[Chapter 19] Checkbox
Author: John Zukowski
Date: Thu Jul 31 15:09:47 1997

#

| Chapter 19 java.awt Reference |

# Checkbox

## Name

Checkbox

##

## 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 `AWTEvent`s 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()`.

## See Also

`CheckboxGroup`, `Component`, `ItemEvent`, `ItemSelectable`, `String`

CardLayout |  | CheckboxGroup