Thread: Trying to iterate through hashmap of objects from a class I created

I am trying to calculate the cost of a "Recipe" object which contains a hashmap<Ingredient, Double>
I have created the Ingredient class which contains pricePerUnit as one of its values.
The Double is the amount of the ingredients that is needed for the recipe.

I want to calculate the cost of the recipe given that each ingredient instance has a costPerUnit and we know how many units we need for each ingredient.
costOfRecipe = ingredient.costPerUnit * amount (looping through all the 3 ingredients in the hashmap)
I create the recipe with a constructor that takes 3 ingredients (since I don't know how to make a constructor with a variable amount of Ingredients/Amounts - help on this would also be appreciated)

Code below for the ingredient and the recipe class and also the main class which works fine when I run the code. Sorry for the messy comments, I am stumbling as I go and I have accepted some "suggestions" from inteliJ like casting to Ingredient and some others.

Recipe Class

package com.mealplanner;
 
import java.util.*;
 
public class Recipe {
    String name = null;
    String category= null;
    double costOfRecipe;
    int numberOfIngredients = 0;
    ArrayList <Ingredient> ingredients = new ArrayList<Ingredient>();
    ArrayList<Double> amounts = new ArrayList<Double>();
    HashMap<Ingredient, Double> recipe = new HashMap();
 
 
    public Recipe(){}
 
    public Recipe(String name, String category, Ingredient ing1Name, double ing1Amount,
                  Ingredient ing2Name, double ing2Amount,Ingredient ing3Name, double ing3Amount ){
        this.name = name;
        this.category = category;
        recipe.put(ing1Name, ing1Amount);
        recipe.put(ing2Name, ing2Amount);
        recipe.put(ing3Name, ing3Amount);
        numberOfIngredients = 3;
        costOfRecipe = calculateCostOfRecipe(recipe);
    }
    public String getName(){
        return name;
    }
 
    public int getNumberOfIngredients() {
        return numberOfIngredients;
    }
 
    public HashMap<Ingredient, Double> getRecipe() {
        return recipe;
    }
 
    /*
        public static double calculateCostOfRecipe(ArrayList<Ingredient> ingredients, ArrayList<Double> localAmounts){
            float costOfRecipe = 0;
 
            for (Ingredient i: ingredients) {
  //*************THIS IS WHERE I AM STUCK*********************
                int counter = 1;
                costOfRecipe += i.pricePerUnit* localAmounts.get(counter);
                counter ++;
            }
            return costOfRecipe;
        }
        */
public static double calculateCostOfRecipe(HashMap<Ingredient, Double> recipe){
    // Need to make the loop through the hashmap and multiply the amount and unit price
        double recipeCost = 0;
    List<Ingredient> listKey;
    List<Double> listValue;
 
    for (Map.Entry<Ingredient, Double> entry: recipe.entrySet()) {
        listKey = (List<Ingredient>) entry.getKey();
        listValue = Collections.singletonList(entry.getValue());
 
        //Ingredient i = new Ingredient();
        //i.(recipe.keySet());
        //if recipe.containsKey();
        //recipeCost = recipeCost;
    }
    int size = listKey.size();
    for(int i =0: i<= size: ++i){
        listKey(i)
    }
    return recipeCost;
}
 
    /*void add1Ingredient(){
        ingredients.
    }*/
}

Ingredient Class

package com.mealplanner;
 
public class Ingredient extends  Recipe{
    String name = null;
    Boolean organic = false;
    String unitPurchased = null;
    String unitOfMeasure;
    float purchasePrice;
    float purchasedAmount;
    float pricePerUnit;
 
    public Ingredient() {
    }
 
    public Ingredient(String ingName, String ingUnitPurchased, boolean ingOrganic, float ingAmount, float ingPrice) {
        name = ingName;
        unitPurchased = ingUnitPurchased;
        unitOfMeasure = null;
        organic = ingOrganic;
        purchasedAmount = ingAmount;
        purchasePrice = ingPrice;
        pricePerUnit = calculatePricePerUnit(this);
    }
 
