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Question

I've a Map like this

This class used as key

class Key {
    private final String type;
    private final String qualifier;
    // getters, equals and hashCode
}

The map is HashMap<Key, Object>

I dont know if a HashMap<String, HashMap<String, Object>> can be a better option or not. (In this case the map be like a relation of keyType -> {keyQualifier -> value, otherQualifier -> value})

Please leave examples

Answer 1

I think your attempt is good. It's probably a bit faster faster (just one get() call) and more readable to access an object with your key object than.

// Complex key object
Map<Key,Object> map;
Object value = map.get(new Key(type, qualifier));

// 'Simple' key object, don't do this
Map<String, Map<String, Object> map;
Map<String, object> tmpMap = map.get(type); // that is actually confusing to read
Object value = tmpMap.get(qualifier));

But don't forget, hashCode() and equals() must be implemented correctly!