/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 java.util;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamField;
import java.io.Serializable;
import java.lang.reflect.Array;
/**
* ArrayList is an implementation of {@link List}, backed by an array. All
* optional operations adding, removing, and replacing are supported. The
* elements can be any objects.
*
* @since Android 1.0
*/
public class ArrayList<E> extends AbstractList<E> implements List<E>, Cloneable,
Serializable, RandomAccess {
private static final long serialVersionUID = 8683452581122892189L;
// BEGIN android-added
/** zero-element array */
private static final Object[] emptyArray = new Object[0];
// END android-added
private transient int firstIndex;
private transient int lastIndex;
private transient E[] array;
/**
* Constructs a new instance of {@code ArrayList} with zero capacity.
*
* @since Android 1.0
*/
public ArrayList() {
this(0);
}
/**
* Constructs a new instance of {@code ArrayList} with the specified
* capacity.
*
* @param capacity
* the initial capacity of this {@code ArrayList}.
* @since Android 1.0
*/
public ArrayList(int capacity) {
firstIndex = lastIndex = 0;
try {
array = newElementArray(capacity);
} catch (NegativeArraySizeException e) {
throw new IllegalArgumentException();
}
}
/**
* Constructs a new instance of {@code ArrayList} containing the elements of
* the specified collection. The initial size of the {@code ArrayList} will
* be 10% higher than the size of the specified collection.
*
* @param collection
* the collection of elements to add.
* @since Android 1.0
*/
public ArrayList(Collection<? extends E> collection) {
int size = collection.size();
firstIndex = lastIndex = 0;
array = newElementArray(size + (size / 10));
addAll(collection);
}
@SuppressWarnings("unchecked")
private E[] newElementArray(int size) {
// BEGIN android-added
if (size == 0) {
return (E[])emptyArray;
}
// END android-added
return (E[])new Object[size];
}
/**
* Inserts the specified object into this {@code ArrayList} at the specified
* location. The object is inserted before any previous element at the
* specified location. If the location is equal to the size of this
* {@code ArrayList}, the object is added at the end.
*
* @param location
* the index at which to insert the object.
* @param object
* the object to add.
* @throws IndexOutOfBoundsException
* when {@code location < 0 || > size()}
* @since Android 1.0
*/
@Override
public void add(int location, E object) {
// BEGIN android-changed: slight performance improvement
int size = lastIndex - firstIndex;
// END android-changed
if (0 < location && location < size) {
if (firstIndex == 0 && lastIndex == array.length) {
growForInsert(location, 1);
} else if ((location < size / 2 && firstIndex > 0)
|| lastIndex == array.length) {
System.arraycopy(array, firstIndex, array, --firstIndex,
location);
} else {
int index = location + firstIndex;
System.arraycopy(array, index, array, index + 1, size
- location);
lastIndex++;
}
array[location + firstIndex] = object;
} else if (location == 0) {
if (firstIndex == 0) {
growAtFront(1);
}
array[--firstIndex] = object;
} else if (location == size) {
if (lastIndex == array.length) {
growAtEnd(1);
}
array[lastIndex++] = object;
} else {
throw new IndexOutOfBoundsException();
}
modCount++;
}
/**
* Adds the specified object at the end of this {@code ArrayList}.
*
* @param object
* the object to add.
* @return always true
* @since Android 1.0
*/
@Override
public boolean add(E object) {
if (lastIndex == array.length) {
growAtEnd(1);
}
array[lastIndex++] = object;
modCount++;
return true;
}
/**
* Inserts the objects in the specified collection at the specified location
* in this List. The objects are added in the order they are returned from
* the collection's iterator.
*
* @param location
* the index at which to insert.
* @param collection
* the collection of objects.
* @return {@code true} if this {@code ArrayList} is modified, {@code false}
* otherwise.
