/*
* 版权所有（c）1997,2013，Oracle和/或其附属公司。 版权所有。ORACLE所有权/机密。 使用须遵守许可条款。
*/
package java.util;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
/**
* @author Josh Bloch
* @author Neal Gafter
* @see Collection
* @see List
* @see LinkedList
* @see Vector
* @since 1.2
*///ArrayList的父子关系图
//实现接口//List,RandomAccess(随机访问),Cloneable(可复制),Serializable(序列化)
public class ArrayList<E>
extends AbstractList<E>
implements List<E>
, RandomAccess, Cloneable, java.io.Serializable
{
private static final long serialVersionUID = 8683452581122892189L
;
/**
* Default initial capacity.初始化默认容量大小
*/
private static final int DEFAULT_CAPACITY = 10
;
/**
* Shared empty array instance used for empty instances. 用于空实例的共享空数组实例
*/
private static final Object[] EMPTY_ELEMENTDATA =
{};
/**
* Shared empty array instance used for default sized empty instances. We
* distinguish this from EMPTY_ELEMENTDATA to know how much to inflate when
* first element is added.用于默认大小的空实例的共享空数组实例（这个与EMPTY_ELEMENTDATA区分开来，上面那个是没有给默认大小的）
*/
private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA =
{};
/**
* The array buffer into which the elements of the ArrayList are stored.储存ArrayList元素的数组缓冲区
* The capacity of the ArrayList is the length of this array buffer. Any 这个属性的长度就是数组的长度，
* empty ArrayList with elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA 任何空的ArrayList数组 elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
* will be expanded to DEFAULT_CAPACITY when the first element is added. 而在添加第一个元素时将会扩展成EMPTY_ELEMENTDATA
*/
transient Object[] elementData;
// non-private to simplify nested class access 非私有化，以简化嵌套类访问
/**
* The size of the ArrayList (the number of elements it contains).ArrayList的大小(它包含元素的个数)
*
* @serial
*/
private int size;
/**
* Constructs an empty list with the specified initial capacity.初始化指定容量大小的空的list的构造器
*
* @param initialCapacity the initial capacity of the list list的初始容量
* @throws IllegalArgumentException if the specified initial capacity
* is negative 如果指定的初始容量为负数，就抛出非法参数异常
*/
public ArrayList(
int initialCapacity) {
if (initialCapacity > 0
) {
this.elementData =
new Object[initialCapacity];
} else if (initialCapacity == 0
) {
this.elementData =
EMPTY_ELEMENTDATA;
} else {
throw new IllegalArgumentException("Illegal Capacity: "+
initialCapacity);
}
}
/**
* Constructs an empty list with an initial capacity of ten.默认构造器，初始化容量为10
*/
public ArrayList() {
this.elementData =
DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
}
/**
* Constructs a list containing the elements of the specified 按照集合的迭代器返回的顺序构造一个包含指定集合元素的列表
* collection, in the order they are returned by the collection's
* iterator.
*
* @param c the collection whose elements are to be placed into this list 要将这些元素放入此list的集合
* @throws NullPointerException if the specified collection is null 如果指定的集合为空，则抛出空指针异常
*/
public ArrayList(Collection<?
extends E>
c) {
elementData =
c.toArray();
if ((size = elementData.length) != 0
) {
// c.toArray might (incorrectly) not return Object[] (see 6260652)
if (elementData.getClass() != Object[].
class)
elementData = Arrays.copyOf(elementData, size, Object[].
class);
} else {
// replace with empty array.
this.elementData =
EMPTY_ELEMENTDATA;
}
}
/**
* Trims the capacity of this <tt>ArrayList</tt> instance to be the 修改这个实列list的容量大小
* list's current size. An application can use this operation to minimize
* the storage of an <tt>ArrayList</tt> instance.
*/
public void trimToSize() {
modCount++
;
if (size <
elementData.length) {
elementData = (size == 0
)
?
EMPTY_ELEMENTDATA
: Arrays.copyOf(elementData, size);
}
}
/**
* Increases the capacity of this <tt>ArrayList</tt> instance, if
* necessary, to ensure that it can hold at least the number of elements
* specified by the minimum capacity argument.
*
* @param minCapacity the desired minimum capacity
*/
public void ensureCapacity(
int minCapacity) {
int minExpand = (elementData !=
DEFAULTCAPACITY_EMPTY_ELEMENTDATA)
// any size if not default element table
? 0
// larger than default for default empty table. It's already
// supposed to be at default size.
