学生成绩（类的应用）

成绩类：

public class Grade {
	int Eng,Mat,Chi;
	
	public Grade(int Eng,int Mat,int Chi){
		this.Eng=Eng;
		this.Mat=Mat;
		this.Chi=Chi;
	}
	
	int getEng(){
		return this.Eng;
	}
	
	int getMat(){
		return Mat;
	}
	
	int getChi(){
		return Chi;
	}
	
	int getGrade(){
		int Sum;
		Sum=Eng+Mat+Chi;
		return Sum;
	}
}

学生类：

public class Student {
    public String studentID;
    public String studentName;
    public Grade grade;
    
    public Student(String ID,String name,Grade grade){
    	studentID = ID;
    	studentName = name;
    	this.grade = grade;
    }
    
    public String getID(){
    	return studentID;
    }
    
    public String getName(){
    	return studentName;
    }
    
    public Grade getGrade(){
    	return grade;
    }
}

主类：

import java.util.*;
public class MainStudent {
	public static void main(String[] args) {
		
		Scanner in = new Scanner(System.in);
		int StudentNum;
		System.out.println("请输入学生人数");
		StudentNum=in.nextInt();
		System.out.println("===========================================================");
		
		List<Student> list = new ArrayList<Student>();
		
		for (int i = 0;i<StudentNum;i++){
            System.out.println("输入学生的学号：");
            String ID = in.next();

            System.out.println("输入学生的姓名：");
            String name = in.next();
            System.out.println("输入英语科目的成绩：");
            int Eng = in.nextInt();
            
            System.out.println("输入数学科目的成绩：");
            int Mat = in.nextInt();

            System.out.println("输入语文科目的成绩：");
            int Chi = in.nextInt();
            
            Grade grade = new Grade(Eng,Mat,Chi);
            Student student = new Student(ID,name,grade);
            list.add(student);
            
            System.out.println("===========================================================");
		}
		
		list.sort(new Comparator<Student>() {
            @Override
            public int compare(Student o1, Student o2) {
                if(o1.getGrade().getGrade()>o2.getGrade().getGrade())
                    return -1;
                else
                    return 1;
            }

        });
		
		for (Student student:list){
			System.out.println("学号："+student.getID()+"\t"+"姓名："+student.getName()+"\t"
                    + "总分："+student.getGrade().getGrade());
		}
	}
}