关于毕老师视频中StudentInfoTest比较器调用问题 - 黑马程序员技术交流社区

/*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：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
*
* 1，描述学生对象
* 2，定义一个可操作学生对象的工具类
*
*
* 思想：
* 1，通过获取键盘录入一行数据，并将该行中的信息取出封装成学生对象
* 2，因为学生有很多，那么就需要存储，使用到集合。因为要对学生的总分排序，
* 所以可以使用TreeSet
* 3，将集合的信息写入到一个文件中
*/
package day21;
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;
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+"]";
}
}
class StudentInfoTool
{
public static Set<Student> getStudents() throws IOException
{
return getStudents(null);
}
public static Set<Student> getStudents(Comparator<Student> cmp) throws IOException
{
BufferedReader bufr =
new BufferedReader(new InputStreamReader(System.in));
String line = null;
Set<Student> stus = null;
if(cmp==null)
stus = new TreeSet<Student>();
else
stus = new TreeSet<Student>(cmp);
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("stuinfo.txt"));
for(Student stu : stus)
{
bufw.write(stu.toString()+"\t");
bufw.write(stu.getSum()+"");
bufw.newLine();
bufw.flush();
}
bufw.close();
}
}
class StudentInfoTest
{
public static void main(String[] args) throws IOException
{
Comparator<Student> cmp = Collections.reverseOrder();
Set<Student> stus = StudentInfoTool.getStudents(cmp);
StudentInfoTool.write2File(stus);
}
}

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