Class CursorableLinkedList<E>

java.lang.Object
org.apache.commons.pool.impl.CursorableLinkedList<E>
Type Parameters:
E - the type of elements held in this collection
All Implemented Interfaces:
Serializable, Iterable<E>, Collection<E>, List<E>
Direct Known Subclasses:
CursorableSubList

class CursorableLinkedList<E> extends Object implements List<E>, Serializable

This class has been copied from Commons Collections, version 3.1 in order to eliminate the dependency of pool on collections. It has package scope to prevent its inclusion in the pool public API. The class declaration below should *not* be changed to public.

A doubly-linked list implementation of the List interface, supporting a ListIterator that allows concurrent modifications to the underlying list.

Implements all of the optional List operations, the stack/queue/dequeue operations available in LinkedList and supports a ListIterator that allows concurrent modifications to the underlying list (see cursor()).

Note that this implementation is not synchronized.

Version:
$Revision: 480452 $ $Date: 2006-11-29 00:45:14 -0700 (Wed, 29 Nov 2006) $
See Also:
  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      Ensure serialization compatibility
      See Also:
    • _size

      protected transient int _size
      The number of elements in me.
    • _head

      protected transient CursorableLinkedList.Listable<E> _head
      A sentry node.

      _head.next() points to the first element in the list, _head.prev() to the last. Note that it is possible for _head.next().prev() and _head.prev().next() to be non-null, as when I am a sublist for some larger list. Use == _head.next() and == _head.prev() to determine if a given org.apache.commons.collections.CursorableLinkedList.Listable is the first or last element in the list.

    • _modCount

      protected transient int _modCount
      Tracks the number of structural modifications to me.
    • _cursors

      protected transient List<WeakReference<CursorableLinkedList<E>.Cursor>> _cursors
      A list of the currently CursorableLinkedList.Cursors currently open in this list.
  • Constructor Details

    • CursorableLinkedList

      CursorableLinkedList()
  • Method Details

    • add

      public boolean add(E o)
      Appends the specified element to the end of this list.
      Specified by:
      add in interface Collection<E>
      Specified by:
      add in interface List<E>
      Parameters:
      o - element to be appended to this list.
      Returns:
      true
    • add

      public void add(int index, E element)
      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).
      Specified by:
      add in interface List<E>
      Parameters:
      index - index at which the specified element is to be inserted.
      element - element to be inserted.
      Throws:
      ClassCastException - if the class of the specified element prevents it from being added to this list.
      IllegalArgumentException - if some aspect of the specified element prevents it from being added to this list.
      IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size()).
    • addAll

      public boolean addAll(Collection<? extends E> c)
      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 unspecified 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.)
      Specified by:
      addAll in interface Collection<E>
      Specified by:
      addAll in interface List<E>
      Parameters:
      c - collection whose elements are to be added to this list.
      Returns:
      true if this list changed as a result of the call.
      Throws:
      ClassCastException - if the class of an element in the specified collection prevents it from being added to this list.
      IllegalArgumentException - if some aspect of an element in the specified collection prevents it from being added to this list.
    • addAll

      public boolean addAll(int index, Collection<? extends E> c)
      Inserts all of the elements in the specified collection into this list 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 this list in the order that they are returned by the specified Collection's Iterator. The behavior of this operation is unspecified 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.)
      Specified by:
      addAll in interface List<E>
      Parameters:
      index - index at which to insert first element from the specified collection.
      c - elements to be inserted into this list.
      Returns:
      true if this list changed as a result of the call.
      Throws:
      ClassCastException - if the class of one of elements of the specified collection prevents it from being added to this list.
      IllegalArgumentException - if some aspect of one of elements of the specified collection prevents it from being added to this list.
      IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size()).
    • addFirst

      public boolean addFirst(E o)
      Inserts the specified element at the beginning of this list. (Equivalent to add(0,o)).
      Parameters:
      o - element to be prepended to this list.
      Returns:
      true
    • addLast

      public boolean addLast(E o)
      Inserts the specified element at the end of this list. (Equivalent to add(java.lang.Object)).
      Parameters:
      o - element to be appended to this list.
      Returns:
      true
    • clear

      public void clear()
      Removes all of the elements from this list. This list will be empty after this call returns (unless it throws an exception).
      Specified by:
      clear in interface Collection<E>
      Specified by:
      clear in interface List<E>
    • contains

      public boolean contains(Object o)
      Returns true if this list contains the specified element. More formally, returns true if and only if this list contains at least one element e such that (o==null ? e==null : o.equals(e)).
      Specified by:
      contains in interface Collection<E>
      Specified by:
      contains in interface List<E>
      Parameters:
      o - element whose presence in this list is to be tested.
      Returns:
      true if this list contains the specified element.
    • containsAll

      public boolean containsAll(Collection<?> c)
      Returns true if this list contains all of the elements of the specified collection.
      Specified by:
      containsAll in interface Collection<E>
      Specified by:
      containsAll in interface List<E>
      Parameters:
      c - collection to be checked for containment in this list.
      Returns:
      true if this list contains all of the elements of the specified collection.
    • cursor

      public CursorableLinkedList<E>.Cursor cursor()
      Returns a ListIterator for iterating through the elements of this list. Unlike iterator(), a cursor is not bothered by concurrent modifications to the underlying list.

