package com.xysd.dataetl.application.impl;import java.util.*;
import java.util.function.Consumer;public class CLinkedList<E>extends AbstractSequentialList<E>implements List<E>, Deque<E>, Cloneable, java.io.Serializable
{transient int size = 0;//元素个数/*** Pointer to first node.* Invariant: (first == null && last == null) ||* (first.prev == null && first.item != null)*/transient Node<E> first;//头节点/*** Pointer to last node.* Invariant: (first == null && last == null) ||* (last.next == null && last.item != null)*/transient Node<E> last;//尾节点/*** Constructs an empty list.*/public CLinkedList() {}/*** 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 CLinkedList(Collection<? extends E> c) {this();addAll(c);}/*** Links e as first element.* 将元素插入到头部*/private void linkFirst(E e) {final Node<E> f = first;//创建一个新节点 新节点prev 属性为nullfinal Node<E> newNode = new Node<>(null, e, f);first = newNode;//将新节点赋值给firstif (f == null)//如果原始first节点是null 则集合中无元素last = newNode;//则将新节点元素赋值给lastelsef.prev = newNode;//否则将新节点指向旧的first.prev属性size++;//元素数量+1modCount++;//修改次数+1}/*** Links e as last element.* 将元素插入到尾部*/void linkLast(E e) {final Node<E> l = last;//创建新节点Node 新节点的prev=last next = nullfinal Node<E> newNode = new Node<>(l, e, null);last = newNode;//将新节点元素赋值给lastif (l == null)//如果尾节点是null 则说明当前集合中没有元素first = newNode;//则将新节点赋值给头节点 此时first，last是同一个元素elsel.next = newNode;//否则，将oldLast的下一个节点next 指向新创建的节点size++;//集合数量+1modCount++;//修改次数+1}/*** Inserts element e before non-null Node succ.*/void linkBefore(E e, Node<E> succ) {// assert succ != null;final Node<E> pred = succ.prev;final Node<E> newNode = new Node<>(pred, e, succ);succ.prev = newNode;if (pred == null)first = newNode;elsepred.next = newNode;size++;modCount++;}/*** Unlinks non-null first node f.*/private E unlinkFirst(Node<E> f) {//解绑头节点 就是将first.prev = null first.item = null first = first.next// assert f == first && f != null;final E element = f.item;final Node<E> next = f.next;//头节点的下一个元素 要成为firstf.item = null;//将头节点值置为nullf.next = null; // help GC//头节点的next 置为nullfirst = next;//将next 赋值给头节点if (next == null)//如果原始头节点的next 是null 则 尾节点也置nulllast = null;elsenext.prev = null;//否则 将next 元素的prev指向置为null(因为头节点的prev属性是null) 成为头节点size--;//元素数量-1modCount++;//修改次数+1return element;//返回要删除的元素值}/*** Unlinks non-null last node l.*/private E unlinkLast(Node<E> l) {//解绑尾节点// assert l == last && l != null;final E element = l.item;final Node<E> prev = l.prev;l.item = null;//将尾节点元素数值置为nulll.prev = null; // help GC 将尾节点的prev元素置为nulllast = prev;//将prev元素赋值给尾节点，将旧的尾节点覆盖if (prev == null)//如果prev是null 则说明集合中没有元素，则将first 也置为nullfirst = null;elseprev.next = null;//否则将prev的next 置为null,因为next指向的是旧的last元素size--;//元素数量-1modCount++;//修改次数+1return element;//返回解绑元素值}/*** Unlinks non-null node x.*/E unlink(Node<E> x) {//解绑x元素// assert x != null;final E element = x.item;final Node<E> next = x.next;final Node<E> prev = x.prev;if (prev == null) {//说明x元素是头节点first = next;//所以将next 元素直接赋值给头节点} else {prev.next = next;//否则将next 元素赋值给prev.nextx.prev = null;//将x元素的prev引用置为null}if (next == null) {//如果x元素的next引用是null 则x是尾节点last = prev;//则直接将prev元素赋值给尾节点} else {next.prev = prev;//否则 将next元素赋值给next元素的prev属性引用x.next = null;//将当前x元素的next引用置为null}x.item = null;//将x元素的属性值置为nullsize--;//元素个数减一modCount++;//修改次数加一return element;//将要删除的值返回}/*** Returns the first element in this list.** @return the first element in this list* @throws NoSuchElementException if this list is empty*/public E getFirst() {//获取头节点元素值，如果头节点不存在，则抛出异常final Node<E> f = first;if (f == null)throw new NoSuchElementException();return f.item;}/*** Returns the last element in this list.** @return the last element in this list* @throws NoSuchElementException if this list is empty*/public E getLast() {//获取尾节点元素值 如果尾节点不存在 则抛出异常final Node<E> l = last;if (l == null)throw new NoSuchElementException();return l.item;}/*** Removes and returns the first element from this list.