Java compact1, compact2, compact3 java.util.concurrent Class ThreadLocalRandom（JDK8）

Method Detail

• current

  public static ThreadLocalRandom current()

  Returns the current thread's ThreadLocalRandom.

  Returns:

  the current thread's ThreadLocalRandom

• setSeed

  public void setSeed(long seed)

  Throws UnsupportedOperationException. Setting seeds in this generator is not supported.

  Overrides:

  setSeed in class Random

  Parameters:

  seed - the initial seed

  Throws:

  UnsupportedOperationException - always

• next

  protected int next(int bits)

  Description copied from class: Random
  Generates the next pseudorandom number. Subclasses should override this, as this is used by all other methods.

  The general contract of next is that it returns an int value and if the argument bits is between 1 and 32 (inclusive), then that many low-order bits of the returned value will be (approximately) independently chosen bit values, each of which is (approximately) equally likely to be 0 or 1. The method next is implemented by class Random by atomically updating the seed to

   (seed * 0x5DEECE66DL + 0xBL) & ((1L << 48) - 1)

  and returning

   (int)(seed >>> (48 - bits)).

  This is a linear congruential pseudorandom number generator, as defined by D. H. Lehmer and described by Donald E. Knuth in The Art of Computer Programming, Volume 3: Seminumerical Algorithms, section 3.2.1.

  Overrides:

  next in class Random

  Parameters:

  bits - random bits

  Returns:

  the next pseudorandom value from this random number generator's sequence

• nextInt

  public int nextInt()

  Returns a pseudorandom int value.

  Overrides:

  nextInt in class Random

  Returns:

  a pseudorandom int value

• nextInt

  public int nextInt(int bound)

  Returns a pseudorandom int value between zero (inclusive) and the specified bound (exclusive).

  Overrides:

  nextInt in class Random

  Parameters:

  bound - the upper bound (exclusive). Must be positive.

  Returns:

  a pseudorandom int value between zero (inclusive) and the bound (exclusive)

  Throws:

  IllegalArgumentException - if bound is not positive

• nextInt

  public int nextInt(int origin,
                     int bound)

  Returns a pseudorandom int value between the specified origin (inclusive) and the specified bound (exclusive).

  Parameters:

  origin - the least value returned

  bound - the upper bound (exclusive)

  Returns:

  a pseudorandom int value between the origin (inclusive) and the bound (exclusive)

  Throws:

  IllegalArgumentException - if origin is greater than or equal to bound

• nextLong

  public long nextLong()

  Returns a pseudorandom long value.

  Overrides:

  nextLong in class Random

  Returns:

  a pseudorandom long value

• nextLong

  public long nextLong(long bound)

  Returns a pseudorandom long value between zero (inclusive) and the specified bound (exclusive).

  Parameters:

  bound - the upper bound (exclusive). Must be positive.

  Returns:

  a pseudorandom long value between zero (inclusive) and the bound (exclusive)

  Throws:

  IllegalArgumentException - if bound is not positive

• nextLong

  public long nextLong(long origin,
                       long bound)

  Returns a pseudorandom long value between the specified origin (inclusive) and the specified bound (exclusive).

  Parameters:

  origin - the least value returned

  bound - the upper bound (exclusive)

  Returns:

  a pseudorandom long value between the origin (inclusive) and the bound (exclusive)

  Throws:

  IllegalArgumentException - if origin is greater than or equal to bound

• nextDouble

  public double nextDouble()

  Returns a pseudorandom double value between zero (inclusive) and one (exclusive).

  Overrides:

  nextDouble in class Random

  Returns:

  a pseudorandom double value between zero (inclusive) and one (exclusive)

  See Also:

  Math.random()

• nextDouble

  public double nextDouble(double bound)

  Returns a pseudorandom double value between 0.0 (inclusive) and the specified bound (exclusive).

  Parameters:

  bound - the upper bound (exclusive). Must be positive.

  Returns:

  a pseudorandom double value between zero (inclusive) and the bound (exclusive)

  Throws:

  IllegalArgumentException - if bound is not positive

• nextDouble

  public double nextDouble(double origin,
                           double bound)

  Returns a pseudorandom double value between the specified origin (inclusive) and bound (exclusive).

