ArrayList源码分析
List:
ArrayList:底层数组实现，线程不安全（不要觉得不安全就觉得不好），效率高。增删改查中查询快，其余比较慢
LinkedList:底层链表实现，线程不安全，效率高。增删改查中查询慢，其余都快
- Vector:线程安全，但是效率低
ArrayList:
类声明：
public class ArrayList<E> extends AbstractList<E>
implements List<E>, RandomAccess, Cloneable, java.io.Serializable定义的一些常量：
- private static final long serialVersionUID = 8683452581122892189L
- private static final int DEFAULT_CAPACITY = 10;
- private static final Object[] EMPTY_ELEMENTDATA = {};
- private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};
说明：
- serialVersionUID ：和序列化有关，等了解完序列化后在补充。
- DEFAULT_CAPACITY ：默认容量。在JDK1.7之前当用无参构造器创建ArrayList对象时，会将初始容量设置成DEFAULT_CAPACITY(jdk1.8中貌似没有使用过这个常量了。。)
- EMPTY_ELEMENTDATA 和 DEFAULTCAPACITY_EMPTY_ELEMENTDATA都是Object的空数组，在原文注释中解释当ArrayList为空时用 EMPTY_ELEMENTDATA ，而当ArrayList对象创建的时候使用无参构造器时DEFAULTCAPACITY_EMPTY_ELEMENTDATA。 二者并没有多大差别
成员变量：
- transient Object[] elementData;（需要说明的是在1.8之前elementData变量有private修饰）
- private int size;
说明：
- elementData：实际存对象的数组
- size：当前存放的对象的数量（不用说也是小于等于elementData的申请长度的）
- transientjava语言的关键字，变量修饰符，如果用transient声明一个实例变量，当对象存储时，它的值不需要维持。换句话来说就是，用transient关键字标记的成员变量不参与序列化过程。
构造器：
1.ArrayList(int initialCapacity):initialCapacity为初始化的容量大小
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);
}
}
2.ArrayList()：无参构造器会将elementData指向DEFAULTCAPACITY_EMPTY_ELEMENTDATA这个空的对象数组
public ArrayList() {
this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
}3.ArrayList(Collection
public ArrayList(Collectionextends 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;
}
}内部类：
Itr：ArrayList的迭代器实现。
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(Consumersuper 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();
}
}说明:
- 除了最后的checkForComodification()方法，其余的四个方法都是重写Iterator接口
- cursor(中文：光标):表示该迭代器的游标，指向的是该元素的’起点’。
- lastRst:表示上一个游标。
- hasNext()方法表示是否有下一个元素。有返回true。没有返回false
- next():返回cursor指向的这个元素,并且cursor指向下一个元素的’起点’
- remvoe():移除lastRst指向的这个元素，并且cursor保持和没有移除前指向的是同一个位置(也就是说cursor前移的一位),而lastRst从新置为-1，也就是说remove()不能连续调用。
- forEachRemaining(Consumer
ListItr：返回列表中元素的列表迭代器（按适当顺序），从列表的指定位置开始。
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();
}
}
}
说明：
- 该类是继承上一个内部类Itr的。
- 该类最重要的补充有两个
- 提供了previous方法，可以让cursor游标前移了
- 提供了set和add方法，可以唉当前游标位置更改或插入元素
SubList:得到容器中的一部分以及定义了各种操作。（由subList(int fromIndex, int toIndex)指定范围）
private class SubList extends AbstractList<E> implements RandomAccess {
private final AbstractList parent;
private final int parentOffset;
private final int offset;
int size;
SubList(AbstractList 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 c) {
return addAll(this.size, c);
}
public boolean addAll(int index, Collection 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 iterator() {
return listIterator();
}
public ListIterator listIterator(final int index) {
checkForComodification();
rangeCheckForAdd(index);
final int offset = this.offset;
return new ListIterator() {
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(Consumersuper 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 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 spliterator() {
checkForComodification();