** @return the first element from this list* @throws NoSuchElementException if this list is empty*/public E removeFirst() {//删除头节点 如果头节点不存在 则抛出异常final Node<E> f = first;if (f == null)throw new NoSuchElementException();return unlinkFirst(f);}/*** Removes and returns the last element from this list.** @return the last element from this list* @throws NoSuchElementException if this list is empty*/public E removeLast() {//删除尾节点final Node<E> l = last;if (l == null)throw new NoSuchElementException();return unlinkLast(l);}/*** Inserts the specified element at the beginning of this list.** @param e the element to add*/public void addFirst(E e) {//将元素e插入，成为头节点linkFirst(e);}/*** Appends the specified element to the end of this list.** <p>This method is equivalent to {@link #add}.** @param e the element to add*/public void addLast(E e) {//将e元素插入尾部，成为尾节点linkLast(e);}/*** Returns {@code true} if this list contains the specified element.* More formally, returns {@code true} if and only if this list contains* at least one element {@code e} such that* <tt>(o==null ? e==null : o.equals(e))</tt>.** @param o element whose presence in this list is to be tested* @return {@code true} if this list contains the specified element*/public boolean contains(Object o) {return indexOf(o) != -1;}/*** Returns the number of elements in this list.** @return the number of elements in this list*/public int size() {return size;}/*** Appends the specified element to the end of this list.** <p>This method is equivalent to {@link #addLast}.** @param e element to be appended to this list* @return {@code true} (as specified by {@link Collection#add})*/public boolean add(E e) {//添加元素在末尾追加元素linkLast(e);return true;}/*** Removes the first occurrence of the specified element from this list,* if it is present. If this list does not contain the element, it is* unchanged. More formally, removes the element with the lowest index* {@code i} such that* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>* (if such an element exists). Returns {@code true} 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 {@code true} if this list contained the specified element*/public boolean remove(Object o) {//删除第一次出现该元素的数据if (o == null) {for (Node<E> x = first; x != null; x = x.next) {if (x.item == null) {unlink(x);return true;}}} else {for (Node<E> x = first; x != null; x = x.next) {if (o.equals(x.item)) {unlink(x);return true;}}}return false;}/*** 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. (Note that this will occur if the specified collection is* this list, and it's nonempty.)** @param c collection containing elements to be added to this list* @return {@code true} 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) {return addAll(size, c);}/*** 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 {@code true} 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) {checkPositionIndex(index);Object[] a = c.toArray();int numNew = a.length;if (numNew == 0)return false;Node<E> pred, succ;if (index == size) {succ = null;pred = last;} else {succ = node(index);pred = succ.prev;}for (Object o : a) {@SuppressWarnings("unchecked") E e = (E) o;Node<E> newNode = new Node<>(pred, e, null);if (pred == null)first = newNode;elsepred.next = newNode;pred = newNode;}if (succ == null) {last = pred;} else {pred.next = succ;succ.prev = pred;}size += numNew;modCount++;return true;}/*** Removes all of the elements from this list.* The list will be empty after this call returns.*/public void clear() {// Clearing all of the links between nodes is "unnecessary", but:// - helps a generational GC if the discarded nodes inhabit// more than one generation// - is sure to free memory even if there is a reachable Iteratorfor (Node<E> x = first; x != null; ) {Node<E> next = x.next;x.item = null;x.next = null;x.prev = null;x = next;}first = last = null;size = 0;modCount++;}// Positional Access Operations/*** 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) {checkElementIndex(index);return node(index).item;}/*** 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) {checkElementIndex(index);Node<E> x = node(index);E oldVal = x.item;x.item = element;return oldVal;}/*** 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) {checkPositionIndex(index);if (index == size)linkLast(element);elselinkBefore(element, node(index));}/*** Removes the element at the specified position in this list. Shifts any* subsequent elements to the left (subtracts one from their indices).