什么时候选择LinkedList？

LinkedList即单链表，如下图

LinkedList优点：

1. 长度可变
2. 插入删除简单

LinkedList缺点：

1. 不能随机访问，必须从head结点顺序访问，所以也就不能够二分查找
2. 存储pointer消耗内存

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下面是LinkedList的简单实现以及简单操作（各个位置插入新节点，打印单链表）：

class LinkedList{    Node head;     class Node    {        int data;        Node next;        Node(int d) {data = d; next = null; }    }    /* Inserts a new Node at front of the list. */    public void push(int new_data)    {        Node new_node = new Node(new_data);        new_node.next = head;        head = new_node;    }    /* Inserts a new node after the given prev_node. */    public void insertAfter(Node prev_node, int new_data)    {        if (prev_node == null)        {            System.out.println("The given previous node cannot be null");            return;        }        Node new_node = new Node(new_data);        new_node.next = prev_node.next;        prev_node.next = new_node;    }    /* Appends a new node at the end.  This method is        defined inside LinkedList class shown above */    public void append(int new_data)    {        Node new_node = new Node(new_data);        if (head == null)        {            head = new Node(new_data);            return;        }        new_node.next = null;        Node last = head;         while (last.next != null)            last = last.next;        last.next = new_node;        return;    }    /* This function prints contents of linked list starting from        the given node */    public void printList()    {        Node tnode = head;        while (tnode != null)        {            System.out.print(tnode.data+" ");            tnode = tnode.next;        }    }    public static void main(String[] args)    {        /* Start with the empty list */        LinkedList llist = new LinkedList();        // Insert 6.  So linked list becomes 6->NUllist        llist.append(6);        // Insert 7 at the beginning. So linked list becomes        // 7->6->NUllist        llist.push(7);        // Insert 1 at the beginning. So linked list becomes        // 1->7->6->NUllist        llist.push(1);        // Insert 4 at the end. So linked list becomes        // 1->7->6->4->NUllist        llist.append(4);        // Insert 8, after 7. So linked list becomes        // 1->7->8->6->4->NUllist        llist.insertAfter(llist.head.next, 8);        System.out.println("\nCreated Linked list is: ");        llist.printList();    }}

供后续方便查阅