Yes, var and the diamond operator can be combined together. The compiler will infer the most specific generic type: var list = new ArrayList<>(); // Infers ArrayList<Object> var list = new ArrayList<>(List.of(1, 2, 3)); // Infers ArrayList<Integer> And you can even combine them with an anonymous class: var list = new ArrayList<>() {};
This was discussed on the “Project Coin” mailing list. In substance (emphasis mine): Internally, a Java compiler operates over a richer set of types than those that can be written down explicitly in a Java program. The compiler-internal types which cannot be written in a Java program are called non-denotable types. Non-denotable types can occur … Read more
It is less verbose, consider the following Map<String,List<String>> map = new HashMap<String,List<String>>(); vs Map<String,List<String>> map = new HashMap<>(); I think you would go for the second option
The issue with List<String> list = new LinkedList(); is that on the left hand side, you are using the generic type List<String> where on the right side you are using the raw type LinkedList. Raw types in Java effectively only exist for compatibility with pre-generics code and should never be used in new code unless … Read more