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.annotations.GwtIncompatible; 025import com.google.common.base.Converter; 026import java.io.Serializable; 027import java.util.AbstractList; 028import java.util.Arrays; 029import java.util.Collection; 030import java.util.Collections; 031import java.util.Comparator; 032import java.util.List; 033import java.util.RandomAccess; 034import javax.annotation.CheckForNull; 035 036/** 037 * Static utility methods pertaining to {@code int} primitives, that are not already found in either 038 * {@link Integer} or {@link Arrays}. 039 * 040 * <p>See the Guava User Guide article on <a 041 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>. 042 * 043 * @author Kevin Bourrillion 044 * @since 1.0 045 */ 046@GwtCompatible(emulated = true) 047@ElementTypesAreNonnullByDefault 048public final class Ints extends IntsMethodsForWeb { 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 @GwtIncompatible( 224 "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.") 225 public static int min(int... array) { 226 checkArgument(array.length > 0); 227 int min = array[0]; 228 for (int i = 1; i < array.length; i++) { 229 if (array[i] < min) { 230 min = array[i]; 231 } 232 } 233 return min; 234 } 235 236 /** 237 * Returns the greatest value present in {@code array}. 238 * 239 * @param array a <i>nonempty</i> array of {@code int} values 240 * @return the value present in {@code array} that is greater than or equal to every other value 241 * in the array 242 * @throws IllegalArgumentException if {@code array} is empty 243 */ 244 @GwtIncompatible( 245 "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.") 246 public static int max(int... array) { 247 checkArgument(array.length > 0); 248 int max = array[0]; 249 for (int i = 1; i < array.length; i++) { 250 if (array[i] > max) { 251 max = array[i]; 252 } 253 } 254 return max; 255 } 256 257 /** 258 * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}. 259 * 260 * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned 261 * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code 262 * value} is greater than {@code max}, {@code max} is returned. 263 * 264 * @param value the {@code int} value to constrain 265 * @param min the lower bound (inclusive) of the range to constrain {@code value} to 266 * @param max the upper bound (inclusive) of the range to constrain {@code value} to 267 * @throws IllegalArgumentException if {@code min > max} 268 * @since 21.0 269 */ 270 @Beta 271 public static int constrainToRange(int value, int min, int max) { 272 checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max); 273 return Math.min(Math.max(value, min), max); 274 } 275 276 /** 277 * Returns the values from each provided array combined into a single array. For example, {@code 278 * concat(new int[] {a, b}, new int[] {}, new int[] {c}} returns the array {@code {a, b, c}}. 279 * 280 * @param arrays zero or more {@code int} arrays 281 * @return a single array containing all the values from the source arrays, in order 282 */ 283 public static int[] concat(int[]... arrays) { 284 int length = 0; 285 for (int[] array : arrays) { 286 length += array.length; 287 } 288 int[] result = new int[length]; 289 int pos = 0; 290 for (int[] array : arrays) { 291 System.arraycopy(array, 0, result, pos, array.length); 292 pos += array.length; 293 } 294 return result; 295 } 296 297 /** 298 * Returns a big-endian representation of {@code value} in a 4-element byte array; equivalent to 299 * {@code ByteBuffer.allocate(4).putInt(value).array()}. For example, the input value {@code 300 * 0x12131415} would yield the byte array {@code {0x12, 0x13, 0x14, 0x15}}. 301 * 302 * <p>If you need to convert and concatenate several values (possibly even of different types), 303 * use a shared {@link java.nio.ByteBuffer} instance, or use {@link 304 * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer. 305 */ 306 public static byte[] toByteArray(int value) { 307 return new byte[] { 308 (byte) (value >> 24), (byte) (value >> 16), (byte) (value >> 8), (byte) value 309 }; 310 } 311 312 /** 313 * Returns the {@code int} value whose big-endian representation is stored in the first 4 bytes of 314 * {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getInt()}. For example, the input 315 * byte array {@code {0x12, 0x13, 0x14, 0x15, 0x33}} would yield the {@code int} value {@code 316 * 0x12131415}. 317 * 318 * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more 319 * flexibility at little cost in readability. 