Back to index...

	/*
	* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.util;

	/**
	* This class provides a skeletal implementation of the {@code List}
	* interface to minimize the effort required to implement this interface
	* backed by a "sequential access" data store (such as a linked list). For
	* random access data (such as an array), {@code AbstractList} should be used
	* in preference to this class.<p>
	*
	* This class is the opposite of the {@code AbstractList} class in the sense
	* that it implements the "random access" methods ({@code get(int index)},
	* {@code set(int index, E element)}, {@code add(int index, E element)} and
	* {@code remove(int index)}) on top of the list's list iterator, instead of
	* the other way around.<p>
	*
	* To implement a list the programmer needs only to extend this class and
	* provide implementations for the {@code listIterator} and {@code size}
	* methods. For an unmodifiable list, the programmer need only implement the
	* list iterator's {@code hasNext}, {@code next}, {@code hasPrevious},
	* {@code previous} and {@code index} methods.<p>
	*
	* For a modifiable list the programmer should additionally implement the list
	* iterator's {@code set} method. For a variable-size list the programmer
	* should additionally implement the list iterator's {@code remove} and
	* {@code add} methods.<p>
	*
	* The programmer should generally provide a void (no argument) and collection
	* constructor, as per the recommendation in the {@code Collection} interface
	* specification.<p>
	*
	* This class is a member of the
	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
	* Java Collections Framework</a>.
	*
	* @author Josh Bloch
	* @author Neal Gafter
	* @see Collection
	* @see List
	* @see AbstractList
	* @see AbstractCollection
	* @since 1.2
	*/

	public abstract class AbstractSequentialList<E> extends AbstractList<E> {
	/**
	* Sole constructor. (For invocation by subclass constructors, typically
	* implicit.)
	*/
	protected AbstractSequentialList() {
	}

	/**
	* Returns the element at the specified position in this list.
	*
	* <p>This implementation first gets a list iterator pointing to the
	* indexed element (with {@code listIterator(index)}). Then, it gets
	* the element using {@code ListIterator.next} and returns it.
	*
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	public E get(int index) {
	try {
	return listIterator(index).next();
	} catch (NoSuchElementException exc) {
	throw new IndexOutOfBoundsException("Index: "+index);
	}
	}

	/**
	* Replaces the element at the specified position in this list with the
	* specified element (optional operation).
	*
	* <p>This implementation first gets a list iterator pointing to the
	* indexed element (with {@code listIterator(index)}). Then, it gets
	* the current element using {@code ListIterator.next} and replaces it
	* with {@code ListIterator.set}.
	*
	* <p>Note that this implementation will throw an
	* {@code UnsupportedOperationException} if the list iterator does not
	* implement the {@code set} operation.
	*
	* @throws UnsupportedOperationException {@inheritDoc}
	* @throws ClassCastException {@inheritDoc}
	* @throws NullPointerException {@inheritDoc}
	* @throws IllegalArgumentException {@inheritDoc}
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	public E set(int index, E element) {
	try {
	ListIterator<E> e = listIterator(index);
	E oldVal = e.next();
	e.set(element);
	return oldVal;
	} catch (NoSuchElementException exc) {
	throw new IndexOutOfBoundsException("Index: "+index);
	}
	}

	/**
	* Inserts the specified element at the specified position in this list
	* (optional operation). Shifts the element currently at that position
	* (if any) and any subsequent elements to the right (adds one to their
	* indices).
	*
	* <p>This implementation first gets a list iterator pointing to the
	* indexed element (with {@code listIterator(index)}). Then, it
	* inserts the specified element with {@code ListIterator.add}.
	*
	* <p>Note that this implementation will throw an
	* {@code UnsupportedOperationException} if the list iterator does not
	* implement the {@code add} operation.
	*
	* @throws UnsupportedOperationException {@inheritDoc}
	* @throws ClassCastException {@inheritDoc}
	* @throws NullPointerException {@inheritDoc}
	* @throws IllegalArgumentException {@inheritDoc}
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	public void add(int index, E element) {
	try {
	listIterator(index).add(element);
	} catch (NoSuchElementException exc) {
	throw new IndexOutOfBoundsException("Index: "+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.
	*
	* <p>This implementation first gets a list iterator pointing to the
	* indexed element (with {@code listIterator(index)}). Then, it removes
	* the element with {@code ListIterator.remove}.
	*
	* <p>Note that this implementation will throw an
	* {@code UnsupportedOperationException} if the list iterator does not
	* implement the {@code remove} operation.
	*
	* @throws UnsupportedOperationException {@inheritDoc}
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	public E remove(int index) {
	try {
	ListIterator<E> e = listIterator(index);
	E outCast = e.next();
	e.remove();
	return outCast;
	} catch (NoSuchElementException exc) {
	throw new IndexOutOfBoundsException("Index: "+index);
	}
	}


	// Bulk Operations

	/**
	* Inserts all of the elements in the specified collection into this
	* list at the specified position (optional operation). 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
	* 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.)
	*
	* <p>This implementation gets an iterator over the specified collection and
	* a list iterator over this list pointing to the indexed element (with
	* {@code listIterator(index)}). Then, it iterates over the specified
	* collection, inserting the elements obtained from the iterator into this
	* list, one at a time, using {@code ListIterator.add} followed by
	* {@code ListIterator.next} (to skip over the added element).
	*
	* <p>Note that this implementation will throw an
	* {@code UnsupportedOperationException} if the list iterator returned by
	* the {@code listIterator} method does not implement the {@code add}
	* operation.
	*
	* @throws UnsupportedOperationException {@inheritDoc}
	* @throws ClassCastException {@inheritDoc}
	* @throws NullPointerException {@inheritDoc}
	* @throws IllegalArgumentException {@inheritDoc}
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	public boolean addAll(int index, Collection<? extends E> c) {
	try {
	boolean modified = false;
	ListIterator<E> e1 = listIterator(index);
	for (E e : c) {
	e1.add(e);
	modified = true;
	}
	return modified;
	} catch (NoSuchElementException exc) {
	throw new IndexOutOfBoundsException("Index: "+index);
	}
	}


	// Iterators

	/**
	* Returns an iterator over the elements in this list (in proper
	* sequence).<p>
	*
	* This implementation merely returns a list iterator over the list.
	*
	* @return an iterator over the elements in this list (in proper sequence)
	*/
	public Iterator<E> iterator() {
	return listIterator();
	}

	/**
	* Returns a list iterator over the elements in this list (in proper
	* sequence).
	*
	* @param index index of first element to be returned from the list
	* iterator (by a call to the {@code next} method)
	* @return a list iterator over the elements in this list (in proper
	* sequence)
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	public abstract ListIterator<E> listIterator(int index);
	}

Back to index...