java - Efficient way to get all map values whose keys match a criterion -

i have following map map<indexderivedkey, collection<data<d>>> indexeddata in indexable data structure.

indexderivedkey conforms index, index consists of keys , corresponding values. keys used extract values elements in indexable data structure.

for example there's index, consists of keys firstname , lastname, use index extract values objects, possess these attributes, operation yields indexderivedkey per object.

that indexderivedkey contains mapping above keys respective values , used store objects in map indexeddata, mentioned before. map value collection type, since possible several objects equal (with respect index).

question how can extract objects firstname = "john", hereby ignoring value of lastname. can iterate on keys , check value of firstname in o(n).

but since indexderivedkey {firstname = "john"} subset of other keys firstname = "john", e.g. {firstname = "john", lastname = "smith"}, suppose there has more efficient way. maybe utilizing treeset?

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1

  public indexderivedkeyimpl(index index, map<string, string> keyvalues)   {     this.keyvalues = keyvalues;     this.index = index;      (string key : keyvalues.keyset())       if (!index.supportskey(key))         throw new indexkeymismatchexception(key, index);   } 

2

  // in data.index.index(indexable)   @override   public indexderivedkey index(indexable data)   {     map<string, string> keyvalues = new hashmap<string, string>();     indexderivedkey key = new indexderivedkeyimpl(this, keyvalues);      (string k : keys)     {       string value = data.get(k);       if (value != null)         keyvalues.put(k, value);     }      return key;   } 

if search on specific order, make key class comparable, , equals.

and use sortedmap, treemap. navigable too. might instance use submap(fromkey, tokey)