com.google.gwt.user.client.ui
Class CheckBox

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.ButtonBase
                  com.google.gwt.user.client.ui.CheckBox

All Implemented Interfaces:

HasAllFocusHandlers, HasAllKeyHandlers, HasAllMouseHandlers, HasBlurHandlers, HasClickHandlers, HasFocusHandlers, HasKeyDownHandlers, HasKeyPressHandlers, HasKeyUpHandlers, HasMouseDownHandlers, HasMouseMoveHandlers, HasMouseOutHandlers, HasMouseOverHandlers, HasMouseUpHandlers, HasMouseWheelHandlers, HasValueChangeHandlers<java.lang.Boolean>, HasHandlers, EventListener, Focusable, HasFocus, HasHTML, HasName, HasText, HasValue<java.lang.Boolean>, SourcesClickEvents, SourcesFocusEvents, SourcesKeyboardEvents, SourcesMouseEvents

Direct Known Subclasses:

RadioButton

public class CheckBox
extends ButtonBase
implements HasName, HasValue<java.lang.Boolean>

A standard check box widget. This class also serves as a base class for RadioButton.

CSS Style Rules

.gwt-CheckBox

the outer element

.gwt-CheckBox-disabled

applied when Checkbox is disabled

Example

public class CheckBoxExample implements EntryPoint {

  public void onModuleLoad() {
    // Make a new check box, and select it by default.
    CheckBox cb = new CheckBox("Foo");
    cb.setChecked(true);

    // Hook up a handler to find out when it's clicked.
    cb.addClickHandler(new ClickHandler() {
      public void onClick(ClickEvent event) {
        boolean checked = ((CheckBox) event.getSource()).isChecked();
        Window.alert("It is " + (checked ? "" : "not ") + "checked");
      }
    });

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

CheckBox

public CheckBox()

Creates a check box with no label.

CheckBox

public CheckBox(java.lang.String label)

Creates a check box with the specified text label.

Parameters:

label - the check box's label

CheckBox

public CheckBox(java.lang.String label,
                boolean asHTML)

Creates a check box with the specified text label.

Parameters:

label - the check box's label

asHTML - true to treat the specified label as html

CheckBox

protected CheckBox(Element elem)

addValueChangeHandler

public HandlerRegistration addValueChangeHandler(ValueChangeHandler<java.lang.Boolean> handler)

Description copied from interface: HasValueChangeHandlers

Adds a ValueChangeEvent handler.

Specified by:

addValueChangeHandler in interface HasValueChangeHandlers<java.lang.Boolean>

Parameters:

handler - the handler

Returns:

the registration for the event

getFormValue

public java.lang.String getFormValue()

Returns the value property of the input element that backs this widget. This is the value that will be associated with the CheckBox name and submitted to the server if a FormPanel that holds it is submitted and the box is checked.

Don't confuse this with getValue(), which returns true or false if the widget is checked.

getHTML

public java.lang.String getHTML()

Description copied from interface: HasHTML

Gets this object's contents as HTML.

Specified by:

getHTML in interface HasHTML

Overrides:

getHTML in class ButtonBase

Returns:

the object's HTML

getName

public java.lang.String getName()

Description copied from interface: HasName

Gets the widget's name.

Specified by:

getName in interface HasName

Returns:

the widget's name

getTabIndex

public int getTabIndex()

Description copied from class: FocusWidget

Gets the tab index.

Specified by:

getTabIndex in interface Focusable

Overrides:

getTabIndex in class FocusWidget

Returns:

the tab index

getText

public java.lang.String getText()

Description copied from interface: HasText

Gets this object's text.

Specified by:

getText in interface HasText

Overrides:

getText in class ButtonBase

Returns:

the object's text

getValue

public java.lang.Boolean getValue()

Determines whether this check box is currently checked.

Note that this is not return the value property of the checkbox input element wrapped by this widget. For access to that property, see getFormValue()

Specified by:

getValue in interface HasValue<java.lang.Boolean>

Returns:

true if the check box is checked, false otherwise. Will not return null

isChecked

@Deprecated
public boolean isChecked()

Deprecated. Use getValue() instead

Determines whether this check box is currently checked.

Returns:

true if the check box is checked

isEnabled

public boolean isEnabled()

Description copied from class: FocusWidget

Gets whether this widget is enabled.

Overrides:

isEnabled in class FocusWidget

Returns:

true if the widget is enabled

setAccessKey

public void setAccessKey(char key)

Description copied from interface: Focusable

Sets the widget's 'access key'. This key is used (in conjunction with a browser-specific modifier key) to automatically focus the widget.

