毕老师视频教程21天-09练习中遇到的问题??? - 黑马程序员技术交流社区

/*
需求:
有五个学生,每个学生有3门课程的成绩,从键盘输入以上数据(包括姓名,三名课的成绩),输入的格式:
张三,30,40,60计算出总成绩,并把学生的信息和计算出的总分数低高顺序存放在磁盘文件"studentInfo.txt"中;
思路:
1.因为有五个学生对象,它们属于同一类事物,所以要建立一个类,用于描述他们;
2.因为学生的信息需要排序,对象的排序,我们自然的想到TreeSet集合;
3.最后,我们要定义一个IO输出流,将集合中的学生信息写入到指定的文件中去;
*/
import java.util.*;
import java.io.*;
class StudentInfo
{
public static void main(String[] args)
{
StudentInfoTool.sortStudent();
}
}
//学生工具类,用于建立学生对象,通过输入流获取学生信息,并把学生对象存入到Set集合中,在Set集合中自动排序后,使用输出流,将学生信息写入到指定的文件中去;
class StudentInfoTool
{
public static void sortStudent()
{
Set<Student> studentInfo=new TreeSet<Student>();
File file=new File("studentInfo.txt");
BufferedWriter bufw=null;
BufferedReader bufr=null;
try
{
if (file.exists())
{
file.createNewFile();
}
bufw=new BufferedWriter(new FileWriter(file));
bufr=new BufferedReader(new InputStreamReader(System.in));
try
{
String line;
while ((line=bufr.readLine())!=null)
{
if (line.equals("over"))
{
break;
}
String[] info=line.split(",");
studentInfo.add(new Student(info[0],Double.parseDouble(info[1]),Double.parseDouble(info[2]),Double.parseDouble(info[3])) );
}
}
catch (ClassCastException c)
{
throw new ClassCastException("类型不匹配!");
}
for (Student s:studentInfo )
{
bufw.write(s.toString());
bufw.newLine();
bufw.flush();
}
}
catch (IOException io)
{
throw new RuntimeException("输出流,输入流读取失败!");
}
finally
{
try
{
if (bufw!=null)
{
bufw.close();
}
}
catch (IOException i)
{
throw new RuntimeException("输出流关闭失败!");
}
try
{
if (bufr!=null)
{
bufr.close();
}
}
catch (IOException i)
{
throw new RuntimeException("输入流关闭失败!");
}
}
}
}
class Student implements Comparable<Student>
{
//声明表示学生属性的变量;
private String name;
private double chineseScore,mathScore,englishScore,sumScore;
//Student类的构造函数;
Student(String name,double chineseScore,double mathScore,double englishScore)
{
this.name=name;
this.chineseScore=chineseScore;
this.mathScore=mathScore;
this.englishScore=englishScore;
this.sumScore=chineseScore+mathScore+englishScore;
}
//定义学生属性的get和set方法;
public void setName(String name)
{
this.name=name;
}
public String getName()
{
return name;
}
public void setChineseScore(double chineseScore)
{
this.chineseScore=chineseScore;
}
public double getMathScore()
{
return mathScore;
}
public void setEnglishScore(double englishScore)
{
this.englishScore=englishScore;
}
public double getEnglishScore()
{
return englishScore;
}
//复写继承至Comparable接口的compareTo方法;
public int compareTo(Student s)
{
if (Double.valueOf(this.sumScore).compareTo(Double.valueOf(s.sumScore))==0)
{
return this.name.compareTo(s.name);
}
return Double.valueOf(this.sumScore).compareTo(Double.valueOf(s.sumScore));
}
//应为学生对象可能会存入到hashSet集合中,所以复写hashCode()和equals();
public int hashCode()
{
return this.name.hashCode()+(int)this.sumScore*38;
}
public boolean equals(Student s)
{
return this.name.equals(s.name)&&(this.sumScore==s.sumScore);
}
//复写继承至Object类中的toString(),便于输出打印;
public String toString()
{
return this.name+"\t"+this.chineseScore+"\t"+this.mathScore+"\t"+this.englishScore+"\t"+this.sumScore;
}
}

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