25 |
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26 |
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package java.util; |
27 |
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|
28 |
– |
import java.security.SecureRandom; |
29 |
– |
import java.net.NetworkInterface; |
30 |
– |
import java.util.Enumeration; |
28 |
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import java.util.concurrent.atomic.AtomicLong; |
29 |
+ |
import java.util.function.DoubleConsumer; |
30 |
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import java.util.function.IntConsumer; |
31 |
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import java.util.function.LongConsumer; |
32 |
< |
import java.util.function.DoubleConsumer; |
35 |
< |
import java.util.stream.StreamSupport; |
32 |
> |
import java.util.stream.DoubleStream; |
33 |
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import java.util.stream.IntStream; |
34 |
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import java.util.stream.LongStream; |
35 |
< |
import java.util.stream.DoubleStream; |
35 |
> |
import java.util.stream.StreamSupport; |
36 |
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|
37 |
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/** |
38 |
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* A generator of uniform pseudorandom values applicable for use in |
52 |
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* types and ranges, but similar properties are expected to hold, at |
53 |
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* least approximately, for others as well. The <em>period</em> |
54 |
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* (length of any series of generated values before it repeats) is at |
55 |
< |
* least 2<sup>64</sup>. </li> |
55 |
> |
* least 2<sup>64</sup>. |
56 |
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* |
57 |
< |
* <li> Method {@link #split} constructs and returns a new |
57 |
> |
* <li>Method {@link #split} constructs and returns a new |
58 |
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* SplittableRandom instance that shares no mutable state with the |
59 |
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* current instance. However, with very high probability, the |
60 |
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* values collectively generated by the two objects have the same |
61 |
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* statistical properties as if the same quantity of values were |
62 |
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* generated by a single thread using a single {@code |
63 |
< |
* SplittableRandom} object. </li> |
63 |
> |
* SplittableRandom} object. |
64 |
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* |
65 |
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* <li>Instances of SplittableRandom are <em>not</em> thread-safe. |
66 |
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* They are designed to be split, not shared, across threads. For |
71 |
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* |
72 |
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* <li>This class provides additional methods for generating random |
73 |
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* streams, that employ the above techniques when used in {@code |
74 |
< |
* stream.parallel()} mode.</li> |
74 |
> |
* stream.parallel()} mode. |
75 |
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* |
76 |
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* </ul> |
77 |
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* |
80 |
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* in security-sensitive applications. Additionally, |
81 |
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* default-constructed instances do not use a cryptographically random |
82 |
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* seed unless the {@linkplain System#getProperty system property} |
83 |
< |
* {@code java.util.secureRandomSeed} is set to {@code true}. |
83 |
> |
* {@systemProperty java.util.secureRandomSeed} is set to {@code true}. |
84 |
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* |
85 |
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* @author Guy Steele |
86 |
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* @author Doug Lea |
87 |
