Package com.google.gwt.user.client.ui

Class ListBox

java.lang.Object
com.google.gwt.user.client.ui.UIObject
com.google.gwt.user.client.ui.Widget
com.google.gwt.user.client.ui.FocusWidget
com.google.gwt.user.client.ui.ListBox
All Implemented Interfaces:
HasAllDragAndDropHandlers, HasAllFocusHandlers, HasAllGestureHandlers, HasAllKeyHandlers, HasAllMouseHandlers, HasAllTouchHandlers, HasBlurHandlers, HasChangeHandlers, HasClickHandlers, HasDoubleClickHandlers, HasDragEndHandlers, HasDragEnterHandlers, HasDragHandlers, HasDragLeaveHandlers, HasDragOverHandlers, HasDragStartHandlers, HasDropHandlers, HasFocusHandlers, HasGestureChangeHandlers, HasGestureEndHandlers, HasGestureStartHandlers, HasKeyDownHandlers, HasKeyPressHandlers, HasKeyUpHandlers, HasMouseDownHandlers, HasMouseMoveHandlers, HasMouseOutHandlers, HasMouseOverHandlers, HasMouseUpHandlers, HasMouseWheelHandlers, HasTouchCancelHandlers, HasTouchEndHandlers, HasTouchMoveHandlers, HasTouchStartHandlers, HasAttachHandlers, HasHandlers, HasDirectionEstimator, EventListener, Focusable, HasEnabled, HasFocus, HasName, HasVisibility, IsWidget, SourcesChangeEvents, SourcesClickEvents, SourcesFocusEvents, SourcesKeyboardEvents, SourcesMouseEvents
public class ListBox extends FocusWidget implements SourcesChangeEvents, HasChangeHandlers, HasName, HasDirectionEstimator
A widget that presents a list of choices to the user, either as a list box or as a drop-down list.

CSS Style Rules

  • .gwt-ListBox { }

Example

public class ListBoxExample implements EntryPoint {

  public void onModuleLoad() {
    // Make a new list box, adding a few items to it.
    ListBox lb = new ListBox();
    lb.addItem("foo");
    lb.addItem("bar");
    lb.addItem("baz");
    lb.addItem("toto");
    lb.addItem("tintin");

    // Make enough room for all five items (setting this value to 1 turns it
    // into a drop-down list).
    lb.setVisibleItemCount(5);

    // Add it to the root panel.
    RootPanel.get().add(lb);
  }
}

Built-in Bidi Text Support

This widget is capable of automatically adjusting its direction according to its content. This feature is controlled by setDirectionEstimator(boolean), and is off by default.

Use in UiBinder Templates

The items of a ListBox element are laid out in <g:item> elements. Each item contains text that will be added to the list of available items that will be shown, either in the drop down or list. (Note that the tags of the item elements are not capitalized. This is meant to signal that the item is not a runtime object, and so cannot have a ui:field attribute.) It is also possible to explicitly specify item's value using value attribute as shown below.

For example: 

 <g:ListBox>
  <g:item>
    first
  </g:item>
  <g:item value='2'>
    second
  </g:item>
 </g:ListBox>

Important usage note

Subclasses should neither read nor write option text directly from the option elements created by this class, since such text may need to be wrapped in Unicode bidi formatting characters. They can use the getOptionText and/or setOptionText methods for this purpose instead.

  • Field Details

    • DEFAULT_DIRECTION_ESTIMATOR

      public static final DirectionEstimator DEFAULT_DIRECTION_ESTIMATOR

  • Constructor Details

    • ListBox

      public ListBox()
      Creates an empty list box in single selection mode.

    • ListBox

      @Deprecated public ListBox(boolean isMultipleSelect)
      Deprecated.
      use setMultipleSelect(boolean) instead.
      Creates an empty list box.
      Parameters:
      isMultipleSelect - specifies if multiple selection is enabled

    • ListBox

      protected ListBox(Element element)
      This constructor may be used by subclasses to explicitly use an existing element. This element must be a <select> element.
      Parameters:
      element - the element to be used

  • Method Details

    • wrap

      public static ListBox wrap(Element element)
      Creates a ListBox widget that wraps an existing <select> element. This element must already be attached to the document. If the element is removed from the document, you must call Widget.removeFromParent().
      Parameters:
      element - the element to be wrapped
      Returns:
      list box

    • addChangeHandler

      public HandlerRegistration addChangeHandler(ChangeHandler handler)
      Description copied from interface: HasChangeHandlers
      Adds a ChangeEvent handler.
      Specified by:
      addChangeHandler in interface HasChangeHandlers
      Parameters:
      handler - the change handler
      Returns:
      HandlerRegistration used to remove this handler

    • addChangeListener

      @Deprecated public void addChangeListener(ChangeListener listener)
      Deprecated.
      Use addChangeHandler(com.google.gwt.event.dom.client.ChangeHandler) instead
      Description copied from interface: SourcesChangeEvents
      Adds a listener interface to receive change events.
      Specified by:
      addChangeListener in interface SourcesChangeEvents
      Parameters:
      listener - the listener interface to add

