有五个学生，每个学生有3门课的成绩，从键盘输入以上数据（包括学生号，姓名，三门课成绩），计算出平均成绩，并存到磁盘中

package arraysdemo;
import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStreamWriter;
 import java.io.UnsupportedEncodingException;
 import java.util.Scanner; /*题目：有五个学生，每个学生有3门课的成绩，从键盘输入以上数据（包括学生号，姓名，三门课成绩），计
 算出平均成绩，况原有的数据和计算出的平均分数存放在磁盘文件"stud"中
 */
 public class ArraysDemo {
     public static void main(String[] args) {
         
         Student[] students = new Student[2];
         
         
         for(int i=0;i<students.length;i++) {
             Scanner in = new Scanner(System.in);
             System.out.println("输入第"+(i+1)+"个学生学号");
             String id = in.nextLine();
             System.out.println("输入姓名");
             String name = in.nextLine();
             System.out.println("输入语文成绩");
             int chinese = in.nextInt();
             System.out.println("输入数学成绩");
             int math = in.nextInt();
             System.out.println("输入英语成绩");
             int english  = in.nextInt();
             Student student = new Student();
             student.id=id;
             student.name=name;
             student.chinese=chinese;
             student.math=math;
             student.english=english;
             student.avg=(chinese+math+english)/3;
             students[i]=student;
         }
         for(int i=0;i<students.length;i++) {
             System.out.println(students[i]);
         }
         File file= new File("f:\\Score.txt");
         if(file.exists()){
             System.out.println("文件存在");
         }
         else{
             System.out.println("文件不存在，正在创建....");
             try {
                 file.createNewFile();
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
         FileOutputStream fileout=null;
         OutputStreamWriter output=null;
         try {
             fileout = new FileOutputStream(file);
             output = new OutputStreamWriter(fileout, "gbk");
             output.write("学号\t"+"姓名\t"+"语文\t"+"数学\t"+"英语\t"+"平均值\t");
             for(int i=0;i<students.length;i++) {
                 output.write("\r\n"+students[i].id+"\t"+students[i].name+"\t"+students[i].chinese
                         +"\t"+students[i].math+"\t"+students[i].english+"\t"+students[i].avg);
                 output.flush();
             }
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (UnsupportedEncodingException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }finally {
             try {
                 output.close();
                 fileout.close();
             }catch (Exception e) {
             }
         }
         
         
     }
     
 }最后放上学生类
 public class Student {
     String name;
     String id;
     int math;
     int chinese;
     int english;
     double avg;
     @Override
     public String toString() {
         return "Student [name=" + name + ", id=" + id + ", math=" + math + ", chinese=" + chinese + ", english="
                 + english + ", avg=" + avg + "]";
     }
     
 }