: DEFAULT_CAPACITY;
if (minCapacity >
minExpand) {
ensureExplicitCapacity(minCapacity);
}
}
private void ensureCapacityInternal(
int minCapacity) {
if (elementData ==
DEFAULTCAPACITY_EMPTY_ELEMENTDATA) {
minCapacity =
Math.max(DEFAULT_CAPACITY, minCapacity);
}
ensureExplicitCapacity(minCapacity);
}
private void ensureExplicitCapacity(
int minCapacity) {
modCount++
;
// overflow-conscious code
if (minCapacity - elementData.length > 0
)
grow(minCapacity);
}
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8
;
/**
* Increases the capacity to ensure that it can hold at least the
* number of elements specified by the minimum capacity argument.
*
* @param minCapacity the desired minimum capacity
*/
private void grow(
int minCapacity) {
// overflow-conscious code
int oldCapacity =
elementData.length;
int newCapacity = oldCapacity + (oldCapacity >> 1
);
if (newCapacity - minCapacity < 0
)
newCapacity =
minCapacity;
if (newCapacity - MAX_ARRAY_SIZE > 0
)
newCapacity =
hugeCapacity(minCapacity);
// minCapacity is usually close to size, so this is a win:
elementData =
Arrays.copyOf(elementData, newCapacity);
}
private static int hugeCapacity(
int minCapacity) {
if (minCapacity < 0)
// overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
}
/**
* Returns the number of elements in this list.
*
* @return the number of elements in this list
*/
public int size() {
return size;
}
/**
* Returns <tt>true</tt> if this list contains no elements.
*
* @return <tt>true</tt> if this list contains no elements
*/
public boolean isEmpty() {
return size == 0
;
}
/**
* Returns <tt>true</tt> if this list contains the specified element.
* More formally, returns <tt>true</tt> if and only if this list contains
* at least one element <tt>e</tt> such that
* <tt>(o==null ? e==null : o.equals(e))</tt>.
*
* @param o element whose presence in this list is to be tested
* @return <tt>true</tt> if this list contains the specified element
*/
public boolean contains(Object o) {
return indexOf(o) >= 0
;
}
/**
* Returns the index of the first occurrence of the specified element
* in this list, or -1 if this list does not contain the element.
* More formally, returns the lowest index <tt>i</tt> such that
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
* or -1 if there is no such index.
*/
public int indexOf(Object o) {
if (o ==
null) {
for (
int i = 0; i < size; i++
)
if (elementData[i]==
null)
return i;
} else {
for (
int i = 0; i < size; i++
)
if (o.equals(elementData[i]))
return i;
}
return -1
;
}
/**
* Returns the index of the last occurrence of the specified element
* in this list, or -1 if this list does not contain the element.
* More formally, returns the highest index <tt>i</tt> such that
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
* or -1 if there is no such index.
*/
public int lastIndexOf(Object o) {
if (o ==
null) {
for (
int i = size-1; i >= 0; i--
)
if (elementData[i]==
null)
return i;
} else {
for (
int i = size-1; i >= 0; i--
)
if (o.equals(elementData[i]))
return i;
}
return -1
;
}
/**
* Returns a shallow copy of this <tt>ArrayList</tt> instance. (The
* elements themselves are not copied.)
*
* @return a clone of this <tt>ArrayList</tt> instance
*/
public Object clone() {
try {
ArrayList<?> v = (ArrayList<?>)
super.clone();
v.elementData =
Arrays.copyOf(elementData, size);
v.modCount = 0
;
return v;
} catch (CloneNotSupportedException e) {
// this shouldn't happen, since we are Cloneable
throw new InternalError(e);
}
}
/**
* Returns an array containing all of the elements in this list
* in proper sequence (from first to last element).
*
* <p>The returned array will be "safe" in that no references to it are
* maintained by this list. (In other words, this method must allocate
* a new array). The caller is thus free to modify the returned array.
*
* <p>This method acts as bridge between array-based and collection-based
* APIs.
*
* @return an array containing all of the elements in this list in
* proper sequence
*/
public Object[] toArray() {
return Arrays.copyOf(elementData, size);
}
/**
* Returns an array containing all of the elements in this list in proper
* sequence (from first to last element); the runtime type of the returned
* array is that of the specified array. If the list fits in the
* specified array, it is returned therein. Otherwise, a new array is
* allocated with the runtime type of the specified array and the size of
* this list.
*
* <p>If the list fits in the specified array with room to spare
* (i.e., the array has more elements than the list), the element in
* the array immediately following the end of the collection is set to
* <tt>null</tt>. (This is useful in determining the length of the
* list <i>only</i> if the caller knows that the list does not contain
* any null elements.)
*
* @param a the array into which the elements of the list are to
* be stored, if it is big enough; otherwise, a new array of the
* same runtime type is allocated for this purpose.
