--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/util/Random.java Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,1227 @@
+/*
+ * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.util;
+import java.io.*;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.DoubleConsumer;
+import java.util.function.IntConsumer;
+import java.util.function.LongConsumer;
+import java.util.stream.DoubleStream;
+import java.util.stream.IntStream;
+import java.util.stream.LongStream;
+import java.util.stream.StreamSupport;
+
+import jdk.internal.misc.Unsafe;
+
+/**
+ * An instance of this class is used to generate a stream of
+ * pseudorandom numbers. The class uses a 48-bit seed, which is
+ * modified using a linear congruential formula. (See Donald Knuth,
+ * <i>The Art of Computer Programming, Volume 2</i>, Section 3.2.1.)
+ * <p>
+ * If two instances of {@code Random} are created with the same
+ * seed, and the same sequence of method calls is made for each, they
+ * will generate and return identical sequences of numbers. In order to
+ * guarantee this property, particular algorithms are specified for the
+ * class {@code Random}. Java implementations must use all the algorithms
+ * shown here for the class {@code Random}, for the sake of absolute
+ * portability of Java code. However, subclasses of class {@code Random}
+ * are permitted to use other algorithms, so long as they adhere to the
+ * general contracts for all the methods.
+ * <p>
+ * The algorithms implemented by class {@code Random} use a
+ * {@code protected} utility method that on each invocation can supply
+ * up to 32 pseudorandomly generated bits.
+ * <p>
+ * Many applications will find the method {@link Math#random} simpler to use.
+ *
+ * <p>Instances of {@code java.util.Random} are threadsafe.
+ * However, the concurrent use of the same {@code java.util.Random}
+ * instance across threads may encounter contention and consequent
+ * poor performance. Consider instead using
+ * {@link java.util.concurrent.ThreadLocalRandom} in multithreaded
+ * designs.
+ *
+ * <p>Instances of {@code java.util.Random} are not cryptographically
+ * secure. Consider instead using {@link java.security.SecureRandom} to
+ * get a cryptographically secure pseudo-random number generator for use
+ * by security-sensitive applications.
+ *
+ * @author Frank Yellin
+ * @since 1.0
+ */
+public
+class Random implements java.io.Serializable {
+ /** use serialVersionUID from JDK 1.1 for interoperability */
+ static final long serialVersionUID = 3905348978240129619L;
+
+ /**
+ * The internal state associated with this pseudorandom number generator.
+ * (The specs for the methods in this class describe the ongoing
+ * computation of this value.)
+ */
+ private final AtomicLong seed;
+
+ private static final long multiplier = 0x5DEECE66DL;
+ private static final long addend = 0xBL;
+ private static final long mask = (1L << 48) - 1;
+
+ private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53)
+
+ // IllegalArgumentException messages
+ static final String BadBound = "bound must be positive";
+ static final String BadRange = "bound must be greater than origin";
+ static final String BadSize = "size must be non-negative";
+
+ /**
+ * Creates a new random number generator. This constructor sets
+ * the seed of the random number generator to a value very likely
+ * to be distinct from any other invocation of this constructor.
+ */
+ public Random() {
+ this(seedUniquifier() ^ System.nanoTime());
+ }
+
+ private static long seedUniquifier() {
+ // L'Ecuyer, "Tables of Linear Congruential Generators of
+ // Different Sizes and Good Lattice Structure", 1999
+ for (;;) {
+ long current = seedUniquifier.get();
+ long next = current * 181783497276652981L;
+ if (seedUniquifier.compareAndSet(current, next))
+ return next;
+ }
+ }
+
+ private static final AtomicLong seedUniquifier
+ = new AtomicLong(8682522807148012L);
+
+ /**
+ * Creates a new random number generator using a single {@code long} seed.
+ * The seed is the initial value of the internal state of the pseudorandom
+ * number generator which is maintained by method {@link #next}.
+ *
+ * <p>The invocation {@code new Random(seed)} is equivalent to:
+ * <pre> {@code
+ * Random rnd = new Random();
+ * rnd.setSeed(seed);}</pre>
+ *
+ * @param seed the initial seed
+ * @see #setSeed(long)
+ */
+ public Random(long seed) {
+ if (getClass() == Random.class)
+ this.seed = new AtomicLong(initialScramble(seed));
+ else {
+ // subclass might have overriden setSeed
+ this.seed = new AtomicLong();
+ setSeed(seed);
+ }
+ }
+
+ private static long initialScramble(long seed) {
+ return (seed ^ multiplier) & mask;
+ }
+
+ /**
+ * Sets the seed of this random number generator using a single
+ * {@code long} seed. The general contract of {@code setSeed} is
+ * that it alters the state of this random number generator object
+ * so as to be in exactly the same state as if it had just been
+ * created with the argument {@code seed} as a seed. The method
+ * {@code setSeed} is implemented by class {@code Random} by
+ * atomically updating the seed to
+ * <pre>{@code (seed ^ 0x5DEECE66DL) & ((1L << 48) - 1)}</pre>
+ * and clearing the {@code haveNextNextGaussian} flag used by {@link
+ * #nextGaussian}.
+ *
+ * <p>The implementation of {@code setSeed} by class {@code Random}
+ * happens to use only 48 bits of the given seed. In general, however,
+ * an overriding method may use all 64 bits of the {@code long}
+ * argument as a seed value.