 
    public float calculatePricePerUnit(Ingredient ingredient) {
        String unit = ingredient.unitPurchased;
        float calculatedPrice = 0;
 
        switch (unit) {
            case "GRAMS" -> {
                calculatedPrice = (1000f / ingredient.purchasedAmount) * ingredient.purchasePrice;
                this.setUnitOfMeasure("KILOGRAM");
            }
            case "KILOGRAMS" -> {
                calculatedPrice = (ingredient.purchasePrice / ingredient.purchasedAmount);
                this.setUnitOfMeasure("KILOGRAM");
            }
            case "MILLILITERS" -> {
                calculatedPrice = (1000f / ingredient.purchasedAmount) * ingredient.purchasePrice;
                this.setUnitOfMeasure("LITER");
            }
            case "LITERS" -> {
                calculatedPrice = (ingredient.purchasePrice / ingredient.purchasedAmount);
                this.setUnitOfMeasure("LITER");
            }
            case "CUPS" -> {
                calculatedPrice = (1000f / (ingredient.purchasedAmount * 0.237f)) * ingredient.purchasePrice;
                this.setUnitOfMeasure("LITER");
            }
            case "TABLESPOONS" -> {
                calculatedPrice = (1000f / (ingredient.purchasedAmount * 0.0147868f)) * ingredient.purchasePrice;
                this.setUnitOfMeasure("LITER");
            }
            case "TEASPOONS" -> {
                calculatedPrice = (1000f / (ingredient.purchasedAmount * 0.00492892f)) * ingredient.purchasePrice;
                this.setUnitOfMeasure("LITER");
            }
        }
        return calculatedPrice;
    }
 
 
    public String getUnitPurchased() {
        return unitPurchased;
    }
 
    public void setUnitPurchased(String unitPurchased) {
        this.unitPurchased = unitPurchased;
    }
 
    public Boolean getOrganic() {
        return organic;
    }
 
    public float getPricePerUnit() {
        return pricePerUnit;
    }
 
    public float getPurchasedAmount() {
        return purchasedAmount;
    }
 
    public float getPurchasePrice() {
        return purchasePrice;
    }
 
    public String getName() {
        return name;
    }
 
    public String getUnitOfMeasure() {
        return unitOfMeasure;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public void setOrganic(Boolean organic) {
        this.organic = organic;
    }
 
    public void setPricePerUnit(float pricePerUnit) {
        this.pricePerUnit = pricePerUnit;
    }
 
    public void setPurchasedAmount(float purchasedAmount) {
        this.purchasedAmount = purchasedAmount;
    }
 
    public void setPurchasePrice(float purchasePrice) {
        this.purchasePrice = purchasePrice;
    }
 
    public void setUnitOfMeasure(String unitOfMeasure) {
        this.unitOfMeasure = unitOfMeasure;
    }
 
    public enum UnitPurchased {
    GRAMS, KILOGRAMS, MILLILITERS, LITERS, CUPS, TABLESPOONS, TEASPOONS
    }
 
    public enum UnitOfMeasure {
    LITER, KILOGRAM
    }
}

Main Class

package com.mealplanner;
 
import java.util.Scanner;
 
public class Main {
 
    public static void main(String[] args){
        /*System.out.println("Welcome to the meal planer");
        System.out.println("type a unit for your new ingredient");
        Scanner scanner = new Scanner(System.in);
        String userInput = scanner.nextLine();
        Ingredient apple = new Ingredient();
        apple.setUnitPurchased(userInput);
        System.out.println(apple.getUnitPurchased());*/
        Ingredient avocado = new Ingredient("avocado", "GRAMS", true,200,5 );
        //System.out.println(avocado.name + ", " + avocado.pricePerUnit + ", " + avocado.unitOfMeasure);
        System.out.println(String.format("Your fruit is %s, which costs %f dollars per %s.", avocado.name, avocado.pricePerUnit, avocado.unitOfMeasure));
        Ingredient rice = new Ingredient("rice", "KILOGRAMS", false, 3, 9);
        Ingredient pepper = new Ingredient("pepper", "GRAMS", true, 500, 5);
 
        Recipe stirFry = new Recipe("Stir Fry", "Dinner", avocado, 500, rice, 0.5, pepper, 1);
        System.out.println("You are about to cook " + stirFry.getName() + "!");
        System.out.println("Your recipe has " + stirFry.getNumberOfIngredients() +" ingredients.");
        System.out.println("Ingredient list and amounts: "+ stirFry.getRecipe());
        System.out.println(stirFry.costOfRecipe);
        System.out.println(stirFry.recipe.keySet());
 
    }
}

Norm,
Thank you for the answer.

