| /* |
| * Copyright (C) 2006 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.internal.util; |
| |
| import java.lang.reflect.Array; |
| import java.util.Collection; |
| |
| // XXX these should be changed to reflect the actual memory allocator we use. |
| // it looks like right now objects want to be powers of 2 minus 8 |
| // and the array size eats another 4 bytes |
| |
| /** |
| * ArrayUtils contains some methods that you can call to find out |
| * the most efficient increments by which to grow arrays. |
| */ |
| public class ArrayUtils |
| { |
| private static Object[] EMPTY = new Object[0]; |
| private static final int CACHE_SIZE = 73; |
| private static Object[] sCache = new Object[CACHE_SIZE]; |
| |
| private ArrayUtils() { /* cannot be instantiated */ } |
| |
| public static int idealByteArraySize(int need) { |
| for (int i = 4; i < 32; i++) |
| if (need <= (1 << i) - 12) |
| return (1 << i) - 12; |
| |
| return need; |
| } |
| |
| public static int idealBooleanArraySize(int need) { |
| return idealByteArraySize(need); |
| } |
| |
| public static int idealShortArraySize(int need) { |
| return idealByteArraySize(need * 2) / 2; |
| } |
| |
| public static int idealCharArraySize(int need) { |
| return idealByteArraySize(need * 2) / 2; |
| } |
| |
| public static int idealIntArraySize(int need) { |
| return idealByteArraySize(need * 4) / 4; |
| } |
| |
| public static int idealFloatArraySize(int need) { |
| return idealByteArraySize(need * 4) / 4; |
| } |
| |
| public static int idealObjectArraySize(int need) { |
| return idealByteArraySize(need * 4) / 4; |
| } |
| |
| public static int idealLongArraySize(int need) { |
| return idealByteArraySize(need * 8) / 8; |
| } |
| |
| /** |
| * Checks if the beginnings of two byte arrays are equal. |
| * |
| * @param array1 the first byte array |
| * @param array2 the second byte array |
| * @param length the number of bytes to check |
| * @return true if they're equal, false otherwise |
| */ |
| public static boolean equals(byte[] array1, byte[] array2, int length) { |
| if (array1 == array2) { |
| return true; |
| } |
| if (array1 == null || array2 == null || array1.length < length || array2.length < length) { |
| return false; |
| } |
| for (int i = 0; i < length; i++) { |
| if (array1[i] != array2[i]) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /** |
| * Returns an empty array of the specified type. The intent is that |
| * it will return the same empty array every time to avoid reallocation, |
| * although this is not guaranteed. |
| */ |
| public static <T> T[] emptyArray(Class<T> kind) { |
| if (kind == Object.class) { |
| return (T[]) EMPTY; |
| } |
| |
| int bucket = ((System.identityHashCode(kind) / 8) & 0x7FFFFFFF) % CACHE_SIZE; |
| Object cache = sCache[bucket]; |
| |
| if (cache == null || cache.getClass().getComponentType() != kind) { |
| cache = Array.newInstance(kind, 0); |
| sCache[bucket] = cache; |
| |
| // Log.e("cache", "new empty " + kind.getName() + " at " + bucket); |
| } |
| |
| return (T[]) cache; |
| } |
| |
| /** |
| * Checks that value is present as at least one of the elements of the array. |
| * @param array the array to check in |
| * @param value the value to check for |
| * @return true if the value is present in the array |
| */ |
| public static <T> boolean contains(T[] array, T value) { |
| for (T element : array) { |
| if (element == null) { |
| if (value == null) return true; |
| } else { |
| if (value != null && element.equals(value)) return true; |
| } |
| } |
| return false; |
| } |
| |
| public static boolean contains(int[] array, int value) { |
| for (int element : array) { |
| if (element == value) { |
| return true; |
| } |
| } |
| return false; |
| } |
| } |