      Specifically, when elements are added to the list before or after the cursor, the cursor simply picks them up automatically. When the "current" (i.e., last returned by ListIterator.next() or ListIterator.previous()) element of the list is removed, the cursor automatically adjusts to the change (invalidating the last returned value--i.e., it cannot be removed).

      Note that the returned ListIterator does not support the ListIterator.nextIndex() and ListIterator.previousIndex() methods (they throw UnsupportedOperationException when invoked.

      Historical Note: In previous versions of this class, the object returned from this method was required to be explicitly closed. This is no longer necessary.

      See Also:
    • cursor

      public CursorableLinkedList<E>.Cursor cursor(int i)
      Returns a ListIterator for iterating through the elements of this list, initialized such that ListIterator.next() will return the element at the specified index (if any) and ListIterator.previous() will return the element immediately preceding it (if any). Unlike iterator(), a cursor is not bothered by concurrent modifications to the underlying list.
      Throws:
      IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size()).
      See Also:
    • equals

      public boolean equals(Object o)
      Compares the specified object with this list for equality. Returns true if and only if the specified object is also a list, both lists have the same size, and all corresponding pairs of elements in the two lists are equal. (Two elements e1 and e2 are equal if (e1==null ? e2==null : e1.equals(e2)).) In other words, two lists are defined to be equal if they contain the same elements in the same order. This definition ensures that the equals method works properly across different implementations of the List interface.
      Specified by:
      equals in interface Collection<E>
      Specified by:
      equals in interface List<E>
      Overrides:
      equals in class Object
      Parameters:
      o - the object to be compared for equality with this list.
      Returns:
      true if the specified object is equal to this list.
    • get

      public E get(int index)
      Returns the element at the specified position in this list.
      Specified by:
      get in interface List<E>
      Parameters:
      index - index of element to return.
      Returns:
      the element at the specified position in this list.
      Throws:
      IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size()).
    • getFirst

      public E getFirst()
      Returns the element at the beginning of this list.
    • getLast

      public E getLast()
      Returns the element at the end of this list.
    • hashCode

      public int hashCode()
      Returns the hash code value for this list. The hash code of a list is defined to be the result of the following calculation:
        hashCode = 1;
        Iterator i = list.iterator();
        while (i.hasNext()) {
            Object obj = i.next();
            hashCode = 31*hashCode + (obj==null ? 0 : obj.hashCode());
        }
       
      This ensures that list1.equals(list2) implies that list1.hashCode()==list2.hashCode() for any two lists, list1 and list2, as required by the general contract of Object.hashCode.
      Specified by:
      hashCode in interface Collection<E>
      Specified by:
      hashCode in interface List<E>
      Overrides:
      hashCode in class Object
      Returns:
      the hash code value for this list.
      See Also:
    • indexOf

      public int indexOf(Object o)
      Returns the index in this list of the first occurrence of the specified element, or -1 if this list does not contain this element. More formally, returns the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.
      Specified by:
      indexOf in interface List<E>
      Parameters:
      o - element to search for.
      Returns:
      the index in this list of the first occurrence of the specified element, or -1 if this list does not contain this element.
    • isEmpty

      public boolean isEmpty()
      Returns true if this list contains no elements.
      Specified by:
      isEmpty in interface Collection<E>
      Specified by:
      isEmpty in interface List<E>
      Returns:
      true if this list contains no elements.
    • iterator

      public Iterator<E> iterator()
      Returns a fail-fast iterator.
      Specified by:
      iterator in interface Collection<E>
      Specified by:
      iterator in interface Iterable<E>
      Specified by:
      iterator in interface List<E>
      See Also:
    • lastIndexOf

      public int lastIndexOf(Object o)
      Returns the index in this list of the last occurrence of the specified element, or -1 if this list does not contain this element. More formally, returns the highest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.
      Specified by:
      lastIndexOf in interface List<E>
      Parameters:
      o - element to search for.
      Returns:
      the index in this list of the last occurrence of the specified element, or -1 if this list does not contain this element.
    • listIterator

      public ListIterator<E> listIterator()
      Returns a fail-fast ListIterator.
      Specified by:
      listIterator in interface List<E>
      See Also:
    • listIterator

      public ListIterator<E> listIterator(int index)
      Returns a fail-fast ListIterator.
      Specified by:
      listIterator in interface List<E>
      See Also:
    • remove

      public boolean remove(Object o)
      Removes the first occurrence in this list of the specified element. If this list does not contain the element, it is unchanged. More formally, removes the element with the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))) (if such an element exists).
      Specified by:
      remove in interface Collection<E>
      Specified by:
      remove in interface List<E>
      Parameters:
      o - element to be removed from this list, if present.
      Returns:
      true if this list contained the specified element.
    • remove