+ *
+ * @param seed the initial seed
+ */
+ public synchronized void setSeed(long seed) {
+ this.seed.set(initialScramble(seed));
+ haveNextNextGaussian = false;
+ }
+
+ /**
+ * Generates the next pseudorandom number. Subclasses should
+ * override this, as this is used by all other methods.
+ *
+ * <p>The general contract of {@code next} is that it returns an
+ * {@code int} value and if the argument {@code bits} is between
+ * {@code 1} and {@code 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 {@code 0} or {@code 1}. The method {@code next} is
+ * implemented by class {@code Random} by atomically updating the seed to
+ * <pre>{@code (seed * 0x5DEECE66DL + 0xBL) & ((1L << 48) - 1)}</pre>
+ * and returning
+ * <pre>{@code (int)(seed >>> (48 - bits))}.</pre>
+ *
+ * This is a linear congruential pseudorandom number generator, as
+ * defined by D. H. Lehmer and described by Donald E. Knuth in
+ * <i>The Art of Computer Programming,</i> Volume 2:
+ * <i>Seminumerical Algorithms</i>, section 3.2.1.
+ *
+ * @param bits random bits
+ * @return the next pseudorandom value from this random number
+ * generator's sequence
+ * @since 1.1
+ */
+ protected int next(int bits) {
+ long oldseed, nextseed;
+ AtomicLong seed = this.seed;
+ do {
+ oldseed = seed.get();
+ nextseed = (oldseed * multiplier + addend) & mask;
+ } while (!seed.compareAndSet(oldseed, nextseed));
+ return (int)(nextseed >>> (48 - bits));
+ }
+
+ /**
+ * Generates random bytes and places them into a user-supplied
+ * byte array. The number of random bytes produced is equal to
+ * the length of the byte array.
+ *
+ * <p>The method {@code nextBytes} is implemented by class {@code Random}
+ * as if by:
+ * <pre> {@code
+ * public void nextBytes(byte[] bytes) {
+ * for (int i = 0; i < bytes.length; )
+ * for (int rnd = nextInt(), n = Math.min(bytes.length - i, 4);
+ * n-- > 0; rnd >>= 8)
+ * bytes[i++] = (byte)rnd;
+ * }}</pre>
+ *
+ * @param bytes the byte array to fill with random bytes
+ * @throws NullPointerException if the byte array is null
+ * @since 1.1
+ */
+ public void nextBytes(byte[] bytes) {
+ for (int i = 0, len = bytes.length; i < len; )
+ for (int rnd = nextInt(),
+ n = Math.min(len - i, Integer.SIZE/Byte.SIZE);
+ n-- > 0; rnd >>= Byte.SIZE)
+ bytes[i++] = (byte)rnd;
+ }
+
+ /**
+ * The form of nextLong used by LongStream Spliterators. If
+ * origin is greater than bound, acts as unbounded form of
+ * nextLong, else as bounded form.
+ *
+ * @param origin the least value, unless greater than bound
+ * @param bound the upper bound (exclusive), must not equal origin
+ * @return a pseudorandom value
+ */
+ final long internalNextLong(long origin, long bound) {
+ long r = nextLong();
+ if (origin < bound) {
+ long n = bound - origin, m = n - 1;
+ if ((n & m) == 0L) // power of two
+ r = (r & m) + origin;
+ else if (n > 0L) { // reject over-represented candidates
+ for (long u = r >>> 1; // ensure nonnegative
+ u + m - (r = u % n) < 0L; // rejection check
+ u = nextLong() >>> 1) // retry
+ ;
+ r += origin;
+ }
+ else { // range not representable as long
+ while (r < origin || r >= bound)
+ r = nextLong();
+ }
+ }
+ return r;
+ }
+
+ /**
+ * The form of nextInt used by IntStream Spliterators.
+ * For the unbounded case: uses nextInt().
+ * For the bounded case with representable range: uses nextInt(int bound)
+ * For the bounded case with unrepresentable range: uses nextInt()
+ *
+ * @param origin the least value, unless greater than bound
+ * @param bound the upper bound (exclusive), must not equal origin
+ * @return a pseudorandom value
+ */
+ final int internalNextInt(int origin, int bound) {
+ if (origin < bound) {
+ int n = bound - origin;
+ if (n > 0) {
+ return nextInt(n) + origin;
+ }
+ else { // range not representable as int
+ int r;
+ do {
+ r = nextInt();
+ } while (r < origin || r >= bound);
+ return r;
+ }
+ }
+ else {
+ return nextInt();
+ }
+ }
+
+ /**
+ * The form of nextDouble used by DoubleStream Spliterators.
+ *
+ * @param origin the least value, unless greater than bound
+ * @param bound the upper bound (exclusive), must not equal origin
+ * @return a pseudorandom value
+ */
+ final double internalNextDouble(double origin, double bound) {
+ double r = nextDouble();
+ if (origin < bound) {
+ r = r * (bound - origin) + origin;
+ if (r >= bound) // correct for rounding
+ r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
+ }
+ return r;
+ }
+
+ /**
+ * Returns the next pseudorandom, uniformly distributed {@code int}
+ * value from this random number generator's sequence. The general
+ * contract of {@code nextInt} is that one {@code int} value is
+ * pseudorandomly generated and returned. All 2<sup>32</sup> possible
+ * {@code int} values are produced with (approximately) equal probability.