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* @since 1.8 |
88 |
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*/ |
89 |
< |
public class SplittableRandom { |
89 |
> |
public final class SplittableRandom { |
90 |
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|
91 |
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/* |
92 |
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* Implementation Overview. |
109 |
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* For nextLong, the mix64 function is based on David Stafford's |
110 |
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* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html) |
111 |
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* "Mix13" variant of the "64-bit finalizer" function in Austin |
112 |
< |
* Appleby's MurmurHash3 algorithm See |
113 |
< |
* http://code.google.com/p/smhasher/wiki/MurmurHash3 . The mix32 |
112 |
> |
* Appleby's MurmurHash3 algorithm (see |
113 |
> |
* http://code.google.com/p/smhasher/wiki/MurmurHash3). The mix32 |
114 |
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* function is based on Stafford's Mix04 mix function, but returns |
115 |
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* the upper 32 bits cast as int. |
116 |
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* |
139 |
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* other cases, this split must be performed in a thread-safe |
140 |
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* manner, so we use an AtomicLong to represent the seed rather |
141 |
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* than use an explicit SplittableRandom. To bootstrap the |
142 |
< |
* defaultGen, we start off using a seed based on current time and |
143 |
< |
* network interface address unless the java.util.secureRandomSeed |
144 |
< |
* property is set. This serves as a slimmed-down (and insecure) |
145 |
< |
* variant of SecureRandom that also avoids stalls that may occur |
149 |
< |
* when using /dev/random. |
142 |
> |
* defaultGen, we start off using a seed based on current time |
143 |
> |
* unless the java.util.secureRandomSeed property is set. This |
144 |
> |
* serves as a slimmed-down (and insecure) variant of SecureRandom |
145 |
> |
* that also avoids stalls that may occur when using /dev/random. |
146 |
|
* |
147 |
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* It is a relatively simple matter to apply the basic design here |
148 |
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* to use 128 bit seeds. However, emulating 128bit arithmetic and |
164 |
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* The least non-zero value returned by nextDouble(). This value |
165 |
|
* is scaled by a random value of 53 bits to produce a result. |
166 |
|
*/ |
167 |
< |
private static final double DOUBLE_ULP = 1.0 / (1L << 53); |
167 |
> |
private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53); |
168 |
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|
169 |
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/** |
170 |
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* The seed. Updated only via method nextSeed. |
188 |
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* Computes Stafford variant 13 of 64bit mix function. |
189 |
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*/ |
190 |
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private static long mix64(long z) { |
191 |
< |
z *= 0xbf58476d1ce4e5b9L; |
196 |
< |
z = (z ^ (z >>> 32)) * 0x94d049bb133111ebL; |
197 |
< |
return z ^ (z >>> 32); |
198 |
< |
} |
199 |
< |
|
200 |
< |
private static long xmix64(long z) { |
201 |
< |
z *= 0xbf58476d1ce4e5b9L; |
191 |
> |
z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; |
192 |
|
z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL; |
193 |
|
return z ^ (z >>> 31); |
194 |
|
} |
197 |
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* Returns the 32 high bits of Stafford variant 4 mix64 function as int. |
198 |
|
*/ |
199 |
|
private static int mix32(long z) { |
200 |
< |
z *= 0x62a9d9ed799705f5L; |
200 |
> |
z = (z ^ (z >>> 33)) * 0x62a9d9ed799705f5L; |
201 |
|
return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32); |
202 |
|
} |
203 |
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|
205 |
