자바 반복문 성적내기

안녕하세요 엘체프 GG 입니다.

package jse_ex_20180125_1;
 
import java.util.Scanner;
 
public class JavaExScoreIf1 {
 
    public static void main(String[] args) {
        
//        java.util.Scanner sc = new java.util.Scanner(System.in);//import 안할시 풀경로 호출
        Scanner sc = new Scanner(System.in);//표준입력(키보드)
        System.out.print("학점을 입력 하세요 : ");
        
        int score = sc.nextInt();
//         System.out.printf("score = %d\n", score);        
        
        char credit = 'F';        
        if(score >= 90 && score <=100){
            credit = 'A';            
        }else if(score >= 80 && score <=89){
            credit = 'B';            
        }else if(score >= 70 && score <=79){
            credit = 'C';            
        }else if(score >= 60 && score <=69){
            credit = 'D';            
        }
//        else if(score >= 50 && score <=59){
//            credit = 'F';        
//        }
        else{            
        }
        System.out.println("학생의 학점은 : " + credit);
    }
 
}
 

package jse_ex_20180125_1;
 
import java.util.Scanner;
 
public class JavaExScoreSwitch {
 
    public static void main(String[] args) {        
 
        Scanner sc = new Scanner(System.in);//표준입력(키보드)
        System.out.print("시험점수 입력 하세요 : ");        
        int score = sc.nextInt();
        char credit ;
        
        score =  score /10;
 
        switch(score){
        case 9 : credit = 'A' ; break ;
        case 8 : credit = 'B' ; break ;
        case 7 : credit = 'C' ; break ;
        case 6 : credit = 'D' ; break ;
        default : credit = 'F' ;    
            }
        
        System.out.println("당신의 학점은 "+ credit + " 입니다.");
        
        
    }//end main
 
}//end class
 

package jse_ex_20180125_1;
 
import java.util.Scanner;
 
public class JavaExScoreSamhang {
 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);//표준입력(키보드)
        System.out.print("시험점수 입력 하세요 : ");        
        int score = sc.nextInt();
        char credit ;
        
        credit = score >= 90 && score <= 100 ? 'A' :
                score >= 80 && score <= 89 ? 'B' :
                score >= 70 && score <= 79 ? 'C' :
                score >= 60 && score <= 69 ? 'D' : 'F';
        
        
        System.out.println("당신의 학점은 "+ credit + " 입니다.");
    }//erd main
 
}//end class
 

감사합니다.