IO流——练习

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/*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：zhagnsan，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。*/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>();elsestus = 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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