* @throws IndexOutOfBoundsException
* when {@code location < 0 || > size()}
* @since Android 1.0
*/
@Override
public boolean addAll(int location, Collection<? extends E> collection) {
int size = size();
if (location < 0 || location > size) {
throw new IndexOutOfBoundsException();
}
int growSize = collection.size();
if (0 < location && location < size) {
if (array.length - size < growSize) {
growForInsert(location, growSize);
} else if ((location < size / 2 && firstIndex > 0)
|| lastIndex > array.length - growSize) {
int newFirst = firstIndex - growSize;
if (newFirst < 0) {
int index = location + firstIndex;
System.arraycopy(array, index, array, index - newFirst,
size - location);
lastIndex -= newFirst;
newFirst = 0;
}
System.arraycopy(array, firstIndex, array, newFirst, location);
firstIndex = newFirst;
} else {
int index = location + firstIndex;
System.arraycopy(array, index, array, index + growSize, size
- location);
lastIndex += growSize;
}
} else if (location == 0) {
growAtFront(growSize);
firstIndex -= growSize;
} else if (location == size) {
if (lastIndex > array.length - growSize) {
growAtEnd(growSize);
}
lastIndex += growSize;
}
if (growSize > 0) {
Iterator<? extends E> it = collection.iterator();
int index = location + firstIndex;
int end = index + growSize;
while (index < end) {
array[index++] = it.next();
}
modCount++;
return true;
}
return false;
}
/**
* Adds the objects in the specified collection to this {@code ArrayList}.
*
* @param collection
* the collection of objects.
* @return {@code true} if this {@code ArrayList} is modified, {@code false}
* otherwise.
* @since Android 1.0
*/
@Override
public boolean addAll(Collection<? extends E> collection) {
int growSize = collection.size();
if (growSize > 0) {
if (lastIndex > array.length - growSize) {
growAtEnd(growSize);
}
Iterator<? extends E> it = collection.iterator();
int end = lastIndex + growSize;
while (lastIndex < end) {
array[lastIndex++] = it.next();
}
modCount++;
return true;
}
return false;
}
/**
* Removes all elements from this {@code ArrayList}, leaving it empty.
*
* @see #isEmpty
* @see #size
* @since Android 1.0
*/
@Override
public void clear() {
if (firstIndex != lastIndex) {
Arrays.fill(array, firstIndex, lastIndex, null);
firstIndex = lastIndex = 0;
modCount++;
}
}
/**
* Returns a new {@code ArrayList} with the same elements, the same size and
* the same capacity as this {@code ArrayList}.
*
* @return a shallow copy of this {@code ArrayList}
* @see java.lang.Cloneable
* @since Android 1.0
*/
@Override
@SuppressWarnings("unchecked")
public Object clone() {
try {
ArrayList<E> newList = (ArrayList<E>) super.clone();
newList.array = array.clone();
return newList;
} catch (CloneNotSupportedException e) {
return null;
}
}
/**
* Searches this {@code ArrayList} for the specified object.
*
* @param object
* the object to search for.
* @return {@code true} if {@code object} is an element of this
* {@code ArrayList}, {@code false} otherwise
* @since Android 1.0
*/
@Override
public boolean contains(Object object) {
if (object != null) {
for (int i = firstIndex; i < lastIndex; i++) {
if (object.equals(array[i])) {
return true;
}
}
} else {
for (int i = firstIndex; i < lastIndex; i++) {
if (array[i] == null) {
return true;
}
}
}
return false;
}
/**
* Ensures that after this operation the {@code ArrayList} can hold the
* specified number of elements without further growing.
*
* @param minimumCapacity
* the minimum capacity asked for.