* @return an array containing the elements of the list
* @throws ArrayStoreException if the runtime type of the specified array
* is not a supertype of the runtime type of every element in
* this list
* @throws NullPointerException if the specified array is null
*/
@SuppressWarnings("unchecked"
)
public <T>
T[] toArray(T[] a) {
if (a.length <
size)
// Make a new array of a's runtime type, but my contents:
return (T[]) Arrays.copyOf(elementData, size, a.getClass());
System.arraycopy(elementData, 0, a, 0
, size);
if (a.length >
size)
a[size] =
null;
return a;
}
// Positional Access Operations
@SuppressWarnings("unchecked"
)
E elementData(int index) {
return (E) elementData[index];
}
/**
* Returns the element at the specified position in this list.
*
* @param index index of the element to return
* @return the element at the specified position in this list
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E get(
int index) {
rangeCheck(index);
return elementData(index);
}
/**
* Replaces the element at the specified position in this list with
* the specified element.
*
* @param index index of the element to replace
* @param element element to be stored at the specified position
* @return the element previously at the specified position
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E set(
int index, E element) {
rangeCheck(index);
E oldValue =
elementData(index);
elementData[index] =
element;
return oldValue;
}
/**
* Appends the specified element to the end of this list.
*
* @param e element to be appended to this list
* @return <tt>true</tt> (as specified by {@link Collection#add})
*/
public boolean add(E e) {
ensureCapacityInternal(size + 1);
// Increments modCount!!
elementData[size++] =
e;
return true;
}
/**
* Inserts the specified element at the specified position in this
* list. Shifts the element currently at that position (if any) and
* any subsequent elements to the right (adds one to their indices).
*
* @param index index at which the specified element is to be inserted
* @param element element to be inserted
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public void add(
int index, E element) {
rangeCheckForAdd(index);
ensureCapacityInternal(size + 1);
// Increments modCount!!
System.arraycopy(elementData, index, elementData, index + 1
,
size -
index);
elementData[index] =
element;
size++
;
}
/**
* Removes the element at the specified position in this list.
* Shifts any subsequent elements to the left (subtracts one from their
* indices).
*
* @param index the index of the element to be removed
* @return the element that was removed from the list
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E remove(
int index) {
rangeCheck(index);
modCount++
;
E oldValue =
elementData(index);
int numMoved = size - index - 1
;
if (numMoved > 0
)
System.arraycopy(elementData, index+1
, elementData, index,
numMoved);
elementData[--size] =
null;
// clear to let GC do its work
return oldValue;
}
/**
* Removes the first occurrence of the specified element from this list,
* if it is present. If the list does not contain the element, it is
* unchanged. More formally, removes the element with the lowest index
* <tt>i</tt> such that
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>
* (if such an element exists). Returns <tt>true</tt> if this list
* contained the specified element (or equivalently, if this list
* changed as a result of the call).
*
* @param o element to be removed from this list, if present
* @return <tt>true</tt> if this list contained the specified element
*/
public boolean remove(Object o) {
if (o ==
null) {
for (
int index = 0; index < size; index++
)
if (elementData[index] ==
null) {
fastRemove(index);
return true;
}
} else {
for (
int index = 0; index < size; index++
)
if (o.equals(elementData[index])) {
fastRemove(index);
return true;
}
}
return false;
}
/*
* Private remove method that skips bounds checking and does not
* return the value removed.
*/
private void fastRemove(
int index) {
modCount++
;
int numMoved = size - index - 1
;
if (numMoved > 0
)
System.arraycopy(elementData, index+1
, elementData, index,
numMoved);
elementData[--size] =
null;
// clear to let GC do its work
}
/**
* Removes all of the elements from this list. The list will
* be empty after this call returns.
*/
public void clear() {
modCount++
;
// clear to let GC do its work
for (
int i = 0; i < size; i++
)
elementData[i] =
null;
size = 0
;
}
/**
* Appends all of the elements in the specified collection to the end of
* this list, in the order that they are returned by the
* specified collection's Iterator. The behavior of this operation is
* undefined if the specified collection is modified while the operation
* is in progress. (This implies that the behavior of this call is
* undefined if the specified collection is this list, and this
* list is nonempty.)
*
* @param c collection containing elements to be added to this list
* @return <tt>true</tt> if this list changed as a result of the call
* @throws NullPointerException if the specified collection is null
*/
public boolean addAll(Collection<?
extends E>
c) {
Object[] a =
c.toArray();
int numNew =
a.length;
ensureCapacityInternal(size + numNew);
// Increments modCount
System.arraycopy(a, 0
, elementData, size, numNew);
size +=
numNew;
return numNew != 0
;
}
/**
* Inserts all of the elements in the specified collection into this
* list, starting at the specified position. Shifts the element
* currently at that position (if any) and any subsequent elements to
* the right (increases their indices). The new elements will appear
* in the list in the order that they are returned by the
* specified collection's iterator.
