Java Reference
In-Depth Information
•s e
•
if
statement (selection)
•
while
statement (repetition)
and that these can be combined in only two ways—
stacking
and
nesting
. Indeed, structured
programming is the essence of simplicity.
Rectangles and Ovals
This section demonstrates drawing rectangles and ovals, using the
Graphics
methods
drawRect
and
drawOval
, respectively. These methods are demonstrated in Fig. 5.27.
1
// Fig. 5.27: Shapes.java
2
// Drawing a cascade of shapes based on the user's choice.
3
import
java.awt.Graphics;
4
import
javax.swing.JPanel;
5
6
public
class
Shapes
extends
JPanel
7
{
8
private
int
choice;
// user's choice of which shape to draw
9
10
// constructor sets the user's choice
11
public
Shapes(
int
userChoice)
12
{
13
choice = userChoice;
14
}
15
16
// draws a cascade of shapes starting from the top-left corner
17
public
void
paintComponent(Graphics g)
18
{
19
super
.paintComponent(g);
20
21
for
(
int
i =
0
; i <
10
; i++)
22
{
23
// pick the shape based on the user's choice
24
switch
(choice)
25
{
26
case
1
:
// draw rectangles
27
g.drawRect(
10
+ i *
10
,
10
+ i *
10
,
50
+ i *
10
,
50
+ i *
10
);
28
29
break
;
30
case
2
:
// draw ovals
31
g.drawOval(
10
+ i *
10
,
10
+ i *
10
,
50
+ i *
10
,
50
+ i *
10
);
32
33
break
;
34
}
35
}
36
}
37
}
// end class Shapes
Fig. 5.27
|
Drawing a cascade of shapes based on the user's choice.