  Parameters:

  origin - the least value returned

  bound - the upper bound (exclusive)

  Returns:

  a pseudorandom double value between the origin (inclusive) and the bound (exclusive)

  Throws:

  IllegalArgumentException - if origin is greater than or equal to bound

• nextBoolean

  public boolean nextBoolean()

  Returns a pseudorandom boolean value.

  Overrides:

  nextBoolean in class Random

  Returns:

  a pseudorandom boolean value

• nextFloat

  public float nextFloat()

  Returns a pseudorandom float value between zero (inclusive) and one (exclusive).

  Overrides:

  nextFloat in class Random

  Returns:

  a pseudorandom float value between zero (inclusive) and one (exclusive)

• nextGaussian

  public double nextGaussian()

  Description copied from class: Random
  Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.

  The general contract of nextGaussian is that one double value, chosen from (approximately) the usual normal distribution with mean 0.0 and standard deviation 1.0, is pseudorandomly generated and returned.

  The method nextGaussian is implemented by class Random as if by a threadsafe version of the following:

   
   private double nextNextGaussian;
   private boolean haveNextNextGaussian = false;
  
   public double nextGaussian() {
     if (haveNextNextGaussian) {
       haveNextNextGaussian = false;
       return nextNextGaussian;
     } else {
       double v1, v2, s;
       do {
         v1 = 2 * nextDouble() - 1;   // between -1.0 and 1.0
         v2 = 2 * nextDouble() - 1;   // between -1.0 and 1.0
         s = v1 * v1 + v2 * v2;
       } while (s >= 1 || s == 0);
       double multiplier = StrictMath.sqrt(-2 * StrictMath.log(s)/s);
       nextNextGaussian = v2 * multiplier;
       haveNextNextGaussian = true;
       return v1 * multiplier;
     }
   }

  This uses the polar method of G. E. P. Box, M. E. Muller, and G. Marsaglia, as described by Donald E. Knuth in The Art of Computer Programming, Volume 3: Seminumerical Algorithms, section 3.4.1, subsection C, algorithm P. Note that it generates two independent values at the cost of only one call to StrictMath.log and one call to StrictMath.sqrt.

  Overrides:

  nextGaussian in class Random

  Returns:

  the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence

• ints

  public IntStream ints(long streamSize)

  Returns a stream producing the given streamSize number of pseudorandom int values.

  Overrides:

  ints in class Random

  Parameters:

  streamSize - the number of values to generate

  Returns:

  a stream of pseudorandom int values

  Throws:

  IllegalArgumentException - if streamSize is less than zero

  Since:

  1.8

• ints

  public IntStream ints()

  Returns an effectively unlimited stream of pseudorandom int values.

  Overrides:

  ints in class Random

  Implementation Note:

  This method is implemented to be equivalent to ints(Long.MAX_VALUE).

  Returns:

  a stream of pseudorandom int values

  Since:

  1.8

• ints

  public IntStream ints(long streamSize,
                        int randomNumberOrigin,
                        int randomNumberBound)

  Returns a stream producing the given streamSize number of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

  Overrides:

  ints in class Random

  Parameters:

  streamSize - the number of values to generate

  randomNumberOrigin - the origin (inclusive) of each random value

  randomNumberBound - the bound (exclusive) of each random value

  Returns:

  a stream of pseudorandom int values, each with the given origin (inclusive) and bound (exclusive)

  Throws:

  IllegalArgumentException - if streamSize is less than zero, or randomNumberOrigin is greater than or equal to randomNumberBound

  Since:

  1.8

• ints

  public IntStream ints(int randomNumberOrigin,
                        int randomNumberBound)

  Returns an effectively unlimited stream of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

  Overrides:

  ints in class Random

  Implementation Note:

  This method is implemented to be equivalent to ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound).

  Parameters:

  randomNumberOrigin - the origin (inclusive) of each random value

  randomNumberBound - the bound (exclusive) of each random value

  Returns:

  a stream of pseudorandom int values, each with the given origin (inclusive) and bound (exclusive)

  Throws:

  IllegalArgumentException - if randomNumberOrigin is greater than or equal to randomNumberBound

  Since:

  1.8

• longs

  public LongStream longs(long streamSize)

  Returns a stream producing the given streamSize number of pseudorandom long values.

