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1. Comparing two LinkedList with ListIterator versus for loop and get(int index)
I have two LinkedList objects that are always of the same size. I want to compare them to see if they are identical in content. What are the general performance and style implications of creating a ListIterator for each list and using a while hasNext loop versus using a counter (int i) and iterating from 0 to linkedlist.size() using linkedlist.get(i) to get and compare the values? Is there a... 
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  /*
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   * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.
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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   *
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   * This code is free software; you can redistribute it and/or modify it
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   * under the terms of the GNU General Public License version 2 only, as
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   * published by the Free Software Foundation.  Sun designates this
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   * particular file as subject to the "Classpath" exception as provided
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   * by Sun in the LICENSE file that accompanied this code.
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  *
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  * This code is distributed in the hope that it will be useful, but WITHOUT
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  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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  * version 2 for more details (a copy is included in the LICENSE file that
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  * accompanied this code).
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  *
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  * You should have received a copy of the GNU General Public License version
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  * 2 along with this work; if not, write to the Free Software Foundation,
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  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  *
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  * CA 95054 USA or visit www.sun.com if you need additional information or
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  * have any questions.
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  */
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 package java.util;

This class provides a skeletal implementation of the 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), AbstractList should be used in preference to this class.

This class is the opposite of the AbstractList class in the sense that it implements the "random access" methods (get(int index), set(int index, E element), add(int index, E element) and remove(int index)) on top of the list's list iterator, instead of the other way around.

To implement a list the programmer needs only to extend this class and provide implementations for the listIterator and size methods. For an unmodifiable list, the programmer need only implement the list iterator's hasNext, next, hasPrevious, previous and index methods.

For a modifiable list the programmer should additionally implement the list iterator's set method. For a variable-size list the programmer should additionally implement the list iterator's remove and add methods.

The programmer should generally provide a void (no argument) and collection constructor, as per the recommendation in the Collection interface specification.

This class is a member of the Java Collections Framework.

Author(s):
Josh Bloch
Neal Gafter
Since:
1.2
See also:
Collection
List
AbstractList
AbstractCollection
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 public abstract class AbstractSequentialList<E> extends AbstractList<E> {
    
Sole constructor. (For invocation by subclass constructors, typically implicit.) 
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     protected AbstractSequentialList() {
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     }

    
Returns the element at the specified position in this list.

This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it gets the element using ListIterator.next and returns it.

Throws:
java.lang.IndexOutOfBoundsException
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     public E get(int index) {
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         try {
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             return listIterator(index).next();
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         } catch (NoSuchElementException exc) {
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             throw new IndexOutOfBoundsException("Index: "+index);
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         }
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     }

    
Replaces the element at the specified position in this list with the specified element (optional operation).

This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it gets the current element using ListIterator.next and replaces it with ListIterator.set.

Note that this implementation will throw an UnsupportedOperationException if the list iterator does not implement the set operation.

Throws:
java.lang.UnsupportedOperationException
java.lang.ClassCastException
java.lang.NullPointerException
java.lang.IllegalArgumentException
java.lang.IndexOutOfBoundsException
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    public E set(int index, E element) {
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        try {
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            ListIterator<E> e = listIterator(index);
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            E oldVal = e.next();
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            e.set(element);
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            return oldVal;
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        } catch (NoSuchElementException exc) {
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            throw new IndexOutOfBoundsException("Index: "+index);
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        }
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    }

    
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).

This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it inserts the specified element with ListIterator.add.

Note that this implementation will throw an UnsupportedOperationException if the list iterator does not implement the add operation.

Throws:
java.lang.UnsupportedOperationException
java.lang.ClassCastException
java.lang.NullPointerException
java.lang.IllegalArgumentException
java.lang.IndexOutOfBoundsException
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    public void add(int index, E element) {
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        try {
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            listIterator(index).add(element);
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        } catch (NoSuchElementException exc) {
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            throw new IndexOutOfBoundsException("Index: "+index);
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        }
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    }

    
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.

This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it removes the element with ListIterator.remove.

Note that this implementation will throw an UnsupportedOperationException if the list iterator does not implement the remove operation.

Throws:
java.lang.UnsupportedOperationException
java.lang.IndexOutOfBoundsException
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    public E remove(int index) {
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        try {
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            ListIterator<E> e = listIterator(index);
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            E outCast = e.next();
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            e.remove();
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            return outCast;
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        } catch (NoSuchElementException exc) {
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            throw new IndexOutOfBoundsException("Index: "+index);
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        }
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    }
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    // Bulk Operations
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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.)

This implementation gets an iterator over the specified collection and a list iterator over this list pointing to the indexed element (with listIterator(index)). Then, it iterates over the specified collection, inserting the elements obtained from the iterator into this list, one at a time, using ListIterator.add followed by ListIterator.next (to skip over the added element).

Note that this implementation will throw an UnsupportedOperationException if the list iterator returned by the listIterator method does not implement the add operation.

Throws:
java.lang.UnsupportedOperationException
java.lang.ClassCastException
java.lang.NullPointerException
java.lang.IllegalArgumentException
java.lang.IndexOutOfBoundsException
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    public boolean addAll(int index, Collection<? extends E> c) {
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        try {
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            boolean modified = false;
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            ListIterator<E> e1 = listIterator(index);
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            Iterator<? extends E> e2 = c.iterator();
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            while (e2.hasNext()) {
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                e1.add(e2.next());
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                modified = true;
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            }
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            return modified;
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        } catch (NoSuchElementException exc) {
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            throw new IndexOutOfBoundsException("Index: "+index);
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        }
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    }
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    // Iterators
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Returns an iterator over the elements in this list (in proper sequence).

This implementation merely returns a list iterator over the list.

Returns:
an iterator over the elements in this list (in proper sequence)
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    public Iterator<E> iterator() {
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        return listIterator();
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    }

    
Returns a list iterator over the elements in this list (in proper sequence).

Parameters:
index index of first element to be returned from the list iterator (by a call to the next method)
Returns:
a list iterator over the elements in this list (in proper sequence)
Throws:
java.lang.IndexOutOfBoundsException
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    public abstract ListIterator<E> listIterator(int index);
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