成绩排序

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static class Student {
        int studentno, grade;
        public Student(int studentno, int grade) {
            this.studentno = studentno;
            this.grade = grade;
        }
        public void setStudentno(int studentno) {
            this.studentno = studentno;
        }
        public int getStudentno() {
            return studentno;
        }
        public void setGrade(int grade) {
            this.grade = grade;

        }
        public int getGrade() {
            return grade;
        }
    }
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        List<Student> students = new ArrayList<Student>();
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            //int b = in.nextInt();
            //System.out.println(a + b);
            for (int i = 0; i < a; i++) {
                int studentno = in.nextInt();
                int grade = in.nextInt();
                students.add(new Student(studentno, grade));
            }
            students.sort((s1, s2)->s1.getGrade() - s2.getGrade()); //升序排序
            Collections.sort(students, (s1,
                                        s2)->s1.getGrade() - s2.getGrade()); //升序排序
            students.sort(Comparator.comparing(Student::getGrade));//升序排序
            Collections.sort(students, Comparator.comparing(Student::getGrade)); //升序排序
            Collections.sort(students, new Comparator<Student>() {
                public int compare(Student s1, Student s2) {
                    if(s1.grade==s2.grade){
                         return s1.getStudentno()-s2.getStudentno();//升序排序
                    }
                    return s1.getGrade()-s2.getGrade();//升序排序
                }
            });//升序排序
        }
        for (Student student : students) {
            System.out.println(String.valueOf(student.studentno) + " " + String.valueOf(
                                   student.grade));
        }
    }
}