Package java.util

Class AbstractList<E>

java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractList<E>
All Implemented Interfaces:
Iterable<E>, Collection<E>, List<E>
Direct Known Subclasses:
AbstractSequentialList, ArrayList, UnsafeArrayList, Vector
public abstract class AbstractList<E>
extends AbstractCollection<E>
implements List<E>
AbstractList is an abstract implementation of the List interface, optimized for a backing store which supports random access. This implementation does not support adding or replacing. A subclass must implement the abstract methods get() and size(), and to create a modifiable List it's necessary to override the add() method that currently throws an UnsupportedOperationException.
Since:
1.2

  • Field Summary

    Fields
    Modifier and Type Field Description
    protected int modCount
    A counter for changes to the list.

  • Constructor Summary

    Constructors
    Modifier Constructor Description
    protected AbstractList()
    Constructs a new instance of this AbstractList.

  • Method Summary

    Modifier and Type Method Description
    void add​(int location, E object)
    Inserts the specified object into this List at the specified location.
    boolean add​(E object)
    Adds the specified object at the end of this List.
    boolean addAll​(int location, Collection<? extends E> collection)
    Inserts the objects in the specified Collection at the specified location in this List.
    void clear()
    Removes all elements from this list, leaving it empty.
    boolean equals​(Object object)
    Compares the specified object to this list and return true if they are equal.
    abstract E get​(int location)
    Returns the element at the specified location in this list.
    int hashCode()
    Returns the hash code of this list.
    int indexOf​(Object object)
    Searches this list for the specified object and returns the index of the first occurrence.
    Iterator<E> iterator()
    Returns an iterator on the elements of this list.
    int lastIndexOf​(Object object)
    Searches this list for the specified object and returns the index of the last occurrence.
    ListIterator<E> listIterator()
    Returns a ListIterator on the elements of this list.
    ListIterator<E> listIterator​(int location)
    Returns a list iterator on the elements of this list.
    E remove​(int location)
    Removes the object at the specified location from this list.
    protected void removeRange​(int start, int end)
    Removes the objects in the specified range from the start to the end index minus one.
    E set​(int location, E object)
    Replaces the element at the specified location in this list with the specified object.
    List<E> subList​(int start, int end)
    Returns a part of consecutive elements of this list as a view.

    Methods inherited from class java.util.AbstractCollection

    addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, size, toArray, toArray, toString

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.util.List

    addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, size, toArray, toArray

  • Field Details

    • modCount

      protected transient int modCount
      A counter for changes to the list.

  • Constructor Details

    • AbstractList

      protected AbstractList()
      Constructs a new instance of this AbstractList.

  • Method Details

    • add

      public void add​(int location, E object)
      Inserts the specified object into this List at the specified location. The object is inserted before any previous element at the specified location. If the location is equal to the size of this List, the object is added at the end.

      Concrete implementations that would like to support the add functionality must override this method.

      Specified by:
      add in interface List<E>
      Parameters:
      location - the index at which to insert.
      object - the object to add.
      Throws:
      UnsupportedOperationException - if adding to this List is not supported.
      ClassCastException - if the class of the object is inappropriate for this List
      IllegalArgumentException - if the object cannot be added to this List
      IndexOutOfBoundsException - if location < 0 || location > size()

    • add

      public boolean add​(E object)
      Adds the specified object at the end of this List.
      Specified by:
      add in interface Collection<E>
      Specified by:
      add in interface List<E>
      Overrides:
      add in class AbstractCollection<E>
      Parameters:
      object - the object to add
      Returns:
      true
      Throws:
      UnsupportedOperationException - if adding to this List is not supported
      ClassCastException - if the class of the object is inappropriate for this List
      IllegalArgumentException - if the object cannot be added to this List

    • addAll

      public boolean addAll​(int location, Collection<? extends E> collection)
      Inserts the objects in the specified Collection at the specified location in this List. The objects are added in the order they are returned from the collection's iterator.
      Specified by:
      addAll in interface List<E>
      Parameters:
      location - the index at which to insert.
      collection - the Collection of objects
      Returns:
      true if this List is modified, false otherwise.
      Throws:
      UnsupportedOperationException - if adding to this list is not supported.
      ClassCastException - if the class of an object is inappropriate for this list.
      IllegalArgumentException - if an object cannot be added to this list.
      IndexOutOfBoundsException - if location < 0 || location > size()

    • clear

      public void clear()
      Removes all elements from this list, leaving it empty.
      Specified by:
      clear in interface Collection<E>
      Specified by:
      clear in interface List<E>
      Overrides:
      clear in class AbstractCollection<E>
      Throws:
      UnsupportedOperationException - if removing from this list is not supported.
      See Also:
      List.isEmpty(), List.size()

    • equals

      public boolean equals​(Object object)
      Compares the specified object to this list and return true if they are equal. Two lists are equal when they both contain the same objects in the same order.
      Specified by:
      equals in interface Collection<E>
      Specified by:
      equals in interface List<E>
      Overrides:
      equals in class Object
      Parameters:
      object - the object to compare to this object.
      Returns:
      true if the specified object is equal to this list, false otherwise.
      See Also:
      hashCode()

