ArrayUtils.java revision 5217cacbd9f382068bb9e176cd5a0b15388a335c
1/* 2 * Copyright (C) 2006 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package com.android.internal.util; 18 19import android.annotation.NonNull; 20import android.annotation.Nullable; 21import android.util.ArraySet; 22 23import dalvik.system.VMRuntime; 24 25import libcore.util.EmptyArray; 26 27import java.lang.reflect.Array; 28import java.util.ArrayList; 29import java.util.Objects; 30 31/** 32 * ArrayUtils contains some methods that you can call to find out 33 * the most efficient increments by which to grow arrays. 34 */ 35public class ArrayUtils { 36 private static final int CACHE_SIZE = 73; 37 private static Object[] sCache = new Object[CACHE_SIZE]; 38 39 private ArrayUtils() { /* cannot be instantiated */ } 40 41 public static byte[] newUnpaddedByteArray(int minLen) { 42 return (byte[])VMRuntime.getRuntime().newUnpaddedArray(byte.class, minLen); 43 } 44 45 public static char[] newUnpaddedCharArray(int minLen) { 46 return (char[])VMRuntime.getRuntime().newUnpaddedArray(char.class, minLen); 47 } 48 49 public static int[] newUnpaddedIntArray(int minLen) { 50 return (int[])VMRuntime.getRuntime().newUnpaddedArray(int.class, minLen); 51 } 52 53 public static boolean[] newUnpaddedBooleanArray(int minLen) { 54 return (boolean[])VMRuntime.getRuntime().newUnpaddedArray(boolean.class, minLen); 55 } 56 57 public static long[] newUnpaddedLongArray(int minLen) { 58 return (long[])VMRuntime.getRuntime().newUnpaddedArray(long.class, minLen); 59 } 60 61 public static float[] newUnpaddedFloatArray(int minLen) { 62 return (float[])VMRuntime.getRuntime().newUnpaddedArray(float.class, minLen); 63 } 64 65 public static Object[] newUnpaddedObjectArray(int minLen) { 66 return (Object[])VMRuntime.getRuntime().newUnpaddedArray(Object.class, minLen); 67 } 68 69 @SuppressWarnings("unchecked") 70 public static <T> T[] newUnpaddedArray(Class<T> clazz, int minLen) { 71 return (T[])VMRuntime.getRuntime().newUnpaddedArray(clazz, minLen); 72 } 73 74 /** 75 * Checks if the beginnings of two byte arrays are equal. 76 * 77 * @param array1 the first byte array 78 * @param array2 the second byte array 79 * @param length the number of bytes to check 80 * @return true if they're equal, false otherwise 81 */ 82 public static boolean equals(byte[] array1, byte[] array2, int length) { 83 if (length < 0) { 84 throw new IllegalArgumentException(); 85 } 86 87 if (array1 == array2) { 88 return true; 89 } 90 if (array1 == null || array2 == null || array1.length < length || array2.length < length) { 91 return false; 92 } 93 for (int i = 0; i < length; i++) { 94 if (array1[i] != array2[i]) { 95 return false; 96 } 97 } 98 return true; 99 } 100 101 /** 102 * Returns an empty array of the specified type. The intent is that 103 * it will return the same empty array every time to avoid reallocation, 104 * although this is not guaranteed. 105 */ 106 @SuppressWarnings("unchecked") 107 public static <T> T[] emptyArray(Class<T> kind) { 108 if (kind == Object.class) { 109 return (T[]) EmptyArray.OBJECT; 110 } 111 112 int bucket = (kind.hashCode() & 0x7FFFFFFF) % CACHE_SIZE; 113 Object cache = sCache[bucket]; 114 115 if (cache == null || cache.getClass().getComponentType() != kind) { 116 cache = Array.newInstance(kind, 0); 117 sCache[bucket] = cache; 118 119 // Log.e("cache", "new empty " + kind.getName() + " at " + bucket); 120 } 121 122 return (T[]) cache; 123 } 124 125 /** 126 * Checks if given array is null or has zero elements. 127 */ 128 public static <T> boolean isEmpty(@Nullable T[] array) { 129 return array == null || array.length == 0; 130 } 131 132 /** 133 * Checks if given array is null or has zero elements. 134 */ 135 public static boolean isEmpty(@Nullable int[] array) { 136 return array == null || array.length == 0; 137 } 138 139 /** 140 * Checks if given array is null or has zero elements. 