2科目の成績の合計、平均点を出す。(クラスメソッド、インスタンス、コンストラクタありVer)

MainStudents.java

public class MainStudents {
	public static void main(String[] args) {

		Students students = new Students();

		students.add(new Student("小貫", 82, 70));
		students.add(new Student("鈴木", 85, 74));
		students.add(new Student("山田", 74, 88));
		students.add(new Student("後藤", 90, 74));
		students.add(new Student("池田", 70, 82));

		students.printTotalScores();
		students.printCount();
		students.printAverages();
	}
}

Student.java

import java.util.HashMap;
import java.util.Map;

public class Student {
	private String name;
	private Map<Subject, Double> scores;

	public Student(String name, double japaneseScore, double englishScore) {
		this.name = name;
		scores = new HashMap<>();
		scores.put(Subject.JAPANESE, japaneseScore);
		scores.put(Subject.ENGLISH, englishScore);
	}

	public double getTotalScore() {
		double total = 0;
		for (Double score : scores.values()) {
			total += score;
		}
		return total;
	}

	public double getScore(Subject subject) {
		return scores.get(subject);
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Map<Subject, Double> getScores() {
		return scores;
	}

	public void setScores(Map<Subject, Double> scores) {
		this.scores = scores;
	}

	public void printTotalScore() {
		System.out.println(name + "の合計点は" + getTotalScore() + "です。");
	}
}

Students.java

import java.util.ArrayList;

public class Students {
	private ArrayList<Student> students;

	public Students() {
		this.students = new ArrayList<>();
	}

	public void add(Student student) {
		students.add(student);
	}

	public int count() {
		return students.size();
	}

	public double getAverage(Subject subject) {
		double sum = 0;
		for (Student student : students) {
			sum += student.getScore(subject);
		}
		return sum / (double) count();
	}

	public void printCount() {
		System.out.println("生徒の数は" + count() + "人です。");
	}

	public void printTotalScores() {
		for (Student student : students) {
			student.printTotalScore();
		}
	}

	public void printAverages() {
		for (Subject subject : Subject.values()) {
			double average = getAverage(subject);
			System.out.println(subject.getName() + "の平均点は" + average + "です。");

		}
	}
}

Subject.java

public enum Subject {
	JAPANESE("国語"), ENGLISH("英語");

	private String name;

	private Subject(String name) {
		this.name = name;
	}

	public String getName() {
		return name;
	}
}