android-34/android/util/SparseArray.java - platform/prebuilts/fullsdk/sources - Git at Google

 /*
  * 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 android.annotation.Nullable;
 import android.compat.annotation.UnsupportedAppUsage;

 import com.android.internal.util.ArrayUtils;
 import com.android.internal.util.GrowingArrayUtils;

 import libcore.util.EmptyArray;

 import java.util.Objects;

 /**
  * <code>SparseArray</code> maps integers to Objects and, unlike a normal array of Objects,
  * its indices can contain gaps. <code>SparseArray</code> is intended to be more memory-efficient
  * than a
  * <a href="/reference/java/util/HashMap"><code>HashMap</code></a>, because it avoids
  * auto-boxing keys 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
  * <code>HashMap</code> because 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 less than 50%.
  *
  * <p>To help with performance, the container includes an optimization when removing
  * keys: instead of compacting its array immediately, it leaves the removed entry marked
  * as deleted. The entry can then be re-used for the same key or compacted later in
  * a single garbage collection of all removed entries. This garbage collection
  * must be performed whenever the array needs to be grown, or when the map size or
  * entry values are retrieved.
  *
  * <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 returns the
  * keys in ascending order. In the case of <code>valueAt(int)</code>, the
  * values corresponding to the keys are returned in ascending order.
  */
 public class SparseArray<E> implements Cloneable {
     private static final Object DELETED = new Object();
     private boolean mGarbage = false;

     @UnsupportedAppUsage(maxTargetSdk = 28) // Use keyAt(int)
     private int[] mKeys;
     @UnsupportedAppUsage(maxTargetSdk = 28) // Use valueAt(int), setValueAt(int, E)
     private Object[] mValues;
     @UnsupportedAppUsage(maxTargetSdk = 28) // Use size()
     private int mSize;

     /**
      * Creates a new SparseArray containing no mappings.
      */
     public SparseArray() {
         this(0);
     }

     /**
      * Creates a new SparseArray 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 SparseArray(int initialCapacity) {
         if (initialCapacity == 0) {
             mKeys = EmptyArray.INT;
             mValues = EmptyArray.OBJECT;
         } else {
             mValues = ArrayUtils.newUnpaddedObjectArray(initialCapacity);
             mKeys = new int[mValues.length];
         }
         mSize = 0;
     }

     @Override
     @SuppressWarnings("unchecked")
     public SparseArray<E> clone() {
         SparseArray<E> clone = null;
         try {
             clone = (SparseArray<E>) super.clone();
             clone.mKeys = mKeys.clone();
             clone.mValues = mValues.clone();
         } catch (CloneNotSupportedException cnse) {
             /* ignore */
         }
         return clone;
     }

     /**
      * Returns true if the key exists in the array. This is equivalent to
      * {@link #indexOfKey(int)} >= 0.
      *
      * @param key Potential key in the mapping
      * @return true if the key is defined in the mapping
      */
     public boolean contains(int key) {
         return indexOfKey(key) >= 0;
     }

     /**
      * Gets the Object mapped from the specified key, or <code>null</code>
      * if no such mapping has been made.
      */
     public E get(int key) {
         return get(key, null);
     }

     /**
      * Gets the Object mapped from the specified key, or the specified Object
      * if no such mapping has been made.
      */
     @SuppressWarnings("unchecked")
     public E get(int key, E valueIfKeyNotFound) {
         int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

         if (i < 0 || mValues[i] == DELETED) {
             return valueIfKeyNotFound;
         } else {
             return (E) 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) {
             if (mValues[i] != DELETED) {
                 mValues[i] = DELETED;
                 mGarbage = true;
             }
         }
     }

     /**
      * @hide
      * Removes the mapping from the specified key, if there was any, returning the old value.
      */
     public E removeReturnOld(int key) {
         int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

         if (i >= 0) {
             if (mValues[i] != DELETED) {
                 final E old = (E) mValues[i];
                 mValues[i] = DELETED;
                 mGarbage = true;
                 return old;
             }
         }
         return null;
     }

     /**
      * Alias for {@link #delete(int)}.
      */
     public void remove(int key) {
         delete(key);
     }

