I have a List<HashMap<String,Object>> which represents a database where each list record is a database row.

I have 10 columns in my database. There are several rows where the values of 2 particular columns are equals. I need to remove the duplicates from the list after the list is updated with all the rows from database.

What is the efficient way?

FYI - I am not able to do distinct while querying the database, because the GroupName is added at a later stage to the Map after the database is loaded. And since Id column is not primary key, once you add GroupName to the Map. You will have duplicates based on Id + GroupName combination!

Hope my question makes sense. Let me know if we need more clarification.