Class RandomGeneratorFactory<T extends RandomGenerator>
java.lang.Object
java.util.random.RandomGeneratorFactory<T>
public final class RandomGeneratorFactory<T extends RandomGenerator> extends Object
This is a factory class for generating multiple random number generators of a specific algorithm.
RandomGeneratorFactory
also provides methods for selecting random number generator algorithms. A specific RandomGeneratorFactory
can be located by using the of(String)
method, where the argument string is the name of the algorithm required. The method all()
produces a non-empty Stream
of all available RandomGeneratorFactorys
that can be searched to locate a RandomGeneratorFactory
suitable to the task. There are three methods for constructing a RandomGenerator instance, depending on the type of initial seed required. create(long)
is used for long seed construction, create(byte[])
is used for byte[] seed construction, and create()
is used for random seed construction. Example;
RandomGeneratorFactory<RandomGenerator> factory = RandomGeneratorFactory.of("Random");
for (int i = 0; i < 10; i++) {
new Thread(() -> {
RandomGenerator random = factory.create(100L);
System.out.println(random.nextDouble());
}).start();
}
RandomGeneratorFactory also provides methods describing the attributes (or properties) of a generator and can be used to select random number generator algorithms. These methods are typically used in conjunction with all()
. In this example, the code locates the RandomGeneratorFactory
that produces RandomGenerators
with the highest number of state bits.
RandomGeneratorFactory<RandomGenerator> best = RandomGeneratorFactory.all()
.sorted(Comparator.comparingInt(RandomGenerator::stateBits).reversed())
.findFirst()
.orElse(RandomGeneratorFactory.of("Random"));
System.out.println(best.name() + " in " + best.group() + " was selected");
RandomGenerator rng = best.create();
System.out.println(rng.nextLong());
- Since:
- 17
- See Also:
Method Summary
Modifier and Type | Method | Description |
---|---|---|
static Stream<RandomGeneratorFactory<RandomGenerator>> |
all() |
Returns a non-empty stream of available RandomGeneratorFactory(s) . |
T |
create() |
Create an instance of RandomGenerator based on algorithm chosen. |
T |
create |
Create an instance of RandomGenerator based on algorithm chosen providing a starting byte[] seed. |
T |
create |
Create an instance of RandomGenerator based on algorithm chosen providing a starting long seed. |
int |
equidistribution() |
Returns the equidistribution of the algorithm. |
static RandomGeneratorFactory<RandomGenerator> |
getDefault() |
Returns a RandomGeneratorFactory meeting the minimal requirement of having an algorithm whose state bits are greater than or equal 64. |
String |
group() |
Return the group name of the algorithm used by the random number generator. |
boolean |
isArbitrarilyJumpable() |
Return true if random generator can jump an arbitrarily specified distant point in the state cycle. |
boolean |
isDeprecated() |
Return true if the implementation of RandomGenerator (algorithm) has been marked for deprecation. |
boolean |
isHardware() |
Return true if random generator uses a hardware device (HRNG) to produce entropic input. |
boolean |
isJumpable() |
Return true if random generator can jump a specified distant point in the state cycle. |
boolean |
isLeapable() |
Return true if random generator is jumpable and can leap to a very distant point in the state cycle. |
boolean |
isSplittable() |
Return true if random generator can be cloned into a separate object with the same properties but positioned further in the state cycle. |
boolean |
isStatistical() |
Return true if random generator is computed using an arithmetic algorithm and is statistically deterministic. |
boolean |
isStochastic() |
Return true if random generator is computed using external or entropic sources as inputs. |
boolean |
isStreamable() |
Return true if random generator can be used to create Streams of random numbers. |
String |
name() |
Return the name of the algorithm used by the random number generator. |
static <T extends RandomGenerator> |
of |
Returns a RandomGeneratorFactory that can produce instances of RandomGenerator that utilize the name algorithm. |
BigInteger |
period() |
Return the period of the algorithm used by the random number generator. |
int |
stateBits() |
Returns number of bits used by the algorithm to maintain state of seed. |
Method Details
of
public static <T extends RandomGenerator> RandomGeneratorFactory<T> of(String name)
Returns a
RandomGeneratorFactory
that can produce instances of RandomGenerator
that utilize the name
algorithm.- Implementation Requirements:
- Availability is determined by RandomGeneratorFactory using the service provider API to locate implementations of the RandomGenerator interface.
