Java™ Platform
Standard Ed. 6

javax.swing
Interface ButtonModel

All Superinterfaces:
ItemSelectable
All Known Implementing Classes:
DefaultButtonModel, JToggleButton.ToggleButtonModel

public interface ButtonModel
extends ItemSelectable

State model for buttons.

This model is used for regular buttons, as well as check boxes and radio buttons, which are special kinds of buttons. In practice, a button's UI takes the responsibility of calling methods on its model to manage the state, as detailed below:

In simple terms, pressing and releasing the mouse over a regular button triggers the button and causes and ActionEvent to be fired. The same behavior can be produced via a keyboard key defined by the look and feel of the button (typically the SPACE BAR). Pressing and releasing this key while the button has focus will give the same results. For check boxes and radio buttons, the mouse or keyboard equivalent sequence just described causes the button to become selected.

In details, the state model for buttons works as follows when used with the mouse:
Pressing the mouse on top of a button makes the model both armed and pressed. As long as the mouse remains down, the model remains pressed, even if the mouse moves outside the button. On the contrary, the model is only armed while the mouse remains pressed within the bounds of the button (it can move in or out of the button, but the model is only armed during the portion of time spent within the button). A button is triggered, and an ActionEvent is fired, when the mouse is released while the model is armed - meaning when it is released over top of the button after the mouse has previously been pressed on that button (and not already released). Upon mouse release, the model becomes unarmed and unpressed.

In details, the state model for buttons works as follows when used with the keyboard:
Pressing the look and feel defined keyboard key while the button has focus makes the model both armed and pressed. As long as this key remains down, the model remains in this state. Releasing the key sets the model to unarmed and unpressed, triggers the button, and causes an ActionEvent to be fired.


Method Summary
 void addActionListener(ActionListener l)
          Adds an ActionListener to the model.
 void addChangeListener(ChangeListener l)
          Adds a ChangeListener to the model.
 void addItemListener(ItemListener l)
          Adds an ItemListener to the model.
 String getActionCommand()
          Returns the action command string for the button.
 int getMnemonic()
          Gets the keyboard mnemonic for the button.
 boolean isArmed()
          Indicates partial commitment towards triggering the button.
 boolean isEnabled()
          Indicates if the button can be selected or triggered by an input device, such as a mouse pointer.
 boolean isPressed()
          Indicates if the button is pressed.
 boolean isRollover()
          Indicates that the mouse is over the button.
 boolean isSelected()
          Indicates if the button has been selected.
 void removeActionListener(ActionListener l)
          Removes an ActionListener from the model.
 void removeChangeListener(ChangeListener l)
          Removes a ChangeListener from the model.
 void removeItemListener(ItemListener l)
          Removes an ItemListener from the model.
 void setActionCommand(String s)
          Sets the action command string that gets sent as part of the ActionEvent when the button is triggered.
 void setArmed(boolean b)
          Marks the button as armed or unarmed.
 void setEnabled(boolean b)
          Enables or disables the button.
 void setGroup(ButtonGroup group)
          Identifies the group the button belongs to -- needed for radio buttons, which are mutually exclusive within their group.
 void setMnemonic(int key)
          Sets the keyboard mnemonic (shortcut key or accelerator key) for the button.
 void setPressed(boolean b)
          Sets the button to pressed or unpressed.
 void setRollover(boolean b)
          Sets or clears the button's rollover state
 void setSelected(boolean b)
          Selects or deselects the button.
 
Methods inherited from interface java.awt.ItemSelectable
getSelectedObjects
 

Method Detail

isArmed

boolean isArmed()
Indicates partial commitment towards triggering the button.

Returns:
true if the button is armed, and ready to be triggered
See Also:
setArmed(boolean)

isSelected

boolean isSelected()
Indicates if the button has been selected. Only needed for certain types of buttons - such as radio buttons and check boxes.

Returns:
true if the button is selected

isEnabled

boolean isEnabled()
Indicates if the button can be selected or triggered by an input device, such as a mouse pointer.

Returns:
true if the button is enabled

isPressed

boolean isPressed()
Indicates if the button is pressed.

Returns:
true if the button is pressed

isRollover

boolean isRollover()
Indicates that the mouse is over the button.

Returns:
true if the mouse is over the button

setArmed

void setArmed(boolean b)
Marks the button as armed or unarmed.

Parameters:
b - whether or not the button should be armed

setSelected

void setSelected(boolean b)
Selects or deselects the button.

Parameters:
b - true selects the button, false deselects the button

setEnabled

void setEnabled(boolean b)
Enables or disables the button.

Parameters:
b - whether or not the button should be enabled
See Also:
isEnabled()

setPressed

void setPressed(boolean b)
Sets the button to pressed or unpressed.

Parameters:
b - whether or not the button should be pressed
See Also:
isPressed()

setRollover

void setRollover(boolean b)
Sets or clears the button's rollover state

Parameters:
b - whether or not the button is in the rollover state
See Also:
isRollover()

setMnemonic

void setMnemonic(int key)
Sets the keyboard mnemonic (shortcut key or accelerator key) for the button.

Parameters:
key - an int specifying the accelerator key

getMnemonic

int getMnemonic()
Gets the keyboard mnemonic for the button.

Returns:
an int specifying the accelerator key
See Also:
setMnemonic(int)

setActionCommand

void setActionCommand(String s)
Sets the action command string that gets sent as part of the ActionEvent when the button is triggered.

Parameters:
s - the String that identifies the generated event
See Also:
getActionCommand(), ActionEvent.getActionCommand()

getActionCommand

String getActionCommand()
Returns the action command string for the button.

Returns:
the String that identifies the generated event
See Also:
setActionCommand(java.lang.String)

setGroup

void setGroup(ButtonGroup group)
Identifies the group the button belongs to -- needed for radio buttons, which are mutually exclusive within their group.

Parameters:
group - the ButtonGroup the button belongs to

addActionListener

void addActionListener(ActionListener l)
Adds an ActionListener to the model.

Parameters:
l - the listener to add

removeActionListener

void removeActionListener(ActionListener l)
Removes an ActionListener from the model.

Parameters:
l - the listener to remove

addItemListener

void addItemListener(ItemListener l)
Adds an ItemListener to the model.

Specified by:
addItemListener in interface ItemSelectable
Parameters:
l - the listener to add
See Also:
ItemEvent

removeItemListener

void removeItemListener(ItemListener l)
Removes an ItemListener from the model.

Specified by:
removeItemListener in interface ItemSelectable
Parameters:
l - the listener to remove
See Also:
ItemEvent

addChangeListener

void addChangeListener(ChangeListener l)
Adds a ChangeListener to the model.

Parameters:
l - the listener to add

removeChangeListener

void removeChangeListener(ChangeListener l)
Removes a ChangeListener from the model.

Parameters:
l - the listener to remove

Java™ Platform
Standard Ed. 6

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