public class Duplicate{

  public static void main(String[] args){
    double dishes = 0.0;
    int studentdiscount = 50;
    int workerdiscount = 25;
    int guestdiscount = 0;
    int discountreal = 0;
    double discountprice = 0.0;
    int isxmas = 0;

    dishes = Terminal.askFloat("how much is the dishes? ");
    isxmas = Terminal.askInt("is today xmas? (y: 1, n: 0)");

    discountreal = isxmas * studentdiscount; //instance1
    discountprice = dishes * (1 - discountreal/100.0); //instance1
    System.out.printf("\nit costs: %.2f dollar for student.\n", discountprice);

    discountreal = isxmas * workerdiscount; //instance2
    discountprice = dishes * (1 - discountreal/100.0); //instance2
    System.out.printf("\nit costs: %.2f dollar for workers.\n", discountprice);

    discountreal = isxmas * guestdiscount; //instance3
    discountprice = dishes * (1 - discountreal/100.0); //instance3
    System.out.printf("\nit costs: %.2f it costs: %.2f dollar for guests.\n", discountprice);

  }
}

위의 코드에서 반복되는 instance 부분들을 메소드를 사용해 간단하게 해야하는게 문제입니다. 아래가 제가 나름대로 해 본 부분인데, 실행하면 자꾸 0 만 나옵니다... 변수선언 위치가 잘못되었는지, 어쨌는지 도대체가 모르겠습니다. 제발 도와주세요..ㅠㅠ

public class Test{

  public static double discountprice(double dishes, int xmas, int studentdiscount){
    return dishes * (1 - (xmas * studentdiscount/100.0));
  }

  public static void main(String[] args){
    double dishes = 0.0;
    int studentdiscount = 50;
    int discountreal = 0;
    double discountprice = 0.0;
    int isxmas = 0;

  dishes = Terminal.askFloat("how much is the dishes? ");
  isxmas = Terminal.askInt("is today xmas? (y: 1, n: 0)");

  System.out.printf("\nit costs: %.2f dollar for student.\n", discountprice);
  System.out.printf("\nit costs: %.2f dollar for workers.\n", discountprice*1.5);
  System.out.printf("\nit costs: %.2f it costs: %.2f dollar for guests.\n", discountprice*2);
  }
}