001/* 002 * Copyright (C) 2008 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.primitives; 016 017import static com.google.common.base.Preconditions.checkArgument; 018import static com.google.common.base.Preconditions.checkElementIndex; 019import static com.google.common.base.Preconditions.checkNotNull; 020import static com.google.common.base.Preconditions.checkPositionIndexes; 021 022import com.google.common.annotations.Beta; 023import com.google.common.annotations.GwtCompatible; 024import com.google.common.base.Converter; 025import java.io.Serializable; 026import java.util.AbstractList; 027import java.util.Arrays; 028import java.util.Collection; 029import java.util.Collections; 030import java.util.Comparator; 031import java.util.List; 032import java.util.RandomAccess; 033import java.util.Spliterator; 034import java.util.Spliterators; 035import org.checkerframework.checker.nullness.qual.Nullable; 036 037/** 038 * Static utility methods pertaining to {@code int} primitives, that are not already found in either 039 * {@link Integer} or {@link Arrays}. 040 * 041 * <p>See the Guava User Guide article on <a 042 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>. 043 * 044 * @author Kevin Bourrillion 045 * @since 1.0 046 */ 047@GwtCompatible 048public final class Ints { 049 private Ints() {} 050 051 /** 052 * The number of bytes required to represent a primitive {@code int} value. 053 * 054 * <p><b>Java 8 users:</b> use {@link Integer#BYTES} instead. 055 */ 056 public static final int BYTES = Integer.SIZE / Byte.SIZE; 057 058 /** 059 * The largest power of two that can be represented as an {@code int}. 060 * 061 * @since 10.0 062 */ 063 public static final int MAX_POWER_OF_TWO = 1 << (Integer.SIZE - 2); 064 065 /** 066 * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Integer) 067 * value).hashCode()}. 068 * 069 * <p><b>Java 8 users:</b> use {@link Integer#hashCode(int)} instead. 070 * 071 * @param value a primitive {@code int} value 072 * @return a hash code for the value 073 */ 074 public static int hashCode(int value) { 075 return value; 076 } 077 078 /** 079 * Returns the {@code int} value that is equal to {@code value}, if possible. 080 * 081 * @param value any value in the range of the {@code int} type 082 * @return the {@code int} value that equals {@code value} 083 * @throws IllegalArgumentException if {@code value} is greater than {@link Integer#MAX_VALUE} or 084 * less than {@link Integer#MIN_VALUE} 085 */ 086 public static int checkedCast(long value) { 087 int result = (int) value; 088 checkArgument(result == value, "Out of range: %s", value); 089 return result; 090 } 091 092 /** 093 * Returns the {@code int} nearest in value to {@code value}. 094 * 095 * @param value any {@code long} value 096 * @return the same value cast to {@code int} if it is in the range of the {@code int} type, 097 * {@link Integer#MAX_VALUE} if it is too large, or {@link Integer#MIN_VALUE} if it is too 098 * small 099 */ 100 public static int saturatedCast(long value) { 101 if (value > Integer.MAX_VALUE) { 102 return Integer.MAX_VALUE; 103 } 104 if (value < Integer.MIN_VALUE) { 105 return Integer.MIN_VALUE; 106 } 107 return (int) value; 108 } 109 110 /** 111 * Compares the two specified {@code int} values. The sign of the value returned is the same as 112 * that of {@code ((Integer) a).compareTo(b)}. 113 * 114 * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the 115 * equivalent {@link Integer#compare} method instead. 116 * 117 * @param a the first {@code int} to compare 118 * @param b the second {@code int} to compare 119 * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is 120 * greater than {@code b}; or zero if they are equal 121 */ 122 public static int compare(int a, int b) { 123 return (a < b) ? -1 : ((a > b) ? 1 : 0); 124 } 125 126 /** 127 * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}. 