Calculating values with different doubles of various indexes in arrays using methods in Java

I'm creating a program that takes in ingredients and its calories per ounce, then recipes and its ingredients and ounces of each ingredients. I want to calculate the total calories of the recipes.

import java.util.*;

public class Restaurant {

	

		for (int i=0; i<numRecipes; i++) { 
			System.out.println(recipeName[i] + ":"); 
			System.out.println(" calories"); // I would call the countCalories method here
		}
	}

}

A few remarks on the code:

1. Each time you ask for the ingredients of a reciet you build a new ingredientsUsed inside the for loop but you don't keep it as class level so after each for loop iteration it is destroyed (it's scope is within the for loop). If in the end you only want to know the total number of calories per recipe, you should calculate these calories after numIngredients loop, but still within the numRecipes loop so you still have your ingredientsUsed list

2. To calculate the total number of calories for one recipe, you need to calculate the calories of each ingredient. The value in calories[0] corresponds to ingredientName[0] but this is not necessarily the same as ingredientsUsed[0]. So for every ingredientsUsed element you first need to lookup the ingredient in ingredientName to know its index number which you then can use to lookup the calories for that ingredient.

3. If you really want to know all recipes and their ingredientsUsed, you need to construct a 2-dimensional array where dimension one is per recipe and dimension 2 is ingredientUsed for a recipe.

   String[] recipeName = new String[numRecipes];
   // extra array to keep calories per recipe
   double[] recipeCalories = new double[];
   for (int i=0; i<numRecipes; i++) {
   recipeName[i] = scan.next(); 
   int numIngredients = scan.nextInt();
   String[] ingredientsUsed = new String[numIngredients];
   double[] numOunces = new double[];
   for (int j=0; j<numIngredients; j++) { 
   ingredientsUsed[j] = scan.next();
   numOunces[j] = scan.nextDouble();
   }
   recipeCalories [i]=countCalories(ingredientsUsed,ingredientName,calories,numOunces);
   }
   for (int i=0; i<numRecipes; i++) { 
   System.out.println(recipeName[i] + ": calories "+recipeCalories[i]); 
   }
   /**
   * ingrediensUsed : names of all ingredients in the recipe
   * ingredientName: names of all known ingredients
   * calories: calories per ingredientName
   * numOunces : ounces per ingredientUsed
   */
   int countCalories (String[] ingredientsUsed, String[] ingredientName, double[] calories, double[] numOunces) {
   int cal=0;
   for (int i=0;i<ingredientsUsed.length;i++) {
   for (int n=0;n<ingredientName.length;n++) {
   if (ingredientsUsed[i].equals(ingredientName[n]) {
   // n is the corresponding index in the ingredientName and calories arrays
   cal = cal+ ((int)(numOunces[i] * calories[n] + 0.5));
   }
   }
   }
   return cal;
   }
   

First you need to change countCalories so that you pass in the names of ingredients. This will let you find the calories for a used ingredient:

public static int countCalories(String[] ingredientName, String[] ingredientsUsed, double[] calories, double[] numOunces) {
double cal = 0;
for (int i = 0; i < ingredientsUsed.length; i++) {
for (int j = 0; j < ingredientName.length; j++) {
if (ingredientsUsed[i].equals(ingredientName[j])) {
cal += numOunces[i] * calories[j];
}
}
}
return (int) Math.round(cal);
}

To call this method, what I would do is merge the two loops over the arrays into one, and count the calories for each recipe as they are read in. This way you don't have to store the ingredients and amounts for more than one recipe at a time.

for (int i = 0; i < numRecipes; i++) {
recipeName[i] = scan.next();
int numIngredients = scan.nextInt();
String[] ingredientsUsed = new String[numIngredients];
double[] numOunces = new double[numIngredients];
for (int j = 0; j < numIngredients; j++) {
ingredientsUsed[j] = scan.next();
numOunces[j] = scan.nextDouble();
}
System.out.println(recipeName[i] + ":");
System.out.println(countCalories(ingredientName, ingredientsUsed, calories, numOunces));
}