Java Reference
In-Depth Information
8.
Java provides two listener interfaces, MouseListener and MouseMotionListener ,
to handle mouse events. Java implements the MouseListener interface to listen
for such actions as mouse pressed, released, clicked, entered, or exited, and the
MouseMotionListener interface to listen for such actions as mouse dragged or
moved.
9. A KeyEvent is fired when a key is pressed, released, or typed. The key value and key
character can be obtained from the key-event object.
10. A listener's keyPressed handler is invoked when a key is pressed, its
keyReleased handler is invoked when a key is released, and its keyTyped handler
is invoked when a Unicode character key is entered. If a key does not have a Unicode
(e.g., function keys, modifier keys, action keys, and control keys), a listener's
keyTyped handler will be not be invoked.
11. You can use the Timer class to control Java animations. A timer fires an ActionEvent
at a fixed rate. The listener updates the painting to simulate an animation.
T EST Q UESTIONS
Do the test questions for this chapter online at www.cs.armstrong.edu/liang/intro9e/test.html .
P ROGRAMMING E XERCISES
Sections 16.2-16.7
*16.1 ( Pick four cards ) Write a program that lets the user click the Refresh button to dis-
play four cards from a deck of 52 cards, as shown in Figure 16.21a. ( Hint : See
Listing 6.2 on how to draw four cards randomly.)
(b)
F IGURE 16.21 (a) Exercise 16.1 displays four cards randomly. (b) Exercise 16.3 uses the buttons to move the ball.
(c) Exercise 16.4 performs addition, subtraction, multiplication, and division on double numbers.
(a)
(c)
16.2
( Find which button has been clicked on the console ) Add the code to Programming
Exercise 12.1 that will display a message on the console indicating which button
has been clicked.
*16.3
( Move the ball ) Write a program that moves the ball in a panel. You should define
a panel class for displaying the ball and provide the methods for moving the ball
left, right, up, and down, as shown in Figure 16.21b. Check the boundary to prevent
the ball from moving out of sight completely.
*16.4
( Create a simple calculator ) Write a program to perform addition, subtraction,
multiplication, and division, as shown in Figure 16.21c.
 
 
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