Choice (Java SE 15 & JDK 15)
Description: declaration: module: java.desktop, package: java.awt, class: Choice
Keywords: java.awt.Choice class

Module java.desktop
Package java.awt

# Class Choice

java.lang.Object
java.awt.Component
java.awt.Choice

All Implemented Interfaces:
  `ImageObserver`, `ItemSelectable`, `MenuContainer`, `Serializable`, `Accessible`

    public class Choice
    extends Component
    implements ItemSelectable, Accessible

The `Choice` class presents a pop-up menu of choices. The current choice is displayed as the title of the menu.

The following code example produces a pop-up menu:

>      Choice ColorChooser = new Choice();
>      ColorChooser.add("Green");
>      ColorChooser.add("Red");
>      ColorChooser.add("Blue");

After this choice menu has been added to a panel, it appears as follows in its normal state:

In the picture, `"Green"` is the current choice. Pushing the mouse button down on the object causes a menu to appear with the current choice highlighted.

Some native platforms do not support arbitrary resizing of `Choice` components and the behavior of `setSize()/getSize()` is bound by such limitations. Native GUI `Choice` components' size are often bound by such attributes as font size and length of items contained within the `Choice`.

Since:
  1.0
See Also:
  Serialized Form

- ## Nested Class Summary

  Nested Classes
  Modifier and Type | Class | Description
  --- | --- | ---
  `protected class` | `Choice.AccessibleAWTChoice` | This class implements accessibility support for the `Choice` class.

  ## Nested classes/interfaces declared in class java.awt.Component

  `Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy`

- ## Field Summary

  ### Fields declared in class java.awt.Component

  `accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT`

  ### Fields declared in interface java.awt.image.ImageObserver

  `ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH`

- ## Constructor Summary

  Constructors
  Constructor | Description
  --- | ---
  `Choice()` | Creates a new choice menu.

- ## Method Summary

  Modifier and Type | Method | Description
  --- | --- | ---
  `void` | `add​(String item)` | Adds an item to this `Choice` menu.
  `void` | `addItem​(String item)` | Obsolete as of Java 2 platform v1.1.
  `void` | `addItemListener​(ItemListener l)` | Adds the specified item listener to receive item events from this `Choice` menu.
  `void` | `addNotify()` | Creates the `Choice`'s peer.
  `int` | `countItems()` | Deprecated. As of JDK version 1.1, replaced by `getItemCount()`.
  `AccessibleContext` | `getAccessibleContext()` | Gets the `AccessibleContext` associated with this `Choice`.
  `String` | `getItem​(int index)` | Gets the string at the specified index in this `Choice` menu.
  `int` | `getItemCount()` | Returns the number of items in this `Choice` menu.
  `ItemListener[]` | `getItemListeners()` | Returns an array of all the item listeners registered on this choice.
  `<T extends EventListener> T[]` | `getListeners​(Class<T> listenerType)` | Returns an array of all the objects currently registered as `FooListener`s upon this `Choice`.
  `int` | `getSelectedIndex()` | Returns the index of the currently selected item.
  `String` | `getSelectedItem()` | Gets a representation of the current choice as a string.
  `Object[]` | `getSelectedObjects()` | Returns an array (length 1) containing the currently selected item.
  `void` | `insert​(String item, int index)` | Inserts the item into this choice at the specified position.
  `protected String` | `paramString()` | Returns a string representing the state of this `Choice` menu.
  `protected void` | `processEvent​(AWTEvent e)` | Processes events on this choice.
  `protected void` | `processItemEvent​(ItemEvent e)` | Processes item events occurring on this `Choice` menu by dispatching them to any registered `ItemListener` objects.
  `void` | `remove​(int position)` | Removes an item from the choice menu at the specified position.
  `void` | `remove​(String item)` | Removes the first occurrence of `item` from the `Choice` menu.
  `void` | `removeAll()` | Removes all items from the choice menu.
  `void` | `removeItemListener​(ItemListener l)` | Removes the specified item listener so that it no longer receives item events from this `Choice` menu.
  `void` | `select​(int pos)` | Sets the selected item in this `Choice` menu to be the item at the specified position.
  `void` | `select​(String str)` | Sets the selected item in this `Choice` menu to be the item whose name is equal to the specified string.

  ### Methods declared in class java.awt.Component

  `action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPreferredSize, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setMixingCutoutShape, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validate`

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- ## Constructor Details

  - ### Choice

    public Choice() throws HeadlessException
    Creates a new choice menu. The menu initially has no items in it.

    By default, the first item added to the choice menu becomes the selected item, until a different selection is made by the user by calling one of the `select` methods.

