练习：存储学生信息

骑猪看日落 2022-08-09 06:20 154阅读 0赞

package exercise;
    
    import java.io.BufferedReader;
    import java.io.BufferedWriter;
    import java.io.FileWriter;
    import java.io.IOException;
    import java.io.InputStreamReader;
    import java.util.Collections;
    import java.util.Comparator;
    import java.util.Set;
    import java.util.TreeSet;
    
    //学生类，实现Comparable接口，能够比较
    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 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;
        }
    
        //覆盖compareTo方法
        @Override
        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 toString() {
            return "student[" + name + ", " + ma + ", " + cn + ", " + en + "]";
        }
    }
    
    //工具类
    class StudentInfoTool {
    
        public static Set<Student> getStudents() throws IOException {
            return getStudents(null);
        }
    
        //Comparator比较器
        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;
        }
    
        //写入文件方法
        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();
        }
    }
    
    public class StudentInfoTest { 
    
        public static void main(String[] args) throws IOException {
    
            // 按照成绩递增
            Set<Student> stus1 = StudentInfoTool.getStudents();
    
            // 按照成绩递减
            Comparator<Student> cmp = Collections.reverseOrder();
            Set<Student> stus2 = StudentInfoTool.getStudents(cmp);
    
            StudentInfoTool.write2File(stus2);
        }
    }