一个类到另一个类的LinkedList中的特定元素

Question

I have this current class that contains all these ingredients which I am trying to add into another linked list but I am struggling.

import java.util.*;
public class Kitchen {
    public static final Category CRUST = new Category("crust", 1, 1);
    public static final Category SAUCE = new Category("sauce", 1, 1);
    public static final Category TOPPING = new Category("topping", 2, 3);
    private Category[] categories = { CRUST, SAUCE, TOPPING };
    private LinkedList<Ingredient> ingredients = new LinkedList<Ingredient>();

    public Kitchen() {
        ingredients.add (new Ingredient("Thin", 3.00, CRUST));
        ingredients.add (new Ingredient("Thick", 3.50, CRUST));
        ingredients.add (new Ingredient("Tomato", 1.00, SAUCE));
        ingredients.add (new Ingredient("Barbeque", 1.00, SAUCE));
        ingredients.add (new Ingredient("Capsicum", 0.50, TOPPING));
        ingredients.add (new Ingredient("Olives", 1.50, TOPPING));
        ingredients.add (new Ingredient("Jalapenos", 1.00, TOPPING));
        ingredients.add (new Ingredient("Beef", 2.75, TOPPING));
        ingredients.add (new Ingredient("Pepperoni", 2.50, TOPPING));
    }

this is the class that contains all of the ingredients and this is the class which I am trying to copy some of the ingredients to.

import java.util.*;
import java.text.*;

public class Pizza {
    private LinkedList<Ingredient> ingredients = new LinkedList<Ingredient>();
    private int sold;

    public void add(){  
        ...
        ...
            if (...);
                ingredients.add(...);
        ...
    }

How should I go about adding SPECIFIC ingredients from Kitchen into ingredients in Pizza (not just clone the whole thing :))? I've tried just adding the ingredient itself but that does not seem to work. (inredients.add(ingredient))

Answer 1

You can use enum instead of LinkedList to store all of the ingredients. Add a enum for ingredient in class Kitchen.

public enum Ingredient {
    THIN("Thin", 3.00, CRUST),
    THICK("Thick", 3.50, CRUST);
    // add other ingredient
    private String name;
    private double cost;
    private Category category;

    private Ingredient(String name, double cost, Category category) {
        this.name = name;
        this.cost = cost;
        this.category = category;
    }
}

Then in class Pizza.

public void add() { 
    ingredients.add(Ingredient.THICK);
    // add other ingredient needed
}

Answer 2

You can add a getIngredients() method to the Kitchen class which returns the provided ingredients by the Kitchen. This allows you to access the ingredients of the Kitchen out of the Pizza class (and further classes).