检查一个String数组是否包含另一个String数组的所有值（Java）

Question

I am a novice coder trying to teach myself how to code. I am trying to create a program that stores a list of recipes with their corresponding ingredients, and then will suggest recipes based on the ingredients entered by the user. I am using a HashMap with String keys (for the recipe name) and a String[] to represent the corresponding ingredients.

The problem I have is that when a user enters the ingredients (split by commas), I can't seem to use the resulting values to check whether or not those values are contained in the corresponding value of the HashMap.

When I try to call my ingredientSearch() method, the program returns the exception: "Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.String; cannot be cast to java.lang.String at RecipeBox.ingredientSearch(RecipeBox.java:55)."

Why doesn't this work, and how can I fix this?

import java.util.*;
import java.util.Map.Entry;

public class RecipeBox {

private String recipe;
private String name;
private String userInput;
private String randomRecipe;


Scanner input = new Scanner(System.in);
HashMap<String, String[]> recipes = new HashMap<String, String[]>();

public void addRecipe() {
    System.out.println("What is the name of your recipe?");
    name = input.nextLine();

    System.out.println("Enter the ingredients for " + name + " separated by commas:");
    recipe = input.nextLine();
    String[] ingredientList = recipe.split(",");

    recipes.put(name, ingredientList);

}

public void ingredientSearch() {

    System.out.println("What ingredients do you have?  Please enter your ingredients, separated by commas.");
    userInput = input.nextLine();
    String[] ingredientList = userInput.split(",");
    String check = ingredientList.toString();

    Iterator<Entry<String, String[]>> entries = recipes.entrySet().iterator();

    while (entries.hasNext()) {
        Entry entry = entries.next();
        String key = (String) entry.getKey();
        String value = (String) entry.getValue();
        if (value.contains(check)) {
            System.out.println("You could make " + key);
        }
    }
}

Answer 1

String value = (String) entry.getValue();

should be

String[] value = entry.getValue();

Your value is a String array.

Answer 2

First off, you're using a raw type, Entry , when it should be Entry<String, String[]> , as that will prevent any ClassCastException s from occurring. Next, you'll have to verify that all elements of check are contained in value . One easy way is to convert value into a Set to allow for efficient searching:

List<String> ingredients = List.of(ingredientList);

while (entries.hasNext()) {
    Entry<String, String[]> entry = entries.next();

    String key = entry.getKey();
    String[] value = entry.getValue();

    if (Set.of(value).containsAll(ingredients)) {
        System.out.println("You could make " + key);
    }
}

Note : This compiles with Java 9. If you're using Java 8 or below, you can replace the call to Set#of and List#of with Arrays#asList , but it will be less efficient.