Why type annotation is not directly supported by java 8 compiler or Eclipse

Question

Currently I am researching on the new features of Java8: http://www.oracle.com/technetwork/java/javase/8-whats-new-2157071.html

From the link above, it is clearly demonstrated:

Type Annotations provide the ability to apply an annotation anywhere a type is used, not just on a declaration. Used with a pluggable type system, this feature enables improved type checking of your code.

But when I tried to add type annotation such as @NotNull or @Readonly etc. in Eclipse Neon, it can not recognize these annotations at all! This is way frustrating.

Did I miss something? or if I need to do more configuration like adding extra jars, how come this is still listed as the Java 8 new feature?

Answer 1

@Jens Thanks :) I searched again from Google and found the following link: https://docs.oracle.com/javase/tutorial/java/annotations/type_annotations.html

In the linked page, it was told The Java SE 8 release does not provide a type checking framework, but it allows you to write (or download) a type checking framework that is implemented as one or more pluggable modules that are used in conjunction with the Java compiler.

So the key is to have a checker framework either DIY or by using existing checker framework . In the end of the the linked page, there is another link page of an existing Checker Framework - https://checkerframework.org/ and this one is probably so far the best framework we can use :)