* Returns the element that was removed from the list.** @param index the index of the element to be removed* @return the element previously at the specified position* @throws IndexOutOfBoundsException {@inheritDoc}*/public E remove(int index) {checkElementIndex(index);return unlink(node(index));}/*** Tells if the argument is the index of an existing element.*/private boolean isElementIndex(int index) {return index >= 0 && index < size;}/*** Tells if the argument is the index of a valid position for an* iterator or an add operation.*/private boolean isPositionIndex(int index) {return index >= 0 && index <= size;}/*** 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;}private void checkElementIndex(int index) {if (!isElementIndex(index))throw new IndexOutOfBoundsException(outOfBoundsMsg(index));}private void checkPositionIndex(int index) {if (!isPositionIndex(index))throw new IndexOutOfBoundsException(outOfBoundsMsg(index));}/*** Returns the (non-null) Node at the specified element index.*/Node<E> node(int index) {// assert isElementIndex(index);if (index < (size >> 1)) {Node<E> x = first;for (int i = 0; i < index; i++)x = x.next;return x;} else {Node<E> x = last;for (int i = size - 1; i > index; i--)x = x.prev;return x;}}// Search Operations/*** 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 {@code i} such that* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,* or -1 if there is no such index.** @param o element to search for* @return the index of the first occurrence of the specified element in* this list, or -1 if this list does not contain the element*/public int indexOf(Object o) {//检索元素所处下标，从头节点开始找，找到第一个符合元素的值，则返回该元素的下标int index = 0;if (o == null) {for (Node<E> x = first; x != null; x = x.next) {if (x.item == null)return index;index++;}} else {for (Node<E> x = first; x != null; x = x.next) {if (o.equals(x.item))return index;index++;}}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 {@code i} such that* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,* or -1 if there is no such index.** @param o element to search for* @return the index of the last occurrence of the specified element in* this list, or -1 if this list does not contain the element*/public int lastIndexOf(Object o) {//检索该元素最后一次出现的下标，从尾节点开始往前找int index = size;if (o == null) {for (Node<E> x = last; x != null; x = x.prev) {index--;if (x.item == null)return index;}} else {for (Node<E> x = last; x != null; x = x.prev) {index--;if (o.equals(x.item))return index;}}return -1;}// Queue operations./*** Retrieves, but does not remove, the head (first element) of this list.** @return the head of this list, or {@code null} if this list is empty* @since 1.5*/public E peek() {//返回头节点元素值，当头节点为null 则返回nullfinal Node<E> f = first;return (f == null) ? null : f.item;}/*** Retrieves, but does not remove, the head (first element) of this list.** @return the head of this list* @throws NoSuchElementException if this list is empty* @since 1.5*/public E element() {//返回头节点值,如果头节点是null 则抛出异常return getFirst();}/*** Retrieves and removes the head (first element) of this list.** @return the head of this list, or {@code null} if this list is empty* @since 1.5*/public E poll() {final Node<E> f = first;return (f == null) ? null : unlinkFirst(f);}/*** Retrieves and removes the head (first element) of this list.** @return the head of this list* @throws NoSuchElementException if this list is empty* @since 1.5*/public E remove() {return removeFirst();}/*** Adds the specified element as the tail (last element) of this list.** @param e the element to add* @return {@code true} (as specified by {@link Queue#offer})* @since 1.5*/public boolean offer(E e) {return add(e);}// Deque operations/*** Inserts the specified element at the front of this list.