128 * 129 * @param array an array of {@code int} values, possibly empty 130 * @param target a primitive {@code int} value 131 * @return {@code true} if {@code array[i] == target} for some value of {@code i} 132 */ 133 public static boolean contains(int[] array, int target) { 134 for (int value : array) { 135 if (value == target) { 136 return true; 137 } 138 } 139 return false; 140 } 141 142 /** 143 * Returns the index of the first appearance of the value {@code target} in {@code array}. 144 * 145 * @param array an array of {@code int} values, possibly empty 146 * @param target a primitive {@code int} value 147 * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no 148 * such index exists. 149 */ 150 public static int indexOf(int[] array, int target) { 151 return indexOf(array, target, 0, array.length); 152 } 153 154 // TODO(kevinb): consider making this public 155 private static int indexOf(int[] array, int target, int start, int end) { 156 for (int i = start; i < end; i++) { 157 if (array[i] == target) { 158 return i; 159 } 160 } 161 return -1; 162 } 163 164 /** 165 * Returns the start position of the first occurrence of the specified {@code target} within 166 * {@code array}, or {@code -1} if there is no such occurrence. 167 * 168 * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array, 169 * i, i + target.length)} contains exactly the same elements as {@code target}. 170 * 171 * @param array the array to search for the sequence {@code target} 172 * @param target the array to search for as a sub-sequence of {@code array} 173 */ 174 public static int indexOf(int[] array, int[] target) { 175 checkNotNull(array, "array"); 176 checkNotNull(target, "target"); 177 if (target.length == 0) { 178 return 0; 179 } 180 181 outer: 182 for (int i = 0; i < array.length - target.length + 1; i++) { 183 for (int j = 0; j < target.length; j++) { 184 if (array[i + j] != target[j]) { 185 continue outer; 186 } 187 } 188 return i; 189 } 190 return -1; 191 } 192 193 /** 194 * Returns the index of the last appearance of the value {@code target} in {@code array}. 195 * 196 * @param array an array of {@code int} values, possibly empty 197 * @param target a primitive {@code int} value 198 * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no 199 * such index exists. 200 */ 201 public static int lastIndexOf(int[] array, int target) { 202 return lastIndexOf(array, target, 0, array.length); 203 } 204 205 // TODO(kevinb): consider making this public 206 private static int lastIndexOf(int[] array, int target, int start, int end) { 207 for (int i = end - 1; i >= start; i--) { 208 if (array[i] == target) { 209 return i; 210 } 211 } 212 return -1; 213 } 214 215 /** 216 * Returns the least value present in {@code array}. 217 * 218 * @param array a <i>nonempty</i> array of {@code int} values 219 * @return the value present in {@code array} that is less than or equal to every other value in 220 * the array 221 * @throws IllegalArgumentException if {@code array} is empty 222 */ 223 public static int min(int... array) { 224 checkArgument(array.length > 0); 225 int min = array[0]; 226 for (int i = 1; i < array.length; i++) { 227 if (array[i] < min) { 228 min = array[i]; 229 } 230 } 231 return min; 232 } 233 234 /** 235 * Returns the greatest value present in {@code array}. 236 * 237 * @param array a <i>nonempty</i> array of {@code int} values 238 * @return the value present in {@code array} that is greater than or equal to every other value 239 * in the array 240 * @throws IllegalArgumentException if {@code array} is empty 241 */ 242 public static int max(int... array) { 243 checkArgument(array.length > 0); 244 int max = array[0]; 245 for (int i = 1; i < array.length; i++) { 246 if (array[i] > max) { 247 max = array[i]; 248 } 249 } 250 return max; 251 } 252 253 /** 254 * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}. 255 * 256 * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned 257 * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code 258 * value} is greater than {@code max}, {@code max} is returned. 