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* Returns the gamma value to use for a new split instance. |
206 |
|
*/ |
207 |
|
private static long mixGamma(long z) { |
208 |
< |
z *= 0xff51afd7ed558ccdL; // MurmurHash3 mix constants |
208 |
> |
z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL; // MurmurHash3 mix constants |
209 |
|
z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L; |
210 |
|
z = (z ^ (z >>> 33)) | 1L; // force to be odd |
211 |
|
int n = Long.bitCount(z ^ (z >>> 1)); // ensure enough transitions |
219 |
|
return seed += gamma; |
220 |
|
} |
221 |
|
|
222 |
+ |
// IllegalArgumentException messages |
223 |
+ |
static final String BAD_BOUND = "bound must be positive"; |
224 |
+ |
static final String BAD_RANGE = "bound must be greater than origin"; |
225 |
+ |
static final String BAD_SIZE = "size must be non-negative"; |
226 |
+ |
|
227 |
|
/** |
228 |
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* The seed generator for default constructors. |
229 |
|
*/ |
230 |
< |
private static final AtomicLong defaultGen = new AtomicLong(initialSeed()); |
231 |
< |
|
232 |
< |
private static long initialSeed() { |
233 |
< |
String pp = java.security.AccessController.doPrivileged( |
234 |
< |
new sun.security.action.GetPropertyAction( |
235 |
< |
"java.util.secureRandomSeed")); |
236 |
< |
if (pp != null && pp.equalsIgnoreCase("true")) { |
230 |
> |
private static final AtomicLong defaultGen |
231 |
> |
= new AtomicLong(mix64(System.currentTimeMillis()) ^ |
232 |
> |
mix64(System.nanoTime())); |
233 |
> |
|
234 |
> |
// at end of <clinit> to survive static initialization circularity |
235 |
> |
static { |
236 |
> |
if (java.security.AccessController.doPrivileged( |
237 |
> |
new java.security.PrivilegedAction<Boolean>() { |
238 |
> |
public Boolean run() { |
239 |
> |
return Boolean.getBoolean("java.util.secureRandomSeed"); |
240 |
> |
}})) { |
241 |
|
byte[] seedBytes = java.security.SecureRandom.getSeed(8); |
242 |
< |
long s = (long)(seedBytes[0]) & 0xffL; |
242 |
> |
long s = (long)seedBytes[0] & 0xffL; |
243 |
|
for (int i = 1; i < 8; ++i) |
244 |
< |
s = (s << 8) | ((long)(seedBytes[i]) & 0xffL); |
245 |
< |
return s; |
244 |
> |
s = (s << 8) | ((long)seedBytes[i] & 0xffL); |
245 |
> |
defaultGen.set(s); |
246 |
|
} |
248 |
– |
long h = 0L; |
249 |
– |
try { |
250 |
– |
Enumeration<NetworkInterface> ifcs = |
251 |
– |
NetworkInterface.getNetworkInterfaces(); |
252 |
– |
boolean retry = false; // retry once if getHardwareAddress is null |
253 |
– |
while (ifcs.hasMoreElements()) { |
254 |
– |
NetworkInterface ifc = ifcs.nextElement(); |
255 |
– |
if (!ifc.isVirtual()) { // skip fake addresses |
256 |
– |
byte[] bs = ifc.getHardwareAddress(); |
257 |
– |
if (bs != null) { |
258 |
– |
int n = bs.length; |
259 |
– |
int m = Math.min(n >>> 1, 4); |
260 |
– |
for (int i = 0; i < m; ++i) |
261 |
– |
h = (h << 16) ^ (bs[i] << 8) ^ bs[n-1-i]; |
262 |
– |
if (m < 4) |
263 |
– |
h = (h << 8) ^ bs[n-1-m]; |
264 |
– |
h = mix64(h); |
265 |
– |
break; |
266 |
– |
} |
267 |
– |
else if (!retry) |
268 |
– |
retry = true; |
269 |
– |
else |
270 |
– |
break; |
271 |
– |
} |
272 |
– |
} |
273 |
– |
} catch (Exception ignore) { |
274 |
– |
} |
275 |
– |
return (h ^ mix64(System.currentTimeMillis()) ^ |
276 |
– |
mix64(System.nanoTime())); |
247 |
|
} |
248 |
|
|
279 |
– |
// IllegalArgumentException messages |
280 |
– |
static final String BadBound = "bound must be positive"; |
281 |
– |
static final String BadRange = "bound must be greater than origin"; |
282 |
– |
static final String BadSize = "size must be non-negative"; |
283 |
– |
|
249 |
|
/* |
250 |
|
* Internal versions of nextX methods used by streams, as well as |
251 |
|
* the public nextX(origin, bound) methods. These exist mainly to |
346 |
|
* @return a pseudorandom value |
347 |
|
*/ |
348 |
|
final double internalNextDouble(double origin, double bound) { |
349 |
< |
double r = (nextLong() >>> 11) * DOUBLE_ULP; |
349 |
> |
double r = (nextLong() >>> 11) * DOUBLE_UNIT; |
350 |
|
if (origin < bound) { |
351 |
|
r = r * (bound - origin) + origin; |
352 |
|
if (r >= bound) // correct for rounding |
375 |
|
* may, and typically does, vary across program invocations. |
376 |
|
*/ |
377 |
|
public SplittableRandom() { // emulate defaultGen.split() |
378 |
< |
long s = defaultGen.getAndAdd(2*GOLDEN_GAMMA); |
378 |
> |
long s = defaultGen.getAndAdd(GOLDEN_GAMMA << 1); |
379 |
