how to instantiate Map>

Question

Im getting compile error when I tried instantiating above method with this:

new HashMap<String, new HashMap<String, JsonNode>()>()

Thanks

Please see the error here

Answer 1

When you call the constructor, you can use Diamond Inference to tell the compiler to "figure it out":

Map<String, Map<String, JsonNode>> myMap = new HashMap<>();

If you really want to declare the whole type, then it's similar to the variable declaration. You only use the parenthesizes when you call the constructor, not for each generic type:

Map<String, Map<String, JsonNode>> myMap = new HashMap<String, Map<String, JsonNode>>();