259 * 260 * @param value the {@code int} value to constrain 261 * @param min the lower bound (inclusive) of the range to constrain {@code value} to 262 * @param max the upper bound (inclusive) of the range to constrain {@code value} to 263 * @throws IllegalArgumentException if {@code min > max} 264 * @since 21.0 265 */ 266 @Beta 267 public static int constrainToRange(int value, int min, int max) { 268 checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max); 269 return Math.min(Math.max(value, min), max); 270 } 271 272 /** 273 * Returns the values from each provided array combined into a single array. For example, {@code 274 * concat(new int[] {a, b}, new int[] {}, new int[] {c}} returns the array {@code {a, b, c}}. 275 * 276 * @param arrays zero or more {@code int} arrays 277 * @return a single array containing all the values from the source arrays, in order 278 */ 279 public static int[] concat(int[]... arrays) { 280 int length = 0; 281 for (int[] array : arrays) { 282 length += array.length; 283 } 284 int[] result = new int[length]; 285 int pos = 0; 286 for (int[] array : arrays) { 287 System.arraycopy(array, 0, result, pos, array.length); 288 pos += array.length; 289 } 290 return result; 291 } 292 293 /** 294 * Returns a big-endian representation of {@code value} in a 4-element byte array; equivalent to 295 * {@code ByteBuffer.allocate(4).putInt(value).array()}. For example, the input value {@code 296 * 0x12131415} would yield the byte array {@code {0x12, 0x13, 0x14, 0x15}}. 297 * 298 * <p>If you need to convert and concatenate several values (possibly even of different types), 299 * use a shared {@link java.nio.ByteBuffer} instance, or use {@link 300 * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer. 301 */ 302 public static byte[] toByteArray(int value) { 303 return new byte[] { 304 (byte) (value >> 24), (byte) (value >> 16), (byte) (value >> 8), (byte) value 305 }; 306 } 307 308 /** 309 * Returns the {@code int} value whose big-endian representation is stored in the first 4 bytes of 310 * {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getInt()}. For example, the input 311 * byte array {@code {0x12, 0x13, 0x14, 0x15, 0x33}} would yield the {@code int} value {@code 312 * 0x12131415}. 313 * 314 * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more 315 * flexibility at little cost in readability. 316 * 317 * @throws IllegalArgumentException if {@code bytes} has fewer than 4 elements 318 */ 319 public static int fromByteArray(byte[] bytes) { 320 checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES); 321 return fromBytes(bytes[0], bytes[1], bytes[2], bytes[3]); 322 } 323 324 /** 325 * Returns the {@code int} value whose byte representation is the given 4 bytes, in big-endian 326 * order; equivalent to {@code Ints.fromByteArray(new byte[] {b1, b2, b3, b4})}. 327 * 328 * @since 7.0 329 */ 330 public static int fromBytes(byte b1, byte b2, byte b3, byte b4) { 331 return b1 << 24 | (b2 & 0xFF) << 16 | (b3 & 0xFF) << 8 | (b4 & 0xFF); 332 } 333 334 private static final class IntConverter extends Converter<String, Integer> 335 implements Serializable { 336 static final IntConverter INSTANCE = new IntConverter(); 337 338 @Override 339 protected Integer doForward(String value) { 340 return Integer.decode(value); 341 } 342 343 @Override 344 protected String doBackward(Integer value) { 345 return value.toString(); 346 } 347 348 @Override 349 public String toString() { 350 return "Ints.stringConverter()"; 351 } 352 353 private Object readResolve() { 354 return INSTANCE; 355 } 356 357 private static final long serialVersionUID = 1; 358 } 359 360 /** 361 * Returns a serializable converter object that converts between strings and integers using {@link 362 * Integer#decode} and {@link Integer#toString()}. The returned converter throws {@link 363 * NumberFormatException} if the input string is invalid. 364 * 365 * <p><b>Warning:</b> please see {@link Integer#decode} to understand exactly how strings are 366 * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the 367 * value {@code 83}. 