+ *
+ * <p>The method {@code nextInt} is implemented by class {@code Random}
+ * as if by:
+ * <pre> {@code
+ * public int nextInt() {
+ * return next(32);
+ * }}</pre>
+ *
+ * @return the next pseudorandom, uniformly distributed {@code int}
+ * value from this random number generator's sequence
+ */
+ public int nextInt() {
+ return next(32);
+ }
+
+ /**
+ * Returns a pseudorandom, uniformly distributed {@code int} value
+ * between 0 (inclusive) and the specified value (exclusive), drawn from
+ * this random number generator's sequence. The general contract of
+ * {@code nextInt} is that one {@code int} value in the specified range
+ * is pseudorandomly generated and returned. All {@code bound} possible
+ * {@code int} values are produced with (approximately) equal
+ * probability. The method {@code nextInt(int bound)} is implemented by
+ * class {@code Random} as if by:
+ * <pre> {@code
+ * public int nextInt(int bound) {
+ * if (bound <= 0)
+ * throw new IllegalArgumentException("bound must be positive");
+ *
+ * if ((bound & -bound) == bound) // i.e., bound is a power of 2
+ * return (int)((bound * (long)next(31)) >> 31);
+ *
+ * int bits, val;
+ * do {
+ * bits = next(31);
+ * val = bits % bound;
+ * } while (bits - val + (bound-1) < 0);
+ * return val;
+ * }}</pre>
+ *
+ * <p>The hedge "approximately" is used in the foregoing description only
+ * because the next method is only approximately an unbiased source of
+ * independently chosen bits. If it were a perfect source of randomly
+ * chosen bits, then the algorithm shown would choose {@code int}
+ * values from the stated range with perfect uniformity.
+ * <p>
+ * The algorithm is slightly tricky. It rejects values that would result
+ * in an uneven distribution (due to the fact that 2^31 is not divisible
+ * by n). The probability of a value being rejected depends on n. The
+ * worst case is n=2^30+1, for which the probability of a reject is 1/2,
+ * and the expected number of iterations before the loop terminates is 2.
+ * <p>
+ * The algorithm treats the case where n is a power of two specially: it
+ * returns the correct number of high-order bits from the underlying
+ * pseudo-random number generator. In the absence of special treatment,
+ * the correct number of <i>low-order</i> bits would be returned. Linear
+ * congruential pseudo-random number generators such as the one
+ * implemented by this class are known to have short periods in the
+ * sequence of values of their low-order bits. Thus, this special case
+ * greatly increases the length of the sequence of values returned by
+ * successive calls to this method if n is a small power of two.
+ *
+ * @param bound the upper bound (exclusive). Must be positive.
+ * @return the next pseudorandom, uniformly distributed {@code int}
+ * value between zero (inclusive) and {@code bound} (exclusive)
+ * from this random number generator's sequence
+ * @throws IllegalArgumentException if bound is not positive
+ * @since 1.2
+ */
+ public int nextInt(int bound) {
+ if (bound <= 0)
+ throw new IllegalArgumentException(BadBound);
+
+ int r = next(31);
+ int m = bound - 1;
+ if ((bound & m) == 0) // i.e., bound is a power of 2
+ r = (int)((bound * (long)r) >> 31);
+ else {
+ for (int u = r;
+ u - (r = u % bound) + m < 0;
+ u = next(31))
+ ;
+ }
+ return r;
+ }
+
+ /**
+ * Returns the next pseudorandom, uniformly distributed {@code long}
+ * value from this random number generator's sequence. The general
+ * contract of {@code nextLong} is that one {@code long} value is
+ * pseudorandomly generated and returned.
+ *
+ * <p>The method {@code nextLong} is implemented by class {@code Random}
+ * as if by:
+ * <pre> {@code
+ * public long nextLong() {
+ * return ((long)next(32) << 32) + next(32);
+ * }}</pre>
+ *
+ * Because class {@code Random} uses a seed with only 48 bits,
+ * this algorithm will not return all possible {@code long} values.
+ *
+ * @return the next pseudorandom, uniformly distributed {@code long}
+ * value from this random number generator's sequence
+ */
+ public long nextLong() {
+ // it's okay that the bottom word remains signed.
+ return ((long)(next(32)) << 32) + next(32);
+ }
+
+ /**
+ * Returns the next pseudorandom, uniformly distributed
+ * {@code boolean} value from this random number generator's
+ * sequence. The general contract of {@code nextBoolean} is that one
+ * {@code boolean} value is pseudorandomly generated and returned. The
+ * values {@code true} and {@code false} are produced with
+ * (approximately) equal probability.
+ *
+ * <p>The method {@code nextBoolean} is implemented by class {@code Random}
+ * as if by:
+ * <pre> {@code
+ * public boolean nextBoolean() {
+ * return next(1) != 0;
+ * }}</pre>
+ *
+ * @return the next pseudorandom, uniformly distributed
+ * {@code boolean} value from this random number generator's
+ * sequence
+ * @since 1.2
+ */
+ public boolean nextBoolean() {
+ return next(1) != 0;
+ }
+
+ /**
+ * Returns the next pseudorandom, uniformly distributed {@code float}
+ * value between {@code 0.0} and {@code 1.0} from this random
+ * number generator's sequence.