I will look into the varargs for sure.
Do you have any input on the question on how to get to the ingredient say for example "avocado.costPerUnit" from having the Ingredient "avocado" inside the Hashmap passed into the calculateCostOfRecipe method?

That method may as well be blank since I don't yet know how to access the and I just have been trying things inside of it. Talking it through should be ver siple since I have a list of ingredients paired with the amount that is needed of that ingredient, so since the ingredient has an "knows" ho much it costs per kilogram say and we know how many kilograms we need then should be a simple multiplication but getting to the value is my issue.

Thank you

Norm,

Yes, although when you say "get the type and amount of each ingredient"
I would say get the costPerUnit (since the Ingredient instance has a costPerUnit) and amount needed for the recipe (found in the values() of the hashmap with each ingredient)" (but I think you mean the same).
And the rest is the same!

Thank you for the help!

--- Update ---

Gozzy,

How would that make the program better/easier/correct? (I'm not saying you are wrong, I just want to understand)
Would I handle the "ingredients"? in this case?
I have been trying to understand subclasses, inheritance etc but still pretty green as you can tell.

Thanks for the input.

Originally Posted by Norm

When working with collections (and some other utility classes) it is better to use the interface instead of the class. For example use a Map to hold the <key, value> pairs. When initializing the Map set it to a new HashMap instance.
Map<String, String> aMap = new HashMap<>();

What goes into the Map you want to use? Why use a Map vs a List to hold the ingredients for a Recipe?
A Map would be useful for storing the cost of an ingredient: Map<ingredient, cost>
.

I will look at the interface vs class (since I don't understand that very well).

So the hashmap is an element of the recipe instance which holds the ingredient (so I'm guessing I could access all the elements of the ingredient) and the amount of that ingredient needed for the recipe (its assumed the amount is entered in the same unit as the costPerUnit unit but that's a detail I can handle)
I don't know why use hashmap than a List, i did some research and I found that hashmaps were something to use which could store value pairs. If there is an easier/better way of doing this I am all eyes. Ultimately I am doing this to learn and I want to learn the best way to do things.

In my main you can see that I declare 3 ingredients for the recipe called stirFry I would like to calculate the cost for that recipe as a test.

I get the ineritance concept now, thanks for that.

Thank you!

Originally Posted by Ian_dude

Gozzy,

How would that make the program better/easier/correct? (I'm not saying you are wrong, I just want to understand)
Would I handle the "ingredients"? in this case?
I have been trying to understand subclasses, inheritance etc but still pretty green as you can tell.

Thanks for the input.

Well you of course need to establish the correct design. A subclass B of A means that B is a specialisation of A. You can surely see that a recipe and an ingredient are separate entities? (even if one contains a collection of the other)

Originally Posted by Norm

How does the program need to access the ingredients?
Does it need to directly access one particular ingredient by name? If so use a Map<name, Ingredient>
If getting the ingredients one at a time in some order, then a List<Ingredient> should work.

Where would the cost of an ingredient be stored? That would be a use of a Map<nameOfIngredient, cost>

Norm,
The program should be able to add ingredients.
The program will need to "know" if the ingredient exists and if it does then it does need to access the ingredient by name (I think that's the easiest way to "grab" an ingredient" ) Right now the cost of 1 Kilogram or 1 Liter is stored in a field in the ingredient instance.

Your answer seems to me like I need a bunch of lists or a map, how would I then go into the list of the ingredient/cost to get the total cost for the ingredients in the recipe, I am having trouble visualizing how to do that.

