| /* |
| * 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 android.util; |
| |
| import com.android.internal.util.ArrayUtils; |
| |
| /** |
| * SparseIntArrays map integers to integers. Unlike a normal array of integers, |
| * there can be gaps in the indices. It is intended to be more memory efficient |
| * than using a HashMap to map Integers to Integers, both because it avoids |
| * auto-boxing keys and values and its data structure doesn't rely on an extra entry object |
| * for each mapping. |
| * |
| * <p>Note that this container keeps its mappings in an array data structure, |
| * using a binary search to find keys. The implementation is not intended to be appropriate for |
| * data structures |
| * that may contain large numbers of items. It is generally slower than a traditional |
| * HashMap, since lookups require a binary search and adds and removes require inserting |
| * and deleting entries in the array. For containers holding up to hundreds of items, |
| * the performance difference is not significant, less than 50%.</p> |
| * |
| * <p>It is possible to iterate over the items in this container using |
| * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using |
| * <code>keyAt(int)</code> with ascending values of the index will return the |
| * keys in ascending order, or the values corresponding to the keys in ascending |
| * order in the case of <code>valueAt(int)</code>.</p> |
| */ |
| public class SparseIntArray implements Cloneable { |
| private int[] mKeys; |
| private int[] mValues; |
| private int mSize; |
| |
| /** |
| * Creates a new SparseIntArray containing no mappings. |
| */ |
| public SparseIntArray() { |
| this(10); |
| } |
| |
| /** |
| * Creates a new SparseIntArray containing no mappings that will not |
| * require any additional memory allocation to store the specified |
| * number of mappings. If you supply an initial capacity of 0, the |
| * sparse array will be initialized with a light-weight representation |
| * not requiring any additional array allocations. |
| */ |
| public SparseIntArray(int initialCapacity) { |
| if (initialCapacity == 0) { |
| mKeys = ContainerHelpers.EMPTY_INTS; |
| mValues = ContainerHelpers.EMPTY_INTS; |
| } else { |
| initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity); |
| mKeys = new int[initialCapacity]; |
| mValues = new int[initialCapacity]; |
| } |
| mSize = 0; |
| } |
| |
| @Override |
| public SparseIntArray clone() { |
| SparseIntArray clone = null; |
| try { |
| clone = (SparseIntArray) super.clone(); |
| clone.mKeys = mKeys.clone(); |
| clone.mValues = mValues.clone(); |
| } catch (CloneNotSupportedException cnse) { |
| /* ignore */ |
| } |
| return clone; |
| } |
| |
| /** |
| * Gets the int mapped from the specified key, or <code>0</code> |
| * if no such mapping has been made. |
| */ |
| public int get(int key) { |
| return get(key, 0); |
| } |
| |
| /** |
| * Gets the int mapped from the specified key, or the specified value |
| * if no such mapping has been made. |
| */ |
| public int get(int key, int valueIfKeyNotFound) { |
| int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
| |
| if (i < 0) { |
| return valueIfKeyNotFound; |
| } else { |
| return mValues[i]; |
| } |
| } |
| |
| /** |
| * Removes the mapping from the specified key, if there was any. |
| */ |
| public void delete(int key) { |
| int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
| |
| if (i >= 0) { |
| removeAt(i); |
| } |
| } |
| |
| /** |
| * Removes the mapping at the given index. |
| */ |
| public void removeAt(int index) { |
| System.arraycopy(mKeys, index + 1, mKeys, index, mSize - (index + 1)); |
| System.arraycopy(mValues, index + 1, mValues, index, mSize - (index + 1)); |
| mSize--; |
| } |
| |
| /** |
| * Adds a mapping from the specified key to the specified value, |
| * replacing the previous mapping from the specified key if there |
| * was one. |
| */ |
| public void put(int key, int value) { |
| int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
| |
| if (i >= 0) { |
| mValues[i] = value; |
| } else { |
| i = ~i; |
| |
| if (mSize >= mKeys.length) { |
| int n = ArrayUtils.idealIntArraySize(mSize + 1); |