     /**
      * Removes the mapping at the specified index.
      *
      * <p>For indices outside of the range <code>0...size()-1</code>,
      * the behavior is undefined for apps targeting {@link android.os.Build.VERSION_CODES#P} and
      * earlier, and an {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
      * {@link android.os.Build.VERSION_CODES#Q} and later.</p>
      */
     public void removeAt(int index) {
         if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
             // The array might be slightly bigger than mSize, in which case, indexing won't fail.
             // Check if exception should be thrown outside of the critical path.
             throw new ArrayIndexOutOfBoundsException(index);
         }
         if (mValues[index] != DELETED) {
             mValues[index] = DELETED;
             mGarbage = true;
         }
     }

     /**
      * Remove a range of mappings as a batch.
      *
      * @param index Index to begin at
      * @param size Number of mappings to remove
      *
      * <p>For indices outside of the range <code>0...size()-1</code>,
      * the behavior is undefined.</p>
      */
     public void removeAtRange(int index, int size) {
         final int end = Math.min(mSize, index + size);
         for (int i = index; i < end; i++) {
             removeAt(i);
         }
     }

     private void gc() {
         // Log.e("SparseArray", "gc start with " + mSize);

         int n = mSize;
         int o = 0;
         int[] keys = mKeys;
         Object[] values = mValues;

         for (int i = 0; i < n; i++) {
             Object val = values[i];

             if (val != DELETED) {
                 if (i != o) {
                     keys[o] = keys[i];
                     values[o] = val;
                     values[i] = null;
                 }

                 o++;
             }
         }

         mGarbage = false;
         mSize = o;

         // Log.e("SparseArray", "gc end with " + mSize);
     }

     /**
      * Alias for {@link #put(int, Object)} to support Kotlin [index]= operator.
      * @see #put(int, Object)
      */
     public void set(int key, E value) {
         put(key, value);
     }

     /**
      * 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, E value) {
         int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

         if (i >= 0) {
             mValues[i] = value;
         } else {
             i = ~i;

             if (i < mSize && mValues[i] == DELETED) {
                 mKeys[i] = key;
                 mValues[i] = value;
                 return;
             }

             if (mGarbage && mSize >= mKeys.length) {
                 gc();

                 // Search again because indices may have changed.
                 i = ~ContainerHelpers.binarySearch(mKeys, mSize, key);
             }

             mKeys = GrowingArrayUtils.insert(mKeys, mSize, i, key);
             mValues = GrowingArrayUtils.insert(mValues, mSize, i, value);
             mSize++;
         }
     }

     /**
      * Returns the number of key-value mappings that this SparseArray
      * currently stores.
      */
     public int size() {
         if (mGarbage) {
             gc();
         }

         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
      * SparseArray 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>
      *
      * <p>For indices outside of the range <code>0...size()-1</code>,
      * the behavior is undefined for apps targeting {@link android.os.Build.VERSION_CODES#P} and
      * earlier, and an {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
      * {@link android.os.Build.VERSION_CODES#Q} and later.</p>
      */
     public int keyAt(int index) {
         if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
             // The array might be slightly bigger than mSize, in which case, indexing won't fail.
             // Check if exception should be thrown outside of the critical path.
             throw new ArrayIndexOutOfBoundsException(index);
         }
         if (mGarbage) {
             gc();
         }

         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
      * SparseArray 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>
      *
      * <p>For indices outside of the range <code>0...size()-1</code>,
      * the behavior is undefined for apps targeting {@link android.os.Build.VERSION_CODES#P} and
      * earlier, and an {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
      * {@link android.os.Build.VERSION_CODES#Q} and later.</p>
      */
     @SuppressWarnings("unchecked")
     public E valueAt(int index) {
         if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
             // The array might be slightly bigger than mSize, in which case, indexing won't fail.
             // Check if exception should be thrown outside of the critical path.
             throw new ArrayIndexOutOfBoundsException(index);
         }
         if (mGarbage) {
             gc();
         }