*
* @param index index at which to insert the first element from the
* specified collection
* @param c collection containing elements to be added to this list
* @return <tt>true</tt> if this list changed as a result of the call
* @throws IndexOutOfBoundsException {@inheritDoc}
* @throws NullPointerException if the specified collection is null
*/
public boolean addAll(
int index, Collection<?
extends E>
c) {
rangeCheckForAdd(index);
Object[] a =
c.toArray();
int numNew =
a.length;
ensureCapacityInternal(size + numNew);
// Increments modCount
int numMoved = size -
index;
if (numMoved > 0
)
System.arraycopy(elementData, index, elementData, index +
numNew,
numMoved);
System.arraycopy(a, 0
, elementData, index, numNew);
size +=
numNew;
return numNew != 0
;
}
/**
* Removes from this list all of the elements whose index is between
* {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
* Shifts any succeeding elements to the left (reduces their index).
* This call shortens the list by {@code (toIndex - fromIndex)} elements.
* (If {@code toIndex==fromIndex}, this operation has no effect.)
*
* @throws IndexOutOfBoundsException if {@code fromIndex} or
* {@code toIndex} is out of range
* ({@code fromIndex < 0 ||
* fromIndex >= size() ||
* toIndex > size() ||
* toIndex < fromIndex})
*/
protected void removeRange(
int fromIndex,
int toIndex) {
modCount++
;
int numMoved = size -
toIndex;
System.arraycopy(elementData, toIndex, elementData, fromIndex,
numMoved);
// clear to let GC do its work
int newSize = size - (toIndex-
fromIndex);
for (
int i = newSize; i < size; i++
) {
elementData[i] =
null;
}
size =
newSize;
}
/**
* Checks if the given index is in range. If not, throws an appropriate
* runtime exception. This method does *not* check if the index is
* negative: It is always used immediately prior to an array access,
* which throws an ArrayIndexOutOfBoundsException if index is negative.
*/
private void rangeCheck(
int index) {
if (index >=
size)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
/**
* A version of rangeCheck used by add and addAll.
*/
private void rangeCheckForAdd(
int index) {
if (index > size || index < 0
)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
/**
* Constructs an IndexOutOfBoundsException detail message.
* Of the many possible refactorings of the error handling code,
* this "outlining" performs best with both server and client VMs.
*/
private String outOfBoundsMsg(
int index) {
return "Index: "+index+", Size: "+
size;
}
/**
* Removes from this list all of its elements that are contained in the
* specified collection.
*
* @param c collection containing elements to be removed from this list
* @return {@code true} if this list changed as a result of the call
* @throws ClassCastException if the class of an element of this list
* is incompatible with the specified collection
* (<a href="Collection.html#optional-restrictions">optional</a>)
* @throws NullPointerException if this list contains a null element and the
* specified collection does not permit null elements
* (<a href="Collection.html#optional-restrictions">optional</a>),
* or if the specified collection is null
* @see Collection#contains(Object)
*/
public boolean removeAll(Collection<?>
c) {
Objects.requireNonNull(c);
return batchRemove(c,
false);
}
/**
* Retains only the elements in this list that are contained in the
* specified collection. In other words, removes from this list all
* of its elements that are not contained in the specified collection.
*
* @param c collection containing elements to be retained in this list
* @return {@code true} if this list changed as a result of the call
* @throws ClassCastException if the class of an element of this list
* is incompatible with the specified collection
* (<a href="Collection.html#optional-restrictions">optional</a>)
* @throws NullPointerException if this list contains a null element and the
* specified collection does not permit null elements
* (<a href="Collection.html#optional-restrictions">optional</a>),
* or if the specified collection is null
* @see Collection#contains(Object)
*/
public boolean retainAll(Collection<?>
c) {
Objects.requireNonNull(c);
return batchRemove(c,
true);
}
private boolean batchRemove(Collection<?> c,
boolean complement) {
final Object[] elementData =
this.elementData;
int r = 0, w = 0
;
boolean modified =
false;
try {
for (; r < size; r++
)
if (c.contains(elementData[r]) ==
complement)
elementData[w++] =
elementData[r];
} finally {
// Preserve behavioral compatibility with AbstractCollection,
// even if c.contains() throws.
if (r !=
size) {
System.arraycopy(elementData, r,
elementData, w,
size -
r);
w += size -
r;
}
if (w !=
size) {
// clear to let GC do its work
for (
int i = w; i < size; i++
)
elementData[i] =
null;
modCount += size -
w;
size =
w;
modified =
true;
}
}
return modified;
}
/**
* Save the state of the <tt>ArrayList</tt> instance to a stream (that
* is, serialize it).
