Run time type checking and casting in java

Question

I am having a map of String and Object and I am getting this map from an external source, for a particular scenario, I am getting this object as

"ArrayList<LinkedHashMap<String, Double>>"

ArrayList<LinkedHashMap<String, Double>> targetDetailContainer = null;
Map<String, Object> confData = getConfData();
if (confData.containsKey("Target-Details")) {
    targetDetailContainer = (ArrayList<LinkedHashMap<String, Double>>) confData
            .get((Object) "Target-Details");
}

now at the last line where I am casting the Object to

"ArrayList<LinkedHashMap<String, Double>>"

I am getting a warning -

Type safety: Unchecked cast from Object to

"ArrayList<LinkedHashMap<String, Double>>"

I have tried to do type check before casting, something like this,

if (confData.containsKey("Target-Details")
    && confData.get((Object) "Target-Details") instanceof ArrayList<?>) {
targetDetailContainer = (ArrayList<LinkedHashMap<String, Double>>) confData
        .get((Object) "Target-Details");
}

But it didn't worked. Please suggest something, How I can get rid of this warning.

Answer 1

I would suggest @SuppressedWarnings ("unchecked") annotation since you cannot do much about this warning. It's not very harmful, but because of type erasure and lack of type information at compile time (for generic types) you can't really do anything else.