         return (E) mValues[index];
     }

     /**
      * Given an index in the range <code>0...size()-1</code>, sets a new
      * value for the <code>index</code>th key-value mapping that this
      * SparseArray stores.
      *
      * <p>For indices outside of the range <code>0...size()-1</code>, the behavior is undefined for
      * apps targeting {@link android.os.Build.VERSION_CODES#P} and earlier, and an
      * {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
      * {@link android.os.Build.VERSION_CODES#Q} and later.</p>
      */
     public void setValueAt(int index, E value) {
         if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
             // The array might be slightly bigger than mSize, in which case, indexing won't fail.
             // Check if exception should be thrown outside of the critical path.
             throw new ArrayIndexOutOfBoundsException(index);
         }
         if (mGarbage) {
             gc();
         }

         mValues[index] = value;
     }

     /**
      * 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) {
         if (mGarbage) {
             gc();
         }

         return ContainerHelpers.binarySearch(mKeys, mSize, key);
     }

     /**
      * Returns an index for which {@link #valueAt} would return the
      * specified value, or a negative number if no keys map to the
      * specified value.
      * <p>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.
      * <p>Note also that unlike most collections' {@code indexOf} methods,
      * this method compares values using {@code ==} rather than {@code equals}.
      */
     public int indexOfValue(E value) {
         if (mGarbage) {
             gc();
         }

         for (int i = 0; i < mSize; i++) {
             if (mValues[i] == value) {
                 return i;
             }
         }

         return -1;
     }

     /**
      * Returns an index for which {@link #valueAt} would return the
      * specified value, or a negative number if no keys map to the
      * specified value.
      * <p>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.
      * <p>Note also that this method uses {@code equals} unlike {@code indexOfValue}.
      * @hide
      */
     public int indexOfValueByValue(E value) {
         if (mGarbage) {
             gc();
         }

         for (int i = 0; i < mSize; i++) {
             if (value == null) {
                 if (mValues[i] == null) {
                     return i;
                 }
             } else {
                 if (value.equals(mValues[i])) {
                     return i;
                 }
             }
         }
         return -1;
     }

     /**
      * Removes all key-value mappings from this SparseArray.
      */
     public void clear() {
         int n = mSize;
         Object[] values = mValues;

         for (int i = 0; i < n; i++) {
             values[i] = null;
         }

         mSize = 0;
         mGarbage = false;
     }

     /**
      * 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, E value) {
         if (mSize != 0 && key <= mKeys[mSize - 1]) {
             put(key, value);
             return;
         }

         if (mGarbage && mSize >= mKeys.length) {
             gc();
         }

         mKeys = GrowingArrayUtils.append(mKeys, mSize, key);
         mValues = GrowingArrayUtils.append(mValues, mSize, value);
         mSize++;
     }

     /**
      * {@inheritDoc}
      *
      * <p>This implementation composes a string by iterating over its mappings. If
      * this map contains itself as a value, the string "(this Map)"
      * will appear in its place.
      */
     @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('=');
             Object value = valueAt(i);
             if (value != this) {
                 buffer.append(value);
             } else {
                 buffer.append("(this Map)");
             }
         }
         buffer.append('}');
         return buffer.toString();
     }

     /**
      * Compares the contents of this {@link SparseArray} to the specified {@link SparseArray}.
      *
      * For backwards compatibility reasons, {@link Object#equals(Object)} cannot be implemented,
      * so this serves as a manually invoked alternative.
      */
     public boolean contentEquals(@Nullable SparseArray<?> other) {
         if (other == null) {
             return false;
         }

         int size = size();
         if (size != other.size()) {
             return false;
         }

         // size() calls above took care about gc() compaction.
         for (int index = 0; index < size; index++) {
             if (mKeys[index] != other.mKeys[index]
                     || !Objects.equals(mValues[index], other.mValues[index])) {
                 return false;
             }
         }

         return true;
     }

     /**
      * Returns a hash code value for the contents of this {@link SparseArray}, combining the
      * {@link Objects#hashCode(Object)} result of all its keys and values.
      *
      * For backwards compatibility, {@link Object#hashCode()} cannot be implemented, so this serves
      * as a manually invoked alternative.
      */
     public int contentHashCode() {
         int hash = 0;
         int size = size();
         // size() call above took care about gc() compaction.
         for (int index = 0; index < size; index++) {
             int key = mKeys[index];
             E value = (E) mValues[index];
             hash = 31 * hash + key;
             hash = 31 * hash + Objects.hashCode(value);
         }
         return hash;
     }
 }
	/*
	* 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 android.annotation.Nullable;
	import android.compat.annotation.UnsupportedAppUsage;

	import com.android.internal.util.ArrayUtils;
	import com.android.internal.util.GrowingArrayUtils;

	import libcore.util.EmptyArray;

	import java.util.Objects;