+ *
+ * <p>The general contract of {@code nextFloat} is that one
+ * {@code float} value, chosen (approximately) uniformly from the
+ * range {@code 0.0f} (inclusive) to {@code 1.0f} (exclusive), is
+ * pseudorandomly generated and returned. All 2<sup>24</sup> possible
+ * {@code float} values of the form <i>m x </i>2<sup>-24</sup>,
+ * where <i>m</i> is a positive integer less than 2<sup>24</sup>, are
+ * produced with (approximately) equal probability.
+ *
+ * <p>The method {@code nextFloat} is implemented by class {@code Random}
+ * as if by:
+ * <pre> {@code
+ * public float nextFloat() {
+ * return next(24) / ((float)(1 << 24));
+ * }}</pre>
+ *
+ * <p>The hedge "approximately" is used in the foregoing description only
+ * because the next method is only approximately an unbiased source of
+ * independently chosen bits. If it were a perfect source of randomly
+ * chosen bits, then the algorithm shown would choose {@code float}
+ * values from the stated range with perfect uniformity.<p>
+ * [In early versions of Java, the result was incorrectly calculated as:
+ * <pre> {@code
+ * return next(30) / ((float)(1 << 30));}</pre>
+ * This might seem to be equivalent, if not better, but in fact it
+ * introduced a slight nonuniformity because of the bias in the rounding
+ * of floating-point numbers: it was slightly more likely that the
+ * low-order bit of the significand would be 0 than that it would be 1.]
+ *
+ * @return the next pseudorandom, uniformly distributed {@code float}
+ * value between {@code 0.0} and {@code 1.0} from this
+ * random number generator's sequence
+ */
+ public float nextFloat() {
+ return next(24) / ((float)(1 << 24));
+ }
+
+ /**
+ * Returns the next pseudorandom, uniformly distributed
+ * {@code double} value between {@code 0.0} and
+ * {@code 1.0} from this random number generator's sequence.
+ *
+ * <p>The general contract of {@code nextDouble} is that one
+ * {@code double} value, chosen (approximately) uniformly from the
+ * range {@code 0.0d} (inclusive) to {@code 1.0d} (exclusive), is
+ * pseudorandomly generated and returned.
+ *
+ * <p>The method {@code nextDouble} is implemented by class {@code Random}
+ * as if by:
+ * <pre> {@code
+ * public double nextDouble() {
+ * return (((long)next(26) << 27) + next(27))
+ * / (double)(1L << 53);
+ * }}</pre>
+ *
+ * <p>The hedge "approximately" is used in the foregoing description only
+ * because the {@code next} method is only approximately an unbiased
+ * source of independently chosen bits. If it were a perfect source of
+ * randomly chosen bits, then the algorithm shown would choose
+ * {@code double} values from the stated range with perfect uniformity.
+ * <p>[In early versions of Java, the result was incorrectly calculated as:
+ * <pre> {@code
+ * return (((long)next(27) << 27) + next(27))
+ * / (double)(1L << 54);}</pre>
+ * This might seem to be equivalent, if not better, but in fact it
+ * introduced a large nonuniformity because of the bias in the rounding
+ * of floating-point numbers: it was three times as likely that the
+ * low-order bit of the significand would be 0 than that it would be 1!
+ * This nonuniformity probably doesn't matter much in practice, but we
+ * strive for perfection.]
+ *
+ * @return the next pseudorandom, uniformly distributed {@code double}
+ * value between {@code 0.0} and {@code 1.0} from this
+ * random number generator's sequence
+ * @see Math#random
+ */
+ public double nextDouble() {
+ return (((long)(next(26)) << 27) + next(27)) * DOUBLE_UNIT;
+ }
+
+ private double nextNextGaussian;
+ private boolean haveNextNextGaussian = false;
+
+ /**
+ * Returns the next pseudorandom, Gaussian ("normally") distributed
+ * {@code double} value with mean {@code 0.0} and standard
+ * deviation {@code 1.0} from this random number generator's sequence.
+ * <p>
+ * The general contract of {@code nextGaussian} is that one
+ * {@code double} value, chosen from (approximately) the usual
+ * normal distribution with mean {@code 0.0} and standard deviation
+ * {@code 1.0}, is pseudorandomly generated and returned.
+ *
+ * <p>The method {@code nextGaussian} is implemented by class
+ * {@code Random} as if by a threadsafe version of the following:
+ * <pre> {@code
+ * 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;
+ * }
+ * }}</pre>
+ * This uses the <i>polar method</i> of G. E. P. Box, M. E. Muller, and
+ * G. Marsaglia, as described by Donald E. Knuth in <i>The Art of
+ * Computer Programming</i>, Volume 2: <i>Seminumerical Algorithms</i>,
+ * section 3.4.1, subsection C, algorithm P. Note that it generates two
+ * independent values at the cost of only one call to {@code StrictMath.log}
+ * and one call to {@code StrictMath.sqrt}.
+ *
+ * @return the next pseudorandom, Gaussian ("normally") distributed
+ * {@code double} value with mean {@code 0.0} and
+ * standard deviation {@code 1.0} from this random number
+ * generator's sequence
+ */
+ public synchronized double nextGaussian() {
+ // See Knuth, ACP, Section 3.4.1 Algorithm C.