|
this.seed = mix64(s); |
380 |
|
this.gamma = mixGamma(s + GOLDEN_GAMMA); |
381 |
|
} |
399 |
|
} |
400 |
|
|
401 |
|
/** |
402 |
+ |
* Fills a user-supplied byte array with generated pseudorandom bytes. |
403 |
+ |
* |
404 |
+ |
* @param bytes the byte array to fill with pseudorandom bytes |
405 |
+ |
* @throws NullPointerException if bytes is null |
406 |
+ |
* @since 10 |
407 |
+ |
*/ |
408 |
+ |
public void nextBytes(byte[] bytes) { |
409 |
+ |
int i = 0; |
410 |
+ |
int len = bytes.length; |
411 |
+ |
for (int words = len >> 3; words--> 0; ) { |
412 |
+ |
long rnd = nextLong(); |
413 |
+ |
for (int n = 8; n--> 0; rnd >>>= Byte.SIZE) |
414 |
+ |
bytes[i++] = (byte)rnd; |
415 |
+ |
} |
416 |
+ |
if (i < len) |
417 |
+ |
for (long rnd = nextLong(); i < len; rnd >>>= Byte.SIZE) |
418 |
+ |
bytes[i++] = (byte)rnd; |
419 |
+ |
} |
420 |
+ |
|
421 |
+ |
/** |
422 |
|
* Returns a pseudorandom {@code int} value. |
423 |
|
* |
424 |
|
* @return a pseudorandom {@code int} value |
438 |
|
*/ |
439 |
|
public int nextInt(int bound) { |
440 |
|
if (bound <= 0) |
441 |
< |
throw new IllegalArgumentException(BadBound); |
441 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
442 |
|
// Specialize internalNextInt for origin 0 |
443 |
|
int r = mix32(nextSeed()); |
444 |
|
int m = bound - 1; |
466 |
|
*/ |
467 |
|
public int nextInt(int origin, int bound) { |
468 |
|
if (origin >= bound) |
469 |
< |
throw new IllegalArgumentException(BadRange); |
469 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
470 |
|
return internalNextInt(origin, bound); |
471 |
|
} |
472 |
|
|
490 |
|
*/ |
491 |
|
public long nextLong(long bound) { |
492 |
|
if (bound <= 0) |
493 |
< |
throw new IllegalArgumentException(BadBound); |
493 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
494 |
|
// Specialize internalNextLong for origin 0 |
495 |
|
long r = mix64(nextSeed()); |
496 |
|
long m = bound - 1; |
518 |
|
*/ |
519 |
|
public long nextLong(long origin, long bound) { |
520 |
|
if (origin >= bound) |
521 |
< |
throw new IllegalArgumentException(BadRange); |
521 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
522 |
|
return internalNextLong(origin, bound); |
523 |
|
} |
524 |
|
|
530 |
|
* (inclusive) and one (exclusive) |
531 |
|
*/ |
532 |
|
public double nextDouble() { |
533 |
< |
return (mix64(nextSeed()) >>> 11) * DOUBLE_ULP; |
533 |
> |
return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT; |
534 |
|
} |
535 |
|
|
536 |
|
/** |
544 |
|
*/ |
545 |
|
public double nextDouble(double bound) { |
546 |
|
if (!(bound > 0.0)) |
547 |
< |
throw new IllegalArgumentException(BadBound); |
548 |
< |
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_ULP * bound; |
547 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
548 |
> |
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound; |
549 |
|
return (result < bound) ? result : // correct for rounding |
550 |
|
Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
551 |
|
} |
563 |
|
*/ |
564 |
|
public double nextDouble(double origin, double bound) { |
565 |
|
if (!(origin < bound)) |
566 |
< |
throw new IllegalArgumentException(BadRange); |
566 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
567 |
|
return internalNextDouble(origin, bound); |
568 |
|
} |
569 |
|
|
591 |
|
*/ |
592 |
|
public IntStream ints(long streamSize) { |
593 |
|
if (streamSize < 0L) |
594 |
< |
throw new IllegalArgumentException(BadSize); |
594 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
595 |
|
return StreamSupport.intStream |
596 |
|
(new RandomIntsSpliterator |
597 |
|
(this, 0L, streamSize, Integer.MAX_VALUE, 0), |
632 |
|
public IntStream ints(long streamSize, int randomNumberOrigin, |
633 |
|
int randomNumberBound) { |
634 |
|
if (streamSize < 0L) |
635 |
< |
throw new IllegalArgumentException(BadSize); |
635 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
636 |
|
if (randomNumberOrigin >= randomNumberBound) |
637 |
< |
throw new IllegalArgumentException(BadRange); |
637 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
638 |
|
return StreamSupport.intStream |
639 |
|
(new RandomIntsSpliterator |
640 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
658 |
|
*/ |
659 |
|
public IntStream ints(int randomNumberOrigin, int randomNumberBound) { |
660 |
|
if (randomNumberOrigin >= randomNumberBound) |
661 |
< |
throw new IllegalArgumentException(BadRange); |
