The book has over a hundred interview questions, relevant to job interviews for Java developers (especially for mid to senior level). This may be helpful for interviewers, as well as potential candidates preparing for a job interview, where Java questions may be asked. It focuses on core Java, but also has questions on topics such as design patterns, or object oriented concepts, which may be asked in a Java interview. For interviewers the book may provide quite a few complete sets of Java interview questions. For professionals who are not preparing for an interview in near future, this could still help understanding certain topics better, or intriguing them into further investigation on certain specific topics. It is, (in my view) easily readable, and may also be convenient for quick recap. In this sense, it can be a substitute for notes on Java interview questions.