The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 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 | |
| 17 | package android.util; |
| 18 | |
| 19 | import com.android.internal.util.ArrayUtils; |
Adam Lesinski | 776abc2 | 2014-03-07 11:30:59 -0500 | [diff] [blame^] | 20 | import com.android.internal.util.GrowingArrayUtils; |
| 21 | |
| 22 | import libcore.util.EmptyArray; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 23 | |
| 24 | /** |
| 25 | * SparseIntArrays map integers to integers. Unlike a normal array of integers, |
Dianne Hackborn | b993f41 | 2013-07-12 17:46:45 -0700 | [diff] [blame] | 26 | * there can be gaps in the indices. It is intended to be more memory efficient |
| 27 | * than using a HashMap to map Integers to Integers, both because it avoids |
| 28 | * auto-boxing keys and values and its data structure doesn't rely on an extra entry object |
| 29 | * for each mapping. |
| 30 | * |
| 31 | * <p>Note that this container keeps its mappings in an array data structure, |
| 32 | * using a binary search to find keys. The implementation is not intended to be appropriate for |
| 33 | * data structures |
| 34 | * that may contain large numbers of items. It is generally slower than a traditional |
| 35 | * HashMap, since lookups require a binary search and adds and removes require inserting |
| 36 | * and deleting entries in the array. For containers holding up to hundreds of items, |
| 37 | * the performance difference is not significant, less than 50%.</p> |
Flavio Lerda | 5771302 | 2013-09-08 18:04:58 +0100 | [diff] [blame] | 38 | * |
| 39 | * <p>It is possible to iterate over the items in this container using |
| 40 | * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using |
| 41 | * <code>keyAt(int)</code> with ascending values of the index will return the |
| 42 | * keys in ascending order, or the values corresponding to the keys in ascending |
Newton Allen | ebb4795 | 2013-11-21 13:27:10 -0800 | [diff] [blame] | 43 | * order in the case of <code>valueAt(int)</code>.</p> |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 44 | */ |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 45 | public class SparseIntArray implements Cloneable { |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 46 | private int[] mKeys; |
| 47 | private int[] mValues; |
| 48 | private int mSize; |
| 49 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 50 | /** |
| 51 | * Creates a new SparseIntArray containing no mappings. |
| 52 | */ |
| 53 | public SparseIntArray() { |
| 54 | this(10); |
| 55 | } |
| 56 | |
| 57 | /** |
| 58 | * Creates a new SparseIntArray containing no mappings that will not |
| 59 | * require any additional memory allocation to store the specified |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 60 | * number of mappings. If you supply an initial capacity of 0, the |
| 61 | * sparse array will be initialized with a light-weight representation |
| 62 | * not requiring any additional array allocations. |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 63 | */ |
| 64 | public SparseIntArray(int initialCapacity) { |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 65 | if (initialCapacity == 0) { |
Adam Lesinski | 776abc2 | 2014-03-07 11:30:59 -0500 | [diff] [blame^] | 66 | mKeys = EmptyArray.INT; |
| 67 | mValues = EmptyArray.INT; |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 68 | } else { |
Adam Lesinski | 776abc2 | 2014-03-07 11:30:59 -0500 | [diff] [blame^] | 69 | mKeys = ArrayUtils.newUnpaddedIntArray(initialCapacity); |
| 70 | mValues = new int[mKeys.length]; |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 71 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 72 | mSize = 0; |
| 73 | } |
| 74 | |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 75 | @Override |
| 76 | public SparseIntArray clone() { |
| 77 | SparseIntArray clone = null; |
| 78 | try { |
| 79 | clone = (SparseIntArray) super.clone(); |
| 80 | clone.mKeys = mKeys.clone(); |
| 81 | clone.mValues = mValues.clone(); |
| 82 | } catch (CloneNotSupportedException cnse) { |
| 83 | /* ignore */ |
| 84 | } |
| 85 | return clone; |
| 86 | } |
| 87 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 88 | /** |
| 89 | * Gets the int mapped from the specified key, or <code>0</code> |
| 90 | * if no such mapping has been made. |
| 91 | */ |
| 92 | public int get(int key) { |
| 93 | return get(key, 0); |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Gets the int mapped from the specified key, or the specified value |
| 98 | * if no such mapping has been made. |
| 99 | */ |
| 100 | public int get(int key, int valueIfKeyNotFound) { |
Dianne Hackborn | 3e82ba1 | 2013-07-16 13:23:55 -0700 | [diff] [blame] | 101 | int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 102 | |
| 103 | if (i < 0) { |
| 104 | return valueIfKeyNotFound; |
| 105 | } else { |
| 106 | return mValues[i]; |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * Removes the mapping from the specified key, if there was any. |
| 112 | */ |
| 113 | public void delete(int key) { |
Dianne Hackborn | 3e82ba1 | 2013-07-16 13:23:55 -0700 | [diff] [blame] | 114 | int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 115 | |
| 116 | if (i >= 0) { |
| 117 | removeAt(i); |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * Removes the mapping at the given index. |
| 123 | */ |
| 124 | public void removeAt(int index) { |
| 125 | System.arraycopy(mKeys, index + 1, mKeys, index, mSize - (index + 1)); |
