ButtonModel (Java SE 9 & JDK 9 )
Keywords: javax.swing.ButtonModel interface

Module java.desktop
Package 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.

  Since:
    1.2

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `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