| |
| int[] nkeys = new int[n]; |
| int[] nvalues = new int[n]; |
| |
| // Log.e("SparseIntArray", "grow " + mKeys.length + " to " + n); |
| System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); |
| System.arraycopy(mValues, 0, nvalues, 0, mValues.length); |
| |
| mKeys = nkeys; |
| mValues = nvalues; |
| } |
| |
| if (mSize - i != 0) { |
| // Log.e("SparseIntArray", "move " + (mSize - i)); |
| System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i); |
| System.arraycopy(mValues, i, mValues, i + 1, mSize - i); |
| } |
| |
| mKeys[i] = key; |
| mValues[i] = value; |
| mSize++; |
| } |
| } |
| |
| /** |
| * Returns the number of key-value mappings that this SparseIntArray |
| * currently stores. |
| */ |
| public int size() { |
| return mSize; |
| } |
| |
| /** |
| * Given an index in the range <code>0...size()-1</code>, returns |
| * the key from the <code>index</code>th key-value mapping that this |
| * SparseIntArray stores. |
| * |
| * <p>The keys corresponding to indices in ascending order are guaranteed to |
| * be in ascending order, e.g., <code>keyAt(0)</code> will return the |
| * smallest key and <code>keyAt(size()-1)</code> will return the largest |
| * key.</p> |
| */ |
| public int keyAt(int index) { |
| return mKeys[index]; |
| } |
| |
| /** |
| * Given an index in the range <code>0...size()-1</code>, returns |
| * the value from the <code>index</code>th key-value mapping that this |
| * SparseIntArray stores. |
| * |
| * <p>The values corresponding to indices in ascending order are guaranteed |
| * to be associated with keys in ascending order, e.g., |
| * <code>valueAt(0)</code> will return the value associated with the |
| * smallest key and <code>valueAt(size()-1)</code> will return the value |
| * associated with the largest key.</p> |
| */ |
| public int valueAt(int index) { |
| return mValues[index]; |
| } |
| |
| /** |
| * Returns the index for which {@link #keyAt} would return the |
| * specified key, or a negative number if the specified |
| * key is not mapped. |
| */ |
| public int indexOfKey(int key) { |
| return ContainerHelpers.binarySearch(mKeys, mSize, key); |
| } |
| |
| /** |
| * Returns an index for which {@link #valueAt} would return the |
| * specified key, or a negative number if no keys map to the |
| * specified value. |
| * Beware that this is a linear search, unlike lookups by key, |
| * and that multiple keys can map to the same value and this will |
| * find only one of them. |
| */ |
| public int indexOfValue(int value) { |
| for (int i = 0; i < mSize; i++) |
| if (mValues[i] == value) |
| return i; |
| |
| return -1; |
| } |
| |
| /** |
| * Removes all key-value mappings from this SparseIntArray. |
| */ |
| public void clear() { |
| mSize = 0; |
| } |
| |
| /** |
| * Puts a key/value pair into the array, optimizing for the case where |
| * the key is greater than all existing keys in the array. |
| */ |
| public void append(int key, int value) { |
| if (mSize != 0 && key <= mKeys[mSize - 1]) { |
| put(key, value); |
| return; |
| } |
| |
| int pos = mSize; |
| if (pos >= mKeys.length) { |
| int n = ArrayUtils.idealIntArraySize(pos + 1); |
| |
| int[] nkeys = new int[n]; |
| int[] nvalues = new int[n]; |
| |
| // Log.e("SparseIntArray", "grow " + mKeys.length + " to " + n); |
| System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); |
| System.arraycopy(mValues, 0, nvalues, 0, mValues.length); |
| |
| mKeys = nkeys; |
| mValues = nvalues; |
| } |
| |
| mKeys[pos] = key; |
| mValues[pos] = value; |
| mSize = pos + 1; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * <p>This implementation composes a string by iterating over its mappings. |
| */ |
| @Override |
| public String toString() { |
| if (size() <= 0) { |
| return "{}"; |
| } |
| |
| StringBuilder buffer = new StringBuilder(mSize * 28); |
| buffer.append('{'); |
| for (int i=0; i<mSize; i++) { |
| if (i > 0) { |
| buffer.append(", "); |
| } |
| int key = keyAt(i); |
| buffer.append(key); |
| buffer.append('='); |
| int value = valueAt(i); |
| buffer.append(value); |
| } |
| buffer.append('}'); |
| return buffer.toString(); |
| } |
| } |