return new ArrayListSpliterator(ArrayList.this, offset,
offset + this.size, this.modCount);
}
}
方法：
1.trimToSize():释放多余的空间。
public void trimToSize() {
modCount++;
if (size < elementData.length) {
elementData = (size == 0)
? EMPTY_ELEMENTDATA
: Arrays.copyOf(elementData, size);
}
}2.ensureCapacity(int minCapacity)：扩容函数，确保elementData的容量足够大
public void ensureCapacity(int minCapacity) {
int minExpand = (elementData != DEFAULTCAPACITY_EMPTY_ELEMENTDATA）? 0: DEFAULT_CAPACITY;
if (minCapacity > minExpand) {
ensureExplicitCapacity(minCapacity); //实际的扩容操作交给了ensureExplicitCapacity(int minCapacity) 函数，下一个就是
}
}3.ensureExplicitCapacity(int minCapacity)：私有方法，explicit:明确的，清楚的
private void ensureExplicitCapacity(int minCapacity) {
modCount++;
// overflow-conscious code
if (minCapacity - elementData.length > 0)
grow(minCapacity); //实际调用
}
关于modCound
4.grow(int minCapacity)：真正的扩容操作。
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
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);
}
如果minCapacity比原来elementData.length的1.5倍还大，就直接扩容到minCapacity这么大；
如果比1.5倍小，那么就扩容到原来的1.5倍
5.hugeCapacity(int minCapacity):grow(int minCapacity)函数中的意外情况：容量大小即将超过int类型了。
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
}6.size() ：得到当前存放元素的总数
public int size() {
return size;
}7.isEmpty():判断当前容器是否为空
public boolean isEmpty() {
return size == 0;
}
8.contains(Object o)：判断是否是否包含对象o
public boolean contains(Object o) {
return indexOf(o) >= 0; //indexOf(o)若对象o在该ArrayList中存在，返回下标，否则返回-1,下一个就是。
}9.indexOf(Object o)：得到满足o.equals的第一个元素的下标（下标的意思是从0开始）
public int indexOf(Object o) {
if (o == null) { //可以看到允许往ArrayList存入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;
}同时注意若在ArrayList中放入了多个相同的对象，那么只会返回最先找到的下标
10.lastIndexOf(Object o) //从后往前找
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;
}
11.clone() :返回此 ArrayList 实例的浅表复制。（不复制这些元素本身。）
注意这是从Object重写过来的方法，所以用List多态时点不出来clone
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();
}
}
12.toArray() ：返回elementData的一份浅拷贝。
public Object[] toArray() {
return Arrays.copyOf(elementData, size);
}13.toArray(T[] a)：大意同上
public T[] toArray(T[] a) {
if (a.length < size) //如果给的数组放不下那就尽量放
// 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) //如果指定的数组能容纳列表并有剩余空间（即数组的元素比列表的多），那么会将数组中紧跟在集合末尾的元素设置为 null。这对确定列表的长度很有用，但只 在调用方知道列表中不包含任何 null 元素时才有用。
a[size] = null;
return a;
} 14.elementData(int index)：注意是默认访问类型，对于我们来说该方法不可调用，是get方法的底层
E elementData(int index) {
return (E) elementData[index];
}15.get(int index):返回指定下标的元素
public E get(int index) {
rangeCheck(index);
return elementData(index);
}16.set(int index, E element):修改给定下表的值，并将旧元素返回
public E set(int index, E element) {
rangeCheck(index);
E oldValue = elementData(index);
elementData[index] = element;
return oldValue;
}17.add(E e):给末尾添加e
public boolean add(E e) {
ensureCapacity(size + 1); // Increments modCount!!
elementData[size++] = e;
return true;
}18.add(int index, E element):给指定下标位置添加
public void add(int index, E element) {
if (index > size || index < 0)
throw new IndexOutOfBoundsException(
"Index: "+index+", Size: "+size);
ensureCapacity(size+1); // Increments modCount!!