*
* @serialData The length of the array backing the <tt>ArrayList</tt>
* instance is emitted (int), followed by all of its elements
* (each an <tt>Object</tt>) in the proper order.
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException{
// Write out element count, and any hidden stuff
int expectedModCount =
modCount;
s.defaultWriteObject();
// Write out size as capacity for behavioural compatibility with clone()
s.writeInt(size);
// Write out all elements in the proper order.
for (
int i=0; i<size; i++
) {
s.writeObject(elementData[i]);
}
if (modCount !=
expectedModCount) {
throw new ConcurrentModificationException();
}
}
/**
* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
* deserialize it).
*/
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
elementData =
EMPTY_ELEMENTDATA;
// Read in size, and any hidden stuff
s.defaultReadObject();
// Read in capacity
s.readInt();
// ignored
if (size > 0
) {
// be like clone(), allocate array based upon size not capacity
ensureCapacityInternal(size);
Object[] a =
elementData;
// Read in all elements in the proper order.
for (
int i=0; i<size; i++
) {
a[i] =
s.readObject();
}
}
}
/**
* Returns a list iterator over the elements in this list (in proper
* sequence), starting at the specified position in the list.
* The specified index indicates the first element that would be
* returned by an initial call to {@link ListIterator#next next}.
* An initial call to {@link ListIterator#previous previous} would
* return the element with the specified index minus one.
*
* <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
*
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public ListIterator<E> listIterator(
int index) {
if (index < 0 || index >
size)
throw new IndexOutOfBoundsException("Index: "+
index);
return new ListItr(index);
}
/**
* Returns a list iterator over the elements in this list (in proper
* sequence).
*
* <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
*
* @see #listIterator(int)
*/
public ListIterator<E>
listIterator() {
return new ListItr(0
);
}
/**
* Returns an iterator over the elements in this list in proper sequence.
*
* <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
*
* @return an iterator over the elements in this list in proper sequence
*/
public Iterator<E>
iterator() {
return new Itr();
}
/**
* An optimized version of AbstractList.Itr
*/
private class Itr
implements Iterator<E>
{
int cursor;
// index of next element to return
int lastRet = -1;
// index of last element returned; -1 if no such
int expectedModCount =
modCount;
public boolean hasNext() {
return cursor !=
size;
}
@SuppressWarnings("unchecked"
)
public E next() {
checkForComodification();
int i =
cursor;
if (i >=
size)
throw new NoSuchElementException();
Object[] elementData = ArrayList.
this.elementData;
if (i >=
elementData.length)
throw new ConcurrentModificationException();
cursor = i + 1
;
return (E) elementData[lastRet =
i];
}
public void remove() {
if (lastRet < 0
)
throw new IllegalStateException();
checkForComodification();
try {
ArrayList.this.remove(lastRet);
cursor =
lastRet;
lastRet = -1
;
expectedModCount =
modCount;
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
@Override
@SuppressWarnings("unchecked"
)
public void forEachRemaining(Consumer<?
super E>
consumer) {
Objects.requireNonNull(consumer);
final int size = ArrayList.
this.size;
int i =
cursor;
if (i >=
size) {
return;
}
final Object[] elementData = ArrayList.
this.elementData;
if (i >=
elementData.length) {
throw new ConcurrentModificationException();
}
while (i != size && modCount ==
expectedModCount) {
consumer.accept((E) elementData[i++
]);
}
// update once at end of iteration to reduce heap write traffic
cursor =
i;
lastRet = i - 1
;
checkForComodification();
}
final void checkForComodification() {
if (modCount !=
expectedModCount)
throw new ConcurrentModificationException();
}
}
/**
* An optimized version of AbstractList.ListItr
*/
private class ListItr
extends Itr
implements ListIterator<E>
{
ListItr(int index) {
super();
cursor =
index;
}
public boolean hasPrevious() {
return cursor != 0
;
}
public int nextIndex() {
return cursor;
}
public int previousIndex() {
return cursor - 1
;
}
@SuppressWarnings("unchecked"
)
public E previous() {
checkForComodification();
int i = cursor - 1
;
if (i < 0
)
throw new NoSuchElementException();
Object[] elementData = ArrayList.
this.elementData;
if (i >=
elementData.length)
throw new ConcurrentModificationException();
cursor =
i;
return (E) elementData[lastRet =
i];
}
public void set(E e) {
if (lastRet < 0
)
throw new IllegalStateException();
checkForComodification();
try {
ArrayList.this.set(lastRet, e);
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
public void add(E e) {
checkForComodification();
try {
int i =
cursor;
ArrayList.this.add(i, e);
cursor = i + 1
;
lastRet = -1
;
expectedModCount =
modCount;
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
}
/**
* Returns a view of the portion of this list between the specified
* {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. (If
* {@code fromIndex} and {@code toIndex} are equal, the returned list is
* empty.) The returned list is backed by this list, so non-structural
* changes in the returned list are reflected in this list, and vice-versa.
