The difference (advantages & disavanteges ) between Arraylist and Linkedlist

先放总结： ArrayList 在时间复杂度上表现出 查询快  更改操作消耗大的特点，而LinkedList则表现出 查询相对耗费大，而更改快的特点 所以两种list可以择优使用！

首先 放上自己打的一段 模仿 残缺的 LinkedList 代码：

public class linkListDemo {
    /**
     * first refer to the first ele
     * last refer to the last ele , Object
     * */
    private Node first = null;
    private Node last  = null;
    
    
    /**
     * the size of the list
     * */
    private int size = 0;
    
    
    
    /**
     * add a new node to the last position
     * */
    public void addLast(Object ele){
        
        //create a new node which pose on the next position of the previous one
        Node node = new Node(ele);
        
        //size would not be lower than zero ,so we don't need out-of-bound check
        if(size == 0){
            /**
             * no doubt that the first and last ele of the very first element is itself 
             * */
            
            /**
             * set the first and last node of the linkedlist
             * */
            this.last  = node; //belongs to a linkedlist
            this.first = node; //belongs to a linkedlist
        }
        else{
            this.last.next = node;
            node.prev = this.last;
            this.last = node;
        
        
        }
        size++;
    }
    
    /**
     * remove operation a node in the linkedlist
     * */
    public void remove(Node nd){
        
    }
    /**
     * add a new node to the first position
     * */
    public void addFirst(){
        
    }
    
    /**
     * class node , which contain its previous node and next node , as well as its own element
     * */
     class Node {
         /**
          * ele , pre ,next
          * */
         Node(Object ele){
             this.ele = ele;
         }
        //element 
        private Object ele;
        
        //previous 
        Node prev;
        
        //next
        Node next;
        
    
        
    /**
     * overwrite toString method 
     * */
    }
    public String toString(){
        
        //the first node
        Node currentNode = this.first;
        if(size == 0){
            String str = "[]";
            return null;
        }
        else{
            StringBuffer sb = new StringBuffer();
            sb.append("[");
            for(int i = 0 ; i < size; i++){
                
                //add element
                sb.append(currentNode.ele);
                currentNode = currentNode.next;
                
                //add ","
                if(i != (size - 1)){
                    sb.append(",");
                }
            }
            sb.append("]");
            
            //@return
            return sb.toString();
        }
    
    }
}

 

还有  ArrayLIst 的：

/**
 * @command 学习仿作一个Arrayist
 * */
public class MyArrayList {
    /**主体数组*/
    Object[] elementData;
    /**初始化后的数组元素个数*/
    private int size = 0;
    /**默认长度*/
    private static final Integer DEFAULT_CAPACITY = 10;
    /**empty list that has initialized*/
    private static final Object[] EMPTY_ELEMENTDATA = null;
    /** Constructor 
     * @throws Exception */
    public MyArrayList() throws Exception{
        this(DEFAULT_CAPACITY);
    }
    /**
     * Constructs an empty list with the specific initial capacity
     * @param initialCapacity the initial capacity of the list
     * @exception IllegalArgumentException if the specific capacity 
     * is negative
     * 
     * */
     public MyArrayList(Integer initialCapacity)throws IllegalArgumentException {
        if(initialCapacity > 0){
        this.elementData = new Object[initialCapacity];
        }else if (initialCapacity ==0){
            this.elementData = EMPTY_ELEMENTDATA;
        }else {
            //真的是 实践学习得最多 ：throw exception 时要用new  因为你这个是一个新的异常 如果不用new 默认当是方法
            throw new IllegalArgumentException("Illegal capacity : " + initialCapacity);
        }
    }
    public static void add(Object obj){
        
    }
    
    /**
     * return true if the arraylist is empty
     * else  return false
     * */
    public boolean isEmpty(){
        return size == 0;
    }
    
    /**
     * return the element of the specific index
     * */
    public Object get(Integer index){
        rangeCheck(index);//checked
        return elementData[index];
    }
    
    /**
     * to check whether if the index is out-of-bound
     * */
    private void rangeCheck(Integer index) {
        // TODO Auto-generated method stub
        if(index > size){
            throw new IndexOutOfBoundsException("index");// actually Java api used outofboundmsg(which is a defined string
        }
    }
}