* @since Android 1.0
*/
public void ensureCapacity(int minimumCapacity) {
if (array.length < minimumCapacity) {
if (firstIndex > 0) {
growAtFront(minimumCapacity - array.length);
} else {
growAtEnd(minimumCapacity - array.length);
}
}
}
@Override
public E get(int location) {
// BEGIN android-changed: slight performance improvement
int _firstIndex = firstIndex;
if (0 <= location && location < lastIndex - _firstIndex) {
return array[_firstIndex + location];
}
throw new IndexOutOfBoundsException("Invalid location " + location
+ ", size is " + (lastIndex - _firstIndex));
// END android-changed
}
private void growAtEnd(int required) {
int size = size();
if (firstIndex >= required - (array.length - lastIndex)) {
int newLast = lastIndex - firstIndex;
if (size > 0) {
System.arraycopy(array, firstIndex, array, 0, size);
int start = newLast < firstIndex ? firstIndex : newLast;
Arrays.fill(array, start, array.length, null);
}
firstIndex = 0;
lastIndex = newLast;
} else {
int increment = size / 2;
if (required > increment) {
increment = required;
}
if (increment < 12) {
increment = 12;
}
E[] newArray = newElementArray(size + increment);
if (size > 0) {
System.arraycopy(array, firstIndex, newArray, 0, size);
firstIndex = 0;
lastIndex = size;
}
array = newArray;
}
}
private void growAtFront(int required) {
int size = size();
if (array.length - lastIndex >= required) {
int newFirst = array.length - size;
if (size > 0) {
System.arraycopy(array, firstIndex, array, newFirst, size);
int length = firstIndex + size > newFirst ? newFirst
: firstIndex + size;
Arrays.fill(array, firstIndex, length, null);
}
firstIndex = newFirst;
lastIndex = array.length;
} else {
int increment = size / 2;
if (required > increment) {
increment = required;
}
if (increment < 12) {
increment = 12;
}
E[] newArray = newElementArray(size + increment);
if (size > 0) {
System.arraycopy(array, firstIndex, newArray, newArray.length
- size, size);
}
firstIndex = newArray.length - size;
lastIndex = newArray.length;
array = newArray;
}
}
private void growForInsert(int location, int required) {
int size = size(), increment = size / 2;
if (required > increment) {
increment = required;
}
if (increment < 12) {
increment = 12;
}
E[] newArray = newElementArray(size + increment);
if (location < size / 2) {
int newFirst = newArray.length - (size + required);
System.arraycopy(array, location, newArray, location + increment,
size - location);
System.arraycopy(array, firstIndex, newArray, newFirst, location);
firstIndex = newFirst;
lastIndex = newArray.length;
} else {
System.arraycopy(array, firstIndex, newArray, 0, location);
System.arraycopy(array, location, newArray, location + required,
size - location);
firstIndex = 0;
lastIndex += required;
}
array = newArray;
}
@Override
public int indexOf(Object object) {
if (object != null) {
for (int i = firstIndex; i < lastIndex; i++) {
if (object.equals(array[i])) {
return i - firstIndex;
}
}
} else {
for (int i = firstIndex; i < lastIndex; i++) {
if (array[i] == null) {
return i - firstIndex;
}
}
}
return -1;
}
@Override
public boolean isEmpty() {
return lastIndex == firstIndex;
}
@Override
public int lastIndexOf(Object object) {
if (object != null) {
for (int i = lastIndex - 1; i >= firstIndex; i--) {
if (object.equals(array[i])) {
return i - firstIndex;
}
}
} else {
for (int i = lastIndex - 1; i >= firstIndex; i--) {
if (array[i] == null) {
return i - firstIndex;
}
}
}
return -1;
}
/**
* Removes the object at the specified location from this list.
*
* @param location
* the index of the object to remove.
* @return the removed object.
* @throws IndexOutOfBoundsException
* when {@code location < 0 || >= size()}
* @since Android 1.0
*/
@Override
public E remove(int location) {
E result;
// BEGIN android-changed: slight performance improvement
int size = lastIndex - firstIndex;
// END android-changed
if (0 <= location && location < size) {
if (location == size - 1) {
result = array[--lastIndex];
array[lastIndex] = null;
} else if (location == 0) {
result = array[firstIndex];
array[firstIndex++] = null;
} else {
int elementIndex = firstIndex + location;
result = array[elementIndex];
if (location < size / 2) {
System.arraycopy(array, firstIndex, array, firstIndex + 1,
location);
array[firstIndex++] = null;
} else {
System.arraycopy(array, elementIndex + 1, array,
elementIndex, size - location - 1);
array[--lastIndex] = null;
}
}
} else {
throw new IndexOutOfBoundsException();
}
modCount++;
return result;
}
// BEGIN android-added
/*
* The remove(Object) implementation from AbstractCollection creates
* a new Iterator on every remove and ends up calling remove(int).
*/
@Override
public boolean remove(Object object) {
int index = indexOf(object);
if (index >= 0) {
remove(index);
return true;
}
return false;
}
// END android-added
/**
* Removes the objects in the specified range from the start to the end, but
* not including the end index.
*
* @param start
* the index at which to start removing.
* @param end
* the index one after the end of the range to remove.
