Java-Class-C：java.util.ArrayList
ylbtech-Java-Class-C：java.util.ArrayList
1.返回顶部
1.1、
import java.util.ArrayList;
import java.util.List;
1.2、
List
newList.add(3);
2、
2.返回顶部
3.返回顶部
4.返回顶部
1、
/*
* Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.util;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
import sun.misc.SharedSecrets;
/**
* Resizable-array implementation of the List interface. Implements
* all optional list operations, and permits all elements, including
* null. In addition to implementing the List interface,
* this class provides methods to manipulate the size of the array that is
* used internally to store the list. (This class is roughly equivalent to
* Vector, except that it is unsynchronized.)
*
*
The size, isEmpty, get, set,
* iterator, and listIterator operations run in constant
* time. The add operation runs in amortized constant time,
* that is, adding n elements requires O(n) time. All of the other operations
* run in linear time (roughly speaking). The constant factor is low compared
* to that for the LinkedList implementation.
*
*
Each ArrayList instance has a capacity. The capacity is
* the size of the array used to store the elements in the list. It is always
* at least as large as the list size. As elements are added to an ArrayList,
* its capacity grows automatically. The details of the growth policy are not
* specified beyond the fact that adding an element has constant amortized
* time cost.
*
*
An application can increase the capacity of an ArrayList instance
* before adding a large number of elements using the ensureCapacity
* operation. This may reduce the amount of incremental reallocation.
*
*
Note that this implementation is not synchronized.
* If multiple threads access an ArrayList instance concurrently,
* and at least one of the threads modifies the list structurally, it
* must be synchronized externally. (A structural modification is
* any operation that adds or deletes one or more elements, or explicitly
* resizes the backing array; merely setting the value of an element is not
* a structural modification.) This is typically accomplished by
* synchronizing on some object that naturally encapsulates the list.
*
* If no such object exists, the list should be "wrapped" using the
* {@link Collections#synchronizedList Collections.synchronizedList}
* method. This is best done at creation time, to prevent accidental
* unsynchronized access to the list:
* List list = Collections.synchronizedList(new ArrayList(…));
*
*
* The iterators returned by this class's {@link #iterator() iterator} and
* {@link #listIterator(int) listIterator} methods are fail-fast:
* if the list is structurally modified at any time after the iterator is
* created, in any way except through the iterator's own
* {@link ListIterator#remove() remove} or
* {@link ListIterator#add(Object) add} methods, the iterator will throw a
* {@link ConcurrentModificationException}. Thus, in the face of
* concurrent modification, the iterator fails quickly and cleanly, rather
* than risking arbitrary, non-deterministic behavior at an undetermined
* time in the future.
*
*
Note that the fail-fast behavior of an iterator cannot be guaranteed
* as it is, generally speaking, impossible to make any hard guarantees in the
* presence of unsynchronized concurrent modification. Fail-fast iterators
* throw {@code ConcurrentModificationException} on a best-effort basis.
* Therefore, it would be wrong to write a program that depended on this
* exception for its correctness: the fail-fast behavior of iterators
* should be used only to detect bugs.
*
*
This class is a member of the
*
* Java Collections Framework.
*
* @author Josh Bloch
* @author Neal Gafter
* @see Collection
* @see List
* @see LinkedList
* @see Vector
* @since 1.2
*/
public class ArrayList
implements List
{
private static final long serialVersionUID = 8683452581122892189L;
/\*\*
\* Default initial capacity.
\*/
private static final int DEFAULT\_CAPACITY = 10;
/\*\*
\* Shared empty array instance used for empty instances.
\*/
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.
\*/
private static final Object\[\] DEFAULTCAPACITY\_EMPTY\_ELEMENTDATA = {};
/\*\*
\* The array buffer into which the elements of the ArrayList are stored.
\* The capacity of the ArrayList is the length of this array buffer. Any
\* empty ArrayList with elementData == DEFAULTCAPACITY\_EMPTY\_ELEMENTDATA
\* will be expanded to DEFAULT\_CAPACITY when the first element is added.
\*/
transient Object\[\] elementData; // non-private to simplify nested class access
/\*\*
\* The size of the ArrayList (the number of elements it contains).
\*
\* @serial
\*/
private int size;
/\*\*
\* Constructs an empty list with the specified initial capacity.
\*
\* @param initialCapacity the initial capacity of the list
\* @throws IllegalArgumentException if the specified initial capacity
\* is negative
\*/
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.
\*/
public ArrayList() {
this.elementData = DEFAULTCAPACITY\_EMPTY\_ELEMENTDATA;
}
/\*\*
\* Constructs a list containing the elements of the specified
\* 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
\* @throws NullPointerException if the specified collection is null
\*/
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
\* 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 static int calculateCapacity(Object\[\] elementData, int minCapacity) {
if (elementData == DEFAULTCAPACITY\_EMPTY\_ELEMENTDATA) {
return Math.max(DEFAULT\_CAPACITY, minCapacity);
}
return minCapacity;
}
private void ensureCapacityInternal(int minCapacity) {
ensureExplicitCapacity(calculateCapacity(elementData, 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
int capacity = calculateCapacity(elementData, size);
SharedSecrets.getJavaOISAccess().checkArray(s, Object\[\].class, 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++;
} }
2、
5.返回顶部
6.返回顶部
作者：ylbtech
出处：http://ylbtech.cnblogs.com/
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
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