661 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
662 |
|
return StreamSupport.intStream |
663 |
|
(new RandomIntsSpliterator |
664 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
677 |
|
*/ |
678 |
|
public LongStream longs(long streamSize) { |
679 |
|
if (streamSize < 0L) |
680 |
< |
throw new IllegalArgumentException(BadSize); |
680 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
681 |
|
return StreamSupport.longStream |
682 |
|
(new RandomLongsSpliterator |
683 |
|
(this, 0L, streamSize, Long.MAX_VALUE, 0L), |
718 |
|
public LongStream longs(long streamSize, long randomNumberOrigin, |
719 |
|
long randomNumberBound) { |
720 |
|
if (streamSize < 0L) |
721 |
< |
throw new IllegalArgumentException(BadSize); |
721 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
722 |
|
if (randomNumberOrigin >= randomNumberBound) |
723 |
< |
throw new IllegalArgumentException(BadRange); |
723 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
724 |
|
return StreamSupport.longStream |
725 |
|
(new RandomLongsSpliterator |
726 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
744 |
|
*/ |
745 |
|
public LongStream longs(long randomNumberOrigin, long randomNumberBound) { |
746 |
|
if (randomNumberOrigin >= randomNumberBound) |
747 |
< |
throw new IllegalArgumentException(BadRange); |
747 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
748 |
|
return StreamSupport.longStream |
749 |
|
(new RandomLongsSpliterator |
750 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
763 |
|
*/ |
764 |
|
public DoubleStream doubles(long streamSize) { |
765 |
|
if (streamSize < 0L) |
766 |
< |
throw new IllegalArgumentException(BadSize); |
766 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
767 |
|
return StreamSupport.doubleStream |
768 |
|
(new RandomDoublesSpliterator |
769 |
|
(this, 0L, streamSize, Double.MAX_VALUE, 0.0), |
799 |
|
* @return a stream of pseudorandom {@code double} values, |
800 |
|
* each with the given origin (inclusive) and bound (exclusive) |
801 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
802 |
< |
* less than zero |
818 |
< |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
802 |
> |
* less than zero, or {@code randomNumberOrigin} |
803 |
|
* is greater than or equal to {@code randomNumberBound} |
804 |
|
*/ |
805 |
|
public DoubleStream doubles(long streamSize, double randomNumberOrigin, |
806 |
|
double randomNumberBound) { |
807 |
|
if (streamSize < 0L) |
808 |
< |
throw new IllegalArgumentException(BadSize); |
808 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
809 |
|
if (!(randomNumberOrigin < randomNumberBound)) |
810 |
< |
throw new IllegalArgumentException(BadRange); |
810 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
811 |
|
return StreamSupport.doubleStream |
812 |
|
(new RandomDoublesSpliterator |
813 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
831 |
|
*/ |
832 |
|
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) { |
833 |
|
if (!(randomNumberOrigin < randomNumberBound)) |
834 |
< |
throw new IllegalArgumentException(BadRange); |
834 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
835 |
|
return StreamSupport.doubleStream |
836 |
|
(new RandomDoublesSpliterator |
837 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
846 |
|
* approach. The long and double versions of this class are |
847 |
|
* identical except for types. |
848 |
|
*/ |
849 |
< |
static final class RandomIntsSpliterator implements Spliterator.OfInt { |
849 |
> |
private static final class RandomIntsSpliterator |
850 |
> |
implements Spliterator.OfInt { |
851 |
|
final SplittableRandom rng; |
852 |
|
long index; |
853 |
|
final long fence; |
902 |
|
/** |
903 |
|
* Spliterator for long streams. |
904 |
|
*/ |
905 |
< |
static final class RandomLongsSpliterator implements Spliterator.OfLong { |
905 |
> |
private static final class RandomLongsSpliterator |
906 |
> |
implements Spliterator.OfLong { |
907 |
|
final SplittableRandom rng; |
908 |
|
long index; |
909 |
|
final long fence; |
959 |
|
/** |
960 |
|
* Spliterator for double streams. |
961 |
|
*/ |
962 |
< |
static final class RandomDoublesSpliterator implements Spliterator.OfDouble { |
962 |
> |
private static final class RandomDoublesSpliterator |
963 |
> |
implements Spliterator.OfDouble { |
964 |
|
final SplittableRandom rng; |
965 |
|
long index; |
966 |
|
final long fence; |