摘要：一簡介內部是通過雙向鏈表存儲的，提供順序訪問。繼承了，實現在迭代器上的隨機訪問。四總結本節分析了的源碼的用法。實現了接口，內部通過鏈表實現，能夠實現鏈表隊列棧和雙端隊列等數據結構的功能。

LinkedList內部是通過雙向鏈表存儲的，提供順序訪問。繼承了AbstractSequentialList，實現在迭代器上的隨機訪問。并且，還實現了List、Deque、Cloneable,Serializable。Deque是雙端隊列接口，繼承自Queue，Queue是隊列接口。LinkedList的定義如下：

public class LinkedList extends AbstractSequentialList
                implements List, Deque, Cloneable, java.io.Serializable {}

數據存儲的結構是鏈表，定義如下：

private static class Node {
    E item;
    Node next;
    Node prev;
    Node(Node prev, E element, Node next) {
        this.item = element;
        this.next = next;
        this.prev = prev;
    }
}

ArrayList提供兩個構造方法，定義如下：

//默認構造方法
public LinkedList() {}
//給定初始化集合c的構造方法
public LinkedList(Collection c) {
     this();
     addAll(c);
}

LinkedList通過鏈表結構實現了雙端隊列、棧等數據結構，下面具體分析源碼：

public class LinkedList
        extends AbstractSequentialList
        implements List, Deque, Cloneable, java.io.Serializable
    {
           //鏈表大小
        transient int size = 0;
    
        /**
         * 指向第一個節點指針
         */
        transient Node first;
    
        /**
         *指向最后一個節點的指針
         */
        transient Node last;
    
        /**
         * 構造一個空的list.
         */
            public LinkedList() {
                 }
    
        /**
         * 構造一個有特定元素的list
         */
        public LinkedList(Collection c) {
            this();
            addAll(c);
        }
    
        /**
         * 添加一個元素，作為第一個節點
         */
        private void linkFirst(E e) {
            final Node f = first;
            final Node newNode = new Node<>(null, e, f);
            first = newNode;
            if (f == null)
                last = newNode;
            else
                f.prev = newNode;
            size++;
            modCount++;
        }
    
        /**
         * 添加一個節點，作為最后一個元素
         */
        void linkLast(E e) {
            final Node l = last;
            final Node newNode = new Node<>(l, e, null);
            last = newNode;
            if (l == null)
                first = newNode;
            else
                l.next = newNode;
            size++;
            modCount++;
        }
    
        /**
         * 在非空節點succ前插入一個元素
         */
        void linkBefore(E e, Node succ) {
            // assert succ != null;
            final Node pred = succ.prev;
            final Node newNode = new Node<>(pred, e, succ);
            succ.prev = newNode;
            if (pred == null)
                first = newNode;
            else
                pred.next = newNode;
            size++;
            modCount++;
        }
    
        /**
         * 刪除一個非空的first節點，將其next節點指向first,如果next節點為空，則last節點也為空
         */
        private E unlinkFirst(Node f) {
            // assert f == first && f != null;
            final E element = f.item;
            final Node next = f.next;
            f.item = null;
            f.next = null; // help GC
            first = next;
            if (next == null)
                last = null;
            else
                next.prev = null;
            size--;
            modCount++;
            return element;
        }
    
        /**
         * 刪除一個非空的last節點，將其prev節點指向last,如果prev節點為空，則first節點也為空
         */
        private E unlinkLast(Node l) {
            // assert l == last && l != null;
            final E element = l.item;
            final Node prev = l.prev;
            l.item = null;
            l.prev = null; // help GC
            last = prev;
            if (prev == null)
                first = null;
            else
                prev.next = null;
            size--;
            modCount++;
            return element;
        }
    
        /**
         * 刪除非空節點x，將其next節點的prev節點指向其prev節點，prev節點的next節點指向其next節點
         */
        E unlink(Node x) {
            // assert x != null;
            final E element = x.item;
            final Node next = x.next;
            final Node prev = x.prev;
    
            if (prev == null) {
                first = next;
            } else {
                prev.next = next;
                x.prev = null;
            }
    
            if (next == null) {
                last = prev;
            } else {
                next.prev = prev;
                x.next = null;
            }
    
            x.item = null;
            size--;
            modCount++;
            return element;
        }
    
        /**
         * 返回first節點，如果節點為空，拋出NoSuchElementException 異常
         */
        public E getFirst() {
            final Node f = first;
            if (f == null)
                throw new NoSuchElementException();
            return f.item;
        }
    
