集合与IO流结合的练习

练习:
有五个学生,每个学生有3门课程:数学,语文,英语
从键盘输入以上数据(包括姓名,三门课成绩),
输入的格式:zhangsan, 30, 40, 40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.描述学生对象;
2.定义一个可操作学生对象的工具类;

思路:
1.通过获取键盘录入的一行数据,并将录入的信息封装成学生对象;
2.因为学生对象很多,且要对学生的总分排序,所以用TreeSet集合;
3.将集合中的信息写入到文件中;

1.import java.io.*;
2.import java.util.*;
3.class  StudentInfoTest
4.{
5.    public static void main(String[] args)  throws IOException
6.    {
7.        Comparator<Student> comp = Collections.reverseOrder();//因为之前的排序是从小到大排,现在从大到小排,所以定义比较器
8.        Set<Student> stus = StudentInfoTool.getStudent(comp);
9.        StudentInfoTool.writeToFile(stus);
10.    }
11.}
12.class Student implements Comparable<Student>
13.{
14.    private String name;
15.    private int ma,cn,en;
16.    private int sum;
17.
18.    Student(String name,int ma,int cn,int en)
19.    {
20.        this.name = name;
21.        this.ma = ma;
22.        this.cn = cn;
23.        this.en = en;
24.        sum = ma + cn + en;
25.    }
26.    public String getName()
27.    {
28.        return name;
29.    }
30.    public int getSum()
31.    {
32.        return sum;
33.    }
34.    public String toString()
35.    {
36.        return "student["+name+", "+ma+", "+cn+", "+en+",]";
37.    }
38.    public int compareTo(Student stu)
39.    {
40.        int num = new Integer(this.sum).compareTo(new Integer(stu.sum));
41.        if (num==0)
42.        {
43.            return this.name.compareTo(stu.name);
44.        }
45.        return num;
46.    }
47.    public int hashCode()
48.    {
49.        return name.hashCode()+sum*39;
50.    }
51.    public boolean equals(Object obj)
52.    {
53.        if (!(obj instanceof Student))
54.        {
55.            throw new ClassCastException("传入类型不正确");
56.        }
57.        Student stu = (Student)obj;
58.        return this.name.equals(stu.name) && this.sum==stu.sum;
59.    }
60.}
61.class StudentInfoTool
62.{
63.    public static Set<Student> getStudent() throws IOException
64.    {
65.        getStudent(null);
66.        return null;
67.    }
68.    public static Set<Student> getStudent(Comparator<Student> comp) throws IOException
69.    {
70.        BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));
71.        String line = null;
72.        Set<Student> stus = null;
73.        if (comp==null)
74.        {
75.            stus = new TreeSet<Student>();
76.        }
77.        else
78.        {
79.            stus = new TreeSet<Student>(comp);
80.        }
81.        while ((line=bufr.readLine()) !=null)
82.        {
83.            if ("over".equals(line))
84.            {
85.                break;
86.            }
87.            String[] arr = line.split(",");
88.            Student stu = new Student(arr[0],Integer.parseInt(arr[1]),
89.                Integer.parseInt(arr[2]),
90.                Integer.parseInt(arr[3]));
91.            stus.add(stu);
92.        }
93.        bufr.close();
94.        return stus;
95.    }
96.    public static void writeToFile(Set<Student> stus) throws IOException
97.    {
98.        BufferedWriter bufw = new BufferedWriter(new FileWriter("e:\\stu.txt"));
99.        for (Student stu : stus)
100.        {
101.            bufw.write(stu.toString());
102.            bufw.write(stu.getSum()+"");
103.            bufw.newLine();
104.            bufw.flush();
105.        }
106.        bufw.close();
107.    }
108.
109.}
110.
111.