    Throws:
      `HeadlessException` - if GraphicsEnvironment.isHeadless() returns true
    See Also:
      `GraphicsEnvironment.isHeadless()`, `select(int)`, `select(java.lang.String)`

- ## Method Details

  - ### addNotify

    public void addNotify()
    Creates the `Choice`'s peer. This peer allows us to change the look of the `Choice` without changing its functionality.
    Overrides:
      `addNotify` in class `Component`
    See Also:
      `Component.getToolkit()`

  - ### getItemCount

    public int getItemCount()
    Returns the number of items in this `Choice` menu.
    Returns:
      the number of items in this `Choice` menu
    Since:
      1.1
    See Also:
      `getItem(int)`

  - ### countItems

    @Deprecated public int countItems()
    Deprecated.
    As of JDK version 1.1, replaced by `getItemCount()`.
    Returns the number of items in this `Choice` menu.
    Returns:
      the number of items in this `Choice` menu

  - ### getItem

    public String getItem​(int index)
    Gets the string at the specified index in this `Choice` menu.
    Parameters:
      `index` - the index at which to begin
    Returns:
      the item at the specified index
    See Also:
      `getItemCount()`

  - ### add

    public void add​(String item)
    Adds an item to this `Choice` menu.
    Parameters:
      `item` - the item to be added
    Throws:
      `NullPointerException` - if the item's value is `null`
    Since:
      1.1

  - ### addItem

    public void addItem​(String item)
    Obsolete as of Java 2 platform v1.1. Please use the `add` method instead.

    Adds an item to this `Choice` menu.

    Parameters:
      `item` - the item to be added
    Throws:
      `NullPointerException` - if the item's value is equal to `null`

  - ### insert

    public void insert​(String item, int index)
    Inserts the item into this choice at the specified position. Existing items at an index greater than or equal to `index` are shifted up by one to accommodate the new item. If `index` is greater than or equal to the number of items in this choice, `item` is added to the end of this choice.

    If the item is the first one being added to the choice, then the item becomes selected. Otherwise, if the selected item was one of the items shifted, the first item in the choice becomes the selected item. If the selected item was no among those shifted, it remains the selected item.

    Parameters:
      `item` - the non-`null` item to be inserted
      `index` - the position at which the item should be inserted
    Throws:
      `IllegalArgumentException` - if index is less than 0

  - ### remove

    public void remove​(String item)
    Removes the first occurrence of `item` from the `Choice` menu. If the item being removed is the currently selected item, then the first item in the choice becomes the selected item. Otherwise, the currently selected item remains selected (and the selected index is updated accordingly).
    Parameters:
      `item` - the item to remove from this `Choice` menu
    Throws:
      `IllegalArgumentException` - if the item doesn't exist in the choice menu
    Since:
      1.1

  - ### remove

    public void remove​(int position)
    Removes an item from the choice menu at the specified position. If the item being removed is the currently selected item, then the first item in the choice becomes the selected item. Otherwise, the currently selected item remains selected (and the selected index is updated accordingly).
    Parameters:
      `position` - the position of the item
    Throws:
      `IndexOutOfBoundsException` - if the specified position is out of bounds
    Since:
      1.1

  - ### removeAll

    public void removeAll()
    Removes all items from the choice menu.
    Since:
      1.1
    See Also:
      `remove(java.lang.String)`

  - ### getSelectedItem

    public String getSelectedItem()
    Gets a representation of the current choice as a string.
    Returns:
      a string representation of the currently selected item in this choice menu
    See Also:
      `getSelectedIndex()`

  - ### getSelectedObjects

    public Object[] getSelectedObjects()
    Returns an array (length 1) containing the currently selected item. If this choice has no items, returns `null`.
    Specified by:
      `getSelectedObjects` in interface `ItemSelectable`
    Returns:
      the list of selected objects, or `null`
    See Also:
      `ItemSelectable`

  - ### getSelectedIndex

    public int getSelectedIndex()
    Returns the index of the currently selected item. If nothing is selected, returns -1.
    Returns:
      the index of the currently selected item, or -1 if nothing is currently selected
    See Also:
      `getSelectedItem()`

  - ### select

    public void select​(int pos)
    Sets the selected item in this `Choice` menu to be the item at the specified position.

    Note that this method should be primarily used to initially select an item in this component. Programmatically calling this method will not trigger an `ItemEvent`. The only way to trigger an `ItemEvent` is by user interaction.

    Parameters:
      `pos` - the position of the selected item
    Throws:
      `IllegalArgumentException` - if the specified position is greater than the number of items or less than zero
    See Also:
      `getSelectedItem()`, `getSelectedIndex()`

  - ### select

    public void select​(String str)
    Sets the selected item in this `Choice` menu to be the item whose name is equal to the specified string. If more than one item matches (is equal to) the specified string, the one with the smallest index is selected.

