Java实现线性表的链式存储

package algorithm.datastructure.linklist;
import java.util.NoSuchElementException;

/*
* 链表
* 物理存储上非连续的存储结构，数据元素的逻辑顺序是通过链表中的指针链接次序实现
* 
* */
public class LinkedList {
 private Node head;//头节点
 private int size;//链表长度
 static private class Node{
  private int data;
  private Node next;
  public Node(){

  }
  private Node(int data,Node next){
   this.data=data;
   this.next=next;
  }
 }

 //初始化空链表
 public LinkedList(){
  //head=null;
 }

 //添加元素
 public Boolean add(int element){
  linkLast(element);
  return true;
 }
 //在某个位置之前添加元素
 public Boolean add(int index,Integer element){
  checkPositionIndex(index);
  if (index==size){
   linkLast(element);
  } else {
   linkBefore(element,node(index));
  }

  return true;
 }
 //根据下标获取元素
 public int get(int index){
  checkElementIndex(index);
  return node(index).data;
 }
 //获取第一个元素
 public Integer getFirst(){
  Node f=head;
  if (f==null){
   throw new NoSuchElementException();
  } else {
   return f.data;
  }
 }
 //获取最后一个元素
 public Integer getLast(){
  if (size==0){
   throw new NoSuchElementException();
  }
  int index=size-1;
  return node(index).data;
 }

 //删除第一个元素
 public Integer removeFirst(){
  Node f=head;
  if (f==null){
   throw new NoSuchElementException();
  } else {
   return unlink(head);
  }
 }

 //删除最后一个元素
 public Integer removeLast(){
  if (size==0){
   throw new NoSuchElementException();
  }
  int index=size-1;
  return unlink(node(index));
 }


 //根据索引删除元素
 public Integer remove(int index){
  checkElementIndex(index);
  return unlink(node(index));
 }

 //销毁链表
 public void destroyList(){
  clearList();
 }
 //将链表置为空表
 public void clearList() {

  for (Node p=head;p!=null;){
   Node next=p.next;//记录下一个结点
   p=null;//删除当前结点
   p=next;//指向下一个结点
  }
  size=0;
  head=null;
 }
 //遍历链表
 public void traverseList(){

  for (Node p=head;p!=null;){
   System.out.println(p.data);
   p=p.next;
  }
 }

 //返回链表元素个数
 public int size(){
  return size;
 }


 //尾部添加结点
 private void linkLast(int element){
  Node cur =null,p;
  if (size==0){//没有结点时
   head=new Node(element,null);
   size++;
   return;
  }
  for (p=head;p!=null;){//有结点时候
   cur=p;
   p=cur.next;
  }
  cur.next= new Node(element,null);//尾部添加元素
  size++;
 }


 //在某结点之前插入结点
 private void linkBefore(int element,Node node){
  if (node==null){
   linkLast(element);
  } else {
   Node p=head,q=p.next;
   if (node.data==p.data){//node为结点时候
    head= new Node(element, p);//在头部插入元素
    size++;
   } else {
    while (p!=null){
     if (q.data==node.data) {
      p.next= new Node(element,q);//在q之前(p之后)插入一个元素
      size++;
      break;
     }
     p=p.next;
     q=p.next;
    }

   }
  }

 }

 //删除结点
 private Integer unlink(Node node){
  Integer deleteNodeData=null;
  Node p=null;
  deleteNodeData=node.data;
  if (node.data==head.data){//该节点为头结点
   p=head;
   head=p.next;
   p=null;
   size--;
  } else {
   Node q=head;
   for (p=q.next;p!=null;){//使用两个指针,p,q
    if (p.data==node.data){
     break;
    }
    q=q.next;//p始终为q的next结点
    p=q.next;
   }
   q.next=p.next;
   p=null;//删除p
   size--;
  }
  return deleteNodeData;
 }

 //数组下标是否越界
 private Boolean isElementIndex(int index){
  return index>=0&&index<size;
 }
 //插入位置是否越界
 public Boolean isPositionIndex(int index){
  return index>=0&&index<=size;
 }

 //检验下标是否越界，抛出异常
 private void checkElementIndex(int index){
  if(!isElementIndex(index)){
   try {
    throw new IndexOutOfBoundsException("下标越界");
   } catch (Exception e) {
    e.printStackTrace();
   }
  }
 }

 //检验插入下标是否越界，抛出异常
 private void checkPositionIndex(int index){
  if(!isPositionIndex(index)){
   try {
    throw new IndexOutOfBoundsException("下标越界");
   } catch (Exception e) {
    e.printStackTrace();
   }
  }
 }







 //返回指定位置的元素
 private Node node(int index){
  int nowIndex = 0;
  if(size>0){
   for (Node p=head;p!=null;){
    if (nowIndex==index){
     return p;
    }
    p=p.next;
    nowIndex++;
   }
  }
  return null;

 }

 public static void main(String[] args) {


  java.util.LinkedList linkedList0=new java.util.LinkedList();
  linkedList0.add(6);
  linkedList0.remove(0);
  linkedList0.size();
  linkedList0.peek();
  //linkedList0.getFirst();
  linkedList0.clear();

  //测试
  LinkedList linkedList=new LinkedList();
  linkedList.add(2);
  linkedList.add(6);
  linkedList.add(0);
  linkedList.add(3);
  linkedList.add(8);
  linkedList.add(10);
  System.out.println(linkedList.get(0));
  System.out.println(linkedList.getFirst());
  System.out.println(linkedList.getLast());
  System.out.println(linkedList.get(5));
  System.out.println(linkedList.remove(5));
  System.out.println(linkedList.remove(4));

  linkedList.remove(2);
  linkedList.remove(0);
  linkedList.remove(0);
  linkedList.remove(0);

  linkedList.add(2);
  linkedList.add(6);
  linkedList.add(0);
  linkedList.add(3);
  linkedList.add(8);
  linkedList.add(10);

  linkedList.removeFirst();
  linkedList.removeFirst();
  linkedList.removeLast();
  System.out.println(linkedList.size());


  System.out.println("遍历链表");
  linkedList.traverseList();
  linkedList.add(0,4);
  linkedList.add(0,5);
  linkedList.add(2,5);

  linkedList.add(4,5);

  linkedList.add(6,9);
  linkedList.add(8,11);
  linkedList.add(9,222);
  // linkedList.linkBefore(3,new Node(3,null));
//  linkedList.linkBefore(3,new Node(2,null));
//  linkedList.linkBefore(3,new Node(2,null));
//  linkedList.linkBefore(7,new Node(2,null));
//  linkedList.linkBefore(9,new Node(7,null));
//  linkedList.linkBefore(9,new Node(8,null));
  System.out.println("遍历链表");
  linkedList.traverseList();
  linkedList.clearList();



 }
}