Map optimization

Question

Map<string, List<Object>> finalMap = new Map<string, List<Object>>();
                    for(Map<String, Object> cus : allJSONValues){
                        for(string key : cus.keyset()){
                            if(finalMap.containsKey(key)){
                            
                                finalMap.get(key).add(cus.get(key)); 
                            }else {
                                List<Object> newObj = new List<Object>();
                                newObj.add(cus.get(key));
                                finalMap.put(key,newObj);
                            }
                        }
                    }

allJSONValues is a List<Map<String, Object>>.

Can anyone please tell me how can I optimize this and can remove double for loop from this.

Answer 1

Generally speaking, you can't.

If you have a nested collection like a List<List<Object>> or Map<String, Map<String, Object>>, using a nested loop is the sensible way to get access to the innermost values.

Nested loops in and of themselves are not inherently evil. They're only really bad when you have something that checks every element in one collection against every element in another collection, e.g.

// This is an example of a "bad" nested loop
// Don't use this in a real class
for(Account a :accountList){
    for(Contact cont :contactList){
        if(cont.AccountId == a.Id){
            // do work
        }
    }
}

Since your loop is not like the bad example above, it is fine. The nested loop you have will only iterate as few times as possible.