368 * 369 * @since 16.0 370 */ 371 @Beta 372 public static Converter<String, Integer> stringConverter() { 373 return IntConverter.INSTANCE; 374 } 375 376 /** 377 * Returns an array containing the same values as {@code array}, but guaranteed to be of a 378 * specified minimum length. If {@code array} already has a length of at least {@code minLength}, 379 * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is 380 * returned, containing the values of {@code array}, and zeroes in the remaining places. 381 * 382 * @param array the source array 383 * @param minLength the minimum length the returned array must guarantee 384 * @param padding an extra amount to "grow" the array by if growth is necessary 385 * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative 386 * @return an array containing the values of {@code array}, with guaranteed minimum length {@code 387 * minLength} 388 */ 389 public static int[] ensureCapacity(int[] array, int minLength, int padding) { 390 checkArgument(minLength >= 0, "Invalid minLength: %s", minLength); 391 checkArgument(padding >= 0, "Invalid padding: %s", padding); 392 return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array; 393 } 394 395 /** 396 * Returns a string containing the supplied {@code int} values separated by {@code separator}. For 397 * example, {@code join("-", 1, 2, 3)} returns the string {@code "1-2-3"}. 398 * 399 * @param separator the text that should appear between consecutive values in the resulting string 400 * (but not at the start or end) 401 * @param array an array of {@code int} values, possibly empty 402 */ 403 public static String join(String separator, int... array) { 404 checkNotNull(separator); 405 if (array.length == 0) { 406 return ""; 407 } 408 409 // For pre-sizing a builder, just get the right order of magnitude 410 StringBuilder builder = new StringBuilder(array.length * 5); 411 builder.append(array[0]); 412 for (int i = 1; i < array.length; i++) { 413 builder.append(separator).append(array[i]); 414 } 415 return builder.toString(); 416 } 417 418 /** 419 * Returns a comparator that compares two {@code int} arrays <a 420 * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it 421 * compares, using {@link #compare(int, int)}), the first pair of values that follow any common 422 * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For 423 * example, {@code [] < [1] < [1, 2] < [2]}. 424 * 425 * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays 426 * support only identity equality), but it is consistent with {@link Arrays#equals(int[], int[])}. 427 * 428 * @since 2.0 429 */ 430 public static Comparator<int[]> lexicographicalComparator() { 431 return LexicographicalComparator.INSTANCE; 432 } 433 434 private enum LexicographicalComparator implements Comparator<int[]> { 435 INSTANCE; 436 437 @Override 438 public int compare(int[] left, int[] right) { 439 int minLength = Math.min(left.length, right.length); 440 for (int i = 0; i < minLength; i++) { 441 int result = Ints.compare(left[i], right[i]); 442 if (result != 0) { 443 return result; 444 } 445 } 446 return left.length - right.length; 447 } 448 449 @Override 450 public String toString() { 451 return "Ints.lexicographicalComparator()"; 452 } 453 } 454 455 /** 456 * Sorts the elements of {@code array} in descending order. 457 * 458 * @since 23.1 459 */ 460 public static void sortDescending(int[] array) { 461 checkNotNull(array); 462 sortDescending(array, 0, array.length); 463 } 464 465 /** 466 * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} 467 * exclusive in descending order. 468 * 469 * @since 23.1 470 */ 471 public static void sortDescending(int[] array, int fromIndex, int toIndex) { 472 checkNotNull(array); 473 checkPositionIndexes(fromIndex, toIndex, array.length); 474 Arrays.sort(array, fromIndex, toIndex); 475 reverse(array, fromIndex, toIndex); 476 } 477 478 /** 479 * Reverses the elements of {@code array}. This is equivalent to {@code 480 * Collections.reverse(Ints.asList(array))}, but is likely to be more efficient. 481 * 482 * @since 23.1 483 */ 484 public static void reverse(int[] array) { 485 checkNotNull(array); 486 reverse(array, 0, array.length); 487 } 488 489 /** 490 * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} 491 * exclusive. This is equivalent to {@code 492 * Collections.reverse(Ints.asList(array).subList(fromIndex, toIndex))}, but is likely to be more 493 * efficient. 