CODEWITHSUNDEEP
java
Peter Penzov
Peter Penzov

Reputation: 1680

Implement search with multiple maps

I have this multimap with Guava which I would like to implement with multiple maps in order to make key-value search:

String key = "first-key";
        Multimap<String, String> map = ArrayListMultimap.create();

        map.put(key, "firstValue");
        map.put(key, "secondValue");
        map.put(key, "thurdValue");

        map.putAll("sec-key", Sets.newHashSet("am", "are", "is"));

        for (String name : map.keySet()) {  
           System.out.println("key: " + name); 
        }

I tried this:

Map<String, String> map1 = new HashMap<String,String>();
        Map<String, Map<String, String>> map2 = new HashMap<String, Map<String, String>>();
        Map<String, Map<String, Map<String, String>>> map3 = new HashMap<String, Map<String, Map<String, String>>>();

        map3.put("AF", Map.of("Afghanistan", Map.of("AFG", "004")));

How for example I can search for key Afghanistan and get value AFG?

Is there some better way to implement this?

Upvotes: 1

Views: 190

Answers (1)

Eritrean
Eritrean

Reputation: 16498

I think using multimaps in your case unnecessarily complicates the task. Why don't you just define a class that stores all values and use a simple map?

Assuming that your example shows the ISO 3166 standard values for Afghanistan, I wold create a class country:

static class Country{
    String name;
    String alpha2;
    String alpha3;
    String numericCode;

    public Country(String name, String alpha2, String alpha3, String numericCode) {
        this.name = name;
        this.alpha2 = alpha2;
        this.alpha3 = alpha3;
        this.numericCode = numericCode;
    }
    //getters and setters
}

and use a simple map Map<String, Country> myMap = new HashMap<>();

    Map<String, Country> myMap = new HashMap<>();
    myMap.put("AF", new Country("Afghanistan", "AF", "AFG", "004"));
    myMap.put("IR", new Country("Iran", "IR", "IRN", "364"));
    myMap.put("IN", new Country("India", "IN", "IND", "356"));
    myMap.put("CN", new Country("China", "CN", "CHN", "156"));

To get the ALPHA_3 code for a search string "Afghanistan" for example 

Optional<Country> search = myMap.values().stream().filter(c -> c.name.equals("Afghanistan")).findFirst();
System.out.println(search.isPresent()? search.get().getAlpha3(): "No results");

If you are interested in using a 3rd party library take a look at Javatuples

Using javatuples the upper one could be rewritten as follows

   Map<String, Quartet> myMap = new HashMap<>();
   myMap.put("AF", Quartet.with("Afghanistan", "AF", "AFG", "004"));
   myMap.put("IR", Quartet.with("Iran", "IR", "IRN", "364"));
   myMap.put("IN", Quartet.with("India", "IN", "IND", "356"));
   myMap.put("CN", Quartet.with("China", "CN", "CHN", "156"));
   Optional<Quartet> result = myMap.values().stream().filter(q -> q.contains("Afghanistan")).findFirst();
   System.out.println(result.isPresent() ? result.get().getValue2():"No results");

Upvotes: 2

Related Questions