        /**
         * 返回last節點，如果節點為空，拋出NoSuchElementException 異常
         */
        public E getLast() {
            final Node l = last;
            if (l == null)
                throw new NoSuchElementException();
            return l.item;
        }
    
        /**
         * 刪除第一個節點，如果節點為空，拋出NoSuchElementException 異常
         */
        public E removeFirst() {
            final Node f = first;
            if (f == null)
                throw new NoSuchElementException();
            return unlinkFirst(f);
        }
    
        /**
         * 刪除最后一個節點，如果節點為空，拋出NoSuchElementException 異常
         */
        public E removeLast() {
            final Node l = last;
            if (l == null)
                throw new NoSuchElementException();
            return unlinkLast(l);
        }
    
        /**
         * 在鏈表的頭部插入節點e
         */
        public void addFirst(E e) {
            linkFirst(e);
        }
    
        /**
         * 在鏈表的頭部插入節點e
         */
        public void addLast(E e) {
            linkLast(e);
        }
    
        /**
         * 返回鏈表中是否包含元素e
         */
        public boolean contains(Object o) {
            return indexOf(o) != -1;
        }
    
        /**
         * 返回鏈表的大小
         */
        public int size() {
            return size;
        }
    
        /**
         * 在鏈表尾部添加一個元素
         */
        public boolean add(E e) {
            linkLast(e);
            return true;
        }
    
        /**
         * 從頭部遍歷，移除鏈表中第一個o元素
         */
        public boolean remove(Object o) {
            if (o == null) {
                for (Node x = first; x != null; x = x.next) {
                    if (x.item == null) {
                        unlink(x);
                        return true;
                    }
                }
            } else {
                for (Node x = first; x != null; x = x.next) {
                    if (o.equals(x.item)) {
                        unlink(x);
                        return true;
                    }
                }
            }
            return false;
        }
    
        /**
         * 將給定集合中的元素插入到鏈表尾部
         */
        public boolean addAll(Collection c) {
            return addAll(size, c);
        }
    
        /**
         * 在指定的位置index后面插入集合c中的元素
         */
        public boolean addAll(int index, Collection c) {
            checkPositionIndex(index);
    
            Object[] a = c.toArray();
            int numNew = a.length;
            if (numNew == 0)
                return false;
    
            Node 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 newNode = new Node<>(pred, e, null);
                if (pred == null)
                    first = newNode;
                else
                    pred.next = newNode;
                pred = newNode;
            }
    
            if (succ == null) {
                last = pred;
            } else {
                pred.next = succ;
                succ.prev = pred;
            }
    
            size += numNew;
            modCount++;
            return true;
        }
    
        /**
         * 刪除list中所有的元素.
         */
        public void clear() {
            //解除節點間的鏈接是沒有必要的，但是，這樣做有助于GC和釋放內存
            for (Node x = first; x != null; ) {
                Node next = x.next;
                x.item = null;
                x.next = null;
                x.prev = null;
                x = next;
            }
            first = last = null;
            size = 0;
            modCount++;
        }
    
    
        // 下面是位置訪問的操作
    
        /**
         * 返回指定位置節點中的元素.
         */
        public E get(int index) {
            checkElementIndex(index);
            return node(index).item;
        }
    
        /**
         * 替換index位置節點中的元素
         */
        public E set(int index, E element) {
            checkElementIndex(index);
            Node x = node(index);
            E oldVal = x.item;
            x.item = element;
            return oldVal;
        }
    
        /**
         * 在指定位置index處插入元素，如果index==size,則在最后位置插入
         */
        public void add(int index, E element) {
            checkPositionIndex(index);
    
            if (index == size)
                linkLast(element);
            else
                linkBefore(element, node(index));
        }
    
        /**
         * 刪除指定位置的元素
         */
        public E remove(int index) {
            checkElementIndex(index);
            return unlink(node(index));
        }
    
        /**
         * index處是否有節點
         */
        private boolean isElementIndex(int index) {
            return index >= 0 && index < size;
        }
    
        /**
         * 返回index是否是有效的位置
         */
        private boolean isPositionIndex(int index) {
            return index >= 0 && index <= size;
        }
    
        /**
         * 數組越界的異常詳細信息
         */
        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));
        }
    