System.arraycopy(elementData, index, elementData, index + 1,
size - index);
elementData[index] = element;
size++;
}arraycopy
public static void arraycopy(Object src,
int srcPos,
Object dest,
int destPos,
int length)
- 从指定源数组中复制一个数组，复制从指定的位置开始，到目标数组的指定位置结束。从 src 引用的源数组到 dest 引用的目标数组，数组组件的一个子序列被复制下来。被复制的组件的编号等于 length 参数。源数组中位置在 srcPos 到 srcPos+length-1 之间的组件被分别复制到目标数组中的 destPos 到 destPos+length-1 位置。
- 该方法是浅表赋值
19.remove(int index):移除下标为index的元素，并且返回该元素
public E remove(int index) {
RangeCheck(index);
modCount++;
E oldValue = (E) elementData[index];
int numMoved = size - index - 1;
if (numMoved > 0)
System.arraycopy(elementData, index+1, elementData, index,
numMoved);
elementData[--size] = null; // Let gc do its work
return oldValue;
}
20.remove(Object o)：移除和o.equals()相等的第一个元素，注意o可以为null
public boolean remove(Object o) {
if (o == null) {
for (int index = 0; index < size; index++)
if (elementData[index] == null) {
fastRemove(index); //下面一个函数
return true;
}
} else {
for (int index = 0; index < size; index++)
if (o.equals(elementData[index])) {
fastRemove(index);
return true;
}
}
return false;
}
21.fastRemove(int index):上一个方法的底层调用，敢取名fast是相比remove方法少调用了RangeCheck(index);所以速度会更快
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; // Let gc do its work
}22.clear()：将容器清空
public void clear() {
modCount++;
// Let gc do its work
for (int i = 0; i < size; i++)
elementData[i] = null;
size = 0;
}23.addAll(Collection
public boolean addAll(Collection c) {
Object[] a = c.toArray();
int numNew = a.length;
ensureCapacity(size + numNew); // Increments modCount
System.arraycopy(a, 0, elementData, size, numNew);
size += numNew;
return numNew != 0;
}24.addAll(int index, Collection
public boolean addAll(int index, Collection c) {
if (index > size || index < 0)
throw new IndexOutOfBoundsException(
"Index: " + index + ", Size: " + size);
Object[] a = c.toArray();
int numNew = a.length;
ensureCapacity(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;
}25.removeRange(int fromIndex, int toIndex):将[formIndex,toIndex)的元素都remove掉
protected void removeRange(int fromIndex, int toIndex) {
modCount++;
int numMoved = size - toIndex;
System.arraycopy(elementData, toIndex, elementData, fromIndex,
numMoved);
// Let gc do its work
int newSize = size - (toIndex-fromIndex);
while (size != newSize)
elementData[--size] = null;
}26.rangeCheck(int index)/rangeCheckForAdd(int index):检查index是否超出范围
private void rangeCheck(int index) {
if (index >= size)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));//outOfBoundsMsg(index) 在下面，用来返回错误的信息的
}
private void rangeCheckForAdd(int index) {
if (index > size || index < 0)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
private String outOfBoundsMsg(int index) {
return "Index: "+index+", Size: "+size;
}27.removeAll(Collection
public boolean removeAll(Collection c) {
Objects.requireNonNull(c); //只是用来检测c是不是空指针，如果是抛出异常。
return batchRemove(c, false); //
}28.retainAll(Collection
public boolean retainAll(Collection c) {
Objects.requireNonNull(c);
return batchRemove(c, true);
}29.writeObject(java.io.ObjectOutputStream s)：java序列化（目前先跳过）
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; iif (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
} 30.readObject(java.io.ObjectInputStream s)：同上
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; i31.listIterator(int index)/listIterator():返回列表中元素的列表迭代器（按适当顺序），从列表的指定位置开始。
public ListIterator listIterator(int index) {
if (index < 0 || index > size)
throw new IndexOutOfBoundsException("Index: "+index);
return new ListItr(index);
}
public ListIterator listIterator() {
return new ListItr(0);
} 32.iterator():返回该列表的迭代器。
public Iterator iterator() {
return new Itr();
} 33.subList(int fromIndex, int toIndex):得到[fromIndex,toIndex)的子容器
public List 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 + ")");
}
###############如下的方法以后再说
34.forEach(Consumer
public void forEach(Consumersuper 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();
}
}35.spliterator():并行遍历迭代器（可以参考这篇博客：http://blog.csdn.net/lh513828570/article/details/56673804）
public Spliterator spliterator() {
return new ArrayListSpliterator<>(this, 0, -1, 0);
}
static final class ArrayListSpliterator implements Spliterator {
private final ArrayList 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 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 lst;
if ((hi = fence) < 0) {
if ((lst = list) == null)
hi = fence = 0;
else {
expectedModCount = lst.modCount;
hi = fence = lst.size;
}
}
return hi;
}
public ArrayListSpliterator trySplit() {
int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
return (lo >= mid) ? null : // divide range in half unless too small
new ArrayListSpliterator(list, lo, index = mid,
expectedModCount);
}
public boolean tryAdvance(Consumersuper 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(Consumersuper E> action) {
int i, hi, mc; // hoist accesses and checks from loop
ArrayList 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;
}
}
removeIf(Predicate
public boolean removeIf(Predicatesuper 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 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(Comparatorsuper E> c) {
final int expectedModCount = modCount;
Arrays.sort((E[]) elementData, 0, size, c);
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
modCount++;
}
}