How to return key and it's values if the string matches a key entry

Question

So I have created a class that creates a map of keys that are string of names of dishes, each key has a set of string values that are the ingredients within the dish. I have managed to get all keys-value pairs to print, but now I want a method that takes a string as an argument and then if that string matches a key, print out the key-value pair, and if not, display an message saying no such key was found.

Here is my attempt:

public void printMapValue(String a) {
    if (recipes.containsKey(a)) {
        System.out.println("The ingredients for " + a + " Are: " + ingredients);
    } else {
        System.out.println("That string does not match a record");
    }
}

Here is my full class code so far as well, which all works as intended up until the printMapVale() method

public class Recipe {
    Map<String, Set<String>> recipes;

    public Recipe() {
        this.recipes = new HashMap<>();
    }

    public void addData() {
        Set<String> ingredients = new HashSet<>();

        ingredients.add("Rice");
        ingredients.add("Stock");
        recipes.put("Risotto", ingredients);

        ingredients = new HashSet<>();
        ingredients.add("Bun");
        ingredients.add("Patty");
        ingredients.add("Cheese");
        ingredients.add("Lettuce");
        recipes.put("Burger", ingredients);

        ingredients = new HashSet<>();
        ingredients.add("Base");
        ingredients.add("Sauce");
        ingredients.add("Cheese");
        ingredients.add("Pepperoni");
        recipes.put("Pizza", ingredients);
    }

    public void printMap() {
        for (String recipeKey : recipes.keySet()) {
            System.out.print("Dish : " + String.valueOf(recipeKey) + " Ingredients:");
            for (String dish : recipes.get(recipeKey)) {
                System.out.print(" " + dish + " ");
            }
            System.out.println();
        }
    }
    public void printMapValue(String a) {
        if (recipes.containsKey(a)) {
            System.out.println("The ingredients for " + a + " Are: " + recipes.keySet(a));
        } else {
            System.out.println("That string does not match a record");
        }
    }
}

Possible duplicate of [Printing Java Collections Nicely (toString Doesn't Return Pretty Output)](https://stackoverflow.com/questions/395401/printing-java-collections-nicely-tostring-doesnt-return-pretty-output) — Gustavo Pagani, May 08 '19 at 08:57
not sure if I understood the question, is it `Set ingredients = recipes.get(a);` inside the `if` block? — user85421, May 08 '19 at 09:56

score 3 · Accepted Answer · answered May 08 '19 at 08:59

3

keySet does not take any parameters. That methods returns the entire set of keys, in this case

[Risotto, Burger, Pizza]

You want to do a look-up which is the get method.

System.out.println("The ingredients for " + a + " Are: " + recipes.get(a));

answered May 08 '19 at 08:59

Michael

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score 0 · Answer 2 · answered May 08 '19 at 09:39

check following code,

public void printMapValue(String a) {
    Set<String> resultSet = null;
    for (Map.Entry<String, Set<String>> entry : recipes.entrySet()) {
        if (entry.getKey().equals(a)) {
            resultSet = entry.getValue();
            System.out.println("The ingredients for " + a + " Are: " + resultSet);
        }
    }
    if (Objects.isNull(resultSet)) {
        System.out.println("That string does not match a record");
    }
}

score 0 · Answer 3 · answered May 08 '19 at 09:57

With java 1.9+, it can be written

public void printMapValue(String a) {
        recipes.entrySet().stream()
                .filter(e -> a.equals(e.getKey()))
                .findFirst().ifPresentOrElse(e -> System.out
                .println("The ingredients for " + e.getKey() + " Are: " + e.getValue(),
                        System.out.println("That string does not match a record"));
    }

How to return key and it's values if the string matches a key entry

3 Answers3