public class RandomGenerator extends 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. |
Paint |
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.
|
float |
nextFloat(float high)
Returns the next float number between 0 and the given maximum.
|
float |
nextFloat(float low,
float high)
Returns the next float number between the given minimum and maximum.
|
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.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 Random
boolean
value from this random number generator's
sequencepublic 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 float nextFloat(float high)
public float nextFloat(float low, float high)
public 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 Paint nextColor()
Color
public static RandomGenerator getInstance()
RandomGenerator
instance that can
be shared among several classes.RandomGenerator
object