        /**
         * 返回指定位置的元素
         */
        Node node(int index) {
            // assert isElementIndex(index);
            //如果元素在前半部分，從前查找，否則，從后面開始查找
            if (index < (size >> 1)) {
                Node x = first;
                for (int i = 0; i < index; i++)
                    x = x.next;
                return x;
            } else {
                Node x = last;
                for (int i = size - 1; i > index; i--)
                    x = x.prev;
                return x;
            }
        }
    
        // 下面是搜索操作
    
        /**
         * 從list頭部開始搜索，返回遇到的第一個給定元素的下標，如果不存在，返回-1
         */
        public int indexOf(Object o) {
            int index = 0;
            if (o == null) {
                for (Node x = first; x != null; x = x.next) {
                    if (x.item == null)
                        return index;
                    index++;
                }
            } else {
                for (Node x = first; x != null; x = x.next) {
                    if (o.equals(x.item))
                        return index;
                    index++;
                }
            }
            return -1;
        }
    
        /**
         * 返回最后一個指定元素的下標，如果不存在，返回-1
         */
        public int lastIndexOf(Object o) {
            int index = size;
            if (o == null) {
                for (Node x = last; x != null; x = x.prev) {
                    index--;
                    if (x.item == null)
                        return index;
                }
            } else {
                for (Node x = last; x != null; x = x.prev) {
                    index--;
                    if (o.equals(x.item))
                        return index;
                }
            }
            return -1;
        }
    
        // 下面是隊列操作
    
        /**
         * 取第一個元素，但是不刪除
         */
        public E peek() {
            final Node f = first;
            return (f == null) ? null : f.item;
        }
    
        /**
         * 去第一個元素，但是不刪除
         */
        public E element() {
            return getFirst();
        }
    
        /**
         * 取第一個元素，并且刪除
         */
        public E poll() {
            final Node f = first;
            return (f == null) ? null : unlinkFirst(f);
        }
    
        /**
         * 返回第一個元素，并且刪除
         */
        public E remove() {
            return removeFirst();
        }
    
        /**
         * 在尾部插入元素e
         */
        public boolean offer(E e) {
            return add(e);
        }
    
        // 下面是雙端隊列的操作
    
        /**
         * 在list的前面插入元素e
         */
        public boolean offerFirst(E e) {
            addFirst(e);
            return true;
        }
    
        /**
         * 在list的后面插入元素e
         */
        public boolean offerLast(E e) {
            addLast(e);
            return true;
        }
    
        /**
         * 返回list中的第一個元素
         */
        public E peekFirst() {
            final Node f = first;
            return (f == null) ? null : f.item;
         }
    
        /**
         * 返回list中的最后一個元素,
         */
        public E peekLast() {
            final Node l = last;
            return (l == null) ? null : l.item;
        }
    
        /**
         * 返回第一個元素，并且刪除
         */
        public E pollFirst() {
            final Node f = first;
            return (f == null) ? null : unlinkFirst(f);
        }
    
        /**
         * 返回最后一個元素，并且刪除
         */
        public E pollLast() {
            final Node l = last;
            return (l == null) ? null : unlinkLast(l);
        }
    
        /**
         * 在list頭部添加節點
         */
        public void push(E e) {
            addFirst(e);
        }
    
        /**
         * 刪除頭部節點
         */
        public E pop() {
            return removeFirst();
        }
    
        /**
         * 從頭部開始遍歷，刪除第一個遇到的元素
         */
        public boolean removeFirstOccurrence(Object o) {
            return remove(o);
        }
    
        /**
         * 從尾部開始遍歷，刪除第一個遇到的元素
         */
        public boolean removeLastOccurrence(Object o) {
            if (o == null) {
                for (Node x = last; x != null; x = x.prev) {
                    if (x.item == null) {
                        unlink(x);
                        return true;
                    }
                }
            } else {
                for (Node x = last; x != null; x = x.prev) {
                    if (o.equals(x.item)) {
                        unlink(x);
                        return true;
                    }
                }
            }
            return false;
        }
    
        /**
         * List迭代器
         */
        public ListIterator listIterator(int index) {
            checkPositionIndex(index);
            return new ListItr(index);
        }
    
             //迭代器內部類
        private class ListItr implements ListIterator {
            private Node lastReturned;
            private Node 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 lastNext = lastReturned.next;
                unlink(lastReturned);
                if (next == lastReturned)
                    next = lastNext;
                else
                    nextIndex--;
                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);
                else
                    linkBefore(e, next);
                nextIndex++;
                expectedModCount++;
            }
    
            public void forEachRemaining(Consumer 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();
            }
        }
        //節點定義
        private static class Node {
            E item;
            Node next;
            Node prev;
    