141 */ 142 public static boolean isEmpty(@Nullable long[] array) { 143 return array == null || array.length == 0; 144 } 145 146 /** 147 * Checks if given array is null or has zero elements. 148 */ 149 public static boolean isEmpty(@Nullable byte[] array) { 150 return array == null || array.length == 0; 151 } 152 153 /** 154 * Checks that value is present as at least one of the elements of the array. 155 * @param array the array to check in 156 * @param value the value to check for 157 * @return true if the value is present in the array 158 */ 159 public static <T> boolean contains(@Nullable T[] array, T value) { 160 return indexOf(array, value) != -1; 161 } 162 163 /** 164 * Return first index of {@code value} in {@code array}, or {@code -1} if 165 * not found. 166 */ 167 public static <T> int indexOf(@Nullable T[] array, T value) { 168 if (array == null) return -1; 169 for (int i = 0; i < array.length; i++) { 170 if (Objects.equals(array[i], value)) return i; 171 } 172 return -1; 173 } 174 175 /** 176 * Test if all {@code check} items are contained in {@code array}. 177 */ 178 public static <T> boolean containsAll(@Nullable T[] array, T[] check) { 179 if (check == null) return true; 180 for (T checkItem : check) { 181 if (!contains(array, checkItem)) { 182 return false; 183 } 184 } 185 return true; 186 } 187 188 public static boolean contains(@Nullable int[] array, int value) { 189 if (array == null) return false; 190 for (int element : array) { 191 if (element == value) { 192 return true; 193 } 194 } 195 return false; 196 } 197 198 public static boolean contains(@Nullable long[] array, long value) { 199 if (array == null) return false; 200 for (long element : array) { 201 if (element == value) { 202 return true; 203 } 204 } 205 return false; 206 } 207 208 public static long total(@Nullable long[] array) { 209 long total = 0; 210 if (array != null) { 211 for (long value : array) { 212 total += value; 213 } 214 } 215 return total; 216 } 217 218 /** 219 * Adds value to given array if not already present, providing set-like 220 * behavior. 221 */ 222 @SuppressWarnings("unchecked") 223 public static @NonNull <T> T[] appendElement(Class<T> kind, @Nullable T[] array, T element) { 224 final T[] result; 225 final int end; 226 if (array != null) { 227 if (contains(array, element)) return array; 228 end = array.length; 229 result = (T[])Array.newInstance(kind, end + 1); 230 System.arraycopy(array, 0, result, 0, end); 231 } else { 232 end = 0; 233 result = (T[])Array.newInstance(kind, 1); 234 } 235 result[end] = element; 236 return result; 237 } 238 239 /** 240 * Removes value from given array if present, providing set-like behavior. 241 */ 242 @SuppressWarnings("unchecked") 243 public static @Nullable <T> T[] removeElement(Class<T> kind, @Nullable T[] array, T element) { 244 if (array != null) { 245 if (!contains(array, element)) return array; 246 final int length = array.length; 247 for (int i = 0; i < length; i++) { 248 if (Objects.equals(array[i], element)) { 249 if (length == 1) { 250 return null; 251 } 252 T[] result = (T[])Array.newInstance(kind, length - 1); 253 System.arraycopy(array, 0, result, 0, i); 254 System.arraycopy(array, i + 1, result, i, length - i - 1); 255 return result; 256 } 257 } 258 } 259 return array; 260 } 261 262 /** 263 * Adds value to given array if not already present, providing set-like 264 * behavior. 265 */ 266 public static @NonNull int[] appendInt(@Nullable int[] cur, int val) { 267 if (cur == null) { 268 return new int[] { val }; 269 } 270 final int N = cur.length; 271 for (int i = 0; i < N; i++) { 272 if (cur[i] == val) { 273 return cur; 274 } 275 } 276 int[] ret = new int[N + 1]; 277 System.arraycopy(cur, 0, ret, 0, N); 278 ret[N] = val; 279 return ret; 280 } 281 282 /** 283 * Removes value from given array if present, providing set-like behavior. 