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A library jar that provides APIs for Applications written for the Google Android Platform.

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/*
 * Copyright (C) 2011 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;
import com.android.internal.util.GrowingArrayUtils;

import libcore.util.EmptyArray;

/**
 * SparseLongArrays map integers to longs.  Unlike a normal array of longs,
 * there can be gaps in the indices.  It is intended to be more memory efficient
 * than using a HashMap to map Integers to Longs, both because it avoids
 * auto-boxing keys and values and its data structure doesn't rely on an extra entry object
 * for each mapping.
 *
 * 

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%.

* *

It is possible to iterate over the items in this container using * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using * keyAt(int) 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 valueAt(int).

*/ public class SparseLongArray implements Cloneable { private int[] mKeys; private long[] mValues; private int mSize; /** * Creates a new SparseLongArray containing no mappings. */ public SparseLongArray() { this(10); } /** * Creates a new SparseLongArray 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 SparseLongArray(int initialCapacity) { if (initialCapacity == 0) { mKeys = EmptyArray.INT; mValues = EmptyArray.LONG; } else { mValues = ArrayUtils.newUnpaddedLongArray(initialCapacity); mKeys = new int[mValues.length]; } mSize = 0; } @Override public SparseLongArray clone() { SparseLongArray clone = null; try { clone = (SparseLongArray) super.clone(); clone.mKeys = mKeys.clone(); clone.mValues = mValues.clone(); } catch (CloneNotSupportedException cnse) { /* ignore */ } return clone; } /** * Gets the long mapped from the specified key, or 0 * if no such mapping has been made. */ public long get(int key) { return get(key, 0); } /** * Gets the long mapped from the specified key, or the specified value * if no such mapping has been made. */ public long get(int key, long 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, long value) { int i = ContainerHelpers.binarySearch(mKeys, mSize, key); if (i >= 0) { mValues[i] = value; } else { i = ~i; mKeys = GrowingArrayUtils.insert(mKeys, mSize, i, key); mValues = GrowingArrayUtils.insert(mValues, mSize, 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 0...size()-1, returns * the key from the indexth key-value mapping that this * SparseLongArray stores. * *

The keys corresponding to indices in ascending order are guaranteed to * be in ascending order, e.g., keyAt(0) will return the * smallest key and keyAt(size()-1) will return the largest * key.

*/ public int keyAt(int index) { return mKeys[index]; } /** * Given an index in the range 0...size()-1, returns * the value from the indexth key-value mapping that this * SparseLongArray stores. * *

The values corresponding to indices in ascending order are guaranteed * to be associated with keys in ascending order, e.g., * valueAt(0) will return the value associated with the * smallest key and valueAt(size()-1) will return the value * associated with the largest key.

*/ public long 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(long 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, long value) { if (mSize != 0 && key <= mKeys[mSize - 1]) { put(key, value); return; } mKeys = GrowingArrayUtils.append(mKeys, mSize, key); mValues = GrowingArrayUtils.append(mValues, mSize, value); mSize++; } /** * {@inheritDoc} * *

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 0) { buffer.append(", "); } int key = keyAt(i); buffer.append(key); buffer.append('='); long value = valueAt(i); buffer.append(value); } buffer.append('}'); return buffer.toString(); } }





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