252 lines
7.0 KiB
Java
252 lines
7.0 KiB
Java
/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.util;
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import com.android.internal.util.ArrayUtils;
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/**
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* SparseIntArrays map integers to integers. Unlike a normal array of integers,
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* there can be gaps in the indices. It is intended to be more efficient
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* than using a HashMap to map Integers to Integers.
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*/
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public class SparseIntArray {
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/**
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* Creates a new SparseIntArray containing no mappings.
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*/
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public SparseIntArray() {
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this(10);
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}
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/**
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* Creates a new SparseIntArray containing no mappings that will not
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* require any additional memory allocation to store the specified
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* number of mappings.
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*/
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public SparseIntArray(int initialCapacity) {
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initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity);
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mKeys = new int[initialCapacity];
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mValues = new int[initialCapacity];
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mSize = 0;
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}
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/**
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* Gets the int mapped from the specified key, or <code>0</code>
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* if no such mapping has been made.
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*/
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public int get(int key) {
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return get(key, 0);
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}
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/**
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* Gets the int mapped from the specified key, or the specified value
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* if no such mapping has been made.
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*/
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public int get(int key, int valueIfKeyNotFound) {
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int i = binarySearch(mKeys, 0, mSize, key);
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if (i < 0) {
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return valueIfKeyNotFound;
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} else {
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return mValues[i];
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}
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}
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/**
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* Removes the mapping from the specified key, if there was any.
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*/
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public void delete(int key) {
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int i = binarySearch(mKeys, 0, mSize, key);
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if (i >= 0) {
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removeAt(i);
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}
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}
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/**
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* Removes the mapping at the given index.
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*/
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public void removeAt(int index) {
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System.arraycopy(mKeys, index + 1, mKeys, index, mSize - (index + 1));
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System.arraycopy(mValues, index + 1, mValues, index, mSize - (index + 1));
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mSize--;
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}
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/**
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* Adds a mapping from the specified key to the specified value,
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* replacing the previous mapping from the specified key if there
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* was one.
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*/
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public void put(int key, int value) {
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int i = binarySearch(mKeys, 0, mSize, key);
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if (i >= 0) {
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mValues[i] = value;
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} else {
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i = ~i;
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if (mSize >= mKeys.length) {
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int n = ArrayUtils.idealIntArraySize(mSize + 1);
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int[] nkeys = new int[n];
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int[] nvalues = new int[n];
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// Log.e("SparseIntArray", "grow " + mKeys.length + " to " + n);
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System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
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System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
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mKeys = nkeys;
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mValues = nvalues;
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}
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if (mSize - i != 0) {
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// Log.e("SparseIntArray", "move " + (mSize - i));
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System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i);
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System.arraycopy(mValues, i, mValues, i + 1, mSize - i);
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}
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mKeys[i] = key;
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mValues[i] = value;
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mSize++;
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}
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}
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/**
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* Returns the number of key-value mappings that this SparseIntArray
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* currently stores.
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*/
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public int size() {
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return mSize;
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}
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/**
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* Given an index in the range <code>0...size()-1</code>, returns
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* the key from the <code>index</code>th key-value mapping that this
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* SparseIntArray stores.
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*/
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public int keyAt(int index) {
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return mKeys[index];
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}
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/**
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* Given an index in the range <code>0...size()-1</code>, returns
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* the value from the <code>index</code>th key-value mapping that this
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* SparseIntArray stores.
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*/
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public int valueAt(int index) {
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return mValues[index];
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}
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/**
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* Returns the index for which {@link #keyAt} would return the
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* specified key, or a negative number if the specified
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* key is not mapped.
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*/
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public int indexOfKey(int key) {
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return binarySearch(mKeys, 0, mSize, key);
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}
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/**
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* Returns an index for which {@link #valueAt} would return the
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* specified key, or a negative number if no keys map to the
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* specified value.
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* Beware that this is a linear search, unlike lookups by key,
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* and that multiple keys can map to the same value and this will
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* find only one of them.
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*/
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public int indexOfValue(int value) {
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for (int i = 0; i < mSize; i++)
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if (mValues[i] == value)
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return i;
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return -1;
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}
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/**
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* Removes all key-value mappings from this SparseIntArray.
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*/
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public void clear() {
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mSize = 0;
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}
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/**
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* Puts a key/value pair into the array, optimizing for the case where
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* the key is greater than all existing keys in the array.
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*/
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public void append(int key, int value) {
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if (mSize != 0 && key <= mKeys[mSize - 1]) {
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put(key, value);
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return;
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}
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int pos = mSize;
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if (pos >= mKeys.length) {
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int n = ArrayUtils.idealIntArraySize(pos + 1);
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int[] nkeys = new int[n];
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int[] nvalues = new int[n];
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// Log.e("SparseIntArray", "grow " + mKeys.length + " to " + n);
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System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
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System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
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mKeys = nkeys;
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mValues = nvalues;
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}
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mKeys[pos] = key;
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mValues[pos] = value;
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mSize = pos + 1;
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}
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private static int binarySearch(int[] a, int start, int len, int key) {
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int high = start + len, low = start - 1, guess;
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while (high - low > 1) {
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guess = (high + low) / 2;
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if (a[guess] < key)
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low = guess;
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else
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high = guess;
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}
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if (high == start + len)
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return ~(start + len);
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else if (a[high] == key)
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return high;
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else
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return ~high;
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}
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private void checkIntegrity() {
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for (int i = 1; i < mSize; i++) {
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if (mKeys[i] <= mKeys[i - 1]) {
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for (int j = 0; j < mSize; j++) {
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Log.e("FAIL", j + ": " + mKeys[j] + " -> " + mValues[j]);
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}
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throw new RuntimeException();
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}
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}
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}
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private int[] mKeys;
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private int[] mValues;
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private int mSize;
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}
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