Java Doc for Checkbox.java in  » 6.0-JDK-Core » AWT » java » awt » Java Source Code / Java DocumentationJava Source Code and Java Documentation

The following code example creates a set of check boxes in a grid layout:

 setLayout(new GridLayout(3, 1));
 add(new Checkbox("one", null, true));
 add(new Checkbox("two"));
 add(new Checkbox("three"));
 

This image depicts the check boxes and grid layout created by this code example:

The button labeled one is in the "on" state, and the other two are in the "off" state. In this example, which uses the GridLayout class, the states of the three check boxes are set independently.

Alternatively, several check boxes can be grouped together under the control of a single object, using the CheckboxGroup class. In a check box group, at most one button can be in the "on" state at any given time. Clicking on a check box to turn it on forces any other check box in the same group that is on into the "off" state.
version:
   1.95 05/05/07
author:
   Sami Shaio
See Also:   java.awt.GridLayout
See Also:   java.awt.CheckboxGroup
since:
   JDK1.0

This method is not called unless item events are enabled for this component.

If the state of this check box is true and the new group already has a check box selected, this check box's state is changed to false.

Note that this method should be primarily used to initialize the state of the checkbox.

Refer to AWT Threading Issues for details on AWT's threading model.
Parameters:
  l - the item listener
See Also:   Checkbox.removeItemListener
See Also:   Checkbox.getItemListeners
See Also:   Checkbox.setState
See Also:   java.awt.event.ItemEvent
See Also:   java.awt.event.ItemListener
since:
   JDK1.1

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

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

Note that if the event parameter is null the behavior is unspecified and may result in an exception.
Parameters:
  e - the event
See Also:   java.awt.event.ItemEvent
See Also:   Checkbox.processItemEvent
since:
   JDK1.1

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
See Also:   java.awt.event.ItemEvent
See Also:   java.awt.event.ItemListener
See Also:   Checkbox.addItemListener
See Also:   java.awt.Component.enableEvents
since:
   JDK1.1

Refer to AWT Threading Issues for details on AWT's threading model.
Parameters:
  l - the item listener
See Also:   Checkbox.addItemListener
See Also:   Checkbox.getItemListeners
See Also:   java.awt.event.ItemEvent
See Also:   java.awt.event.ItemListener
since:
   JDK1.1

If the state of this check box is true and the new group already has a check box selected, this check box's state is changed to false. If the state of this check box is true and the new group has no check box selected, this check box becomes the selected checkbox for the new group and its state is true.
Parameters:
  g - the new check box group, or nullto remove this check box from any check box group
See Also:   Checkbox.getCheckboxGroup

Note that this method should be primarily used to initialize the state of the checkbox. Programmatically setting the state of the checkbox will not trigger an ItemEvent. The only way to trigger an ItemEvent is by user interaction.
Parameters:
  state - the boolean state of the check box
See Also:   Checkbox.getState