    • get

      public abstract E get​(int location)
      Returns the element at the specified location in this list.
      Specified by:
      get in interface List<E>
      Parameters:
      location - the index of the element to return.
      Returns:
      the element at the specified index.
      Throws:
      IndexOutOfBoundsException - if location < 0 || location >= size()

    • hashCode

      public int hashCode()
      Returns the hash code of this list. The hash code is calculated by taking each element's hashcode into account.
      Specified by:
      hashCode in interface Collection<E>
      Specified by:
      hashCode in interface List<E>
      Overrides:
      hashCode in class Object
      Returns:
      the hash code.
      See Also:
      equals(java.lang.Object), List.hashCode()

    • indexOf

      public int indexOf​(Object object)
      Searches this list for the specified object and returns the index of the first occurrence.
      Specified by:
      indexOf in interface List<E>
      Parameters:
      object - the object to search for.
      Returns:
      the index of the first occurrence of the object, or -1 if it was not found.

    • iterator

      public Iterator<E> iterator()
      Returns an iterator on the elements of this list. The elements are iterated in the same order as they occur in the list.
      Specified by:
      iterator in interface Collection<E>
      Specified by:
      iterator in interface Iterable<E>
      Specified by:
      iterator in interface List<E>
      Specified by:
      iterator in class AbstractCollection<E>
      Returns:
      an iterator on the elements of this list.
      See Also:
      Iterator

    • lastIndexOf

      public int lastIndexOf​(Object object)
      Searches this list for the specified object and returns the index of the last occurrence.
      Specified by:
      lastIndexOf in interface List<E>
      Parameters:
      object - the object to search for.
      Returns:
      the index of the last occurrence of the object, or -1 if the object was not found.

    • listIterator

      public ListIterator<E> listIterator()
      Returns a ListIterator on the elements of this list. The elements are iterated in the same order that they occur in the list.
      Specified by:
      listIterator in interface List<E>
      Returns:
      a ListIterator on the elements of this list
      See Also:
      ListIterator

    • listIterator

      public ListIterator<E> listIterator​(int location)
      Returns a list iterator on the elements of this list. The elements are iterated in the same order as they occur in the list. The iteration starts at the specified location.
      Specified by:
      listIterator in interface List<E>
      Parameters:
      location - the index at which to start the iteration.
      Returns:
      a ListIterator on the elements of this list.
      Throws:
      IndexOutOfBoundsException - if location < 0 || location > size()
      See Also:
      ListIterator

    • remove

      public E remove​(int location)
      Removes the object at the specified location from this list.
      Specified by:
      remove in interface List<E>
      Parameters:
      location - the index of the object to remove.
      Returns:
      the removed object.
      Throws:
      UnsupportedOperationException - if removing from this list is not supported.
      IndexOutOfBoundsException - if location < 0 || location >= size()

    • removeRange

      protected void removeRange​(int start, int end)
      Removes the objects in the specified range from the start to the end index minus one.
      Parameters:
      start - the index at which to start removing.
      end - the index after the last element to remove.
      Throws:
      UnsupportedOperationException - if removing from this list is not supported.
      IndexOutOfBoundsException - if start < 0 or start >= size().

    • set

      public E set​(int location, E object)
      Replaces the element at the specified location in this list with the specified object.
      Specified by:
      set in interface List<E>
      Parameters:
      location - the index at which to put the specified object.
      object - the object to add.
      Returns:
      the previous element at the index.
      Throws:
      UnsupportedOperationException - if replacing elements in this list is not supported.
      ClassCastException - if the class of an object is inappropriate for this list.
      IllegalArgumentException - if an object cannot be added to this list.
      IndexOutOfBoundsException - if location < 0 || location >= size()

    • subList

      public List<E> subList​(int start, int end)
      Returns a part of consecutive elements of this list as a view. The returned view will be of zero length if start equals end. Any change that occurs in the returned subList will be reflected to the original list, and vice-versa. All the supported optional operations by the original list will also be supported by this subList.

      This method can be used as a handy method to do some operations on a sub range of the original list, for example list.subList(from, to).clear();

      If the original list is modified in other ways than through the returned subList, the behavior of the returned subList becomes undefined.

      The returned subList is a subclass of AbstractList. The subclass stores offset, size of itself, and modCount of the original list. If the original list implements RandomAccess interface, the returned subList also implements RandomAccess interface.

      The subList's set(int, Object), get(int), add(int, Object), remove(int), addAll(int, Collection) and removeRange(int, int) methods first check the bounds, adjust offsets and then call the corresponding methods of the original AbstractList. addAll(Collection c) method of the returned subList calls the original addAll(offset + size, c).

      The listIterator(int) method of the subList wraps the original list iterator. The iterator() method of the subList invokes the original listIterator() method, and the size() method merely returns the size of the subList.

      All methods will throw a ConcurrentModificationException if the modCount of the original list is not equal to the expected value.

      Specified by:
      subList in interface List<E>
      Parameters:
      start - start index of the subList (inclusive).
      end - end index of the subList, (exclusive).
      Returns:
      a subList view of this list starting from start (inclusive), and ending with end (exclusive)
      Throws:
      IndexOutOfBoundsException - if (start < 0 || end > size())
      IllegalArgumentException - if (start > end)