    • addItem

      public void addItem(String item)
      Adds an item to the list box. This method has the same effect as 
       addItem(item, item)
      Parameters:
      item - the text of the item to be added

    • addItem

      public void addItem(String item, HasDirection.Direction dir)
      Adds an item to the list box, specifying its direction. This method has the same effect as 
       addItem(item, dir, item)
      Parameters:
      item - the text of the item to be added
      dir - the item's direction

    • addItem

      public void addItem(String item, String value)
      Adds an item to the list box, specifying an initial value for the item.
      Parameters:
      item - the text of the item to be added
      value - the item's value, to be submitted if it is part of a FormPanel; cannot be null

    • addItem

      public void addItem(String item, HasDirection.Direction dir, String value)
      Adds an item to the list box, specifying its direction and an initial value for the item.
      Parameters:
      item - the text of the item to be added
      dir - the item's direction
      value - the item's value, to be submitted if it is part of a FormPanel; cannot be null

    • clear

      public void clear()
      Removes all items from the list box.

    • getDirectionEstimator

      public DirectionEstimator getDirectionEstimator()
      Description copied from interface: HasDirectionEstimator
      Returns the DirectionEstimator object.
      Specified by:
      getDirectionEstimator in interface HasDirectionEstimator

    • getItemCount

      public int getItemCount()
      Gets the number of items present in the list box.
      Returns:
      the number of items

    • getItemText

      public String getItemText(int index)
      Gets the text associated with the item at the specified index.
      Parameters:
      index - the index of the item whose text is to be retrieved
      Returns:
      the text associated with the item
      Throws:
      IndexOutOfBoundsException - if the index is out of range

    • getSelectedItemText

      public String getSelectedItemText()
      Gets the text for currently selected item. If multiple items are selected, this method will return the text of the first selected item.
      Returns:
      the text for selected item, or null if none is selected

    • getName

      public String getName()
      Description copied from interface: HasName
      Gets the widget's name.
      Specified by:
      getName in interface HasName
      Returns:
      the widget's name

    • getSelectedIndex

      public int getSelectedIndex()
      Gets the currently-selected item. If multiple items are selected, this method will return the first selected item (isItemSelected(int) can be used to query individual items).
      Returns:
      the selected index, or -1 if none is selected

    • getValue

      public String getValue(int index)
      Gets the value associated with the item at a given index.
      Parameters:
      index - the index of the item to be retrieved
      Returns:
      the item's associated value
      Throws:
      IndexOutOfBoundsException - if the index is out of range

    • getSelectedValue

      public String getSelectedValue()
      Gets the value for currently selected item. If multiple items are selected, this method will return the value of the first selected item.
      Returns:
      the value for selected item, or null if none is selected

    • getVisibleItemCount

      public int getVisibleItemCount()
      Gets the number of items that are visible. If only one item is visible, then the box will be displayed as a drop-down list.
      Returns:
      the visible item count

    • insertItem

      public void insertItem(String item, int index)
      Inserts an item into the list box. Has the same effect as 
       insertItem(item, item, index)
      Parameters:
      item - the text of the item to be inserted
      index - the index at which to insert it

    • insertItem

      public void insertItem(String item, HasDirection.Direction dir, int index)
      Inserts an item into the list box, specifying its direction. Has the same effect as 
       insertItem(item, dir, item, index)
      Parameters:
      item - the text of the item to be inserted
      dir - the item's direction
      index - the index at which to insert it

    • insertItem

      public void insertItem(String item, String value, int index)
      Inserts an item into the list box, specifying an initial value for the item. Has the same effect as 
       insertItem(item, null, value, index)
      Parameters:
      item - the text of the item to be inserted
      value - the item's value, to be submitted if it is part of a FormPanel.
      index - the index at which to insert it

    • insertItem

      public void insertItem(String item, HasDirection.Direction dir, String value, int index)
      Inserts an item into the list box, specifying its direction and an initial value for the item. If the index is less than zero, or greater than or equal to the length of the list, then the item will be appended to the end of the list.
      Parameters:
      item - the text of the item to be inserted
      dir - the item's direction. If null, the item is displayed in the widget's overall direction, or, if a direction estimator has been set, in the item's estimated direction.
      value - the item's value, to be submitted if it is part of a FormPanel.
      index - the index at which to insert it

    • isItemSelected

      public boolean isItemSelected(int index)
      Determines whether an individual list item is selected.
      Parameters:
      index - the index of the item to be tested
      Returns:
      true if the item is selected
      Throws:
      IndexOutOfBoundsException - if the index is out of range

    • isMultipleSelect

      public boolean isMultipleSelect()
      Gets whether this list allows multiple selection.
      Returns:
      true if multiple selection is allowed

