2集知识点

1. 手写Linklist的常用方法：

   1. add(Object obj)

   2. add(int index,Object obj)

   3. size()

   4. get(int index)

   5. rangCheck(int index)

   6. remove(int index)

   7. node(int index)

演示代码

package com.collection;public class Node {        Node previous;  //这里没加private是为了方便演示，应该加        Object obj;     //这里没加private是为了方便演示，应该加        Node next;   //这里没加private是为了方便演示，应该加                public void setPrevious(Node previous){            this.previous = previous;        }                public Object getPrevious(){            return previous;        }                public void setObj(Object obj){            this.obj = obj;        }                public Object getObj(){            return obj;        }                public void setNext(Node next){            this.next = next;        }                public Object getNext(){            return next;        }                        }

package com.collection;import java.util.List;public class SxtLinkedList /*implements List*/ {    private Node first;    private Node last;    private int size;    public void add(Object obj){        Node n = new Node();        if(first==null){            n.setPrevious(null);            n.setObj(obj);            n.setNext(null);                        first = n;            last = n;        } else {            //直接往last节点后增加新的节点            n.setPrevious(last);            n.setObj(obj);            n.setNext(null);                        last.setNext(n);            last = n;        }        size++;    }        public int size(){        return size;    }        public Object get(int index){        rangeCheck(index);        Node temp = node(index);        if(temp!=null){            return temp.obj;        }        return null;    }        public void rangeCheck(int index){        if(index<0||index>size){            try {                throw new Exception();            } catch (Exception e) {                e.printStackTrace();            }        }    }        public void remove(int index){        Node temp = node(index);        if(temp!=null){            Node up = temp.previous;            Node down = temp.next;            up.next = down;            down.previous = up;            size--;        }        }        public Node node(int index){        Node temp = null;        if(first!=null){            temp = first;            for(int i=0;i