Java Reference
In-Depth Information
and Fields
;
for now, you can take my word that it simply creates an instance of the given sub-
class, which we store in a
Plotter
reference named “r” and use to draw the plot:
plotter/PlotDriver.java
public
public class
class
PlotDriver
PlotDriver
{
/** Construct a Plotter driver, and try it out. */
public
public static
void
main
(
String
[]
argv
) {
Plotter r
;
iif
(
argv
.
length
!=
1
) {
System
.
err
.
println
(
"Usage: PlotDriver driverclass"
);
return
static
void
return
;
}
try
try
{
Class
<?>
c
=
Class
.
forName
(
argv
[
0
]);
Object o
=
c
.
newInstance
();
iif
(!(
o
instanceof
instanceof
Plotter
))
throw
new
ClassNotFoundException
(
"Not instanceof Plotter"
);
r
= (
Plotter
)
o
;
}
catch
throw new
catch
(
ClassNotFoundException e
) {
System
.
err
.
println
(
"Sorry, class "
+
argv
[
0
] +
" not a plotter class"
);
return
;
}
catch
return
catch
(
Exception e
) {
e
.
printStackTrace
();
return
return
;
}
r
.
penDown
();
r
.
penColor
(
1
);
r
.
moveTo
(
200
,
200
);
r
.
penColor
(
2
);
r
.
drawBox
(
123
,
200
);
r
.
rmoveTo
(
10
,
20
);
r
.
penColor
(
3
);
r
.
drawBox
(
123
,
200
);
r
.
penUp
();
r
.
moveTo
(
300
,
100
);
r
.
penDown
();
r
.
setFont
(
"Helvetica"
,
14
);
r
.
drawString
(
"Hello World"
);
r
.
penColor
(
4
);
r
.
drawBox
(
10
,
10
);
}
}