Thank you,

Ian

--- Update ---

Originally Posted by gozzy

Well you of course need to establish the correct design. A subclass B of A means that B is a specialisation of A. You can surely see that a recipe and an ingredient are separate entities? (even if one contains a collection of the other)

That makes total sense.
So basically I have to copy the code of Ingredient into the Recipe class. But I still have my initial issue of how to iterate throgh the hasmap or ma or list to get the oneIngredient.costPerUnit and then from there perform the operation to multiply by the amount.

I though I had the design figured out but I am new at this and most likely my design has some serious flaws.

Right now as it stands the ingredient lets call it avocado (since I have it in the code above)
has all these values right off the bat.
String name = null; // this would be "avocado" for example
Boolean organic = false; // no important for this issue but could be true
String unitPurchased = null; // this is to determine the case that would be picked up to get the operation to turn whatever they bought into Kilograms in this case since its sold by weight, not volume. (they bough 200 grams etc..)
String unitOfMeasure; // This one simply gets defined by the constructor if they enter anything to do with mass it'll go to Kilograms if its identified with volume it'll go to Litters
float purchasePrice; //prince they paid at the store
float purchasedAmount; // the actual ammount they purchased - from the line unitPurhased above this would be 200
float pricePerUnit; // the constructor calls the calculatePricePerUnit method with some of the values entered (code in the original post) and this is supposed to calculate the $/Kilogram or $/Liter of product.

Then the with Recipe Class one can create a recipe which will have:
String name = null; // in the code of the original post this would be the stirFry
String category= null; // not concerned with this now, it could be "main dish" or "dinner" or "entree" but its not important right now its just a tag to organize recipes in the future.
double costOfRecipe; // this is the method is the one which is giving me trouble. I have the hashmap with the (Ingredient_instance, amount of the ingredient) since I made a constructor for a recipe that takes 3
ingredients and they are passed into the hashmap called recipe inside of the instance of Recipe called stirFry.
int numberOfIngredients = 0; // as of right now i just have this set to 3 manually since the only constructor I have reicieves 3 ingredients but once I add an "addOneIngredient method or a way to add an unspecified number of
ingredients this will have to change.
ArrayList <Ingredient> ingredients = new ArrayList<Ingredient>(); // currently I am not using this.
ArrayList<Double> amounts = new ArrayList<Double>(); // currently I am not using this.
HashMap<Ingredient, Double> recipe = new HashMap(); //I am using this hashmap to try to get the ingredients into the object stirFry and be able to use them to calculate the cost, he ingredient I asme I could do something like (avocado.costPerUnit) * (amount) since those two things are on each entry of the hashmap the avocado as an ingredient and the amount needed for the recipe (thats why i thought using a hashmap was good)

I hope I'm explaining things properly and they make sense. I am doing the best I can while reading up and learning as much as possible.

Thank you,

Ian

Originally Posted by Norm

Is the above complete? Can you trying writing the code for it?

Norm,

In my original post above I copied the code for the Ingredient Class and for the Recipe Class and for the Main which uses the classes for now. I tried to write a for each loop in several ways but i only could get the for each to add the amounts up which logically makes no sense if they are not individually multiplied by their unit cost first.

If you look in the Recipe Class' code above I have a comment like this:
//*************THIS IS WHERE I AM STUCK*********************
that is the for loop that started all this.

I think that is what you are asking, but I am not sure.

Ian

From long experience I can tell you one guiding principle: never write code until you have the design completely worked out. I gave it some thought and RecipeElement is probably a good way to go. If you were writing a real world app (and actually it could be pretty useful for pricing up recipes) you might like to think about a Unit class too. All ingredients have a default unit, and they can vary quite a lot. An enum might be a candidate here

Originally Posted by gozzy

From long experience I can tell you one guiding principle: never write code until you have the design completely worked out. I gave it some thought and RecipeElement is probably a good way to go. If you were writing a real world app (and actually it could be pretty useful for pricing up recipes) you might like to think about a Unit class too. All ingredients have a default unit, and they can vary quite a lot. An enum might be a candidate here

Gozzy,

I am not very experienced with Java as you can tell but I though I had it well specked out. But obviously not.
I acually have 2 enums in my Ingredient Class
public enum UnitPurchased {
GRAMS, KILOGRAMS, MILLILITERS, LITERS, CUPS, TABLESPOONS, TEASPOONS
}

public enum UnitOfMeasure {
LITER, KILOGRAM
}

I think that they will be useful for when I actually have people (or me) entering info through an interface and the enums will be the only options they can choose. As of now I am not really using them.
The UnitPurchased has may options since I think that those are all the options that one may have and the UnitOfMeasure is basically how I am planning to manage the costing:
if its a liquid or measured by volume it'll be liters and if its measured in weight the unit will be Kilograms.