** @param e the element to insert* @return {@code true} (as specified by {@link Deque#offerFirst})* @since 1.6*/public boolean offerFirst(E e) {addFirst(e);return true;}/*** Inserts the specified element at the end of this list.** @param e the element to insert* @return {@code true} (as specified by {@link Deque#offerLast})* @since 1.6*/public boolean offerLast(E e) {addLast(e);return true;}/*** Retrieves, but does not remove, the first element of this list,* or returns {@code null} if this list is empty.** @return the first element of this list, or {@code null}* if this list is empty* @since 1.6*/public E peekFirst() {//返回头节点值final Node<E> f = first;return (f == null) ? null : f.item;}/*** Retrieves, but does not remove, the last element of this list,* or returns {@code null} if this list is empty.** @return the last element of this list, or {@code null}* if this list is empty* @since 1.6*/public E peekLast() {//返回尾节点值final Node<E> l = last;return (l == null) ? null : l.item;}/*** Retrieves and removes the first element of this list,* or returns {@code null} if this list is empty.** @return the first element of this list, or {@code null} if* this list is empty* @since 1.6*/public E pollFirst() {//返回头节点值，并且将头节点解绑final Node<E> f = first;return (f == null) ? null : unlinkFirst(f);}/*** Retrieves and removes the last element of this list,* or returns {@code null} if this list is empty.** @return the last element of this list, or {@code null} if* this list is empty* @since 1.6*/public E pollLast() {//将尾节点值返回，并且将尾节点解绑final Node<E> l = last;return (l == null) ? null : unlinkLast(l);}/*** Pushes an element onto the stack represented by this list. In other* words, inserts the element at the front of this list.** <p>This method is equivalent to {@link #addFirst}.** @param e the element to push* @since 1.6*/public void push(E e) {//将元素插入到头节点addFirst(e);}/*** Pops an element from the stack represented by this list. In other* words, removes and returns the first element of this list.** <p>This method is equivalent to {@link #removeFirst()}.** @return the element at the front of this list (which is the top* of the stack represented by this list)* @throws NoSuchElementException if this list is empty* @since 1.6*/public E pop() {//删除头节点，如果头节点不存在 则抛出异常return removeFirst();}/*** Removes the first occurrence of the specified element in this* list (when traversing the list from head to tail). If the list* does not contain the element, it is unchanged.** @param o element to be removed from this list, if present* @return {@code true} if the list contained the specified element* @since 1.6*/public boolean removeFirstOccurrence(Object o) {//删除链表中第一次出现的指定元素return remove(o);}/*** Removes the last occurrence of the specified element in this* list (when traversing the list from head to tail). If the list* does not contain the element, it is unchanged.** @param o element to be removed from this list, if present* @return {@code true} if the list contained the specified element* @since 1.6*/public boolean removeLastOccurrence(Object o) {//删除链表中最后一次出现的指定元素if (o == null) {for (Node<E> x = last; x != null; x = x.prev) {if (x.item == null) {unlink(x);return true;}}} else {for (Node<E> x = last; x != null; x = x.prev) {if (o.equals(x.item)) {unlink(x);return true;}}}return false;}/*** Returns a list-iterator of the elements in this list (in proper* sequence), starting at the specified position in the list.* Obeys the general contract of {@code List.listIterator(int)}.<p>** The list-iterator is <i>fail-fast</i>: if the list is structurally* modified at any time after the Iterator is created, in any way except* through the list-iterator's own {@code remove} or {@code add}* methods, the list-iterator will throw a* {@code 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.