* The returned list supports all of the optional list operations.
*
* <p>This method eliminates the need for explicit range operations (of
* the sort that commonly exist for arrays). Any operation that expects
* a list can be used as a range operation by passing a subList view
* instead of a whole list. For example, the following idiom
* removes a range of elements from a list:
* <pre>
* list.subList(from, to).clear();
* </pre>
* Similar idioms may be constructed for {@link #indexOf(Object)} and
* {@link #lastIndexOf(Object)}, and all of the algorithms in the
* {@link Collections} class can be applied to a subList.
*
* <p>The semantics of the list returned by this method become undefined if
* the backing list (i.e., this list) is <i>structurally modified</i> in
* any way other than via the returned list. (Structural modifications are
* those that change the size of this list, or otherwise perturb it in such
* a fashion that iterations in progress may yield incorrect results.)
*
* @throws IndexOutOfBoundsException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
public List<E> subList(
int fromIndex,
int toIndex) {
subListRangeCheck(fromIndex, toIndex, size);
return new SubList(
this, 0
, fromIndex, toIndex);
}
static void subListRangeCheck(
int fromIndex,
int toIndex,
int size) {
if (fromIndex < 0
)
throw new IndexOutOfBoundsException("fromIndex = " +
fromIndex);
if (toIndex >
size)
throw new IndexOutOfBoundsException("toIndex = " +
toIndex);
if (fromIndex >
toIndex)
throw new IllegalArgumentException("fromIndex(" + fromIndex +
") > toIndex(" + toIndex + ")"
);
}
private class SubList
extends AbstractList<E>
implements RandomAccess {
private final AbstractList<E>
parent;
private final int parentOffset;
private final int offset;
int size;
SubList(AbstractList<E>
parent,
int offset,
int fromIndex,
int toIndex) {
this.parent =
parent;
this.parentOffset =
fromIndex;
this.offset = offset +
fromIndex;
this.size = toIndex -
fromIndex;
this.modCount = ArrayList.
this.modCount;
}
public E set(
int index, E e) {
rangeCheck(index);
checkForComodification();
E oldValue = ArrayList.
this.elementData(offset +
index);
ArrayList.this.elementData[offset + index] =
e;
return oldValue;
}
public E get(
int index) {
rangeCheck(index);
checkForComodification();
return ArrayList.
this.elementData(offset +
index);
}
public int size() {
checkForComodification();
return this.size;
}
public void add(
int index, E e) {
rangeCheckForAdd(index);
checkForComodification();
parent.add(parentOffset +
index, e);
this.modCount =
parent.modCount;
this.size++
;
}
public E remove(
int index) {
rangeCheck(index);
checkForComodification();
E result = parent.remove(parentOffset +
index);
this.modCount =
parent.modCount;
this.size--
;
return result;
}
protected void removeRange(
int fromIndex,
int toIndex) {
checkForComodification();
parent.removeRange(parentOffset +
fromIndex,
parentOffset +
toIndex);
this.modCount =
parent.modCount;
this.size -= toIndex -
fromIndex;
}
public boolean addAll(Collection<?
extends E>
c) {
return addAll(
this.size, c);
}
public boolean addAll(
int index, Collection<?
extends E>
c) {
rangeCheckForAdd(index);
int cSize =
c.size();
if (cSize==0
)
return false;
checkForComodification();
parent.addAll(parentOffset +
index, c);
this.modCount =
parent.modCount;
this.size +=
cSize;
return true;
}
public Iterator<E>
iterator() {
return listIterator();
}
public ListIterator<E> listIterator(
final int index) {
checkForComodification();
rangeCheckForAdd(index);
final int offset =
this.offset;
return new ListIterator<E>
() {
int cursor =
index;
int lastRet = -1
;
int expectedModCount = ArrayList.
this.modCount;
public boolean hasNext() {
return cursor != SubList.
this.size;
}
@SuppressWarnings("unchecked"
)
public E next() {
checkForComodification();
int i =
cursor;
if (i >= SubList.
this.size)
throw new NoSuchElementException();
Object[] elementData = ArrayList.
this.elementData;
if (offset + i >=
elementData.length)
throw new ConcurrentModificationException();
cursor = i + 1
;
return (E) elementData[offset + (lastRet =
i)];
}
public boolean hasPrevious() {
return cursor != 0
;
}
@SuppressWarnings("unchecked"
)
public E previous() {
checkForComodification();
int i = cursor - 1
;
if (i < 0
)
throw new NoSuchElementException();
Object[] elementData = ArrayList.