+ if (haveNextNextGaussian) {
+ haveNextNextGaussian = false;
+ return nextNextGaussian;
+ } else {
+ double v1, v2, s;
+ do {
+ v1 = 2 * nextDouble() - 1; // between -1 and 1
+ v2 = 2 * nextDouble() - 1; // between -1 and 1
+ 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;
+ }
+ }
+
+ // stream methods, coded in a way intended to better isolate for
+ // maintenance purposes the small differences across forms.
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number of
+ * pseudorandom {@code int} values.
+ *
+ * <p>A pseudorandom {@code int} value is generated as if it's the result of
+ * calling the method {@link #nextInt()}.
+ *
+ * @param streamSize the number of values to generate
+ * @return a stream of pseudorandom {@code int} values
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero
+ * @since 1.8
+ */
+ public IntStream ints(long streamSize) {
+ if (streamSize < 0L)
+ throw new IllegalArgumentException(BadSize);
+ return StreamSupport.intStream
+ (new RandomIntsSpliterator
+ (this, 0L, streamSize, Integer.MAX_VALUE, 0),
+ false);
+ }
+
+ /**
+ * Returns an effectively unlimited stream of pseudorandom {@code int}
+ * values.
+ *
+ * <p>A pseudorandom {@code int} value is generated as if it's the result of
+ * calling the method {@link #nextInt()}.
+ *
+ * @implNote This method is implemented to be equivalent to {@code
+ * ints(Long.MAX_VALUE)}.
+ *
+ * @return a stream of pseudorandom {@code int} values
+ * @since 1.8
+ */
+ public IntStream ints() {
+ return StreamSupport.intStream
+ (new RandomIntsSpliterator
+ (this, 0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0),
+ false);
+ }
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number
+ * of pseudorandom {@code int} values, each conforming to the given
+ * origin (inclusive) and bound (exclusive).
+ *
+ * <p>A pseudorandom {@code int} value is generated as if it's the result of
+ * calling the following method with the origin and bound:
+ * <pre> {@code
+ * int nextInt(int origin, int bound) {
+ * int n = bound - origin;
+ * if (n > 0) {
+ * return nextInt(n) + origin;
+ * }
+ * else { // range not representable as int
+ * int r;
+ * do {
+ * r = nextInt();
+ * } while (r < origin || r >= bound);
+ * return r;
+ * }
+ * }}</pre>
+ *
+ * @param streamSize the number of values to generate
+ * @param randomNumberOrigin the origin (inclusive) of each random value
+ * @param randomNumberBound the bound (exclusive) of each random value
+ * @return a stream of pseudorandom {@code int} values,
+ * each with the given origin (inclusive) and bound (exclusive)
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero, or {@code randomNumberOrigin}
+ * is greater than or equal to {@code randomNumberBound}
+ * @since 1.8
+ */
+ public IntStream ints(long streamSize, int randomNumberOrigin,
+ int randomNumberBound) {
+ if (streamSize < 0L)
+ throw new IllegalArgumentException(BadSize);
+ if (randomNumberOrigin >= randomNumberBound)
+ throw new IllegalArgumentException(BadRange);
+ return StreamSupport.intStream
+ (new RandomIntsSpliterator
+ (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
+ false);
+ }
+
+ /**
+ * Returns an effectively unlimited stream of pseudorandom {@code
+ * int} values, each conforming to the given origin (inclusive) and bound
+ * (exclusive).
+ *
+ * <p>A pseudorandom {@code int} value is generated as if it's the result of
+ * calling the following method with the origin and bound:
+ * <pre> {@code
+ * int nextInt(int origin, int bound) {
+ * int n = bound - origin;
+ * if (n > 0) {
+ * return nextInt(n) + origin;
+ * }
+ * else { // range not representable as int
+ * int r;
+ * do {
+ * r = nextInt();
+ * } while (r < origin || r >= bound);
+ * return r;
+ * }
+ * }}</pre>
+ *
+ * @implNote This method is implemented to be equivalent to {@code
+ * ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
+ *
+ * @param randomNumberOrigin the origin (inclusive) of each random value
+ * @param randomNumberBound the bound (exclusive) of each random value
+ * @return a stream of pseudorandom {@code int} values,
+ * each with the given origin (inclusive) and bound (exclusive)
+ * @throws IllegalArgumentException if {@code randomNumberOrigin}
+ * is greater than or equal to {@code randomNumberBound}
+ * @since 1.8
+ */
+ public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
+ if (randomNumberOrigin >= randomNumberBound)
+ throw new IllegalArgumentException(BadRange);
+ return StreamSupport.intStream
+ (new RandomIntsSpliterator
+ (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
+ false);
+ }
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number of
+ * pseudorandom {@code long} values.
+ *
+ * <p>A pseudorandom {@code long} value is generated as if it's the result
+ * of calling the method {@link #nextLong()}.
+ *
+ * @param streamSize the number of values to generate
+ * @return a stream of pseudorandom {@code long} values
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero
+ * @since 1.8
+ */
+ public LongStream longs(long streamSize) {
+ if (streamSize < 0L)
+ throw new IllegalArgumentException(BadSize);
+ return StreamSupport.longStream
+ (new RandomLongsSpliterator
+ (this, 0L, streamSize, Long.MAX_VALUE, 0L),
+ false);
+ }
+
+ /**
+ * Returns an effectively unlimited stream of pseudorandom {@code long}
+ * values.