320 * 321 * @throws IllegalArgumentException if {@code bytes} has fewer than 4 elements 322 */ 323 public static int fromByteArray(byte[] bytes) { 324 checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES); 325 return fromBytes(bytes[0], bytes[1], bytes[2], bytes[3]); 326 } 327 328 /** 329 * Returns the {@code int} value whose byte representation is the given 4 bytes, in big-endian 330 * order; equivalent to {@code Ints.fromByteArray(new byte[] {b1, b2, b3, b4})}. 331 * 332 * @since 7.0 333 */ 334 public static int fromBytes(byte b1, byte b2, byte b3, byte b4) { 335 return b1 << 24 | (b2 & 0xFF) << 16 | (b3 & 0xFF) << 8 | (b4 & 0xFF); 336 } 337 338 private static final class IntConverter extends Converter<String, Integer> 339 implements Serializable { 340 static final IntConverter INSTANCE = new IntConverter(); 341 342 @Override 343 protected Integer doForward(String value) { 344 return Integer.decode(value); 345 } 346 347 @Override 348 protected String doBackward(Integer value) { 349 return value.toString(); 350 } 351 352 @Override 353 public String toString() { 354 return "Ints.stringConverter()"; 355 } 356 357 private Object readResolve() { 358 return INSTANCE; 359 } 360 361 private static final long serialVersionUID = 1; 362 } 363 364 /** 365 * Returns a serializable converter object that converts between strings and integers using {@link 366 * Integer#decode} and {@link Integer#toString()}. The returned converter throws {@link 367 * NumberFormatException} if the input string is invalid. 368 * 369 * <p><b>Warning:</b> please see {@link Integer#decode} to understand exactly how strings are 370 * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the 371 * value {@code 83}. 372 * 373 * @since 16.0 374 */ 375 @Beta 376 public static Converter<String, Integer> stringConverter() { 377 return IntConverter.INSTANCE; 378 } 379 380 /** 381 * Returns an array containing the same values as {@code array}, but guaranteed to be of a 382 * specified minimum length. If {@code array} already has a length of at least {@code minLength}, 383 * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is 384 * returned, containing the values of {@code array}, and zeroes in the remaining places. 385 * 386 * @param array the source array 387 * @param minLength the minimum length the returned array must guarantee 388 * @param padding an extra amount to "grow" the array by if growth is necessary 389 * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative 390 * @return an array containing the values of {@code array}, with guaranteed minimum length {@code 391 * minLength} 392 */ 393 public static int[] ensureCapacity(int[] array, int minLength, int padding) { 394 checkArgument(minLength >= 0, "Invalid minLength: %s", minLength); 395 checkArgument(padding >= 0, "Invalid padding: %s", padding); 396 return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array; 397 } 398 399 /** 400 * Returns a string containing the supplied {@code int} values separated by {@code separator}. For 401 * example, {@code join("-", 1, 2, 3)} returns the string {@code "1-2-3"}. 402 * 403 * @param separator the text that should appear between consecutive values in the resulting string 404 * (but not at the start or end) 405 * @param array an array of {@code int} values, possibly empty 406 */ 407 public static String join(String separator, int... array) { 408 checkNotNull(separator); 409 if (array.length == 0) { 410 return ""; 411 } 412 413 // For pre-sizing a builder, just get the right order of magnitude 414 StringBuilder builder = new StringBuilder(array.length * 5); 415 builder.append(array[0]); 416 for (int i = 1; i < array.length; i++) { 417 builder.append(separator).append(array[i]); 418 } 419 return builder.toString(); 420 } 421 422 /** 423 * Returns a comparator that compares two {@code int} arrays <a 424 * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it 425 * compares, using {@link #compare(int, int)}), the first pair of values that follow any common 426 * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For 427 * example, {@code [] < [1] < [1, 2] < [2]}. 428 * 429 * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays 430 * support only identity equality), but it is consistent with {@link Arrays#equals(int[], int[])}. 431 * 432 * @since 2.0 433 */ 434 public static Comparator<int[]> lexicographicalComparator() { 435 return LexicographicalComparator.INSTANCE; 436 } 437 438 private enum LexicographicalComparator implements Comparator<int[]> { 439 INSTANCE; 440 441 @Override 442 public int compare(int[] left, int[] right) { 443 int minLength = Math.min(left.length, right.length); 444 for (int i = 0; i < minLength; i++) { 445 int result = Ints.compare(left[i], right[i]); 446 if (result != 0) { 447 return result; 448 } 449 } 450 return left.length - right.length; 451 } 452 453 @Override 454 public String toString() { 455 return "Ints.lexicographicalComparator()"; 456 } 457 } 458 459 /** 460 * Sorts the elements of {@code array} in descending order. 