OOP – Learn Object Oriented Thinking and Programming, by Rudolf Pecinovsky, is free to download in pdf format. It is divided into three parts.
Free Java Books
Introduction to Web Services with Java, by Kiet T. Tran, focuses more on the details of a hands-on approach to Web Service programming than its specifications.
Read the free online version of O’Reilly Media’s Learning Java, 4th Edition by Patrick Niemeyer and Daniel Leuck.
Java Enterprise Performance is a free online eBook by technology experts at the Compuware dynaTrace® Center of Excellence. This book is for IT senior managers, team leaders and practitioners responsible for the performance of business-critical applications.
This is the third edition of Duane A. Bailey’s Java Structures: Data Structures in Java for the Principled Programmer. You can download the complete book in pdf format for free.
Java for Python Programmers is a short online book by Brad Miller. This book assumes that you are already familiar with the Python programming language.
“Java: Learning to Program with Robots” is an innovative approach to teaching and learning introductory object-oriented programming. Students are introduced to object-oriented concepts with simulated robots, a hands-on approach that is engaging and fun for both students and instructors.
“Programming Grails”, by Burt Beckwith, is still under development. You can read the completed chapters online for free from O’Reilly Media’s Open Feedback Publishing System. Grails is an open source web application framework which uses the Groovy programming language.
Third edition of “Data Structures and Algorithm Analysis in Java” by Dr. Clifford A. Shaffer is available in pdf format for free. This book describes many techniques for representing data.
“Object-oriented Programming in Java”, written by Richard L. Halterman, is a text still under development. It is used in a beginning computer programming course.