标题: 跟着老师做练习 [打印本页] 作者: 小骆驼 时间: 2015-5-30 20:57 标题: 跟着老师做练习 有五个学生，每个学生有3门课程成绩，
从键盘输入以上数据（包括姓名，三门课的成绩）
输入的格式：如：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高低顺序存放在磁盘文件“stud.txt”中。
代码如下：
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)//比较sum大小，如果相同按名称比较
{
int sum = new Integer(this.sum).compareTo(new Integer(s.sum));
if(sum==0)
return this.name.compareTo(s.name);
return sum;
}
public String getName()
{
return name;
}
public int getSum()
{
return sum;
}
public int hashCode()
{
return name.hashCode()+sum*78;
}
public boolean equals(Object obj)//判断是不是Student类
{
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()//Student类对应的字符串表现形式
{
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();//反向比较器
Set<Student> stus = StudentInfoTool.getStudents(cmp);
StudentInfoTool.write2File(stus);
}
}