461 * 462 * @since 23.1 463 */ 464 public static void sortDescending(int[] array) { 465 checkNotNull(array); 466 sortDescending(array, 0, array.length); 467 } 468 469 /** 470 * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} 471 * exclusive in descending order. 472 * 473 * @since 23.1 474 */ 475 public static void sortDescending(int[] array, int fromIndex, int toIndex) { 476 checkNotNull(array); 477 checkPositionIndexes(fromIndex, toIndex, array.length); 478 Arrays.sort(array, fromIndex, toIndex); 479 reverse(array, fromIndex, toIndex); 480 } 481 482 /** 483 * Reverses the elements of {@code array}. This is equivalent to {@code 484 * Collections.reverse(Ints.asList(array))}, but is likely to be more efficient. 485 * 486 * @since 23.1 487 */ 488 public static void reverse(int[] array) { 489 checkNotNull(array); 490 reverse(array, 0, array.length); 491 } 492 493 /** 494 * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} 495 * exclusive. This is equivalent to {@code 496 * Collections.reverse(Ints.asList(array).subList(fromIndex, toIndex))}, but is likely to be more 497 * efficient. 498 * 499 * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or 500 * {@code toIndex > fromIndex} 501 * @since 23.1 502 */ 503 public static void reverse(int[] array, int fromIndex, int toIndex) { 504 checkNotNull(array); 505 checkPositionIndexes(fromIndex, toIndex, array.length); 506 for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) { 507 int tmp = array[i]; 508 array[i] = array[j]; 509 array[j] = tmp; 510 } 511 } 512 513 /** 514 * Returns an array containing each value of {@code collection}, converted to a {@code int} value 515 * in the manner of {@link Number#intValue}. 516 * 517 * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}. 518 * Calling this method is as thread-safe as calling that method. 519 * 520 * @param collection a collection of {@code Number} instances 521 * @return an array containing the same values as {@code collection}, in the same order, converted 522 * to primitives 523 * @throws NullPointerException if {@code collection} or any of its elements is null 524 * @since 1.0 (parameter was {@code Collection<Integer>} before 12.0) 525 */ 526 public static int[] toArray(Collection<? extends Number> collection) { 527 if (collection instanceof IntArrayAsList) { 528 return ((IntArrayAsList) collection).toIntArray(); 529 } 530 531 Object[] boxedArray = collection.toArray(); 532 int len = boxedArray.length; 533 int[] array = new int[len]; 534 for (int i = 0; i < len; i++) { 535 // checkNotNull for GWT (do not optimize) 536 array[i] = ((Number) checkNotNull(boxedArray[i])).intValue(); 537 } 538 return array; 539 } 540 541 /** 542 * Returns a fixed-size list backed by the specified array, similar to {@link 543 * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to 544 * set a value to {@code null} will result in a {@link NullPointerException}. 545 * 546 * <p>The returned list maintains the values, but not the identities, of {@code Integer} objects 547 * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for 548 * the returned list is unspecified. 549 * 550 * <p><b>Note:</b> when possible, you should represent your data as an {@link ImmutableIntArray} 551 * instead, which has an {@link ImmutableIntArray#asList asList} view. 552 * 553 * @param backingArray the array to back the list 554 * @return a list view of the array 555 */ 556 public static List<Integer> asList(int... backingArray) { 557 if (backingArray.length == 0) { 558 return Collections.emptyList(); 559 } 560 return new IntArrayAsList(backingArray); 561 } 562 563 @GwtCompatible 564 private static class IntArrayAsList extends AbstractList<Integer> 565 implements RandomAccess, Serializable { 566 final int[] array; 567 final int start; 568 final int end; 569 570 IntArrayAsList(int[] array) { 571 this(array, 0, array.length); 572 } 573 574 IntArrayAsList(int[] array, int start, int end) { 575 this.array = array; 576 this.start = start; 577 this.end = end; 578 } 579 580 @Override 581 public int size() { 582 return end - start; 583 } 584 585 @Override 586 public boolean isEmpty() { 587 return false; 588 } 589 590 @Override 591 public Integer get(int index) { 592 checkElementIndex(index, size()); 593 return array[start + index]; 594 } 595 596 @Override 597 public boolean contains(@CheckForNull Object target) { 598 // Overridden to prevent a ton of boxing 599 return (target instanceof Integer) && Ints.indexOf(array, (Integer) target, start, end) != -1; 600 } 601 602 @Override 603 public int