+ *
+ * <p>A pseudorandom {@code long} value is generated as if it's the result
+ * of calling the method {@link #nextLong()}.
+ *
+ * @implNote This method is implemented to be equivalent to {@code
+ * longs(Long.MAX_VALUE)}.
+ *
+ * @return a stream of pseudorandom {@code long} values
+ * @since 1.8
+ */
+ public LongStream longs() {
+ return StreamSupport.longStream
+ (new RandomLongsSpliterator
+ (this, 0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L),
+ false);
+ }
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number of
+ * pseudorandom {@code long}, each conforming to the given origin
+ * (inclusive) and bound (exclusive).
+ *
+ * <p>A pseudorandom {@code long} value is generated as if it's the result
+ * of calling the following method with the origin and bound:
+ * <pre> {@code
+ * long nextLong(long origin, long bound) {
+ * long r = nextLong();
+ * long n = bound - origin, m = n - 1;
+ * if ((n & m) == 0L) // power of two
+ * r = (r & m) + origin;
+ * else if (n > 0L) { // reject over-represented candidates
+ * for (long u = r >>> 1; // ensure nonnegative
+ * u + m - (r = u % n) < 0L; // rejection check
+ * u = nextLong() >>> 1) // retry
+ * ;
+ * r += origin;
+ * }
+ * else { // range not representable as long
+ * while (r < origin || r >= bound)
+ * r = nextLong();
+ * }
+ * return r;
+ * }}</pre>
+ *
+ * @param streamSize the number of values to generate
+ * @param randomNumberOrigin the origin (inclusive) of each random value
+ * @param randomNumberBound the bound (exclusive) of each random value
+ * @return a stream of pseudorandom {@code long} values,
+ * each with the given origin (inclusive) and bound (exclusive)
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero, or {@code randomNumberOrigin}
+ * is greater than or equal to {@code randomNumberBound}
+ * @since 1.8
+ */
+ public LongStream longs(long streamSize, long randomNumberOrigin,
+ long randomNumberBound) {
+ if (streamSize < 0L)
+ throw new IllegalArgumentException(BadSize);
+ if (randomNumberOrigin >= randomNumberBound)
+ throw new IllegalArgumentException(BadRange);
+ return StreamSupport.longStream
+ (new RandomLongsSpliterator
+ (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
+ false);
+ }
+
+ /**
+ * Returns an effectively unlimited stream of pseudorandom {@code
+ * long} values, each conforming to the given origin (inclusive) and bound
+ * (exclusive).
+ *
+ * <p>A pseudorandom {@code long} value is generated as if it's the result
+ * of calling the following method with the origin and bound:
+ * <pre> {@code
+ * long nextLong(long origin, long bound) {
+ * long r = nextLong();
+ * long n = bound - origin, m = n - 1;
+ * if ((n & m) == 0L) // power of two
+ * r = (r & m) + origin;
+ * else if (n > 0L) { // reject over-represented candidates
+ * for (long u = r >>> 1; // ensure nonnegative
+ * u + m - (r = u % n) < 0L; // rejection check
+ * u = nextLong() >>> 1) // retry
+ * ;
+ * r += origin;
+ * }
+ * else { // range not representable as long
+ * while (r < origin || r >= bound)
+ * r = nextLong();
+ * }
+ * return r;
+ * }}</pre>
+ *
+ * @implNote This method is implemented to be equivalent to {@code
+ * longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
+ *
+ * @param randomNumberOrigin the origin (inclusive) of each random value
+ * @param randomNumberBound the bound (exclusive) of each random value
+ * @return a stream of pseudorandom {@code long} values,
+ * each with the given origin (inclusive) and bound (exclusive)
+ * @throws IllegalArgumentException if {@code randomNumberOrigin}
+ * is greater than or equal to {@code randomNumberBound}
+ * @since 1.8
+ */
+ public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
+ if (randomNumberOrigin >= randomNumberBound)
+ throw new IllegalArgumentException(BadRange);
+ return StreamSupport.longStream
+ (new RandomLongsSpliterator
+ (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
+ false);
+ }
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number of
+ * pseudorandom {@code double} values, each between zero
+ * (inclusive) and one (exclusive).
+ *
+ * <p>A pseudorandom {@code double} value is generated as if it's the result
+ * of calling the method {@link #nextDouble()}.
+ *
+ * @param streamSize the number of values to generate
+ * @return a stream of {@code double} values
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero
+ * @since 1.8
+ */
+ public DoubleStream doubles(long streamSize) {
+ if (streamSize < 0L)
+ throw new IllegalArgumentException(BadSize);
+ return StreamSupport.doubleStream
+ (new RandomDoublesSpliterator
+ (this, 0L, streamSize, Double.MAX_VALUE, 0.0),
+ false);
+ }
+
+ /**
+ * Returns an effectively unlimited stream of pseudorandom {@code
+ * double} values, each between zero (inclusive) and one
+ * (exclusive).
+ *
+ * <p>A pseudorandom {@code double} value is generated as if it's the result
+ * of calling the method {@link #nextDouble()}.
+ *
+ * @implNote This method is implemented to be equivalent to {@code
+ * doubles(Long.MAX_VALUE)}.