	/**
	* <code>SparseArray</code> maps integers to Objects and, unlike a normal array of Objects,
	* its indices can contain gaps. <code>SparseArray</code> is intended to be more memory-efficient
	* than a
	* <a href="/reference/java/util/HashMap"><code>HashMap</code></a>, because it avoids
	* auto-boxing keys 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
	* <code>HashMap</code> because 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 less than 50%.
	*
	* <p>To help with performance, the container includes an optimization when removing
	* keys: instead of compacting its array immediately, it leaves the removed entry marked
	* as deleted. The entry can then be re-used for the same key or compacted later in
	* a single garbage collection of all removed entries. This garbage collection
	* must be performed whenever the array needs to be grown, or when the map size or
	* entry values are retrieved.
	*
	* <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 returns the
	* keys in ascending order. In the case of <code>valueAt(int)</code>, the
	* values corresponding to the keys are returned in ascending order.
	*/
	public class SparseArray<E> implements Cloneable {
	private static final Object DELETED = new Object();
	private boolean mGarbage = false;

	@UnsupportedAppUsage(maxTargetSdk = 28) // Use keyAt(int)
	private int[] mKeys;
	@UnsupportedAppUsage(maxTargetSdk = 28) // Use valueAt(int), setValueAt(int, E)
	private Object[] mValues;
	@UnsupportedAppUsage(maxTargetSdk = 28) // Use size()
	private int mSize;

	/**
	* Creates a new SparseArray containing no mappings.
	*/
	public SparseArray() {
	this(0);
	}

	/**
	* Creates a new SparseArray 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 SparseArray(int initialCapacity) {
	if (initialCapacity == 0) {
	mKeys = EmptyArray.INT;
	mValues = EmptyArray.OBJECT;
	} else {
	mValues = ArrayUtils.newUnpaddedObjectArray(initialCapacity);
	mKeys = new int[mValues.length];
	}
	mSize = 0;
	}

	@Override
	@SuppressWarnings("unchecked")
	public SparseArray<E> clone() {
	SparseArray<E> clone = null;
	try {
	clone = (SparseArray<E>) super.clone();
	clone.mKeys = mKeys.clone();
	clone.mValues = mValues.clone();
	} catch (CloneNotSupportedException cnse) {
	/* ignore */
	}
	return clone;
	}

	/**
	* Returns true if the key exists in the array. This is equivalent to
	* {@link #indexOfKey(int)} >= 0.
	*
	* @param key Potential key in the mapping
	* @return true if the key is defined in the mapping
	*/
	public boolean contains(int key) {
	return indexOfKey(key) >= 0;
	}

	/**
	* Gets the Object mapped from the specified key, or <code>null</code>
	* if no such mapping has been made.
	*/
	public E get(int key) {
	return get(key, null);
	}

	/**
	* Gets the Object mapped from the specified key, or the specified Object
	* if no such mapping has been made.
	*/
	@SuppressWarnings("unchecked")
	public E get(int key, E valueIfKeyNotFound) {
	int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

	if (i < 0 \|\| mValues[i] == DELETED) {
	return valueIfKeyNotFound;
	} else {
	return (E) 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) {
	if (mValues[i] != DELETED) {
	mValues[i] = DELETED;
	mGarbage = true;
	}
	}
	}

	/**
	* @hide
	* Removes the mapping from the specified key, if there was any, returning the old value.
	*/
	public E removeReturnOld(int key) {
	int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

	if (i >= 0) {
	if (mValues[i] != DELETED) {
	final E old = (E) mValues[i];
	mValues[i] = DELETED;
	mGarbage = true;
	return old;
	}
	}
	return null;
	}

	/**
	* Alias for {@link #delete(int)}.
	*/
	public void remove(int key) {
	delete(key);
	}