            Node(Node prev, E element, Node next) {
                this.item = element;
                this.next = next;
                this.prev = prev;
            }
        }
    
        /**
         * 降序迭代器，從后向前遍歷
         */
        public Iterator descendingIterator() {
            return new DescendingIterator();
        }
    
        /**
         * 降序迭代器實現
         */
        private class DescendingIterator implements Iterator {
            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 LinkedList superClone() {
            try {
                return (LinkedList) super.clone();
            } catch (CloneNotSupportedException e) {
                throw new InternalError(e);
            }
        }
    
        /**
         * 克隆list對象
         */
        public Object clone() {
            LinkedList clone = superClone();
    
            // Put clone into "virgin" state
            clone.first = clone.last = null;
            clone.size = 0;
            clone.modCount = 0;
    
            // Initialize clone with our elements
            for (Node x = first; x != null; x = x.next)
                clone.add(x.item);
    
            return clone;
        }
    
        /**
         * 將list轉換為數組，順序遍歷，取每一個節點元素，放入數組
         */
        public Object[] toArray() {
            Object[] result = new Object[size];
            int i = 0;
            for (Node x = first; x != null; x = x.next)
                result[i++] = x.item;
            return result;
        }
    
        /**
         * 將list轉換為數組，使用示例：String[] y = x.toArray(new String[0])
         * @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[] 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 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;
    
        /**
         * 將list寫入輸出流
         */
        private void writeObject(java.io.ObjectOutputStream s)
            throws java.io.IOException {
            // Write out any hidden serialization magic
            s.defaultWriteObject();
    
            // Write out size
            s.writeInt(size);
    
            // Write out all elements in the proper order.
            for (Node x = first; x != null; x = x.next)
                s.writeObject(x.item);
        }
    
        /**
         * 從輸出流構造list
         */
        @SuppressWarnings("unchecked")
        private void readObject(java.io.ObjectInputStream s)
            throws java.io.IOException, ClassNotFoundException {
            // Read in any hidden serialization magic
            s.defaultReadObject();
    
            // Read in size
            int size = s.readInt();
    
            // Read in all elements in the proper order.
            for (int i = 0; i < size; i++)
                linkLast((E)s.readObject());
        }
    
            /**
              *以下方法為1.8新增
               */
    
        /**
         * 
         * @since 1.8
         */
        @Override
        public Spliterator spliterator() {
            return new LLSpliterator(this, -1, 0);
        }
    
        /** A customized variant of Spliterators.IteratorSpliterator */
        static final class LLSpliterator implements Spliterator {
            static final int BATCH_UNIT = 1 << 10;  // batch array size increment
            static final int MAX_BATCH = 1 << 25;  // max batch array size;
            final LinkedList list; // null OK unless traversed
            Node current;      // current node; null until initialized
            int est;              // size estimate; -1 until first needed
            int expectedModCount; // initialized when est set
            int batch;            // batch size for splits
    
            LLSpliterator(LinkedList list, int est, int expectedModCount) {
                this.list = list;
                this.est = est;
                this.expectedModCount = expectedModCount;
            }
    
            final int getEst() {
                int s; // force initialization
                final LinkedList 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 trySplit() {
                Node 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 action) {
                Node 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 action) {
                Node 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;
            }
        }
    
