在哈希图中搜索对象内的标签

Question

I am trying to set up a search function where the user can search for a food item based on user input. The items in the HashMap are set up to have the UUID of a Food class object and the object itself.

This is the repository for the food items

import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class FoodRepository {

    // Create a hash map
    private HashMap foods = new HashMap();

    // Constructor
    public FoodRepository () {

        //Food Objects
        NutritionFacts cokeNutritionFacts = new NutritionFacts(190, 0, 60, 54, 54, 0);
        String[] cokeTags = {"Drink", "Cola", "Coca-Cola"};
        Food coke = new Food("Coca-Cola", cokeNutritionFacts, cokeTags);
        foods.put(coke.getUUID(), coke);

        NutritionFacts drpepperNutritionFacts = new NutritionFacts(180, 0, 75, 48, 47, 0);
        String[] drpepperTags = {"Drink", "Cola", "Dr Pepper"};
        Food drpepper = new Food( "Dr Pepper", drpepperNutritionFacts, drpepperTags);
        foods.put(drpepper.getUUID(), drpepper);

        NutritionFacts cfaSandwichNutritionFacts = new NutritionFacts(440, 19, 1350, 40, 5, 28);
        String[] cfaSandwichTags = {"Entree", "Sandwich", "Dinner", "Lunch", "Chick Fil A"};
        Food cfaSandwich = new Food( "Chick Fil A Chicken Sandwich", cfaSandwichNutritionFacts, cfaSandwichTags);
        foods.put(cfaSandwich.getUUID(), cfaSandwich);

        NutritionFacts bigMacNutritionFacts = new NutritionFacts(540, 28, 940, 42, 9, 25);
        String[] bigMacTags = {"Entree", "Burger", "Dinner", "Lunch", "McDonalds"};
        Food bigMac = new Food( "McDonalds Big Mac", bigMacNutritionFacts, bigMacTags);
        foods.put(bigMac.getUUID(), cfaSandwich);

        // Get a set of the entries
        Set foodSet = foods.entrySet();
    }

    // Getter methods
    public HashMap getFoods() {
        return foods;
    }

    // Setter methods
    public void setFoods(HashMap foods) {
        this.foods = foods;
    }
}

This is the Food class which defines the objects going into the HashMap (getters and setters omitted)

public class Food {
    // Class variables
    private String uuid;
    private String name;
    private NutritionFacts nutritionFacts;
    private String[] tags;

    // Constructor
    public Food(String name, NutritionFacts nutritionFacts, String[] tags) {
        this.uuid = UUID.randomUUID().toString();
        this.name = name;
        this.nutritionFacts = nutritionFacts;
        this.tags = tags;
    }
}

And finally, this is the nutrition facts class

public class NutritionFacts {
    // Class Variables
    private int calories;
    private int fat;
    private int sodium;
    private int carbs;
    private int sugar;
    private int protein;

    //private int iron;
    //private int calcium;
    //private int vitaminA;
    //private int VitaminC;

    //Constructor
    public NutritionFacts(int calories, int fat, int sodium, int carbs, int sugar, int protein){
        this.calories = calories;
        this.fat = fat;
        this.sodium = sodium;
        this.carbs = carbs;
        this.sugar = sugar;
        this.protein = protein;
    }
}

A note, I'm sorry if this is too much; this is my partner and I's first time using android studio and we are both rather inexperienced with java.

We had been thinking something along these lines could work:

int caloriesConsumed = 0;
String searchValue = scan.nextString();
boolean flag = Arrays.asList(foods.get(key).tags).contains(searchValue);   if(flag == true) {
     caloriesConsumed = (caloriesConsumed + xxx;}

But the problem is that if the user is searching for the food using a tag like "burger" hoping for a big mac to show, that method requires the key to be known and in the code; thus, defeating the purpose of searching along the value.

Alternatively we have seen some people use methods like this:

String needle = "burger"
for(Map.Entry<String, Food> entry : foods.entrySet()) {
     Food v = entry.getValue();
     if(v.contains(needle))
          caloriesConsumed = (caloriesConsumed + xxx);
     }

but the .contains() method doesn't work for strings / isn't compatible since the HashMap's value is a special object and not a regular data type.

Thanks for any and all help, it is much appreciated!

Answer 1

The last snippet could be a working solution.

if(v.contains(needle)){
    caloriesConsumed = (caloriesConsumed + xxx);
}

Here, v is a type of Food, so obviously it doesn't have a contains method as you not implemented it. As i see you will need to search in the v.tags field, but it is an array of Strings, which doesn't have contains method. I would suggest to change the tags field's type from String[] to List< String >, and then you can use tags.contains(needle) to look for the specified search item in tags.

Edit: For the Map< String,Food> issue

In your code I see you use raw HashMap type

// Create a hash map
private HashMap foods = new HashMap();

The problem is, that in that way, noone knows that this is a String,Food hashmap, so obviously you will get error if you want to assign it to a String,Food entry.

I suggest using it like that: private Map< String, Food > foods = new HashMap<>();

Also change the getter setter to return/accept Map< String, Food>

Note: Using Interfaces instead of concrete types is a better approach in programming, but if you still want to specify that this is a HashMap (which i can't see why you would, but lets assume) then declare your variable as HashMap< String,Food> foods

That should do the job :)