      public E remove(int index)
      Removes the element at the specified position in this list (optional operation). Shifts any subsequent elements to the left (subtracts one from their indices). Returns the element that was removed from the list.
      Specified by:
      remove in interface List<E>
      Parameters:
      index - the index of the element to removed.
      Returns:
      the element previously at the specified position.
      Throws:
      IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size()).
    • removeAll

      public boolean removeAll(Collection<?> c)
      Removes from this list all the elements that are contained in the specified collection.
      Specified by:
      removeAll in interface Collection<E>
      Specified by:
      removeAll in interface List<E>
      Parameters:
      c - collection that defines which elements will be removed from this list.
      Returns:
      true if this list changed as a result of the call.
    • removeFirst

      public E removeFirst()
      Removes the first element of this list, if any.
    • removeLast

      public E removeLast()
      Removes the last element of this list, if any.
    • retainAll

      public boolean retainAll(Collection<?> c)
      Retains only the elements in this list that are contained in the specified collection. In other words, removes from this list all the elements that are not contained in the specified collection.
      Specified by:
      retainAll in interface Collection<E>
      Specified by:
      retainAll in interface List<E>
      Parameters:
      c - collection that defines which elements this set will retain.
      Returns:
      true if this list changed as a result of the call.
    • set

      public E set(int index, E element)
      Replaces the element at the specified position in this list with the specified element.
      Specified by:
      set in interface List<E>
      Parameters:
      index - index of element to replace.
      element - element to be stored at the specified position.
      Returns:
      the element previously at the specified position.
      Throws:
      ClassCastException - if the class of the specified element prevents it from being added to this list.
      IllegalArgumentException - if some aspect of the specified element prevents it from being added to this list.
      IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size()).
    • size

      public int size()
      Returns the number of elements in this list.
      Specified by:
      size in interface Collection<E>
      Specified by:
      size in interface List<E>
      Returns:
      the number of elements in this list.
    • toArray

      public Object[] toArray()
      Returns an array containing all of the elements in this list in proper sequence. Obeys the general contract of the Collection.toArray() method.
      Specified by:
      toArray in interface Collection<E>
      Specified by:
      toArray in interface List<E>
      Returns:
      an array containing all of the elements in this list in proper sequence.
    • toArray

      public <T> T[] toArray(T[] a)
      Returns an array containing all of the elements in this list in proper sequence; the runtime type of the returned array is that of the specified array. Obeys the general contract of the Collection.toArray() method.
      Specified by:
      toArray in interface Collection<E>
      Specified by:
      toArray in interface List<E>
      Parameters:
      a - the array into which the elements of this list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
      Returns:
      an array containing the elements of this 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.
    • toString

      public String toString()
      Returns a String representation of this list, suitable for debugging.
      Overrides:
      toString in class Object
      Returns:
      a String representation of this list, suitable for debugging.
    • subList

      public List<E> subList(int i, int j)
      Returns a fail-fast sublist.
      Specified by:
      subList in interface List<E>
      See Also:
    • insertListable

      protected CursorableLinkedList.Listable<E> insertListable(CursorableLinkedList.Listable<E> before, CursorableLinkedList.Listable<E> after, E value)
      Inserts a new value into my list, after the specified before element, and before the specified after element
      Returns:
      the newly created org.apache.commons.collections.CursorableLinkedList.Listable
    • removeListable

      protected void removeListable(CursorableLinkedList.Listable<E> elt)
      Removes the given org.apache.commons.collections.CursorableLinkedList.Listable from my list.
    • getListableAt

      protected CursorableLinkedList.Listable<E> getListableAt(int index)
      Returns the org.apache.commons.collections.CursorableLinkedList.Listable at the specified index.
      Throws:
      IndexOutOfBoundsException - if index is less than zero or greater than or equal to the size of this list.
    • registerCursor

      protected void registerCursor(CursorableLinkedList<E>.Cursor cur)
      Registers a CursorableLinkedList.Cursor to be notified of changes to this list.
    • unregisterCursor

      protected void unregisterCursor(CursorableLinkedList<E>.Cursor cur)
      Removes a CursorableLinkedList.Cursor from the set of cursors to be notified of changes to this list.
    • invalidateCursors

      protected void invalidateCursors()
      Informs all of my registered cursors that they are now invalid.
    • broadcastListableChanged

      protected void broadcastListableChanged(CursorableLinkedList.Listable<E> elt)
      Informs all of my registered cursors that the specified element was changed.
      See Also:
    • broadcastListableRemoved

      protected void broadcastListableRemoved(CursorableLinkedList.Listable<E> elt)
      Informs all of my registered cursors that the specified element was just removed from my list.
    • broadcastListableInserted

      protected void broadcastListableInserted(CursorableLinkedList.Listable<E> elt)
      Informs all of my registered cursors that the specified element was just added to my list.
    • writeObject

      private void writeObject(ObjectOutputStream out) throws IOException
      Throws:
      IOException
    • readObject

      private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException
      Throws:
      IOException
      ClassNotFoundException