java实现单链表LinkList

大二的数据结构，链表。我一直都很头疼。

leetcode刷到一道关于链表的题，脑中一片混沌。

所以来复习一下。

import java.util.*;
import java.io.*;
class Node
{
    protected Node next;
    protected int val;
    public Node(int x)
    {
        val=x;
    }
    public void display()
    {
        System.out.print(val+" ");
    }
}

public class LinkList
{
    public Node first;
    int size;
    int pos=0;
    public LinkList()
    {
        this.first=null;
    }
    public LinkList(int x)
    {
        this.first=new Node(x);
        this.size++;
    }
    public boolean add(int index,int x)
    {
        if(index>size)
            return false;
        Node p=new Node(x);
        if(this.first==null)
        {
            this.first=p;
            size++;
            return true;
        }

        Node previous=this.first;
        Node current=this.first;
        while(pos<index)
        {
            previous=current;
            current=current.next;
            pos++;
        }
        p.next=current;
        previous.next=p;
        pos=0;
        size++;
        return true;
    }
    public Boolean remove(int index)
    {
        if(index>=size)
            return false;
        Node previous=this.first;
        Node current=this.first;
        while(pos<index)
        {
            previous=current;
            current=current.next;
            pos++;
        }
        current=current.next;
        previous.next=current;
        pos=0;
        size--;
        return true;
    }
    public int getSize()
    {
        return this.size;
    }
    public int findElement(int x)
    {
        Node p=this.first;
        int r=0;
        while(p!=null)
        {
            if(p.val==x)
                return r;
            else
                p=p.next;
                r++;
        }
        return -1;

    }
    public void show()
    {
        Node p=first;
        while(p!=null)
        {
            p.display();
            p=p.next;
        }
    }
    public static void main(String[] args)
    {
        Boolean flag;
        LinkList l1=new LinkList();
        LinkList l2=new LinkList(2);
        flag=l2.add(1,3);
        flag=l2.add(2,4);
        flag=l2.add(3,5);
        flag=l2.add(4,6);
        System.out.println(l2.findElement(7));
        System.out.println(l2.findElement(3));
        l2.show();
    }
}