494 * 495 * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or 496 * {@code toIndex > fromIndex} 497 * @since 23.1 498 */ 499 public static void reverse(int[] array, int fromIndex, int toIndex) { 500 checkNotNull(array); 501 checkPositionIndexes(fromIndex, toIndex, array.length); 502 for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) { 503 int tmp = array[i]; 504 array[i] = array[j]; 505 array[j] = tmp; 506 } 507 } 508 509 /** 510 * Returns an array containing each value of {@code collection}, converted to a {@code int} value 511 * in the manner of {@link Number#intValue}. 512 * 513 * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}. 514 * Calling this method is as thread-safe as calling that method. 515 * 516 * @param collection a collection of {@code Number} instances 517 * @return an array containing the same values as {@code collection}, in the same order, converted 518 * to primitives 519 * @throws NullPointerException if {@code collection} or any of its elements is null 520 * @since 1.0 (parameter was {@code Collection<Integer>} before 12.0) 521 */ 522 public static int[] toArray(Collection<? extends Number> collection) { 523 if (collection instanceof IntArrayAsList) { 524 return ((IntArrayAsList) collection).toIntArray(); 525 } 526 527 Object[] boxedArray = collection.toArray(); 528 int len = boxedArray.length; 529 int[] array = new int[len]; 530 for (int i = 0; i < len; i++) { 531 // checkNotNull for GWT (do not optimize) 532 array[i] = ((Number) checkNotNull(boxedArray[i])).intValue(); 533 } 534 return array; 535 } 536 537 /** 538 * Returns a fixed-size list backed by the specified array, similar to {@link 539 * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to 540 * set a value to {@code null} will result in a {@link NullPointerException}. 541 * 542 * <p>The returned list maintains the values, but not the identities, of {@code Integer} objects 543 * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for 544 * the returned list is unspecified. 545 * 546 * <p><b>Note:</b> when possible, you should represent your data as an {@link ImmutableIntArray} 547 * instead, which has an {@link ImmutableIntArray#asList asList} view. 548 * 549 * @param backingArray the array to back the list 550 * @return a list view of the array 551 */ 552 public static List<Integer> asList(int... backingArray) { 553 if (backingArray.length == 0) { 554 return Collections.emptyList(); 555 } 556 return new IntArrayAsList(backingArray); 557 } 558 559 @GwtCompatible 560 private static class IntArrayAsList extends AbstractList<Integer> 561 implements RandomAccess, Serializable { 562 final int[] array; 563 final int start; 564 final int end; 565 566 IntArrayAsList(int[] array) { 567 this(array, 0, array.length); 568 } 569 570 IntArrayAsList(int[] array, int start, int end) { 571 this.array = array; 572 this.start = start; 573 this.end = end; 574 } 575 576 @Override 577 public int size() { 578 return end - start; 579 } 580 581 @Override 582 public boolean isEmpty() { 583 return false; 584 } 585 586 @Override 587 public Integer get(int index) { 588 checkElementIndex(index, size()); 589 return array[start + index]; 590 } 591 592 @Override 593 public Spliterator.OfInt spliterator() { 594 return Spliterators.spliterator(array, start, end, 0); 595 } 596 597 @Override 598 public boolean contains(Object target) { 599 // Overridden to prevent a ton of boxing 600 return (target instanceof Integer) && Ints.indexOf(array, (Integer) target, start, end) != -1; 601 } 602 603 @Override 604 public int indexOf(Object target) { 605 // Overridden to prevent a ton of boxing 606 if (target instanceof Integer) { 607 int i = Ints.indexOf(array, (Integer) target, start, end); 608 if (i >= 0) { 609 return i - start; 610 } 611 } 612 return -1; 613 } 614 615 @Override 616 public int lastIndexOf(Object target) { 617 // Overridden to prevent a ton of boxing 618 if (target instanceof Integer) { 619 int i = Ints.lastIndexOf(array, (Integer) target, start, end); 