    }

//獲取第一個元素，不刪除節點
public E getFirst()
//獲取最后一個元素，不刪除節點
public E getLast()
//刪除第一個節點
public E removeFirst()
//刪除最后一個節點
public E removeLast()
//在頭部添加一個節點
public void addFirst(E e)
//在尾部添加一個節點
public void addLast(E e)
//在尾部添加一個節點
public boolean add(E e)
//順序遍歷，刪除鏈表中第一個元素的節點
public boolean remove(Object o)
//將集合c中的元素添加到尾部
public boolean addAll(Collection c)
//將集合c中的元素添加到index位置后面
public boolean addAll(int index, Collection c)
//獲取位置index處的元素，不刪除節點
public E get(int index)
//替換位置index處的位置           
public E set(int index, E element)
//在位置index前插入節點
public void add(int index, E element)
//刪除位置index處的節點
public E remove(int index)
//從頭部遍歷，返回第一個元素的位置
public int indexOf(Object o)
//從尾部遍歷，返回最后一個元素的位置
public int lastIndexOf(Object o)
//返回第一個節點元素，不刪除節點
public E peek() 
//返回第一個節點元素
public E element()
//返回第一個節點元素，并且刪除節點
public E poll()
//刪除第一個節點 
public E remove()
//在尾部添加節點
public boolean offer(E e)
//在頭部添加節點
public boolean offerFirst(E e)
//在尾部添加節點
public boolean offerLast(E e)
//獲取第一個節點元素，不刪除節點
public E peekFirst()
//獲取最后一個節點元素，不刪除節點
public E peekLast()
//獲取第一個節點元素，刪除節點
public E pollFirst()
//獲取最后一個節點元素，刪除節點
public E pollLast()
//在頭部添加節點
public void push(E e)
//返回第一個節點元素，刪除節點
public E pop()

由于LikedList實現了接口List、Queue、Deque,內部通過鏈表存儲，所以支持鏈表、隊列、雙端隊列和棧等數據結構，下面分別介紹作為這幾種數據結構的使用方法：

作為隊列使用

隊列是一種先進先出的數據結構，可以通過add()和poll()兩個方法實現，具體代碼如下：

        /**
         * LinkedList作為隊列的使用
         */
        public static void queueTest(){
            Queue queue = new LinkedList<>();
            Integer[] arrays = new Integer[10];
            int size = 10;
            //隊尾加入元素
            for (int i = 0; i < size; i++){
                queue.add(i);
            }
            System.out.println("queue:" + queue.toString());
            //取隊頭元素--不刪除
            for (int i = 0; i < size; i++){
                arrays[i] = queue.peek();
            }
            System.out.println("peek:" + Arrays.toString(arrays));
            System.out.println("queue:" + queue.toString());
            arrays = new Integer[10];
            //取隊頭元素--刪除
            for (int i = 0; i < size; i++){
                arrays[i] = queue.poll();
            }
            System.out.println("poll" + Arrays.toString(arrays));
            System.out.println("queue:" + queue.toString());
        }

運行結果如下：

作為棧使用

棧是一種先進后出的數據結構，可以通過push()和pop()兩個方法實現，具體代碼如下：

        /**
         * LinkedList作為棧的使用
         */
            public static void stackTest(){
                Deque stack = new LinkedList<>();
                Integer[] arrays = new Integer[10];
                int size = 10;
                //元素入棧
                for (int i = 0; i < size; i++){
                    stack.push(i);
                }
                System.out.println("stack:" + stack.toString());
        
                //元素出棧
                for (int i = 0; i < size; i++){
                    arrays[i] = stack.pop();
                }
                System.out.println("pop:" + Arrays.toString(arrays));
                System.out.println("stack:" + stack.toString());
            }

運行結果如下：

作為雙端隊列使用

雙端隊列是一種在兩端都可以進出的數據結構，可以通過offerFirst()、offerLast() 和pollFirst()、pollLast()等方法實現，具體代碼如下：

            /**
             * LinkedList作為雙端隊列的使用
             */
            public static void dequeTest(){
                Deque deque = new LinkedList<>();
                Integer[] arrays = new Integer[10];
                int size = 5;
        
                //從隊頭和隊尾各入隊五個
                for (int i = 0; i < size; i++){
                    deque.offerFirst(i);
                    deque.offerLast(i);
                }
                System.out.println("deque:" + deque.toString());
                int n = 0;
                //從隊頭和隊尾各出隊五個
                for (; n < 10;){
                    arrays[n++] = deque.pollFirst();
                    arrays[n++] = deque.pollLast();
                }
                System.out.println("poll:" + Arrays.toString(arrays));
                System.out.println("deque:" + deque.toString());
            }

運行結果如下：

遍歷方式

和ArrayList一樣，進行四種遍歷方式的比較，遍歷代碼和ArrayList一樣，運行結果如下：

從上圖中的結果可以看出，通過下標遍歷LinkedList效率是非常低的。遍歷中，get(i)方法每次都從頭部或者尾部遍歷，找到位置i的節點，取出節點中的元素，所以導致效率低。

本節分析了LinkedList的源碼的用法。LinkedList實現了List、Queue、Deque接口，內部通過鏈表實現，能夠實現鏈表、隊列、棧和雙端隊列等數據結構的功能。