    Note that this method should be primarily used to initially select an item in this component. Programmatically calling this method will not trigger an `ItemEvent`. The only way to trigger an `ItemEvent` is by user interaction.

    Parameters:
      `str` - the specified string
    See Also:
      `getSelectedItem()`, `getSelectedIndex()`

  - ### addItemListener

    public void addItemListener​(ItemListener l)
    Adds the specified item listener to receive item events from this `Choice` menu. Item events are sent in response to user input, but not in response to calls to `select`. If l is `null`, no exception is thrown and no action is performed.

    Refer to AWT Threading Issues for details on AWT's threading model.

    Specified by:
      `addItemListener` in interface `ItemSelectable`
    Parameters:
      `l` - the item listener
    Since:
      1.1
    See Also:
      `removeItemListener(java.awt.event.ItemListener)`, `getItemListeners()`, `select(int)`, `ItemEvent`, `ItemListener`

  - ### removeItemListener

    public void removeItemListener​(ItemListener l)
    Removes the specified item listener so that it no longer receives item events from this `Choice` menu. If l is `null`, no exception is thrown and no action is performed.

    Refer to AWT Threading Issues for details on AWT's threading model.

    Specified by:
      `removeItemListener` in interface `ItemSelectable`
    Parameters:
      `l` - the item listener
    Since:
      1.1
    See Also:
      `addItemListener(java.awt.event.ItemListener)`, `getItemListeners()`, `ItemEvent`, `ItemListener`

  - ### getItemListeners

    public ItemListener[] getItemListeners()
    Returns an array of all the item listeners registered on this choice.
    Returns:
      all of this choice's `ItemListener`s or an empty array if no item listeners are currently registered
    Since:
      1.4
    See Also:
      `addItemListener(java.awt.event.ItemListener)`, `removeItemListener(java.awt.event.ItemListener)`, `ItemEvent`, `ItemListener`

  - ### getListeners

    public <T extends EventListener> T[] getListeners​(Class<T> listenerType)
    Returns an array of all the objects currently registered as `FooListener`s upon this `Choice`. `FooListener`s are registered using the `addFooListener` method.

    You can specify the `listenerType` argument with a class literal, such as `FooListener.class`. For example, you can query a `Choice c` for its item listeners with the following code:

        ItemListener[] ils = (ItemListener[])(c.getListeners(ItemListener.class));

    If no such listeners exist, this method returns an empty array.
    Overrides:
      `getListeners` in class `Component`
    Type Parameters:
      `T` - the type of the listeners
    Parameters:
      `listenerType` - the type of listeners requested; this parameter should specify an interface that descends from `java.util.EventListener`
    Returns:
      an array of all objects registered as `FooListener`s on this choice, or an empty array if no such listeners have been added
    Throws:
      `ClassCastException` - if `listenerType` doesn't specify a class or interface that implements `java.util.EventListener`
    Since:
      1.3
    See Also:
      `getItemListeners()`

  - ### processEvent

    protected void processEvent​(AWTEvent e)
    Processes events on this choice. If the event is an instance of `ItemEvent`, it invokes the `processItemEvent` method. Otherwise, it calls its superclass's `processEvent` method.

    Note that if the event parameter is `null` the behavior is unspecified and may result in an exception.

    Overrides:
      `processEvent` in class `Component`
    Parameters:
      `e` - the event
    Since:
      1.1
    See Also:
      `ItemEvent`, `processItemEvent(java.awt.event.ItemEvent)`

  - ### processItemEvent

    protected void processItemEvent​(ItemEvent e)
    Processes item events occurring on this `Choice` menu by dispatching them to any registered `ItemListener` objects.

    This method is not called unless item events are enabled for this component. Item events are enabled when one of the following occurs:

    - An `ItemListener` object is registered via `addItemListener`.
    - Item events are enabled via `enableEvents`.

    Note that if the event parameter is `null` the behavior is unspecified and may result in an exception.

    Parameters:
      `e` - the item event
    Since:
      1.1
    See Also:
      `ItemEvent`, `ItemListener`, `addItemListener(ItemListener)`, `Component.enableEvents(long)`

  - ### paramString

    protected String paramString()
    Returns a string representing the state of this `Choice` menu. 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 `Component`
    Returns:
      the parameter string of this `Choice` menu

  - ### getAccessibleContext

    public AccessibleContext getAccessibleContext()
    Gets the `AccessibleContext` associated with this `Choice`. For `Choice` components, the `AccessibleContext` takes the form of an `AccessibleAWTChoice`. A new `AccessibleAWTChoice` instance is created if necessary.
    Specified by:
      `getAccessibleContext` in interface `Accessible`
    Overrides:
      `getAccessibleContext` in class `Component`
    Returns:
      an `AccessibleAWTChoice` that serves as the `AccessibleContext` of this `Choice`
    Since:
      1.3