+ *
+ * @return a stream of pseudorandom {@code double} values
+ * @since 1.8
+ */
+ public DoubleStream doubles() {
+ return StreamSupport.doubleStream
+ (new RandomDoublesSpliterator
+ (this, 0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0),
+ false);
+ }
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number of
+ * pseudorandom {@code double} values, each conforming to the given origin
+ * (inclusive) and bound (exclusive).
+ *
+ * <p>A pseudorandom {@code double} value is generated as if it's the result
+ * of calling the following method with the origin and bound:
+ * <pre> {@code
+ * double nextDouble(double origin, double bound) {
+ * double r = nextDouble();
+ * r = r * (bound - origin) + origin;
+ * if (r >= bound) // correct for rounding
+ * r = Math.nextDown(bound);
+ * return r;
+ * }}</pre>
+ *
+ * @param streamSize the number of values to generate
+ * @param randomNumberOrigin the origin (inclusive) of each random value
+ * @param randomNumberBound the bound (exclusive) of each random value
+ * @return a stream of pseudorandom {@code double} values,
+ * each with the given origin (inclusive) and bound (exclusive)
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero
+ * @throws IllegalArgumentException if {@code randomNumberOrigin}
+ * is greater than or equal to {@code randomNumberBound}
+ * @since 1.8
+ */
+ public DoubleStream doubles(long streamSize, double randomNumberOrigin,
+ double randomNumberBound) {
+ if (streamSize < 0L)
+ throw new IllegalArgumentException(BadSize);
+ if (!(randomNumberOrigin < randomNumberBound))
+ throw new IllegalArgumentException(BadRange);
+ return StreamSupport.doubleStream
+ (new RandomDoublesSpliterator
+ (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
+ false);
+ }
+
+ /**
+ * Returns an effectively unlimited stream of pseudorandom {@code
+ * double} values, each conforming to the given origin (inclusive) and bound
+ * (exclusive).
+ *
+ * <p>A pseudorandom {@code double} value is generated as if it's the result
+ * of calling the following method with the origin and bound:
+ * <pre> {@code
+ * double nextDouble(double origin, double bound) {
+ * double r = nextDouble();
+ * r = r * (bound - origin) + origin;
+ * if (r >= bound) // correct for rounding
+ * r = Math.nextDown(bound);
+ * return r;
+ * }}</pre>
+ *
+ * @implNote This method is implemented to be equivalent to {@code
+ * doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
+ *
+ * @param randomNumberOrigin the origin (inclusive) of each random value
+ * @param randomNumberBound the bound (exclusive) of each random value
+ * @return a stream of pseudorandom {@code double} values,
+ * each with the given origin (inclusive) and bound (exclusive)
+ * @throws IllegalArgumentException if {@code randomNumberOrigin}
+ * is greater than or equal to {@code randomNumberBound}
+ * @since 1.8
+ */
+ public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
+ if (!(randomNumberOrigin < randomNumberBound))
+ throw new IllegalArgumentException(BadRange);
+ return StreamSupport.doubleStream
+ (new RandomDoublesSpliterator
+ (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
+ false);
+ }
+
+ /**
+ * Spliterator for int streams. We multiplex the four int
+ * versions into one class by treating a bound less than origin as
+ * unbounded, and also by treating "infinite" as equivalent to
+ * Long.MAX_VALUE. For splits, it uses the standard divide-by-two
+ * approach. The long and double versions of this class are
+ * identical except for types.
+ */
+ static final class RandomIntsSpliterator implements Spliterator.OfInt {
+ final Random rng;
+ long index;
+ final long fence;
+ final int origin;
+ final int bound;
+ RandomIntsSpliterator(Random rng, long index, long fence,
+ int origin, int bound) {
+ this.rng = rng; this.index = index; this.fence = fence;
+ this.origin = origin; this.bound = bound;
+ }
+
+ public RandomIntsSpliterator trySplit() {
+ long i = index, m = (i + fence) >>> 1;
+ return (m <= i) ? null :
+ new RandomIntsSpliterator(rng, i, index = m, origin, bound);
+ }
+
+ public long estimateSize() {
+ return fence - index;
+ }
+
+ public int characteristics() {
+ return (Spliterator.SIZED | Spliterator.SUBSIZED |
+ Spliterator.NONNULL | Spliterator.IMMUTABLE);
+ }
+
+ public boolean tryAdvance(IntConsumer consumer) {
+ if (consumer == null) throw new NullPointerException();
+ long i = index, f = fence;
+ if (i < f) {
+ consumer.accept(rng.internalNextInt(origin, bound));
+ index = i + 1;
+ return true;
+ }
+ return false;
+ }
+
+ public void forEachRemaining(IntConsumer consumer) {
+ if (consumer == null) throw new NullPointerException();
+ long i = index, f = fence;
+ if (i < f) {
+ index = f;
+ Random r = rng;
+ int o = origin, b = bound;
+ do {
+ consumer.accept(r.internalNextInt(o, b));
+ } while (++i < f);
+ }
+ }
+ }
+
+ /**
+ * Spliterator for long streams.