    • removeChangeListener

      @Deprecated public void removeChangeListener(ChangeListener listener)
      Deprecated.
      Use the HandlerRegistration.removeHandler() method on the object returned by addChangeHandler(com.google.gwt.event.dom.client.ChangeHandler) instead
      Description copied from interface: SourcesChangeEvents
      Removes a previously added listener interface.
      Specified by:
      removeChangeListener in interface SourcesChangeEvents
      Parameters:
      listener - the listener interface to remove

    • removeItem

      public void removeItem(int index)
      Removes the item at the specified index.
      Parameters:
      index - the index of the item to be removed
      Throws:
      IndexOutOfBoundsException - if the index is out of range

    • setDirectionEstimator

      public void setDirectionEstimator(boolean enabled)
      Toggles on / off direction estimation. See note at setDirectionEstimator(com.google.gwt.i18n.shared.DirectionEstimator).
      Specified by:
      setDirectionEstimator in interface HasDirectionEstimator
      Parameters:
      enabled - Whether to enable direction estimation. If true, sets the DirectionEstimator object to a default DirectionEstimator.

    • setDirectionEstimator

      public void setDirectionEstimator(DirectionEstimator directionEstimator)
      Sets the DirectionEstimator object. Note: this does not affect the direction of already-existing content.
      Specified by:
      setDirectionEstimator in interface HasDirectionEstimator
      Parameters:
      directionEstimator - The DirectionEstimator to be set. null means turning off direction estimation.

    • setItemSelected

      public void setItemSelected(int index, boolean selected)
      Sets whether an individual list item is selected.

      Note that setting the selection programmatically does not cause the ChangeHandler.onChange(ChangeEvent) event to be fired.

      Parameters:
      index - the index of the item to be selected or unselected
      selected - true to select the item
      Throws:
      IndexOutOfBoundsException - if the index is out of range

    • setItemText

      public void setItemText(int index, String text)
      Sets the text associated with the item at a given index.
      Parameters:
      index - the index of the item to be set
      text - the item's new text
      Throws:
      IndexOutOfBoundsException - if the index is out of range

    • setItemText

      public void setItemText(int index, String text, HasDirection.Direction dir)
      Sets the text associated with the item at a given index.
      Parameters:
      index - the index of the item to be set
      text - the item's new text
      dir - the item's direction.
      Throws:
      IndexOutOfBoundsException - if the index is out of range

    • setMultipleSelect

      public void setMultipleSelect(boolean multiple)
      Sets whether this list allows multiple selections. NOTE: Using this method can spuriously fail on Internet Explorer 6.0.
      Parameters:
      multiple - true to allow multiple selections

    • setName

      public void setName(String name)
      Description copied from interface: HasName
      Sets the widget's name.
      Specified by:
      setName in interface HasName
      Parameters:
      name - the widget's new name

    • setSelectedIndex

      public void setSelectedIndex(int index)
      Sets the currently selected index. After calling this method, only the specified item in the list will remain selected. For a ListBox with multiple selection enabled, see setItemSelected(int, boolean) to select multiple items at a time.

      Note that setting the selected index programmatically does not cause the ChangeHandler.onChange(ChangeEvent) event to be fired.

      Parameters:
      index - the index of the item to be selected

    • setValue

      public void setValue(int index, String value)
      Sets the value associated with the item at a given index. This value can be used for any purpose, but is also what is passed to the server when the list box is submitted as part of a FormPanel.
      Parameters:
      index - the index of the item to be set
      value - the item's new value; cannot be null
      Throws:
      IndexOutOfBoundsException - if the index is out of range

    • setVisibleItemCount

      public void setVisibleItemCount(int visibleItems)
      Sets the number of items that are visible. If only one item is visible, then the box will be displayed as a drop-down list.
      Parameters:
      visibleItems - the visible item count

    • getOptionText

      protected String getOptionText(OptionElement option)
      Retrieves the text of an option element. If the text was set by setOptionText(com.google.gwt.dom.client.OptionElement, java.lang.String, com.google.gwt.i18n.client.HasDirection.Direction) and was wrapped with Unicode bidi formatting characters, also removes those additional formatting characters.
      Parameters:
      option - an option element
      Returns:
      the element's text

    • onEnsureDebugId

      protected void onEnsureDebugId(String baseID)
      Affected Elements:
      • -item# = the option at the specified index.
      Overrides:
      onEnsureDebugId in class UIObject
      Parameters:
      baseID - the base ID used by the main element
      See Also:

    • setOptionText

      protected void setOptionText(OptionElement option, String text, HasDirection.Direction dir)
      Sets the text of an option element. If the direction of the text is opposite to the page's direction, also wraps it with Unicode bidi formatting characters to prevent garbling, and indicates that this was done by setting the option's BIDI_ATTR_NAME custom attribute.
      Parameters:
      option - an option element
      text - text to be set to the element
      dir - the text's direction. If null and direction estimation is turned off, direction is ignored.