620 if (i >= 0) { 621 return i - start; 622 } 623 } 624 return -1; 625 } 626 627 @Override 628 public Integer set(int index, Integer element) { 629 checkElementIndex(index, size()); 630 int oldValue = array[start + index]; 631 // checkNotNull for GWT (do not optimize) 632 array[start + index] = checkNotNull(element); 633 return oldValue; 634 } 635 636 @Override 637 public List<Integer> subList(int fromIndex, int toIndex) { 638 int size = size(); 639 checkPositionIndexes(fromIndex, toIndex, size); 640 if (fromIndex == toIndex) { 641 return Collections.emptyList(); 642 } 643 return new IntArrayAsList(array, start + fromIndex, start + toIndex); 644 } 645 646 @Override 647 public boolean equals(@Nullable Object object) { 648 if (object == this) { 649 return true; 650 } 651 if (object instanceof IntArrayAsList) { 652 IntArrayAsList that = (IntArrayAsList) object; 653 int size = size(); 654 if (that.size() != size) { 655 return false; 656 } 657 for (int i = 0; i < size; i++) { 658 if (array[start + i] != that.array[that.start + i]) { 659 return false; 660 } 661 } 662 return true; 663 } 664 return super.equals(object); 665 } 666 667 @Override 668 public int hashCode() { 669 int result = 1; 670 for (int i = start; i < end; i++) { 671 result = 31 * result + Ints.hashCode(array[i]); 672 } 673 return result; 674 } 675 676 @Override 677 public String toString() { 678 StringBuilder builder = new StringBuilder(size() * 5); 679 builder.append('[').append(array[start]); 680 for (int i = start + 1; i < end; i++) { 681 builder.append(", ").append(array[i]); 682 } 683 return builder.append(']').toString(); 684 } 685 686 int[] toIntArray() { 687 return Arrays.copyOfRange(array, start, end); 688 } 689 690 private static final long serialVersionUID = 0; 691 } 692 693 /** 694 * Parses the specified string as a signed decimal integer value. The ASCII character {@code '-'} 695 * (<code>'\u002D'</code>) is recognized as the minus sign. 696 * 697 * <p>Unlike {@link Integer#parseInt(String)}, this method returns {@code null} instead of 698 * throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, 699 * and returns {@code null} if non-ASCII digits are present in the string. 700 * 701 * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even under JDK 7, despite 702 * the change to {@link Integer#parseInt(String)} for that version. 703 * 704 * @param string the string representation of an integer value 705 * @return the integer value represented by {@code string}, or {@code null} if {@code string} has 706 * a length of zero or cannot be parsed as an integer value 707 * @since 11.0 708 */ 709 @Beta 710 public static @Nullable Integer tryParse(String string) { 711 return tryParse(string, 10); 712 } 713 714 /** 715 * Parses the specified string as a signed integer value using the specified radix. The ASCII 716 * character {@code '-'} (<code>'\u002D'</code>) is recognized as the minus sign. 717 * 718 * <p>Unlike {@link Integer#parseInt(String, int)}, this method returns {@code null} instead of 719 * throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, 720 * and returns {@code null} if non-ASCII digits are present in the string. 721 * 722 * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even under JDK 7, despite 723 * the change to {@link Integer#parseInt(String, int)} for that version. 724 * 725 * @param string the string representation of an integer value 726 * @param radix the radix to use when parsing 727 * @return the integer value represented by {@code string} using {@code radix}, or {@code null} if 728 * {@code string} has a length of zero or cannot be parsed as an integer value 729 * @throws IllegalArgumentException if {@code radix < Character.MIN_RADIX} or {@code radix > 730 * Character.MAX_RADIX} 731 * @since 19.0 732 */ 733 @Beta 734 public static @Nullable Integer tryParse(String string, int radix) { 735 Long result = Longs.tryParse(string, radix); 736 if (result == null || result.longValue() != result.intValue()) { 737 return null; 738 } else { 739 return result.intValue(); 740 } 741 } 742}