Java Reference
In-Depth Information
Math.random()
generates a different sequence each time an application starts run-
ning.
Tip
Random(long seed)
gives you the opportunity to reuse the same seed
value,allowingthesamesequenceofrandomnumberstobegenerated.Youwillfind
thiscapabilityusefulwhendebuggingafaultyapplicationthatinvolvesrandomnum-
bers.
Random(long seed)
callsthe
void setSeed(long seed)
methodtoset
theseedtothespecifiedvalue.Ifyoucall
setSeed()
afterinstantiating
Random
,the
random number generator is reset to the state that it was in immediately after calling
Random(long seed)
.
The previous code fragment demonstrates
Random
's
double nextDouble()
method, which returns the next pseudorandom, uniformly distributed double precision
floating-point value between 0.0 and 1.0 in this random number generator's sequence.
Random
also declares the following methods for returning other kinds of values:
•
boolean nextBoolean()
returnsthenextpseudorandom,uniformlydis-
tributedBooleanvalueinthisrandomnumbergenerator'ssequence.Valuestrue
and false are generated with (approximately) equal probability.
•
void nextBytes(byte[] bytes)
generatespseudorandombyteinteger
values and stores them in the
bytes
array. The number of generated bytes is
equal to the length of the
bytes
array.
•
float nextFloat()
returnsthenextpseudorandom,uniformlydistributed
floating-pointvaluebetween0.0and1.0inthisrandomnumbergenerator'sse-
quence.
•
double nextGaussian()
returnsthenextpseudorandom,Gaussian(“nor-
mally”) distributed double precision floating-point value with mean 0.0 and
standard deviation 1.0 in this random number generator's sequence.
•
int nextInt()
returns the next pseudorandom, uniformly distributed in-
tegervalueinthisrandomnumbergenerator'ssequence.All2
32
possibleinteger
values are generated with (approximately) equal probability.
•
int nextInt(int n)
returns a pseudorandom, uniformly distributed in-
teger value between 0 (inclusive) and the specified value (exclusive), drawn
from this random number generator's sequence. All
n
possible integer values
are generated with (approximately) equal probability.