indexOf(@CheckForNull Object target) { 604 // Overridden to prevent a ton of boxing 605 if (target instanceof Integer) { 606 int i = Ints.indexOf(array, (Integer) target, start, end); 607 if (i >= 0) { 608 return i - start; 609 } 610 } 611 return -1; 612 } 613 614 @Override 615 public int lastIndexOf(@CheckForNull Object target) { 616 // Overridden to prevent a ton of boxing 617 if (target instanceof Integer) { 618 int i = Ints.lastIndexOf(array, (Integer) target, start, end); 619 if (i >= 0) { 620 return i - start; 621 } 622 } 623 return -1; 624 } 625 626 @Override 627 public Integer set(int index, Integer element) { 628 checkElementIndex(index, size()); 629 int oldValue = array[start + index]; 630 // checkNotNull for GWT (do not optimize) 631 array[start + index] = checkNotNull(element); 632 return oldValue; 633 } 634 635 @Override 636 public List<Integer> subList(int fromIndex, int toIndex) { 637 int size = size(); 638 checkPositionIndexes(fromIndex, toIndex, size); 639 if (fromIndex == toIndex) { 640 return Collections.emptyList(); 641 } 642 return new IntArrayAsList(array, start + fromIndex, start + toIndex); 643 } 644 645 @Override 646 public boolean equals(@CheckForNull Object object) { 647 if (object == this) { 648 return true; 649 } 650 if (object instanceof IntArrayAsList) { 651 IntArrayAsList that = (IntArrayAsList) object; 652 int size = size(); 653 if (that.size() != size) { 654 return false; 655 } 656 for (int i = 0; i < size; i++) { 657 if (array[start + i] != that.array[that.start + i]) { 658 return false; 659 } 660 } 661 return true; 662 } 663 return super.equals(object); 664 } 665 666 @Override 667 public int hashCode() { 668 int result = 1; 669 for (int i = start; i < end; i++) { 670 result = 31 * result + Ints.hashCode(array[i]); 671 } 672 return result; 673 } 674 675 @Override 676 public String toString() { 677 StringBuilder builder = new StringBuilder(size() * 5); 678 builder.append('[').append(array[start]); 679 for (int i = start + 1; i < end; i++) { 680 builder.append(", ").append(array[i]); 681 } 682 return builder.append(']').toString(); 683 } 684 685 int[] toIntArray() { 686 return Arrays.copyOfRange(array, start, end); 687 } 688 689 private static final long serialVersionUID = 0; 690 } 691 692 /** 693 * Parses the specified string as a signed decimal integer value. The ASCII character {@code '-'} 694 * (<code>'\u002D'</code>) is recognized as the minus sign. 695 * 696 * <p>Unlike {@link Integer#parseInt(String)}, this method returns {@code null} instead of 697 * throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, 698 * and returns {@code null} if non-ASCII digits are present in the string. 699 * 700 * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even under JDK 7, despite 701 * the change to {@link Integer#parseInt(String)} for that version. 702 * 703 * @param string the string representation of an integer value 704 * @return the integer value represented by {@code string}, or {@code null} if {@code string} has 705 * a length of zero or cannot be parsed as an integer value 706 * @throws NullPointerException if {@code string} is {@code null} 707 * @since 11.0 708 */ 709 @Beta 710 @CheckForNull 711 public static Integer tryParse(String string) { 712 return tryParse(string, 10); 713 } 714 715 /** 716 * Parses the specified string as a signed integer value using the specified radix. The ASCII 717 * character {@code '-'} (<code>'\u002D'</code>) is recognized as the minus sign. 718 * 719 * <p>Unlike {@link Integer#parseInt(String, int)}, this method returns {@code null} instead of 720 * throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, 721 * and returns {@code null} if non-ASCII digits are present in the string. 722 * 723 * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even under JDK 7, despite 724 * the change to {@link Integer#parseInt(String, int)} for that version. 725 * 726 * @param string the string representation of an integer value 727 * @param radix the radix to use when parsing 728 * @return the integer value represented by {@code string} using {@code radix}, or {@code null} if 729 * {@code string} has a length of zero or cannot be parsed as an integer value 730 * @throws IllegalArgumentException if {@code radix < Character.MIN_RADIX} or {@code radix > 731 * Character.MAX_RADIX} 732 * @throws NullPointerException if {@code string} is {@code null} 733 * @since 19.0 734 */ 735 @Beta 736 @CheckForNull 737 public static Integer tryParse(String string, int radix) { 738 Long result = Longs.tryParse(string, radix); 739 if (result == null || result.longValue() != result.intValue()) { 740 return null; 741 } else { 742 return result.intValue(); 743 } 744 } 745}