284 */ 285 public static @Nullable int[] removeInt(@Nullable int[] cur, int val) { 286 if (cur == null) { 287 return null; 288 } 289 final int N = cur.length; 290 for (int i = 0; i < N; i++) { 291 if (cur[i] == val) { 292 int[] ret = new int[N - 1]; 293 if (i > 0) { 294 System.arraycopy(cur, 0, ret, 0, i); 295 } 296 if (i < (N - 1)) { 297 System.arraycopy(cur, i + 1, ret, i, N - i - 1); 298 } 299 return ret; 300 } 301 } 302 return cur; 303 } 304 305 /** 306 * Removes value from given array if present, providing set-like behavior. 307 */ 308 public static @Nullable String[] removeString(@Nullable String[] cur, String val) { 309 if (cur == null) { 310 return null; 311 } 312 final int N = cur.length; 313 for (int i = 0; i < N; i++) { 314 if (Objects.equals(cur[i], val)) { 315 String[] ret = new String[N - 1]; 316 if (i > 0) { 317 System.arraycopy(cur, 0, ret, 0, i); 318 } 319 if (i < (N - 1)) { 320 System.arraycopy(cur, i + 1, ret, i, N - i - 1); 321 } 322 return ret; 323 } 324 } 325 return cur; 326 } 327 328 /** 329 * Adds value to given array if not already present, providing set-like 330 * behavior. 331 */ 332 public static @NonNull long[] appendLong(@Nullable long[] cur, long val) { 333 if (cur == null) { 334 return new long[] { val }; 335 } 336 final int N = cur.length; 337 for (int i = 0; i < N; i++) { 338 if (cur[i] == val) { 339 return cur; 340 } 341 } 342 long[] ret = new long[N + 1]; 343 System.arraycopy(cur, 0, ret, 0, N); 344 ret[N] = val; 345 return ret; 346 } 347 348 /** 349 * Removes value from given array if present, providing set-like behavior. 350 */ 351 public static @Nullable long[] removeLong(@Nullable long[] cur, long val) { 352 if (cur == null) { 353 return null; 354 } 355 final int N = cur.length; 356 for (int i = 0; i < N; i++) { 357 if (cur[i] == val) { 358 long[] ret = new long[N - 1]; 359 if (i > 0) { 360 System.arraycopy(cur, 0, ret, 0, i); 361 } 362 if (i < (N - 1)) { 363 System.arraycopy(cur, i + 1, ret, i, N - i - 1); 364 } 365 return ret; 366 } 367 } 368 return cur; 369 } 370 371 public static @Nullable long[] cloneOrNull(@Nullable long[] array) { 372 return (array != null) ? array.clone() : null; 373 } 374 375 public static @NonNull <T> ArraySet<T> add(@Nullable ArraySet<T> cur, T val) { 376 if (cur == null) { 377 cur = new ArraySet<>(); 378 } 379 cur.add(val); 380 return cur; 381 } 382 383 public static @Nullable <T> ArraySet<T> remove(@Nullable ArraySet<T> cur, T val) { 384 if (cur == null) { 385 return null; 386 } 387 cur.remove(val); 388 if (cur.isEmpty()) { 389 return null; 390 } else { 391 return cur; 392 } 393 } 394 395 public static <T> boolean contains(@Nullable ArraySet<T> cur, T val) { 396 return (cur != null) ? cur.contains(val) : false; 397 } 398 399 public static @NonNull <T> ArrayList<T> add(@Nullable ArrayList<T> cur, T val) { 400 if (cur == null) { 401 cur = new ArrayList<>(); 402 } 403 cur.add(val); 404 return cur; 405 } 406 407 public static @Nullable <T> ArrayList<T> remove(@Nullable ArrayList<T> cur, T val) { 408 if (cur == null) { 409 return null; 410 } 411 cur.remove(val); 412 if (cur.isEmpty()) { 413 return null; 414 } else { 415 return cur; 416 } 417 } 418 419 public static <T> boolean contains(@Nullable ArrayList<T> cur, T val) { 420 return (cur != null) ? cur.contains(val) : false; 421 } 422 423 /** 424 * Returns true if the two ArrayLists are equal with respect to the objects they contain. 425 * The objects must be in the same order and be reference equal (== not .equals()). 426 */ 427 public static <T> boolean referenceEquals(ArrayList<T> a, ArrayList<T> b) { 428 if (a == b) { 429 return true; 430 } 431 432 final int sizeA = a.size(); 433 final int sizeB = b.size(); 434 if (a == null || b == null || sizeA != sizeB) { 435 return false; 436 } 437 438 boolean diff = false; 439 for (int i = 0; i < sizeA && !diff; i++) { 440 diff |= a.get(i) != b.get(i); 441 } 442 return !diff; 443 } 444} 445