Specified by:

setAccessKey in interface Focusable

Overrides:

setAccessKey in class FocusWidget

Parameters:

key - the widget's access key

setChecked

@Deprecated
public void setChecked(boolean checked)

Deprecated. Use setValue(Boolean) instead

Checks or unchecks this check box. Does not fire ValueChangeEvent. (If you want the event to fire, use setValue(Boolean, boolean))

Parameters:

checked - true to check the check box.

setEnabled

public void setEnabled(boolean enabled)

Description copied from class: FocusWidget

Sets whether this widget is enabled.

Overrides:

setEnabled in class FocusWidget

Parameters:

enabled - true to enable the widget, false to disable it

setFocus

public void setFocus(boolean focused)

Description copied from interface: Focusable

Explicitly focus/unfocus this widget. Only one widget can have focus at a time, and the widget that does will receive all keyboard events.

Specified by:

setFocus in interface Focusable

Overrides:

setFocus in class FocusWidget

Parameters:

focused - whether this widget should take focus or release it

setFormValue

public void setFormValue(java.lang.String value)

Set the value property on the input element that backs this widget. This is the value that will be associated with the CheckBox's name and submitted to the server if a FormPanel that holds it is submitted and the box is checked.

Don't confuse this with setValue(java.lang.Boolean), which actually checks and unchecks the box.

Parameters:

value -

setHTML

public void setHTML(java.lang.String html)

Description copied from interface: HasHTML

Sets this object's contents via HTML. Use care when setting an object's HTML; it is an easy way to expose script-based security problems. Consider using HasText.setText(String) whenever possible.

Specified by:

setHTML in interface HasHTML

Overrides:

setHTML in class ButtonBase

Parameters:

html - the object's new HTML

setName

public void setName(java.lang.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

setTabIndex

public void setTabIndex(int index)

Description copied from interface: Focusable

Sets the widget's position in the tab index. If more than one widget has the same tab index, each such widget will receive focus in an arbitrary order. Setting the tab index to -1 will cause this widget to be removed from the tab order.

Specified by:

setTabIndex in interface Focusable

Overrides:

setTabIndex in class FocusWidget

Parameters:

index - the widget's tab index

setText

public void setText(java.lang.String text)

Description copied from interface: HasText

Sets this object's text.

Specified by:

setText in interface HasText

Overrides:

setText in class ButtonBase

Parameters:

text - the object's new text

setValue

public void setValue(java.lang.Boolean value)

Checks or unchecks the text box.

Note that this does not set the value property of the checkbox input element wrapped by this widget. For access to that property, see setFormValue(String)

Specified by:

setValue in interface HasValue<java.lang.Boolean>

Parameters:

value - true to check, false to uncheck; must not be null

Throws:

java.lang.IllegalArgumentException - if value is null

setValue

public void setValue(java.lang.Boolean value,
                     boolean fireEvents)

Checks or unchecks the text box, firing ValueChangeEvent if appropriate.

Note that this does not set the value property of the checkbox input element wrapped by this widget. For access to that property, see setFormValue(String)

Specified by:

setValue in interface HasValue<java.lang.Boolean>

Parameters:

value - true to check, false to uncheck; must not be null

fireEvents - If true, and value has changed, fire a ValueChangeEvent

Throws:

java.lang.IllegalArgumentException - if value is null

sinkEvents

public void sinkEvents(int eventBitsToAdd)

Description copied from class: Widget

Overridden to defer the call to super.sinkEvents until the first time this widget is attached to the dom, as a performance enhancement. Subclasses wishing to customize sinkEvents can preserve this deferred sink behavior by putting their implementation behind a check of isOrWasAttached():

 @Override
 public void sinkEvents(int eventBitsToAdd) {
   if (isOrWasAttached()) {
     /* customized sink code goes here */
   } else {
     super.sinkEvents(eventBitsToAdd);
  }
} 

Overrides:

sinkEvents in class Widget

Parameters:

eventBitsToAdd - a bitfield representing the set of events to be added to this element's event set

See Also:

Event

ensureDomEventHandlers

protected void ensureDomEventHandlers()

onEnsureDebugId

protected void onEnsureDebugId(java.lang.String baseID)

Affected Elements:

• -label = label next to checkbox.

Overrides:

onEnsureDebugId in class UIObject

Parameters:

baseID - the base ID used by the main element

See Also:

UIObject.onEnsureDebugId(String)

onLoad

protected void onLoad()

This method is called when a widget is attached to the browser's document. onAttach needs special handling for the CheckBox case. Must still call Widget.onAttach() to preserve the onAttach contract.

Overrides:

onLoad in class Widget

onUnload

protected void onUnload()

This method is called when a widget is detached from the browser's document. Overridden because of IE bug that throws away checked state and in order to clear the event listener off of the inputElem.

Overrides:

onUnload in class Widget

replaceInputElement

protected void replaceInputElement(Element elem)

Replace the current input element with a new one. Preserves all state except for the name property, for nasty reasons related to radio button grouping. (See implementation of RadioButton.setName(java.lang.String).)

Parameters:

elem - the new input element