	/**
	* Removes the mapping at the specified index.
	*
	* <p>For indices outside of the range <code>0...size()-1</code>,
	* the behavior is undefined for apps targeting {@link android.os.Build.VERSION_CODES#P} and
	* earlier, and an {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
	* {@link android.os.Build.VERSION_CODES#Q} and later.</p>
	*/
	public void removeAt(int index) {
	if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
	// The array might be slightly bigger than mSize, in which case, indexing won't fail.
	// Check if exception should be thrown outside of the critical path.
	throw new ArrayIndexOutOfBoundsException(index);
	}
	if (mValues[index] != DELETED) {
	mValues[index] = DELETED;
	mGarbage = true;
	}
	}

	/**
	* Remove a range of mappings as a batch.
	*
	* @param index Index to begin at
	* @param size Number of mappings to remove
	*
	* <p>For indices outside of the range <code>0...size()-1</code>,
	* the behavior is undefined.</p>
	*/
	public void removeAtRange(int index, int size) {
	final int end = Math.min(mSize, index + size);
	for (int i = index; i < end; i++) {
	removeAt(i);
	}
	}

	private void gc() {
	// Log.e("SparseArray", "gc start with " + mSize);

	int n = mSize;
	int o = 0;
	int[] keys = mKeys;
	Object[] values = mValues;

	for (int i = 0; i < n; i++) {
	Object val = values[i];

	if (val != DELETED) {
	if (i != o) {
	keys[o] = keys[i];
	values[o] = val;
	values[i] = null;
	}

	o++;
	}
	}

	mGarbage = false;
	mSize = o;

	// Log.e("SparseArray", "gc end with " + mSize);
	}

	/**
	* Alias for {@link #put(int, Object)} to support Kotlin [index]= operator.
	* @see #put(int, Object)
	*/
	public void set(int key, E value) {
	put(key, value);
	}

	/**
	* 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, E value) {
	int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

	if (i >= 0) {
	mValues[i] = value;
	} else {
	i = ~i;

	if (i < mSize && mValues[i] == DELETED) {
	mKeys[i] = key;
	mValues[i] = value;
	return;
	}

	if (mGarbage && mSize >= mKeys.length) {
	gc();

	// Search again because indices may have changed.
	i = ~ContainerHelpers.binarySearch(mKeys, mSize, key);
	}

	mKeys = GrowingArrayUtils.insert(mKeys, mSize, i, key);
	mValues = GrowingArrayUtils.insert(mValues, mSize, i, value);
	mSize++;
	}
	}

	/**
	* Returns the number of key-value mappings that this SparseArray
	* currently stores.
	*/
	public int size() {
	if (mGarbage) {
	gc();
	}

	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
	* SparseArray 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>
	*
	* <p>For indices outside of the range <code>0...size()-1</code>,
	* the behavior is undefined for apps targeting {@link android.os.Build.VERSION_CODES#P} and
	* earlier, and an {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
	* {@link android.os.Build.VERSION_CODES#Q} and later.</p>
	*/
	public int keyAt(int index) {
	if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
	// The array might be slightly bigger than mSize, in which case, indexing won't fail.
	// Check if exception should be thrown outside of the critical path.
	throw new ArrayIndexOutOfBoundsException(index);
	}
	if (mGarbage) {
	gc();
	}

	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
	* SparseArray 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>
	*
	* <p>For indices outside of the range <code>0...size()-1</code>,
	* the behavior is undefined for apps targeting {@link android.os.Build.VERSION_CODES#P} and
	* earlier, and an {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
	* {@link android.os.Build.VERSION_CODES#Q} and later.</p>
	*/
	@SuppressWarnings("unchecked")
	public E valueAt(int index) {
	if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
	// The array might be slightly bigger than mSize, in which case, indexing won't fail.
	// Check if exception should be thrown outside of the critical path.
	throw new ArrayIndexOutOfBoundsException(index);
	}
	if (mGarbage) {
	gc();
	}

