Answers to Self-Review Questions - Java Software Solutions: Foundations of Program Design - page 783

SR 11.20 A mnemonic is a character that can be used to activate a control

such as a button as if the user had used to mouse to do so. The user
activates a mnemonic by holding down the ALT key and pressing the
appropriate character.

SR 11.21 A component should be disabled if it is not a viable option for the user

at a given time. Not only does this prevent user error, but also it helps
clarify what the current valid actions are.

SR 11.22 The class(es), and the line(s) of code from the class(es), that provide

the listed functionality are:

a. LightBulb − panel.setBackground (Color.black)
b. LightBulbControls - offButton.setToolTipText ( " Turn it
off!")
c. LightBulbControls - onButton.setMnemonic ('n')
OffListener - onButton.setEnabled (true)
d. OnListener - onButton.setEnabled (false)
e. LightBulbPanel − on = true

11.8 Combo Boxes
SR 11.23

A combo box is a component that allows the user to choose from a
set of options in a pull-down list. An editable combo box also allows
the user to enter a specific value.

SR 11.24 The JukeBox program ensures that it doesn't try to play a song associ-

ated with the "Make a Selection. . ." combo box option by setting
the corresponding entry in the music array to null .

SR 11.25 There are two action listeners defined in the JukeBox program. The

ComboListener listens for a mouseclick on the combo box selection
list. The ButtonListener listens for a mouseclick on one of the two
buttons (play and stop).

SR 11.26 The JukeBox program associates the combo box selection made by the

user with a specific audio clip by storing the audio clips in an array
music ; storing the descriptions of the music, in the same order, in an
array musicNames ; generating the combo box used to make music selec-
tions based on the array musicNames ; and using the index returned from
a combo box selection to set the current audio clip from the music array.

11.9 Scroll Panes
SR 11.27

A scroll pane can have a vertical scroll bar on the right side and/or a hor-
izontal scroll bar along the bottom. The programmer can determine, in