public class RandomGenerator
extends java.util.Random
private RandomGenerator rgen = RandomGenerator.getInstance();
By default, the RandomGenerator
object is initialized to begin
at an unpredictable point in a pseudorandom sequence. During debugging, it is
often useful to set the internal seed for the random generator explicitly so
that it always returns the same sequence. To do so, you need to invoke the
setSeed
method.
The RandomGenerator
object returned by getInstance
is shared across all classes in an application. Using this shared instance of
the generator is preferable to allocating new instances of
RandomGenerator
. If you create several random generators in
succession, they will typically generate the same sequence of values.
Constructor and Description |
---|
RandomGenerator()
Creates a new random generator.
|
Modifier and Type | Method and Description |
---|---|
static RandomGenerator |
getInstance()
Returns a
RandomGenerator instance that can be shared among
several classes. |
boolean |
nextBoolean()
Returns a random
boolean value that is true or
false with equal probability. |
boolean |
nextBoolean(double p)
Returns a random
boolean value with the specified probability. |
java.awt.Color |
nextColor()
Returns a random opaque color whose components are chosen uniformly in the
0-255 range.
|
double |
nextDouble(double low,
double high)
Returns the next random real number in the specified range.
|
int |
nextInt(int n)
Returns the next random integer between 0 and
n -1, inclusive. |
int |
nextInt(int low,
int high)
Returns the next random integer in the specified range.
|
public RandomGenerator()
getInstance
to obtain a
RandomGenerator
object that is shared by all classes in the
application.public int nextInt(int n)
n
-1, inclusive.
This method is in modern implementations of the Random
class,
but is missing from JDK 1.1.nextInt
in class java.util.Random
public boolean nextBoolean()
boolean
value that is true
or
false
with equal probability. This method is in modern
implementations of the Random
class, but is missing from JDK
1.1.nextBoolean
in class java.util.Random
public int nextInt(int low, int high)
rgen.nextInt(1, 6);
or a random decimal digit by calling
rgen.nextInt(0, 9);
low
- The low end of the rangehigh
- The high end of the rangeint
between low
and
high
, inclusivepublic double nextDouble(double low, double high)
low
but always strictly less than
high
. You can use this method to generate continuous random
values. For example, you can set the variables x
and
y
to specify a random point inside the unit square as follows:
double x = rgen.nextDouble(0.0, 1.0);
double y = rgen.nextDouble(0.0, 1.0);
low
- The low end of the rangehigh
- The high end of the rangedouble
value d in the range
low
≤ d < high
public boolean nextBoolean(double p)
boolean
value with the specified probability.
You can use this method to simulate an event that occurs with a particular
probability. For example, you could simulate the result of tossing a coin
like this:
String coinFlip = rgen.nextBoolean(0.5) ? "HEADS" : "TAILS";
p
- A value between 0 (impossible) and 1 (certain) indicating the
probabilitytrue
with probability p
public java.awt.Color nextColor()
Color
public static RandomGenerator getInstance()
RandomGenerator
instance that can be shared among
several classes.RandomGenerator
object