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（包括姓名，三门课成绩）， 输入的格式：如：zhagnsan，30，40，60计算出总成绩， 并把学生的信息和计算出的总分数高低顺序存放在磁盘文

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（包括姓名，三门课成绩），

输入的格式：如：zhagnsan，30，40，60计算出总成绩，

并把学生的信息和计算出的总分数高低顺序存放在磁盘文件"stud.txt"中。

1:定义一个描述学生的类

2定义一个操作学生的工具类.0

//比较棒的程序，用到了流读写文件，集合泛型

import java.io.*;

import java.util.*;

class Student implements Comparable<Student>

{

private String name;

private int shu,yu,eng;

private int sum;

public Student(){}

public Student(String name,int shu,int yu,int eng)

{

this.name = name;

this.shu = shu;

this.yu = yu;

this.eng = eng;

sum = shu+yu+eng;

}

public int compareTo(Student stu)

{

int num = this.sum-stu.sum;

return num==0?this.name.compareTo(stu.name):num;

}

public String getName()

{

return name;

}

public int getShu()

{

return shu;

}

public int getYu()

{

return yu;

}

public int getEng()

{

return eng;

}

public int getSum()

{

return sum;

}

public String toString()

{

return name+","+shu+","+yu+","+eng;

}

}

class StuTool

{

public static Set<Student> getStudents() throws IOException

{

return getStudents(null);

}

//从键盘获取学员信息，存到集合中

public static Set<Student> getStudents(Comparator<Student> com)throws IOException

{

TreeSet<Student> ts = null;

if(com==null)

ts = new TreeSet<>();

else

ts = new TreeSet<>(com);

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

String line = null;

for(int i=1;i<=3;i++)

{

System.out.println("请输入第"+i+"个学员的信息");

line = br.readLine();

String[] arr = line.split(",");

ts.add(new Student(arr[0],Integer.parseInt(arr[1]),Integer.parseInt(arr[2]),Integer.parseInt(arr[3])));

}

br.close();

return ts;

}

//把学员信息 按照成绩从高到低写入到文件中

public static void writeInfo(Set<Student> stus)throws IOException

{

BufferedWriter bw = new BufferedWriter(new FileWriter("stud.txt"));

for(Student stu:stus)

{

bw.write(stu.toString()+" ");

bw.write(""+stu.getSum());

bw.newLine();

bw.flush();

}

bw.close();

}

}

class n1

{

public static void main(String[] args) throws IOException

{

Comparator<Student> com = Collections.reverseOrder();

Set<Student> stus = StuTool.getStudents(com);

//但是这一句采用由低到高的默认顺序

// Set<Student> stus = StuTool.getStudents();

StuTool.writeInfo(stus);

}

}

//采用更简明的解法

import java.io.*;

import java.util.*;

class Student {

private String name;

private int chinese;

private int math;

private int english;

private int sum;

public Student(){}

public Student(String name, int chinese, int math, int english){

super();

this.name = name;

this.chinese = chinese;

this.math = math;

this.english = english;

this.sum = this.chinese + this.math + this.english;

}

public int getSum(){

return sum;

}

public String toString(){

return name+","+chinese+","+math+","+english+",总成绩："+sum;

}

}

class ComBySum implements Comparator<Student>

{

public int compare(Student t1, Student t2)

{

int num=t1.getSum()-t2.getSum();

return num;

}

}

public class n1 {

public static void main(String[] args) throws IOException

{

getMassage();

}

public static void getMassage() throws IOException{

Scanner sc = new Scanner(System.in);

System.out.println("请输入学生信息，输入格式为：name,30,30,30");

ComBySum comBySum=new ComBySum();

TreeSet<Student> ts = new TreeSet<>(comBySum);

for(int i=0;i<5;i++)

{

String line = sc.nextLine();

String[] arr;

int chinese;

int math;

int english;

try {

arr = line.split("\\,");

chinese = Integer.parseInt(arr[1]);

math = Integer.parseInt(arr[2]);

english = Integer.parseInt(arr[3]);

ts.add(new Student(arr[0],chinese,math,english));

} catch (NumberFormatException e) {

System.out.println("录入格式错误，请重新录入。。。。");

}

}

BufferedWriter bw = new BufferedWriter(new FileWriter("stu.txt"));

for(Student s : ts)

{

bw.write(s.toString());

bw.newLine();

}

bw.close();

}

}