  Overrides:

  longs in class Random

  Parameters:

  streamSize - the number of values to generate

  Returns:

  a stream of pseudorandom long values

  Throws:

  IllegalArgumentException - if streamSize is less than zero

  Since:

  1.8

• longs

  public LongStream longs()

  Returns an effectively unlimited stream of pseudorandom long values.

  Overrides:

  longs in class Random

  Implementation Note:

  This method is implemented to be equivalent to longs(Long.MAX_VALUE).

  Returns:

  a stream of pseudorandom long values

  Since:

  1.8

• longs

  public LongStream longs(long streamSize,
                          long randomNumberOrigin,
                          long randomNumberBound)

  Returns a stream producing the given streamSize number of pseudorandom long, each conforming to the given origin (inclusive) and bound (exclusive).

  Overrides:

  longs in class Random

  Parameters:

  streamSize - the number of values to generate

  randomNumberOrigin - the origin (inclusive) of each random value

  randomNumberBound - the bound (exclusive) of each random value

  Returns:

  a stream of pseudorandom long values, each with the given origin (inclusive) and bound (exclusive)

  Throws:

  IllegalArgumentException - if streamSize is less than zero, or randomNumberOrigin is greater than or equal to randomNumberBound

  Since:

  1.8

• longs

  public LongStream longs(long randomNumberOrigin,
                          long randomNumberBound)

  Returns an effectively unlimited stream of pseudorandom long values, each conforming to the given origin (inclusive) and bound (exclusive).

  Overrides:

  longs in class Random

  Implementation Note:

  This method is implemented to be equivalent to longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound).

  Parameters:

  randomNumberOrigin - the origin (inclusive) of each random value

  randomNumberBound - the bound (exclusive) of each random value

  Returns:

  a stream of pseudorandom long values, each with the given origin (inclusive) and bound (exclusive)

  Throws:

  IllegalArgumentException - if randomNumberOrigin is greater than or equal to randomNumberBound

  Since:

  1.8

• doubles

  public DoubleStream doubles(long streamSize)

  Returns a stream producing the given streamSize number of pseudorandom double values, each between zero (inclusive) and one (exclusive).

  Overrides:

  doubles in class Random

  Parameters:

  streamSize - the number of values to generate

  Returns:

  a stream of double values

  Throws:

  IllegalArgumentException - if streamSize is less than zero

  Since:

  1.8

• doubles

  public DoubleStream doubles()

  Returns an effectively unlimited stream of pseudorandom double values, each between zero (inclusive) and one (exclusive).

  Overrides:

  doubles in class Random

  Implementation Note:

  This method is implemented to be equivalent to doubles(Long.MAX_VALUE).

  Returns:

  a stream of pseudorandom double values

  Since:

  1.8

• doubles

  public DoubleStream doubles(long streamSize,
                              double randomNumberOrigin,
                              double randomNumberBound)

  Returns a stream producing the given streamSize number of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

  Overrides:

  doubles in class Random

  Parameters:

  streamSize - the number of values to generate

  randomNumberOrigin - the origin (inclusive) of each random value

  randomNumberBound - the bound (exclusive) of each random value

  Returns:

  a stream of pseudorandom double values, each with the given origin (inclusive) and bound (exclusive)

  Throws:

  IllegalArgumentException - if streamSize is less than zero

  IllegalArgumentException - if randomNumberOrigin is greater than or equal to randomNumberBound

  Since:

  1.8

• doubles

  public DoubleStream doubles(double randomNumberOrigin,
                              double randomNumberBound)

  Returns an effectively unlimited stream of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

  Overrides:

  doubles in class Random

  Implementation Note:

  This method is implemented to be equivalent to doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound).

  Parameters:

  randomNumberOrigin - the origin (inclusive) of each random value

  randomNumberBound - the bound (exclusive) of each random value

  Returns:

  a stream of pseudorandom double values, each with the given origin (inclusive) and bound (exclusive)

  Throws:

  IllegalArgumentException - if randomNumberOrigin is greater than or equal to randomNumberBound

  Since:

  1.8