java 9

Java 9 features

Java 9 has introduced a couple of nice features. Let's try to use them? :)
1) Factory Methods for Immutable List, Set, Map and Map.Entry
You can easily create an immutable List, Set or Map by using a .of() method like this:

List<String> newList = List.of("a", "b", "c");
Set<String> newSet = Set.of("a", "b", "c");
Map<Integer, String> newMap = Map.of(1, "first", 2, "second", 3, "third");

Very convenient, I must say. On previous versions of Java you had to make a loop or use some other library to achieve the same result.