	return (E) mValues[index];
	}

	/**
	* Given an index in the range <code>0...size()-1</code>, sets a new
	* value for the <code>index</code>th key-value mapping that this
	* SparseArray stores.
	*
	* <p>For indices outside of the range <code>0...size()-1</code>, the behavior is undefined for
	* apps targeting {@link android.os.Build.VERSION_CODES#P} and earlier, and an
	* {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
	* {@link android.os.Build.VERSION_CODES#Q} and later.</p>
	*/
	public void setValueAt(int index, E value) {
	if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
	// The array might be slightly bigger than mSize, in which case, indexing won't fail.
	// Check if exception should be thrown outside of the critical path.
	throw new ArrayIndexOutOfBoundsException(index);
	}
	if (mGarbage) {
	gc();
	}

	mValues[index] = value;
	}

	/**
	* 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) {
	if (mGarbage) {
	gc();
	}

	return ContainerHelpers.binarySearch(mKeys, mSize, key);
	}

	/**
	* Returns an index for which {@link #valueAt} would return the
	* specified value, or a negative number if no keys map to the
	* specified value.
	* <p>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.
	* <p>Note also that unlike most collections' {@code indexOf} methods,
	* this method compares values using {@code ==} rather than {@code equals}.
	*/
	public int indexOfValue(E value) {
	if (mGarbage) {
	gc();
	}

	for (int i = 0; i < mSize; i++) {
	if (mValues[i] == value) {
	return i;
	}
	}

	return -1;
	}

	/**
	* Returns an index for which {@link #valueAt} would return the
	* specified value, or a negative number if no keys map to the
	* specified value.
	* <p>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.
	* <p>Note also that this method uses {@code equals} unlike {@code indexOfValue}.
	* @hide
	*/
	public int indexOfValueByValue(E value) {
	if (mGarbage) {
	gc();
	}

	for (int i = 0; i < mSize; i++) {
	if (value == null) {
	if (mValues[i] == null) {
	return i;
	}
	} else {
	if (value.equals(mValues[i])) {
	return i;
	}
	}
	}
	return -1;
	}

	/**
	* Removes all key-value mappings from this SparseArray.
	*/
	public void clear() {
	int n = mSize;
	Object[] values = mValues;

	for (int i = 0; i < n; i++) {
	values[i] = null;
	}

	mSize = 0;
	mGarbage = false;
	}

	/**
	* 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, E value) {
	if (mSize != 0 && key <= mKeys[mSize - 1]) {
	put(key, value);
	return;
	}

	if (mGarbage && mSize >= mKeys.length) {
	gc();
	}

	mKeys = GrowingArrayUtils.append(mKeys, mSize, key);
	mValues = GrowingArrayUtils.append(mValues, mSize, value);
	mSize++;
	}

	/**
	* {@inheritDoc}
	*
	* <p>This implementation composes a string by iterating over its mappings. If
	* this map contains itself as a value, the string "(this Map)"
	* will appear in its place.
	*/
	@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('=');
	Object value = valueAt(i);
	if (value != this) {
	buffer.append(value);
	} else {
	buffer.append("(this Map)");
	}
	}
	buffer.append('}');
	return buffer.toString();
	}

	/**
	* Compares the contents of this {@link SparseArray} to the specified {@link SparseArray}.
	*
	* For backwards compatibility reasons, {@link Object#equals(Object)} cannot be implemented,
	* so this serves as a manually invoked alternative.
	*/
	public boolean contentEquals(@Nullable SparseArray<?> other) {
	if (other == null) {
	return false;
	}

	int size = size();
	if (size != other.size()) {
	return false;
	}

	// size() calls above took care about gc() compaction.
	for (int index = 0; index < size; index++) {
	if (mKeys[index] != other.mKeys[index]
	\|\| !Objects.equals(mValues[index], other.mValues[index])) {
	return false;
	}
	}

	return true;
	}

	/**
	* Returns a hash code value for the contents of this {@link SparseArray}, combining the
	* {@link Objects#hashCode(Object)} result of all its keys and values.
	*
	* For backwards compatibility, {@link Object#hashCode()} cannot be implemented, so this serves
	* as a manually invoked alternative.
	*/
	public int contentHashCode() {
	int hash = 0;
	int size = size();
	// size() call above took care about gc() compaction.
	for (int index = 0; index < size; index++) {
	int key = mKeys[index];
	E value = (E) mValues[index];
	hash = 31 * hash + key;
	hash = 31 * hash + Objects.hashCode(value);
	}
	return hash;
	}
	}