this.elementData;
if (offset + i >=
elementData.length)
throw new ConcurrentModificationException();
cursor =
i;
return (E) elementData[offset + (lastRet =
i)];
}
@SuppressWarnings("unchecked"
)
public void forEachRemaining(Consumer<?
super E>
consumer) {
Objects.requireNonNull(consumer);
final int size = SubList.
this.size;
int i =
cursor;
if (i >=
size) {
return;
}
final Object[] elementData = ArrayList.
this.elementData;
if (offset + i >=
elementData.length) {
throw new ConcurrentModificationException();
}
while (i != size && modCount ==
expectedModCount) {
consumer.accept((E) elementData[offset + (i++
)]);
}
// update once at end of iteration to reduce heap write traffic
lastRet = cursor =
i;
checkForComodification();
}
public int nextIndex() {
return cursor;
}
public int previousIndex() {
return cursor - 1
;
}
public void remove() {
if (lastRet < 0
)
throw new IllegalStateException();
checkForComodification();
try {
SubList.this.remove(lastRet);
cursor =
lastRet;
lastRet = -1
;
expectedModCount = ArrayList.
this.modCount;
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
public void set(E e) {
if (lastRet < 0
)
throw new IllegalStateException();
checkForComodification();
try {
ArrayList.this.set(offset +
lastRet, e);
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
public void add(E e) {
checkForComodification();
try {
int i =
cursor;
SubList.this.add(i, e);
cursor = i + 1
;
lastRet = -1
;
expectedModCount = ArrayList.
this.modCount;
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
final void checkForComodification() {
if (expectedModCount != ArrayList.
this.modCount)
throw new ConcurrentModificationException();
}
};
}
public List<E> subList(
int fromIndex,
int toIndex) {
subListRangeCheck(fromIndex, toIndex, size);
return new SubList(
this, offset, fromIndex, toIndex);
}
private void rangeCheck(
int index) {
if (index < 0 || index >=
this.size)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
private void rangeCheckForAdd(
int index) {
if (index < 0 || index >
this.size)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
private String outOfBoundsMsg(
int index) {
return "Index: "+index+", Size: "+
this.size;
}
private void checkForComodification() {
if (ArrayList.
this.modCount !=
this.modCount)
throw new ConcurrentModificationException();
}
public Spliterator<E>
spliterator() {
checkForComodification();
return new ArrayListSpliterator<E>(ArrayList.
this, offset,
offset +
this.size,
this.modCount);
}
}
@Override
public void forEach(Consumer<?
super E>
action) {
Objects.requireNonNull(action);
final int expectedModCount =
modCount;
@SuppressWarnings("unchecked"
)
final E[] elementData = (E[])
this.elementData;
final int size =
this.size;
for (
int i=0; modCount == expectedModCount && i < size; i++
) {
action.accept(elementData[i]);
}
if (modCount !=
expectedModCount) {
throw new ConcurrentModificationException();
}
}
/**
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
* and <em>fail-fast</em> {@link Spliterator} over the elements in this
* list.
*
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
* {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
* Overriding implementations should document the reporting of additional
* characteristic values.
*
* @return a {@code Spliterator} over the elements in this list
* @since 1.8
*/
@Override
public Spliterator<E>
spliterator() {
return new ArrayListSpliterator<>(
this, 0, -1, 0
);
}
/** Index-based split-by-two, lazily initialized Spliterator */
static final class ArrayListSpliterator<E>
implements Spliterator<E>
{
/*
* If ArrayLists were immutable, or structurally immutable (no
* adds, removes, etc), we could implement their spliterators
* with Arrays.spliterator. Instead we detect as much
* interference during traversal as practical without
* sacrificing much performance. We rely primarily on
* modCounts. These are not guaranteed to detect concurrency
* violations, and are sometimes overly conservative about
* within-thread interference, but detect enough problems to
* be worthwhile in practice. To carry this out, we (1) lazily
* initialize fence and expectedModCount until the latest
* point that we need to commit to the state we are checking
* against; thus improving precision. (This doesn't apply to
* SubLists, that create spliterators with current non-lazy
* values). (2) We perform only a single
* ConcurrentModificationException check at the end of forEach
* (the most performance-sensitive method). When using forEach
* (as opposed to iterators), we can normally only detect
* interference after actions, not before. Further
* CME-triggering checks apply to all other possible
* violations of assumptions for example null or too-small
* elementData array given its size(), that could only have
* occurred due to interference. This allows the inner loop
* of forEach to run without any further checks, and
* simplifies lambda-resolution. While this does entail a
* number of checks, note that in the common case of
* list.stream().forEach(a), no checks or other computation
* occur anywhere other than inside forEach itself. The other
* less-often-used methods cannot take advantage of most of
* these streamlinings.
