有五个学生,每个学生有3门课的成绩,
从键盘输入以上的数据(包括姓名,三门课成绩), 输入的格式:如:zhangsan,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。
import java.io.*;
import java.util.*;
class Student implements Comparable<Student>{
private String name;
private int ma,cn,en;
private int sum;
Student(String name, int ma, int cn, int en){
this.name = name;
this.ma = ma;
this.cn = cn;
this.en = en;
this.sum = ma+cn+en;
}
public int compareTo(Student s){
int num = new Integer(this.sum).compareTo(new Integer(s.sum));
if(num==0)
return this.name.compareTo(s.name);
return num;
}
public String getName(){
return name;
}
public int getSum(){
return sum;
}
public int hashCode(){
return name.hashCode()+sum*78;
}
public boolean equals(Object obj){
if(!(obj instanceof Student)){
throw new ClassCastException("类型不匹配");
}
Student s = (Student)obj;
return this.name.equals(s.name) && this.sum==s.sum;
}
public String toString(){
return "student["+name+","+ma+","+cn+","+en+"]";//好像是这句话的问题,毕老师视频中", "逗号后面有个空格。不明白为什么?
}
}
class StudentInfoTool{
public static Set<Student> getStudents() throws NumberFormatException, IOException{
BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));
String line = null;
Set<Student> stus = new TreeSet<Student>();
while((line=bufr.readLine())!=null){
if("over".equals(line))
break;
String[] info = line.split(",");
Student stu = new Student(info[0],Integer.parseInt(info[1]),
Integer.parseInt(info[2]),Integer.parseInt(info[3]));
stus.add(stu);
}
bufr.close();
return stus;
}
public static void write2File(Set<Student> stus) throws IOException{
BufferedWriter bufw = new BufferedWriter(new FileWriter("stus.txt"));
for(Student stu : stus){
bufw.write(stu.toString()+"\t");//制表位Tab
bufw.write(stu.getSum()+"");//这儿加上字符串,否则乱码。
bufw.newLine();
bufw.flush();
}
bufw.close();
}
}
public class StudentInfoDemo {
public static void main(String[] args) throws NumberFormatException, IOException {
Set<Student> stus = StudentInfoTool.getStudents();
StudentInfoTool.write2File(stus);
}
}
用记事本打开后,有一组数据没有制表符。代码红色的应该出问题的地方。我按照毕老师的视频,", "逗号后加入空格后问题就消失。求大神解释一下为什么会这样?
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