There is more to acing a Java interview than understanding the language. For most roles, knowing the syntax and how to run a Java application is assumed; it is the knowledge of how to use the language to interact, manipulate, and display data.
Many reusable pieces of code, such as algorithms, code to connect to the Internet, or writing to disk have been modularized and abstracted into their own libraries. One of Java’s main strengths is that it is mature enough that most common scenarios have their own library, saving you the time and effort of writing and rewriting the functionality from scratch every time. This part focuses on common libraries and application frameworks to help you produce professional, robust applications capable of communicating with the outside world, whether that is by producing a server that displays web pages, or an application that is used to persist information to a database.