keySelectionManager

actionCommand

protected java.lang.String actionCommand

This actionCommand is used in ActionEvent that is fired to JComboBox's ActionListeneres.

lightWeightPopupEnabled

protected boolean lightWeightPopupEnabled

This property indicates if heavyweight popup or lightweight popup will be used to diplay JComboBox's elements.

action

private Action action

The action taken when new item is selected in the JComboBox

prototypeDisplayValue

private java.lang.Object prototypeDisplayValue

since 1.4 If this field is set then comboBox's display area for the selected item will be set by default to this value.

Constructor Detail

JComboBox

public JComboBox(ComboBoxModel model)

Constructs JComboBox object with specified data model for it.

Note that the JComboBox will not change the value that is preselected by your ComboBoxModel implementation.

JComboBox

public JComboBox(java.lang.Object[] itemArray)

Constructs JComboBox with specified list of items.

JComboBox

public JComboBox(java.util.Vector itemVector)

Constructs JComboBox object with specified list of items.

JComboBox

public JComboBox()

Constructor. Creates new empty JComboBox. ComboBox's data model is set to DefaultComboBoxModel.

Method Detail

isEditable

public boolean isEditable()

This method returns true JComboBox is editable and false otherwise

installAncestorListener

protected void installAncestorListener()

setUI

public void setUI(javax.swing.plaf.ComboBoxUI ui)

Set the "UI" property of the combo box, which is a look and feel class responsible for handling comboBox's input events and painting it.

updateUI

public void updateUI()

This method sets this comboBox's UI to the UIManager's default for the current look and feel.

Overrides:: updateUI in class JComponent

getUIClassID

public java.lang.String getUIClassID()

This method returns the String identifier for the UI class to the used with the JComboBox.

Overrides:: getUIClassID in class JComponent

getUI

public javax.swing.plaf.ComboBoxUI getUI()

This method returns the UI used to display the JComboBox.

setModel

public void setModel(ComboBoxModel newDataModel)

Set the data model for this JComboBox. This un-registers all listeners associated with the current model, and re-registers them with the new model.

getModel

public ComboBoxModel getModel()

This method returns data model for this comboBox.

setLightWeightPopupEnabled

public void setLightWeightPopupEnabled(boolean enabled)

This method sets JComboBox's popup to be either lightweight or heavyweight. If 'enabled' is true then lightweight popup is used and heavyweight otherwise. By default lightweight popup is used to display this JComboBox's elements.

isLightWeightPopupEnabled

public boolean isLightWeightPopupEnabled()

This method returns whether popup menu that is used to display list of combo box's item is lightWeight or not.

setEditable

public void setEditable(boolean editable)

This method sets editability of the combo box. If combo box is editable the user can choose component from the combo box list by typing component's name in the editor(JTextfield by default). Otherwise if not editable, the user should use the list to choose the component. This method fires PropertyChangeEvents to JComboBox's registered PropertyChangeListeners to indicate that 'editable' property of the JComboBox has changed.

setMaximumRowCount

public void setMaximumRowCount(int rowCount)

Sets number of rows that should be visible in this JComboBox's popup. If this JComboBox's popup has more elements that maximum number or rows then popup will have a scroll pane to allow users to view other elements.

getMaximumRowCount

public int getMaximumRowCount()

This method returns number of rows visible in the JComboBox's list of items.

setRenderer

public void setRenderer(ListCellRenderer aRenderer)

This method sets cell renderer for this JComboBox that will be used to paint combo box's items. The Renderer should only be used only when JComboBox is not editable. In the case when JComboBox is editable the editor must be used. This method also fires PropertyChangeEvent when cellRendered for this JComboBox has changed.

getRenderer

public ListCellRenderer getRenderer()

This method returns renderer responsible for rendering selected item in the combo box

setEditor

public void setEditor(ComboBoxEditor newEditor)

Sets editor for this JComboBox

getEditor

public ComboBoxEditor getEditor()

Returns editor component that is responsible for displaying/editing selected item in the combo box.

setSelectedItem

public void setSelectedItem(java.lang.Object item)

Forces combo box to select given item

getSelectedItem

public java.lang.Object getSelectedItem()

Returns currently selected item in the combo box. The result may be null to indicate that nothing is currently selected.

setSelectedIndex

public void setSelectedIndex(int index)

Forces JComboBox to select component located in the given index in the combo box.

If the index is below -1 or exceeds the upper bound an IllegalArgumentException is thrown.

If the index is -1 then no item gets selected.

getSelectedIndex

public int getSelectedIndex()

Returns index of the item that is currently selected in the combo box. If no item is currently selected, then -1 is returned.

Note: For performance reasons you should minimize invocation of this method. If the data model is not an instance of DefaultComboBoxModel the complexity is O(n) where n is the number of elements in the combo box.

getPrototypeDisplayValue

public java.lang.Object getPrototypeDisplayValue()

Returns an object that is used as the display value when calculating the preferred size for the combo box. This value is, of course, never displayed anywhere.

Since:: 1.4

setPrototypeDisplayValue

public void setPrototypeDisplayValue(java.lang.Object value)

Sets the object that is assumed to be the displayed item when calculating the preferred size for the combo box. A java.beans.PropertyChangeEvent (with the name prototypeDisplayValue) is sent to all registered listeners.

Since:: 1.4