Question

Possible Duplicate:
Java Hashmap: How to get key from value?
Bi-directional Map in Java?

I want a key value data structure to use for Android App. I can use Map<K,V>, but in Map I can’t get key for particular Value.

Is there any good Java data structure using which I can retrieve key by value and vice-versa.

Answer 1

You can use Map with entrySet and Map.Entry class to iterate and get both keys and values even if you don’t know any of the keys in the Map.

Map <Integer,String> myMap = new HashMap<Integer,String>();

Iterator<Entry<Integer, String>> iterator = myMap.entrySet().iterator();
while (iterator.hasNext()) {
    Map.Entry<Integer,String> pairs = (Map.Entry<Integer,String>)iterator.next();
    String value =  pairs.getValue();
    Integer key = pairs.getKey();
    System.out.println(key +"--->"+value);
}