* @throws IndexOutOfBoundsException
* when {@code start < 0, start > end} or {@code end > size()}
* @since Android 1.0
*/
@Override
protected void removeRange(int start, int end) {
if (start >= 0 && start <= end && end <= size()) {
if (start == end) {
return;
}
int size = size();
if (end == size) {
Arrays.fill(array, firstIndex + start, lastIndex, null);
lastIndex = firstIndex + start;
} else if (start == 0) {
Arrays.fill(array, firstIndex, firstIndex + end, null);
firstIndex += end;
} else {
System.arraycopy(array, firstIndex + end, array, firstIndex
+ start, size - end);
int newLast = lastIndex + start - end;
Arrays.fill(array, newLast, lastIndex, null);
lastIndex = newLast;
}
modCount++;
} else {
throw new IndexOutOfBoundsException();
}
}
/**
* Replaces the element at the specified location in this {@code ArrayList}
* with the specified object.
*
* @param location
* the index at which to put the specified object.
* @param object
* the object to add.
* @return the previous element at the index.
* @throws IndexOutOfBoundsException
* when {@code location < 0 || >= size()}
* @since Android 1.0
*/
@Override
public E set(int location, E object) {
// BEGIN android-changed: slight performance improvement
if (0 <= location && location < (lastIndex - firstIndex)) {
// END android-changed
E result = array[firstIndex + location];
array[firstIndex + location] = object;
return result;
}
throw new IndexOutOfBoundsException();
}
/**
* Returns the number of elements in this {@code ArrayList}.
*
* @return the number of elements in this {@code ArrayList}.
* @since Android 1.0
*/
@Override
public int size() {
return lastIndex - firstIndex;
}
/**
* Returns a new array containing all elements contained in this
* {@code ArrayList}.
*
* @return an array of the elements from this {@code ArrayList}
* @since Android 1.0
*/
@Override
public Object[] toArray() {
int size = size();
Object[] result = new Object[size];
System.arraycopy(array, firstIndex, result, 0, size);
return result;
}
/**
* Returns an array containing all elements contained in this
* {@code ArrayList}. If the specified array is large enough to hold the
* elements, the specified array is used, otherwise an array of the same
* type is created. If the specified array is used and is larger than this
* {@code ArrayList}, the array element following the collection elements
* is set to null.
*
* @param contents
* the array.
* @return an array of the elements from this {@code ArrayList}.
* @throws ArrayStoreException
* when the type of an element in this {@code ArrayList} cannot
* be stored in the type of the specified array.
* @since Android 1.0
*/
@Override
@SuppressWarnings("unchecked")
public <T> T[] toArray(T[] contents) {
int size = size();
if (size > contents.length) {
Class<?> ct = contents.getClass().getComponentType();
contents = (T[]) Array.newInstance(ct, size);
}
System.arraycopy(array, firstIndex, contents, 0, size);
if (size < contents.length) {
contents[size] = null;
}
return contents;
}
/**
* Sets the capacity of this {@code ArrayList} to be the same as the current
* size.
*
* @see #size
* @since Android 1.0
*/
public void trimToSize() {
int size = size();
E[] newArray = newElementArray(size);
System.arraycopy(array, firstIndex, newArray, 0, size);
array = newArray;
firstIndex = 0;
lastIndex = array.length;
}
private static final ObjectStreamField[] serialPersistentFields = { new ObjectStreamField(
"size", Integer.TYPE) }; //$NON-NLS-1$
private void writeObject(ObjectOutputStream stream) throws IOException {
ObjectOutputStream.PutField fields = stream.putFields();
fields.put("size", size()); //$NON-NLS-1$
stream.writeFields();
stream.writeInt(array.length);
Iterator<?> it = iterator();
while (it.hasNext()) {
stream.writeObject(it.next());
}
}
@SuppressWarnings("unchecked")
private void readObject(ObjectInputStream stream) throws IOException,
ClassNotFoundException {
ObjectInputStream.GetField fields = stream.readFields();
lastIndex = fields.get("size", 0); //$NON-NLS-1$
array = newElementArray(stream.readInt());
for (int i = 0; i < lastIndex; i++) {
array[i] = (E)stream.readObject();
}
}
}
|
