Question

I have a Map of Maps that looks like this:

Map<String, Map<String, Object>> data;

I want to update the inner map.

Should I do the following everytime I want to update the innermap or is there any other direct/better way of accomplishing it?

Map<String, Object> innerMap = data.get("outer_key");
innerMap.put("inner_key", value);
data.put("outer_key", innerMap);

Answer 1

I think you may have a typo in there and I’m assuming inner is actually innerMap. I would probably change it a bit to account for null values in the outer map:

Map<String, Object> innerMap = data.get("outer_key");

// Added this if statement to handle null values in the outer map.
if (innerMap == null) {
    innerMap = new HashMap<String, Object>();
    data.put("outer_key", innerMap);
}

innerMap.put("inner_key", value);
// data.put("outer_key", innerMap); <-- This is not needed, innerMap is already a value in
                                     // the outer map.