Java Reference
In-Depth Information
Math.abs(
-2
)
returns
2
Math.abs(
-2.1
)
returns
2.1
5.10.5 The
random
Method
You have used the
random()
method to generate a random
double
value greater than or
equal to
0.0
and less than
1.0
(
0 <= Math.random() < 1.0
). This method is very useful.
You can use it to write a simple expression to generate random numbers in any range. For
example,
Returns a random integer
between
0
and
9
(
int
) (
Math.random
( ) *
10
)
Returns a random integer
between
50
and
99
50
+ (
int
) (
Math.random
( ) *
50
)
In general,
Returns a random number between
a
and
a + b,
excluding
a + b
a +
Math.random
( ) *
b
Tip
You can view the complete documentation for the
Math
class online at
download
.oracle.com/javase/7/docs/api
, as shown in Figure 5.7.
Note
Not all classes need a
main
method. The
Math
class and the
JOptionPane
class do
not have
main
methods. These classes contain methods for other classes to use.
F
IGURE
5.7
You can view the documentation for the Java API online.