- Type Parameters:
-
T
- Sub-interface ofRandomGenerator
to produce - Parameters:
-
name
- Name of random number generator algorithm - Returns:
-
RandomGeneratorFactory
ofRandomGenerator
- Throws:
-
NullPointerException
- if name is null -
IllegalArgumentException
- if the named algorithm is not found
getDefault
public static RandomGeneratorFactory<RandomGenerator> getDefault()
Returns a
RandomGeneratorFactory
meeting the minimal requirement of having an algorithm whose state bits are greater than or equal 64.- Implementation Requirements:
- Since algorithms will improve over time, there is no guarantee that this method will return the same algorithm over time.
- Returns:
- a
RandomGeneratorFactory
all
public static Stream<RandomGeneratorFactory<RandomGenerator>> all()
Returns a non-empty stream of available
RandomGeneratorFactory(s)
. RandomGenerators that are marked as deprecated are not included in the result.- Implementation Requirements:
- Availability is determined by RandomGeneratorFactory using the service provider API to locate implementations of the RandomGenerator interface.
- Returns:
- a non-empty stream of all available
RandomGeneratorFactory(s)
.
name
public String name()
Return the name of the algorithm used by the random number generator.
- Returns:
- Name of the algorithm.
group
public String group()
Return the group name of the algorithm used by the random number generator.
- Returns:
- Group name of the algorithm.
stateBits
public int stateBits()
Returns number of bits used by the algorithm to maintain state of seed.
- Returns:
- number of bits used by the algorithm to maintain state of seed.
equidistribution
public int equidistribution()
Returns the equidistribution of the algorithm.
- Returns:
- the equidistribution of the algorithm.
period
public BigInteger period()
Return the period of the algorithm used by the random number generator. Returns BigInteger.ZERO if period is not determinable.
- Returns:
- BigInteger period.
isStatistical
public boolean isStatistical()
Return true if random generator is computed using an arithmetic algorithm and is statistically deterministic.
- Returns:
- true if random generator is statistical.
isStochastic
public boolean isStochastic()
Return true if random generator is computed using external or entropic sources as inputs.
- Returns:
- true if random generator is stochastic.
isHardware
public boolean isHardware()
Return true if random generator uses a hardware device (HRNG) to produce entropic input.
- Returns:
- true if random generator is generated by hardware.
isArbitrarilyJumpable
public boolean isArbitrarilyJumpable()
Return true if random generator can jump an arbitrarily specified distant point in the state cycle.
- Returns:
- true if random generator is arbitrarily jumpable.
isJumpable
public boolean isJumpable()
Return true if random generator can jump a specified distant point in the state cycle.
- Returns:
- true if random generator is jumpable.
isLeapable
public boolean isLeapable()
Return true if random generator is jumpable and can leap to a very distant point in the state cycle.
- Returns:
- true if random generator is leapable.
isSplittable
public boolean isSplittable()
Return true if random generator can be cloned into a separate object with the same properties but positioned further in the state cycle.
- Returns:
- true if random generator is splittable.
isStreamable
public boolean isStreamable()
Return true if random generator can be used to create
Streams
of random numbers.- Returns:
- true if random generator is streamable.
isDeprecated
public boolean isDeprecated()
Return true if the implementation of RandomGenerator (algorithm) has been marked for deprecation.
- Implementation Note:
- Random number generator algorithms evolve over time; new algorithms will be introduced and old algorithms will lose standing. If an older algorithm is deemed unsuitable for continued use, it will be marked as deprecated to indicate that it may be removed at some point in the future.
- Returns:
- true if the implementation of RandomGenerator (algorithm) has been marked for deprecation
create
public T create()
Create an instance of
RandomGenerator
based on algorithm chosen.- Returns:
- new in instance of
RandomGenerator
.
create
public T create(long seed)
Create an instance of
RandomGenerator
based on algorithm chosen providing a starting long seed. If long seed is not supported by an algorithm then the no argument form of create is used.- Parameters:
-
seed
- long random seed value. - Returns:
- new in instance of
RandomGenerator
.
create
public T create(byte[] seed)
Create an instance of
RandomGenerator
based on algorithm chosen providing a starting byte[] seed. If byte[] seed is not supported by an algorithm then the no argument form of create is used.- Parameters:
-
seed
- byte array random seed value. - Returns:
- new in instance of
RandomGenerator
. - Throws:
-
NullPointerException
- if seed is null.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/random/RandomGeneratorFactory.html