[Java] 학점 구하기

import java.util.*;

class  Grade {

	Scanner scr = new Scanner(System.in);
	String[] sub = {"국어", "영어", "수학", "과학"};
	String scoreStr;
	int i = 0;
	int score = 0;
	int sum = 0;
	int avg = 0;
	char gra;

	void input() { 
		while(i<sub.length) {
			System.out.print(sub[i]+": ");
			scoreStr = scr.nextLine();
			try {
				score = Integer.parseInt(scoreStr);
			}catch(Exception e){
				System.out.println("숫자로만 입력하세요!");
				continue;
			}
			if(score<0 || score>100) {
				System.out.println("0~100까지 점수만 입력하세요!");
				continue;
			}
			i++;
			sum = sum+score;
			avg = sum/sub.length;
		}
	}

	void output() {
		gra = (avg >= 90) ? 'A' :
			  (avg >= 80) ? 'B' :
			  (avg >= 70) ? 'C' :
			  (avg >= 60) ? 'D' : 'F';
			  
		System.out.println("학점: "+gra+" (총점: "+sum+"점, 평균: "+avg+"점)");
	}

	public static void main(String[] args) {
		System.out.println("점수를 입력해주세요!");
		Grade g = new Grade();
		g.input();
		g.output();
	}
}