从键盘上获取名字、语文、数学的成绩,计算总分然后填充到Student对象中,并将对象写入文件
下面是源文件
Students.java文件

package com.kingsoft.main;import java.io.BufferedReader;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStreamReader;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.io.Serializable;class Students implements Serializable {  String name;  int[] record = new int[4];  int total;  float avg;  String grade;  public Students() {  }  public String getName() {    return name;  }  public int[] getRecord() {    return record;  }  public int getTotal() {    int s = 0;    for (int i = 0; i < record.length; i++)      s += record[i];    return s;  }  public float getAvg() {    float f = getTotal() / 4f;    return f;  }  public String getGrade() {    String str;    if (avg < 100 && avg > 90)      str = "A";    else if (avg > 80)      str = "B";    else if (avg > 70)      str = "C";    else if (avg > 60)      str = "D";    else      str = "F";    return str;  }}

package com.kingsoft.main;import java.io.*;public class Students1 {  public static int s = 0;  /** Creates a new instance of Students1 */  public Students1() {  }  public static void main(String[] args) throws Exception {    InputStreamReader isr = new InputStreamReader(System.in);    BufferedReader br = new BufferedReader(isr);    System.out.println("请顺序输入名字及国语,英语,数学,科学的成绩.(eof:输入完毕)");    String data;    String[] str = new String[5];    FileOutputStream fos = new FileOutputStream("C:\\Documents and Settings\\tliu\\桌面\\新建文件夹\\xi.txt");    ObjectOutputStream oos = new ObjectOutputStream(fos);    while (true) {      data = br.readLine();      s++;      if (data.equals("eof"))        break;      str = data.split(" ");      Students stu = new Students();      stu.name = str[0];      System.out.println(stu.name);      stu.record[0] = Integer.parseInt(str[1]);      System.out.println(stu.record[0]);      stu.record[1] = Integer.parseInt(str[2]);      stu.record[2] = Integer.parseInt(str[3]);      stu.record[3] = Integer.parseInt(str[4]);      stu.total = stu.getTotal();      stu.avg = stu.getAvg();      stu.grade = stu.getGrade();      oos.writeObject(stu);    }    oos.close();    System.out.println("文件内容");    FileInputStream fis = new FileInputStream("D:\\xi.txt");    ObjectInputStream ois = new ObjectInputStream(fis);    for (int j = 1; j < s; j++) {      Students stud;      stud = (Students) ois.readObject();      System.out.println("Students对象" + j + " " + "{" + stud.name + " " + stud.record[0] + " " + stud.record[1] + " "          + stud.record[2] + " " + stud.record[3] + " " + stud.total + " " + stud.avg + " " + stud.grade + "}");    }    ois.close();  }}class Students2 {  public Students2() {  }  public static void main(String[] args) throws Exception {    // TODO code application logic here    int d = Students1.s;    int[] a = new int[d];    FileInputStream fis = new FileInputStream("C:\\Documents and Settings\\tliu\\桌面\\新建文件夹\\xi.txt");    ObjectInputStream ois = new ObjectInputStream(fis);    Students[] students = new Students[d];    for (int i = 1; i < d; i++) {      students[i] = (Students) ois.readObject();    }    ois.close();    System.out.println("名字   " + "国语  " + "英语  " + "数学  " + "科学  " + "总分  " + "平均分  " + "学分  " + "顺序");    for (int i = 1; i < d; i++) {      int max = i;      for (int j = i; j < d; j++) {        if (students[j].avg > students[i].avg)          max = j;      }      System.out.println(students[max].name + "   " + students[max].record[0] + "  " + students[max].record[1] + "  "          + students[max].record[2] + "  " + students[max].record[3] + "  " + students[max].total + "  " + students[max].avg          + "  " + students[max].grade + "  " + i);    }  }}