| 126 | System.arraycopy(mValues, index + 1, mValues, index, mSize - (index + 1)); |
| 127 | mSize--; |
| 128 | } |
| 129 | |
| 130 | /** |
| 131 | * Adds a mapping from the specified key to the specified value, |
| 132 | * replacing the previous mapping from the specified key if there |
| 133 | * was one. |
| 134 | */ |
| 135 | public void put(int key, int value) { |
Dianne Hackborn | 3e82ba1 | 2013-07-16 13:23:55 -0700 | [diff] [blame] | 136 | int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 137 | |
| 138 | if (i >= 0) { |
| 139 | mValues[i] = value; |
| 140 | } else { |
| 141 | i = ~i; |
| 142 | |
Adam Lesinski | 776abc2 | 2014-03-07 11:30:59 -0500 | [diff] [blame^] | 143 | mKeys = GrowingArrayUtils.insert(mKeys, mSize, i, key); |
| 144 | mValues = GrowingArrayUtils.insert(mValues, mSize, i, value); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 145 | mSize++; |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | /** |
| 150 | * Returns the number of key-value mappings that this SparseIntArray |
| 151 | * currently stores. |
| 152 | */ |
| 153 | public int size() { |
| 154 | return mSize; |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Given an index in the range <code>0...size()-1</code>, returns |
| 159 | * the key from the <code>index</code>th key-value mapping that this |
Flavio Lerda | 5771302 | 2013-09-08 18:04:58 +0100 | [diff] [blame] | 160 | * SparseIntArray stores. |
| 161 | * |
| 162 | * <p>The keys corresponding to indices in ascending order are guaranteed to |
| 163 | * be in ascending order, e.g., <code>keyAt(0)</code> will return the |
| 164 | * smallest key and <code>keyAt(size()-1)</code> will return the largest |
| 165 | * key.</p> |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 166 | */ |
| 167 | public int keyAt(int index) { |
| 168 | return mKeys[index]; |
| 169 | } |
Flavio Lerda | 5771302 | 2013-09-08 18:04:58 +0100 | [diff] [blame] | 170 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 171 | /** |
| 172 | * Given an index in the range <code>0...size()-1</code>, returns |
| 173 | * the value from the <code>index</code>th key-value mapping that this |
Flavio Lerda | 5771302 | 2013-09-08 18:04:58 +0100 | [diff] [blame] | 174 | * SparseIntArray stores. |
| 175 | * |
| 176 | * <p>The values corresponding to indices in ascending order are guaranteed |
| 177 | * to be associated with keys in ascending order, e.g., |
| 178 | * <code>valueAt(0)</code> will return the value associated with the |
| 179 | * smallest key and <code>valueAt(size()-1)</code> will return the value |
| 180 | * associated with the largest key.</p> |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 181 | */ |
| 182 | public int valueAt(int index) { |
| 183 | return mValues[index]; |
| 184 | } |
| 185 | |
| 186 | /** |
| 187 | * Returns the index for which {@link #keyAt} would return the |
| 188 | * specified key, or a negative number if the specified |
| 189 | * key is not mapped. |
| 190 | */ |
| 191 | public int indexOfKey(int key) { |
Dianne Hackborn | 3e82ba1 | 2013-07-16 13:23:55 -0700 | [diff] [blame] | 192 | return ContainerHelpers.binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 193 | } |
| 194 | |
| 195 | /** |
| 196 | * Returns an index for which {@link #valueAt} would return the |
| 197 | * specified key, or a negative number if no keys map to the |
| 198 | * specified value. |
| 199 | * Beware that this is a linear search, unlike lookups by key, |
| 200 | * and that multiple keys can map to the same value and this will |
| 201 | * find only one of them. |
| 202 | */ |
| 203 | public int indexOfValue(int value) { |
| 204 | for (int i = 0; i < mSize; i++) |
| 205 | if (mValues[i] == value) |
| 206 | return i; |
| 207 | |
| 208 | return -1; |
| 209 | } |
| 210 | |
| 211 | /** |
| 212 | * Removes all key-value mappings from this SparseIntArray. |
| 213 | */ |
| 214 | public void clear() { |
| 215 | mSize = 0; |
| 216 | } |
| 217 | |
| 218 | /** |
| 219 | * Puts a key/value pair into the array, optimizing for the case where |
| 220 | * the key is greater than all existing keys in the array. |
| 221 | */ |
| 222 | public void append(int key, int value) { |
| 223 | if (mSize != 0 && key <= mKeys[mSize - 1]) { |
| 224 | put(key, value); |
| 225 | return; |
| 226 | } |
| 227 | |
Adam Lesinski | 776abc2 | 2014-03-07 11:30:59 -0500 | [diff] [blame^] | 228 | mKeys = GrowingArrayUtils.append(mKeys, mSize, key); |
| 229 | mValues = GrowingArrayUtils.append(mValues, mSize, value); |
| 230 | mSize++; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 231 | } |
Dianne Hackborn | 3e82ba1 | 2013-07-16 13:23:55 -0700 | [diff] [blame] | 232 | |
| 233 | /** |
| 234 | * {@inheritDoc} |
| 235 | * |
| 236 | * <p>This implementation composes a string by iterating over its mappings. |
| 237 | */ |
| 238 | @Override |
| 239 | public String toString() { |
| 240 | if (size() <= 0) { |
| 241 | return "{}"; |
| 242 | } |
| 243 | |
| 244 | StringBuilder buffer = new StringBuilder(mSize * 28); |
| 245 | buffer.append('{'); |
| 246 | for (int i=0; i<mSize; i++) { |
| 247 | if (i > 0) { |
| 248 | buffer.append(", "); |
| 249 | } |
| 250 | int key = keyAt(i); |
| 251 | buffer.append(key); |
| 252 | buffer.append('='); |
| 253 | int value = valueAt(i); |
| 254 | buffer.append(value); |
| 255 | } |
| 256 | buffer.append('}'); |
| 257 | return buffer.toString(); |
| 258 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 259 | } |