自己实现LinkedListJAVA103-104

package com.test.linkedlist;

/**
* 用来表示一个节点
*/
public class Node {
Node previous;//该节点的前一个节点
Object obj;//该节点存放的对象
Node next;//该节点的后一个节点

public Node(){
}
public Node(Node previous, Object obj, Node next) {
super();
this.previous = previous;
this.obj = obj;
this.next = next;
}
public Node getPrevious() {
return previous;
}
public void setPrevious(Node previous) {
this.previous = previous;
}
public Object getObj() {
return obj;
}
public void setObj(Object obj) {
this.obj = obj;
}
public Node getNext() {
return next;
}
public void setNext(Node next) {
this.next = next;
}
}
////////////////////////////////////////
package com.test.linkedlist;

public class MyLinkedList {
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;//第一个节点
last = n;//也是最后一个节点
}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);//之前的last指向下一个节点n(之后的last)
last = n;//n为最后一个节点
}
size++;
}

public int size(){
return size;
}

public Object get(int index){
Node temp = getNode(index);
return temp.obj;
}

//index越界处理
public void rangeCheck(int index){
if(index < 0 || index >= size){
try {
throw new Exception();
} catch (Exception e) {
e.printStackTrace();
}
}
}

public Node getNode(int index){//获得相应索引的节点
rangeCheck(index);
Node temp = null;
if(first != null){
temp = first;
for (int i = 0; i < index; i++) {//遍历节点
temp = temp.next;
}
}
return temp;
}

public void remove(int index){
Node temp = getNode(index);
if(temp != null){
Node up = temp.previous;
Node down = temp.next;
up.next = down;
down.previous = up;
size--;
}
}

public void add(int index,Object obj){
Node temp = getNode(index);
Node newNode = new Node();
newNode.obj = obj;

if(temp != null){
Node up = temp.previous;
up.next = newNode;
newNode.previous = up;
newNode.next = temp;
temp.previous = newNode;
size++;
}
}

public static void main(String[] args) {
MyLinkedList list = new MyLinkedList();
list.add("aaa");
list.add("bbb");
list.add("ccc");
//      list.remove(1);
list.add(1, "BBB");
System.out.println(list.get(1));
}
}