** @param index index of the first element to be returned from the* list-iterator (by a call to {@code next})* @return a ListIterator of the elements in this list (in proper* sequence), starting at the specified position in the list* @throws IndexOutOfBoundsException {@inheritDoc}* @see List#listIterator(int)*/public ListIterator<E> listIterator(int index) {checkPositionIndex(index);return new ListItr(index);}private class ListItr implements ListIterator<E> {private Node<E> lastReturned;private Node<E> next;private int nextIndex;private int expectedModCount = modCount;ListItr(int index) {// assert isPositionIndex(index);next = (index == size) ? null : node(index);nextIndex = index;}public boolean hasNext() {return nextIndex < size;}public E next() {checkForComodification();if (!hasNext())throw new NoSuchElementException();lastReturned = next;next = next.next;nextIndex++;return lastReturned.item;}public boolean hasPrevious() {return nextIndex > 0;}public E previous() {checkForComodification();if (!hasPrevious())throw new NoSuchElementException();lastReturned = next = (next == null) ? last : next.prev;nextIndex--;return lastReturned.item;}public int nextIndex() {return nextIndex;}public int previousIndex() {return nextIndex - 1;}public void remove() {checkForComodification();if (lastReturned == null)throw new IllegalStateException();Node<E> lastNext = lastReturned.next;unlink(lastReturned);if (next == lastReturned)next = lastNext;elsenextIndex--;lastReturned = null;expectedModCount++;}public void set(E e) {if (lastReturned == null)throw new IllegalStateException();checkForComodification();lastReturned.item = e;}public void add(E e) {checkForComodification();lastReturned = null;if (next == null)linkLast(e);elselinkBefore(e, next);nextIndex++;expectedModCount++;}public void forEachRemaining(Consumer<? super E> action) {Objects.requireNonNull(action);while (modCount == expectedModCount && nextIndex < size) {action.accept(next.item);lastReturned = next;next = next.next;nextIndex++;}checkForComodification();}final void checkForComodification() {if (modCount != expectedModCount)throw new ConcurrentModificationException();}}private static class Node<E> {E item;Node<E> next;Node<E> prev;Node(Node<E> prev, E element, Node<E> next) {this.item = element;this.next = next;this.prev = prev;}}/*** @since 1.6*/public Iterator<E> descendingIterator() {return new DescendingIterator();}/*** Adapter to provide descending iterators via ListItr.previous*/private class DescendingIterator implements Iterator<E> {private final ListItr itr = new ListItr(size());public boolean hasNext() {return itr.hasPrevious();}public E next() {return itr.previous();}public void remove() {itr.remove();}}@SuppressWarnings("unchecked")private CLinkedList<E> superClone() {try {return (CLinkedList<E>) super.clone();} catch (CloneNotSupportedException e) {throw new InternalError(e);}}/*** Returns a shallow copy of this {@code CLinkedList}. (The elements* themselves are not cloned.)** @return a shallow copy of this {@code CLinkedList} instance*/public Object clone() {CLinkedList<E> clone = superClone();// Put clone into "virgin" stateclone.first = clone.last = null;clone.size = 0;clone.modCount = 0;// Initialize clone with our elementsfor (Node<E> x = first; x != null; x = x.next)clone.add(x.item);return clone;}/*** 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() {Object[] result = new Object[size];int i = 0;for (Node<E> x = first; x != null; x = x.next)result[i++] = x.item;return result;}/*** 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 list is set to {@code null}.* (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.)** <p>Like the {@link #toArray()} method, this method acts as bridge between* array-based and collection-based APIs. Further, this method allows* precise control over the runtime type of the output array, and may,* under certain circumstances, be used to save allocation costs.** <p>Suppose {@code x} is a list known to contain only strings.* The following code can be used to dump the list into a newly* allocated array of {@code String}:** <pre>* String[] y = x.toArray(new String[0]);</pre>** Note that {@code toArray(new Object[0])} is identical in function to* {@code toArray()}.