Check if Java ArrayList of HashMap<String,String> contains a key

Question

I have this type ArrayList<HashMap<String,String>> . I want to check if a key exist in that array list . I can do this through a for loop but is there any alternative way to do this ?

Answer 1

Along the line of @Bhushan's answer, create a new class that encapsulates the ArrayList of maps, and a Map of the key values. Eg

public class EncapsulatedLookup {
    private ArrayList<HashMap<String,String>> data;
    private Map<String, Integer> keyToArrayListPosition lookup; 
}

Add methods to ensure whenever you add/remove from data , you also update the lookup

Answer 2

While building those individual HashMaps, if you could build a super hashmap, then there is no need for for loop. But don't know if it is possible for you. Just look-up in that super-hashmap.

Answer 3

The most easiest way that comes into my mind and maight work is to extend the HashMap class and implement .equals() method. Anyway, this method also internally uses interation.