Chapter 19
java.awt Reference

Checkbox

Name

Checkbox

[Graphic: Figure from the text]

Description

The Checkbox is a Component that provides a true or false toggle switch for user input.

Class Definition

public class java.awt.Checkbox
    extends java.awt.Component
    implements java.awt.ItemSelectable {
  
  // Constructors
  public Checkbox();
  public Checkbox (String label);
  public Checkbox (String label, boolean state); 
  public Checkbox (String label, boolean state, CheckboxGroup group); 
  public Checkbox (String label, CheckboxGroup group, boolean state);
  
  // Instance Methods
  public void addItemListener (ItemListener l); 
  public void addNotify();
  public CheckboxGroup getCheckboxGroup();
  public String getLabel();
  public Object[] getSelectedObjects(); 
  public boolean getState();
  public void removeItemListener (ItemListener l); 
  public void setCheckboxGroup (CheckboxGroup group);
  public synchronized void setLabel (String label);
  public void setState (boolean state);
  
  // Protected Instance Methods
  protected String paramString();
  protected void processEvent (AWTEvent e); 
  protected void processItemEvent (ItemEvent e); 
}

Constructors

Checkbox

public Checkbox()

Description: Constructs a Checkbox object with no label that is initially false.

public Checkbox (String label)

Parameters

label: Text to display with the Checkbox.

Description

Constructs a Checkbox object with the given label that is initially false.

public Checkbox (String label, boolean state)

Parameters

label

Text to display with the Checkbox.

state

Intial value of the Checkbox.

Description

Constructs a Checkbox with the given label, initialized to the given state.

public Checkbox (String label, boolean state, CheckboxGroup group)

Parameters

label

Text to display with the Checkbox.

state

Intial value of the Checkbox.

group

The CheckboxGroup this Checkbox should belong to.

Description

Constructs a Checkbox with the given label, initialized to the given state and belonging to group.

public Checkbox (String label, CheckboxGroup group, boolean state)

Parameters

label

Text to display with the Checkbox.

group

The CheckboxGroup this Checkbox should belong to.

state

Intial value of the Checkbox.

Description

Constructs a Checkbox object with the given settings.

Instance Methods

addItemListener

public void addItemListener (ItemListener l)

Parameters

l: The listener to be added.

Implements

ItemSelectable.addItemListener(ItemListener l)

Description

Adds a listener for the ItemEvent objects this Checkbox generates.

addNotify

public void addNotify()

Overrides

Component.addNotify()

Description

Creates Checkbox peer.

getCheckboxGroup

public CheckboxGroup getCheckboxGroup()

Returns: The current CheckboxGroup associated with the Checkbox, if any.

getLabel

public String getLabel()

Returns: The text associated with the Checkbox.

getSelectedObjects

public Object[] getSelectedObjects()

Implements

ItemSelectable.getSelectedObjects()

Description

If the Checkbox is checked, returns an array with length 1 containing the label of the Checkbox; otherwise returns null.

getState

public boolean getState()

Returns: The current state of the Checkbox.

removeItemListener

public void removeItemListener (ItemListener l)

Parameters

l: The listener to be removed.

Implements

ItemSelectable.removeItemListener (ItemListener l)

Description

Removes the specified ItemListener so it will not receive ItemEvent objects from this Checkbox.

setCheckboxGroup

public void setCheckboxGroup (CheckboxGroup group)

Parameters

group: New group in which to place the Checkbox.

Description

Associates the Checkbox with a different CheckboxGroup.

setLabel

public synchronized void setLabel (String label)

Parameters

label: New text to associate with Checkbox.

Description

Changes the text associated with the Checkbox.

setState

public void setState (boolean state)

Parameters

state: New state for the Checkbox.

Description

Changes the state of the Checkbox.

Protected Instance Methods

paramString

protected String paramString()

Returns

String with current settings of Checkbox.

Overrides

Component.paramString()

Description

Helper method for toString() to generate string of current settings.

processEvent

protected void processEvent(AWTEvent e)

Parameters

e: The event to process.

Description

Low level AWTEvents are passed to this method for processing.

processItemEvent

protected void processItemEvent(ItemEvent e)

Parameters

e: The item event to process.

Description

Item events are passed to this method for processing. Normally, this method is called by processEvent().