How to get Map collection out of a list?

Question

I currently have a multi-demensional map/list object that is defined like this:

Map <Id,List <Map <Id,Custom_Inventory__c> >> complexMap = getComplexMapObject();

The object was difficult to create but it works perfectly fine, the first Id is AccountId, and the second index is ProductId.

Now I need a method that uses this object to verify if a record has a matching Account and Product Id within this collection. The first check is easy, something like this:

if(!complexMap.containsKey(line_item.Account__c)){
    return FALSE;
}

The question I have is about the deeper index. I know I can loop through the map list within but wondering if I have to loop if I know what index I'm looking for. For example:

for (Map <Id,Custom_Inventory__c> inventoryMap : complexMap.get(variable.Account__c) ) {
    // Iterate through inventoryMap, but I already know which 
    // index within this map I need... variable.Product__c)
    if(inventoryMap.containsKey(rsLineItem.Product__c)){
        return TRUE;
    } else {
        return FALSE;
    }
}

If I can avoid the above loop I would like to. It will never be a very large loop but if I can avoid it I think its for the better.

Answer 1

If it's just a contains check, then an additional, set holding all the ProductId values would be the simplest approach to avoiding the iteration over the AccountId values and would probably make the code a bit clearer too. The set could be generated from the complexMap using:

Set<Id> productIds = new Set<Id>();
for (List<Map<Id, Custom_Inventory__c>> l : complexMap.values()) {
    for (Map<Id, Custom_Inventory__c> m : l) {
        productIds.addAll(m.keySet());
    }
}

or returned from the getComplexMapObject method using a simple class with a field for the set and a field for the map and any methods that help.

But if your present code works and there are only ever a few inventory maps I'd stick with the current code.

(The equivalent set for the AccountId values is complexMap.keySet().)