As a part of the constructor of the Ingredient (code above in my first post) I have this switch statement that assigns a string either KILOGRAM or LITER which is exactly the enums but I most likely am not using the enum functionality correctly here either.

Let me know your thoughts.

Thank you,

Ian

Originally Posted by Norm

What is that loop supposed to do? Is it what I talked about in post#4?

Some comments on the code in post#1
Why is a reference to an instance of a Recipe passed to any method in the Recipe class? The contents of the class are automatically available to all the methods in the class. The same with the Ingredients class.

Norm,

Yes it is what you are talking about in post #4.
You may as well ignore the code I have for the 2 attempts at creating the method called "calculateRecipeCost"
since they don't work and I have tried 10 different things on each so I may as well start that method from scratch.

If you see in my second attempt at the method (the one which is not commented out) i have a "recipe.entrySet()"
this is because I called my hashmap "recipe" that is part of every Recipe instance of a Recipe, in this case in my min called stirFry
I am trying to get the inredient.pricePerUnit basically so that I can multiply against the amount in the value() of the hashmap. ( I thought this would be fairly easy but seems to be a pain)

In my mind if I could do something like:

hashmap(counter) ---- and this gave me the ingredient "avocado" (for the stirFry recipe found in Main)
then it would be like saying
avocado.pricePerUnit if I did (hashmap(counter).getKey).pricePerUnit) or something.
then I could multiply this by "amount" so to get amount I could do hashmap(counter).getValue()
and that would be the amount of avocado needed.

so in my head if this would work (which I dont know how to write)
recipeCost = (hashmap(counter).getKey).pricePerUnit) * (hashmap(counter).getValue())

the for each loop iterates and keeps adding to the recipeCost variable.

In the end, I am not married to hashmaps, thats what I try to use, but if you can show me how to do this with another object type I would gladly change it, I write my answers in with that word since its what I have in the code.

Thank you again!

Ian

I am so happy Norm:

public static double calculateCostOfRecipe(HashMap<Ingredient, Double> recipe){
// loops through the hashmap and multiplies the amount and unit price
double recipeCost = 0;
double multiplication = 0;

for (Map.Entry<Ingredient, Double> entry: recipe.entrySet()) {
multiplication = (entry.getKey().pricePerUnit) * entry.getValue();
recipeCost += multiplication;
}
return recipeCost;

This totally works!

From my Main, which I declare the 3 ingredients, and then the stirFry recipe i get this:

From this line:
System.out.println("Stir Fry costs: " + stirFry.costOfRecipe + " dollars, for one family dinner");

I get:
Stir Fry costs: 24.0 dollars, for one family dinner

Which is accurate (i have done the math on paper)

Thank you for the help!

Now one more question:
Gozzy said that Ingredient should be a sub class of recipe or that there should be a RecipeElement and ingredient should be in there.

Do you agree? and how would that change the way I interact with my code?

Thank you so much!

Originally Posted by Norm

Go back and read that again. I didn't think he said that.

The fields in the classes should be private. Their values should be retrieved with a get method, not directly accessed.

Norm,

Post 5 "I think you need to establish your abstractions and classes properly. An Ingredient certainly doesn't extend Recipe. A Recipe is composed of ingredients. You might consider something like a subclass of Ingredient called RecipeIngredient that encapsulates an amount (that's just off the top of my head)
Or you could do have a class RecipeElement initialised with Ingredient and amount"

I have the code working now but I want to learn so that is why I ask this question.
Would moving the Ingredient Class off from a separate class and making it a sub Class of Recipe make any difference?

Thank you,

Ian