*/
private final ArrayList<E>
list;
private int index;
// current index, modified on advance/split
private int fence;
// -1 until used; then one past last index
private int expectedModCount;
// initialized when fence set
/** Create new spliterator covering the given range */
ArrayListSpliterator(ArrayList<E> list,
int origin,
int fence,
int expectedModCount) {
this.list = list;
// OK if null unless traversed
this.index =
origin;
this.fence =
fence;
this.expectedModCount =
expectedModCount;
}
private int getFence() {
// initialize fence to size on first use
int hi;
// (a specialized variant appears in method forEach)
ArrayList<E>
lst;
if ((hi = fence) < 0
) {
if ((lst = list) ==
null)
hi = fence = 0
;
else {
expectedModCount =
lst.modCount;
hi = fence =
lst.size;
}
}
return hi;
}
public ArrayListSpliterator<E>
trySplit() {
int hi = getFence(), lo = index, mid = (lo + hi) >>> 1
;
return (lo >= mid) ?
null :
// divide range in half unless too small
new ArrayListSpliterator<E>(list, lo, index =
mid,
expectedModCount);
}
public boolean tryAdvance(Consumer<?
super E>
action) {
if (action ==
null)
throw new NullPointerException();
int hi = getFence(), i =
index;
if (i <
hi) {
index = i + 1
;
@SuppressWarnings("unchecked") E e =
(E)list.elementData[i];
action.accept(e);
if (list.modCount !=
expectedModCount)
throw new ConcurrentModificationException();
return true;
}
return false;
}
public void forEachRemaining(Consumer<?
super E>
action) {
int i, hi, mc;
// hoist accesses and checks from loop
ArrayList<E>
lst; Object[] a;
if (action ==
null)
throw new NullPointerException();
if ((lst = list) !=
null && (a = lst.elementData) !=
null) {
if ((hi = fence) < 0
) {
mc =
lst.modCount;
hi =
lst.size;
}
else
mc =
expectedModCount;
if ((i = index) >= 0 && (index = hi) <=
a.length) {
for (; i < hi; ++
i) {
@SuppressWarnings("unchecked") E e =
(E) a[i];
action.accept(e);
}
if (lst.modCount ==
mc)
return;
}
}
throw new ConcurrentModificationException();
}
public long estimateSize() {
return (
long) (getFence() -
index);
}
public int characteristics() {
return Spliterator.ORDERED | Spliterator.SIZED |
Spliterator.SUBSIZED;
}
}
@Override
public boolean removeIf(Predicate<?
super E>
filter) {
Objects.requireNonNull(filter);
// figure out which elements are to be removed
// any exception thrown from the filter predicate at this stage
// will leave the collection unmodified
int removeCount = 0
;
final BitSet removeSet =
new BitSet(size);
final int expectedModCount =
modCount;
final int size =
this.size;
for (
int i=0; modCount == expectedModCount && i < size; i++
) {
@SuppressWarnings("unchecked"
)
final E element =
(E) elementData[i];
if (filter.test(element)) {
removeSet.set(i);
removeCount++
;
}
}
if (modCount !=
expectedModCount) {
throw new ConcurrentModificationException();
}
// shift surviving elements left over the spaces left by removed elements
final boolean anyToRemove = removeCount > 0
;
if (anyToRemove) {
final int newSize = size -
removeCount;
for (
int i=0, j=0; (i < size) && (j < newSize); i++, j++
) {
i =
removeSet.nextClearBit(i);
elementData[j] =
elementData[i];
}
for (
int k=newSize; k < size; k++
) {
elementData[k] =
null;
// Let gc do its work
}
this.size =
newSize;
if (modCount !=
expectedModCount) {
throw new ConcurrentModificationException();
}
modCount++
;
}
return anyToRemove;
}
@Override
@SuppressWarnings("unchecked"
)
public void replaceAll(UnaryOperator<E>
operator) {
Objects.requireNonNull(operator);
final int expectedModCount =
modCount;
final int size =
this.size;
for (
int i=0; modCount == expectedModCount && i < size; i++
) {
elementData[i] =
operator.apply((E) elementData[i]);
}
if (modCount !=
expectedModCount) {
throw new ConcurrentModificationException();
}
modCount++
;
}
@Override
@SuppressWarnings("unchecked"
)
public void sort(Comparator<?
super E>
c) {
final int expectedModCount =
modCount;
Arrays.sort((E[]) elementData, 0
, size, c);
if (modCount !=
expectedModCount) {
throw new ConcurrentModificationException();
}
modCount++
;
}
}
转载于:https://www.cnblogs.com/lk617-home/p/9842399.html
