import java.util.*;

public class student
{
    class Node
    {
         public String name ;
         public String ID;
         public int java ;
         public int os;
         public int PE;
         public int total;
    }
   public  Node data;
    public student next;
    public student creat()
    {
        student head,p,r,s1;
        int x1,x2,x3,x4;
        String n,i;
        head=r=null;
        System.out.print("请输入学生的姓名  学号   java成绩    os成绩     Internet 成绩");
       System.out.print("请输入一个x整形数据以0结束：");
        Scanner c= new Scanner(System.in);
        n=c.nextLine();
        Scanner c0= new Scanner(System.in);
        i=c0.nextLine();
        Scanner c1= new Scanner(System.in);
        x1=c1.nextInt();
        Scanner c2= new Scanner(System.in);
        x2=c2.nextInt();
        Scanner c3= new Scanner(System.in);
        x3=c3.nextInt();
        
        while (x1!=0)
        {
            student s11=new student();
            s11.data.name=n;
            s11.data.ID=i;
            s11.data.java=x1;
            s11.data.os=x2;
            s11.data.PE=x3;
            s11.data.total=s11.data.java+s11.data.os+s11.data.PE;
            if(head==null)
                head=s11;
            else
                r.next=s11;
               
            r=s11;
            Scanner b= new Scanner(System.in);
            n=b.nextLine();
            Scanner b0= new Scanner(System.in);
            i=b0.nextLine();
            Scanner b1= new Scanner(System.in);
            x1=b1.nextInt();
            Scanner b2= new Scanner(System.in);
            x2=b2.nextInt();
            Scanner b3= new Scanner(System.in);
            x3=b3.nextInt();
        }
        if(r!=null)
            r.next=null;
        return head;
    }
    public void out(student head)
    {
        student p;
        p=head;
        System.out.print("List is:");
        while(p!=null)
        {
            System.out.println("\t"+p.data.name+"\t"+p.data.ID+"\t"+p.data.java+"\t"+p.data.os+"\t"+p.data.PE+"\t"+p.data.total);
            p=p.next;
        }
    }
    public student sortup(student head)
    {
        student p=head,pre=null,s=null,q=null;
           head.next=null;
           while(p!=null)
           {
               s=p;
               p=p.next;
               pre=head;
               q=head.next;
               while(q!=null && q.data.total<s.data.total)
               {
                   pre=q;
                   q=q.next;
               }
               s.next=q;
               pre.next=s;
           }
        return head;
    }
    public student sortdown(student head)
    {
        student p=head,pre=null,s=null,q=null;
           head.next=null;
           while(p!=null)
           {
               s=p;
               p=p.next;
               pre=head;
               q=head.next;
               while(q!=null && q.data.total<s.data.total)
               {
                   pre=q;
                   q=q.next;
               }
               s.next=q;
               pre.next=s;
           }
        return head;
    }
    public static void main(String[] args) {
        student x,y;
        student a=new student();
        x=a.creat();
        a.out(x);
        a.sortdown(x);
        a.out(x);
        a.sortup(x);
        a.out(x);
        
    }
}
我是一个java初学者  我们老师布置了一个实验  用java编一个学生成绩管理的一个小程序 （学生人数为10人）
 要求：输入姓名  学号  三门课的成绩  计算总成绩  然后对这10个学生的总成绩排序  我编了一个但是行不通 我是按c语言  链表的思想来用java做的  不知道那出了问题  求各位大侠不胜赐教  帮我把它该对  谢谢 ！小女子不胜感激  ！！！  4.30之前就要交 希望大侠们.。。。

谢谢

非常感谢你给我的解答  有些地方我看不怎么懂  再次向你请教
为什么每一个Student的类的每一个属性都有   return xx  ，this.xx=xx 呢？是什么含义
 public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }