How to properly use Enums for simple price calculation (Java)

Question

I am trying to optimize a code-snippet that looks like this:

public class Kvarteret {
    public static final String ONE_BEER = "hansa";
    public static final String ONE_CIDER = "grans";
    public static final String REAL_BEER = "vestkyst";
    public static final String GT = "gt";
    public static final String BACARDI_SPECIAL = "bacardi_special";

    public int calculatePrice(String drink, boolean student, int amount) {

        if (amount > 2 && (drink == GT || drink == BACARDI_SPECIAL)) {
            throw new RuntimeException("Too many drinks, max 2.");
        }

        int price;

        if (drink.equals(ONE_BEER)) { price = 74;}
        else if (drink.equals(ONE_CIDER)) { price = 103;}
        else if (drink.equals(REAL_BEER)) { price = 110; }
        else if (drink.equals(GT)) { price = ingredient6() + ingredient5() + ingredient4();}
        else if (drink.equals(BACARDI_SPECIAL)) {
            price = ingredient6()/2 + ingredient1() + ingredient2() + ingredient3();
        } else { throw new RuntimeException("Item not in menu"); }

        if (student && (drink == ONE_BEER || drink == ONE_CIDER || drink == REAL_BEER)) { price = price - price/10;}
        return price*amount;
    }

    //rom unit
    private int ingredient1() { return 65;}

    // grenadine unit
    private int ingredient2() { return 10;}

    //lime-juice unit
    private int ingredient3() { return 10;}

    //mint-leafs unit
    private int ingredient4() { return 10; }

    //tonic-water unit
    private int ingredient5() { return 20; }

    //gin unit
    private int ingredient6() { return 85; }
}

The code is a simple program that calculates the price of drinks. I used this code as a starting point because it seemed like they we're trying to do something similar.

My code so far looks like this:

import java.util.*;

public class Kvarteret2 {
    private static double price;
    private static double order;

    // Enums defines common values
    private enum Beer_Cider {
        BEER("Hansa", 74), CIDER("Grans", 103), REAL_BEER("Vestkyst", 110);

        private static String order;

        Beer_Cider(String order, double cost) {
            order = order;
            price = cost;
        }

        private static String getOrder() {return order;}
        private static double getCost() {return price;}
    }

    private enum DrinkIngredients {

        ROM("Rom", 65), GRENADINE("Grenadine", 10), LIME("Lime-juice", 10),
        MINT("Mint", 10), TONIC("Tonic-water", 20), GIN("Gin", 85);

        private static String ingredient;

        DrinkIngredients(String ingredient, double cost){
            ingredient = ingredient;
            price = cost;
        }

        private static String getIngredient() {return ingredient;}
        private static double getCost() {return price;}
    }

    // Dictionary with the drink as Key and a list of the ingredients and prices as value
    Map<String, List<DrinkIngredients>> Drinks = new HashMap<String, List<DrinkIngredients>>(); 

    public Kvarteret2() {
        Drinks.put("GT", [DrinkIngredients.GIN, DrinkIngredients.TONIC, DrinkIngredients.MINT]);

    }


    private static double calculate_price(String drink, boolean student, int amount){

        if (amount > 2) {
            throw new IllegalArgumentException("Too many drinks! You can order max 2 drinks at a time.");
        }

        double student_discount = 0.1;

        if (student){
            if (drink == "BEER" || drink == "CIDER" || drink == "REAL BEER") {
                price = amount * (price - price * student_discount);
            }
        }
        return price;
    }
}

I'm getting an error because of this code:

public Kvarteret2() {
    Drinks.put("GT", [DrinkIngredients.GIN, DrinkIngredients.TONIC, DrinkIngredients.MINT]);

}

I am trying to add elements to the dictionary, but I dont think this is the right way to do it.

I know my code might not be 100% optimized yet, but I just want to see if I can make this solution work before I try to make it even better (because there's most likely a better way to do this).

How do I properly create the dictionary I am trying to create using the enums?

Answer 1

Though you haven't mentioned what error you got, but this is how you can populate your Kvarteret2 constructor:

// Dictionary with the drink as Key and a list of the ingredients and prices as value
    Map<String, List<DrinkIngredients>> Drinks = new HashMap<String, List<DrinkIngredients>>(); 
   List<DrinkIngredients> list=new ArrayList<DrinkIngredients>(); // define ArrayList outside constructor

public Kvarteret2() {
  list.add(DrinkIngredients.GIN);
  list.add(DrinkIngredients.TONIC);
  list.add(DrinkIngredients.MINT);
  Drinks.put("GT", ls);
}