CODEWITHSUNDEEP
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Surendra Royal
Surendra Royal

Reputation: 97

Associative array in java?

I want add duplicate keys in map,output like the one below:

google:Android,google:Maps,apple:iPod,apple:iPhone,apple:iOS

Is it possible in java or json? please help me.

Upvotes: 0

Views: 1281

Answers (5)

Andrew
Andrew

Reputation: 3332

Another good solution apart from Apache's library is to use Google's guava libraries. Guava implements a Multimap, and here's a blog post that explains how to use Guava's Multimaps

Upvotes: 0

Taymon
Taymon

Reputation: 25676

Even better than a map of lists is a map of sets, assuming you only want to allow duplicate keys and not duplicate associations. It could be done like this:

import java.util.*;
Map<K, Set<V>> yourMap = new HashMap<K, Set<V>>();

public void add(K key, V value) {
    if (!yourMap.containsKey(key)) {
        yourMap.put(key, new HashSet<V>());
    }
    yourMap.get(key).add(value);
}

Replace K and V with the actual key and value types.

Upvotes: 3

kundan bora
kundan bora

Reputation: 3889

Map in java can never has duplicate key, however you can put multiple values for a particular key:

Map<String, List<String>> map = new HashMap<String, List<String>>();

You can also use MultivaluedMap.

Upvotes: 2

Marvo
Marvo

Reputation: 18143

I like the MultiMap answer above. But if you want to stick to the java.util collections, try a map of lists.

Upvotes: 3

Tom
Tom

Reputation: 45144

Yes, it is possible in Java. Check apache's MultiMap.

Upvotes: 3

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