When comparing Core Java vs Hackr.io, the Slant community recommends Hackr.io for most people. In the question“What are the best resources to learn Java?” Hackr.io is ranked 7th while Core Java is ranked 8th. The most important reason people chose Hackr.io is:
Instead of getting a recommendation from a single dev, you get recommendation from the entire programming community.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Both a tutorial and a reference
It's well-written enough to read cover-to-cover, and well organized enough to make a good reference.
Pro Very thorough
It really does cover the whole language. If you read both volumes, consider yourself a Java expert.
Pro Up to date contents
This book explains Java 8, which is the most recent version of Java.
Pro Community trust
Instead of getting a recommendation from a single dev, you get recommendation from the entire programming community.
Pro Recommendation for every programming language/framework/library
You can find Python as well as Jenkins.
Pro Nice filters
Free, Video, Book, Beginner, Advanced, etc.
Cons
Con Long
This is a weighty tome at over a thousand pages, and that's just Volume 1. Don't expect to read it overnight.