Which is the best website to learn java in deep?

Here is a step-by-step approach to learn Java from Core Java to Advanced Java in the shortest possible time - a journey from novice to expert.

Although the question has specifically asked for a single website, yet I’ll go for a mix-and-match approach, as I believe this is the best way to make a journey from novice to expert in Java and also to prepare for Job Interviews

1. Step 1 - Core Java - Buy a Java certification book (even if you do not have any plan to do certification) because over the years I have seen that the certification books are extremely helpful to learn the subject. Read the book cover to cover and you will be quite comfortable with the important concepts of Core Java. Buy the book after checking the review in Amazon.
2. Step 2 - Java New Features - Starting from Java 5 through to Java9, search in the Google for the top 10 new features introduced in each version. Do further research in the internet to learn about each new feature
3. Step 3 - GoF Design Patterns - This StackOverflow answer is (my personal opinion) the best set of examples of the GoF Design Pattern Examples of GoF Design Patterns in Java's core libraries. This answer tells you which Java libraries implement which design patterns. Keep this as a reference and reserach in the internet for each of these design patterns until you understand most of the design patterns
4. Step 4 - Enter Spring Framework - Learn about dependency Injection (DI) and Inversion of Control (IoC) patterns and also how to use these patterns using core Spring or Spring DI. Also learn about Spring JDBC
5. Step 5 - Enter JEE - This StackOverflow answer A summary of all Java EE specifications will give you an idea about what JEE is and a brief overview of each specification. Just know what they are used for. Focus and learn in detail the following:
1. Servlet
2. Web Socket
3. Concurrency Utilities
4. JAX-RS
5. JAX-WS
6. JAXP
7. JAXB
8. JMS
9. JPA
6. Step 6 - JEE new features - Starting from JEE 5 through to JEE 8, search in the Google for the top 10 new features introduced in each version. Do further research in the internet to learn about each new feature
7. Step 7 - Enter Web Development - Learn developing an web application using any one of the following
1. Spring MVC
2. Struts 2
3. JSF
8. Step 8 - Start Open Source Journey - Some of the important open source projects worth learning
1. Log4j 2
2. Maven
3. Tomcat JDBC Connection Pool
9. Step 9 - Beginning of the Journey -
1. Deep dive into all of the above
2. Learn about new open source projects
3. Develop a complete web application e2e for practice

After all these steps, stop remaining solely focused in Java. Look around. Learn about new technologies. The ultimate goal is to provide performing, cost-effective, scaleable software solutions by mix-and-match of right technologies.