+ */
+ static final class RandomLongsSpliterator implements Spliterator.OfLong {
+ final Random rng;
+ long index;
+ final long fence;
+ final long origin;
+ final long bound;
+ RandomLongsSpliterator(Random rng, long index, long fence,
+ long origin, long bound) {
+ this.rng = rng; this.index = index; this.fence = fence;
+ this.origin = origin; this.bound = bound;
+ }
+
+ public RandomLongsSpliterator trySplit() {
+ long i = index, m = (i + fence) >>> 1;
+ return (m <= i) ? null :
+ new RandomLongsSpliterator(rng, i, index = m, origin, bound);
+ }
+
+ public long estimateSize() {
+ return fence - index;
+ }
+
+ public int characteristics() {
+ return (Spliterator.SIZED | Spliterator.SUBSIZED |
+ Spliterator.NONNULL | Spliterator.IMMUTABLE);
+ }
+
+ public boolean tryAdvance(LongConsumer consumer) {
+ if (consumer == null) throw new NullPointerException();
+ long i = index, f = fence;
+ if (i < f) {
+ consumer.accept(rng.internalNextLong(origin, bound));
+ index = i + 1;
+ return true;
+ }
+ return false;
+ }
+
+ public void forEachRemaining(LongConsumer consumer) {
+ if (consumer == null) throw new NullPointerException();
+ long i = index, f = fence;
+ if (i < f) {
+ index = f;
+ Random r = rng;
+ long o = origin, b = bound;
+ do {
+ consumer.accept(r.internalNextLong(o, b));
+ } while (++i < f);
+ }
+ }
+
+ }
+
+ /**
+ * Spliterator for double streams.
+ */
+ static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
+ final Random rng;
+ long index;
+ final long fence;
+ final double origin;
+ final double bound;
+ RandomDoublesSpliterator(Random rng, long index, long fence,
+ double origin, double bound) {
+ this.rng = rng; this.index = index; this.fence = fence;
+ this.origin = origin; this.bound = bound;
+ }
+
+ public RandomDoublesSpliterator trySplit() {
+ long i = index, m = (i + fence) >>> 1;
+ return (m <= i) ? null :
+ new RandomDoublesSpliterator(rng, i, index = m, origin, bound);
+ }
+
+ public long estimateSize() {
+ return fence - index;
+ }
+
+ public int characteristics() {
+ return (Spliterator.SIZED | Spliterator.SUBSIZED |
+ Spliterator.NONNULL | Spliterator.IMMUTABLE);
+ }
+
+ public boolean tryAdvance(DoubleConsumer consumer) {
+ if (consumer == null) throw new NullPointerException();
+ long i = index, f = fence;
+ if (i < f) {
+ consumer.accept(rng.internalNextDouble(origin, bound));
+ index = i + 1;
+ return true;
+ }
+ return false;
+ }
+
+ public void forEachRemaining(DoubleConsumer consumer) {
+ if (consumer == null) throw new NullPointerException();
+ long i = index, f = fence;
+ if (i < f) {
+ index = f;
+ Random r = rng;
+ double o = origin, b = bound;
+ do {
+ consumer.accept(r.internalNextDouble(o, b));
+ } while (++i < f);
+ }
+ }
+ }
+
+ /**
+ * Serializable fields for Random.
+ *
+ * @serialField seed long
+ * seed for random computations
+ * @serialField nextNextGaussian double
+ * next Gaussian to be returned
+ * @serialField haveNextNextGaussian boolean
+ * nextNextGaussian is valid
+ */
+ private static final ObjectStreamField[] serialPersistentFields = {
+ new ObjectStreamField("seed", Long.TYPE),
+ new ObjectStreamField("nextNextGaussian", Double.TYPE),
+ new ObjectStreamField("haveNextNextGaussian", Boolean.TYPE)
+ };
+
+ /**
+ * Reconstitute the {@code Random} instance from a stream (that is,
+ * deserialize it).
+ */
+ private void readObject(java.io.ObjectInputStream s)
+ throws java.io.IOException, ClassNotFoundException {
+
+ ObjectInputStream.GetField fields = s.readFields();
+
+ // The seed is read in as {@code long} for
+ // historical reasons, but it is converted to an AtomicLong.
+ long seedVal = fields.get("seed", -1L);
+ if (seedVal < 0)
+ throw new java.io.StreamCorruptedException(
+ "Random: invalid seed");
+ resetSeed(seedVal);
+ nextNextGaussian = fields.get("nextNextGaussian", 0.0);
+ haveNextNextGaussian = fields.get("haveNextNextGaussian", false);
+ }
+
+ /**
+ * Save the {@code Random} instance to a stream.
+ */
+ private synchronized void writeObject(ObjectOutputStream s)
+ throws IOException {
+
+ // set the values of the Serializable fields
+ ObjectOutputStream.PutField fields = s.putFields();
+
+ // The seed is serialized as a long for historical reasons.
+ fields.put("seed", seed.get());
+ fields.put("nextNextGaussian", nextNextGaussian);
+ fields.put("haveNextNextGaussian", haveNextNextGaussian);
+
+ // save them
+ s.writeFields();
+ }
+
+ // Support for resetting seed while deserializing
+ private static final Unsafe unsafe = Unsafe.getUnsafe();
+ private static final long seedOffset;
+ static {
+ try {
+ seedOffset = unsafe.objectFieldOffset
+ (Random.class.getDeclaredField("seed"));
+ } catch (Exception ex) { throw new Error(ex); }
+ }
+ private void resetSeed(long seedVal) {
+ unsafe.putObjectVolatile(this, seedOffset, new AtomicLong(seedVal));
+ }
+}