** @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)a = (T[])java.lang.reflect.Array.newInstance(a.getClass().getComponentType(), size);int i = 0;Object[] result = a;for (Node<E> x = first; x != null; x = x.next)result[i++] = x.item;if (a.length > size)a[size] = null;return a;}private static final long serialVersionUID = 876323262645176354L;/*** Saves the state of this {@code CLinkedList} instance to a stream* (that is, serializes it).** @serialData The size of the list (the number of elements it* contains) is emitted (int), followed by all of its* elements (each an Object) in the proper order.*/private void writeObject(java.io.ObjectOutputStream s)throws java.io.IOException {// Write out any hidden serialization magics.defaultWriteObject();// Write out sizes.writeInt(size);// Write out all elements in the proper order.for (Node<E> x = first; x != null; x = x.next)s.writeObject(x.item);}/*** Reconstitutes this {@code CLinkedList} instance from a stream* (that is, deserializes it).*/@SuppressWarnings("unchecked")private void readObject(java.io.ObjectInputStream s)throws java.io.IOException, ClassNotFoundException {// Read in any hidden serialization magics.defaultReadObject();// Read in sizeint size = s.readInt();// Read in all elements in the proper order.for (int i = 0; i < size; i++)linkLast((E)s.readObject());}/*** 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} and* {@link Spliterator#ORDERED}. Overriding implementations should document* the reporting of additional characteristic values.** @implNote* The {@code Spliterator} additionally reports {@link Spliterator#SUBSIZED}* and implements {@code trySplit} to permit limited parallelism..** @return a {@code Spliterator} over the elements in this list* @since 1.8*/@Overridepublic Spliterator<E> spliterator() {return new LLSpliterator<E>(this, -1, 0);}/** A customized variant of Spliterators.IteratorSpliterator */static final class LLSpliterator<E> implements Spliterator<E> {static final int BATCH_UNIT = 1 << 10; // batch array size incrementstatic final int MAX_BATCH = 1 << 25; // max batch array size;final CLinkedList<E> list; // null OK unless traversedNode<E> current; // current node; null until initializedint est; // size estimate; -1 until first neededint expectedModCount; // initialized when est setint batch; // batch size for splitsLLSpliterator(CLinkedList<E> list, int est, int expectedModCount) {this.list = list;this.est = est;this.expectedModCount = expectedModCount;}final int getEst() {int s; // force initializationfinal CLinkedList<E> lst;if ((s = est) < 0) {if ((lst = list) == null)s = est = 0;else {expectedModCount = lst.modCount;current = lst.first;s = est = lst.size;}}return s;}public long estimateSize() { return (long) getEst(); }public Spliterator<E> trySplit() {Node<E> p;int s = getEst();if (s > 1 && (p = current) != null) {int n = batch + BATCH_UNIT;if (n > s)n = s;if (n > MAX_BATCH)n = MAX_BATCH;Object[] a = new Object[n];int j = 0;do { a[j++] = p.item; } while ((p = p.next) != null && j < n);current = p;batch = j;est = s - j;return Spliterators.spliterator(a, 0, j, Spliterator.ORDERED);}return null;}public void forEachRemaining(Consumer<? super E> action) {Node<E> p; int n;if (action == null) throw new NullPointerException();if ((n = getEst()) > 0 && (p = current) != null) {current = null;est = 0;do {E e = p.item;p = p.next;action.accept(e);} while (p != null && --n > 0);}if (list.modCount != expectedModCount)throw new ConcurrentModificationException();}public boolean tryAdvance(Consumer<? super E> action) {Node<E> p;if (action == null) throw new NullPointerException();if (getEst() > 0 && (p = current) != null) {--est;E e = p.item;current = p.next;action.accept(e);if (list.modCount != expectedModCount)throw new ConcurrentModificationException();return true;}return false;}public int characteristics() {return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;}}}