1. Thinking in Java (Third Edition)
By author Bruce Eckel and it’s the most popular free java ebook of all time. From early stages of Java, this free downloadable Java ebook is popular. It is good for a systematic study of Java and has good code samples. It is free till Third Edition only and the fourth edition is priced, but still a favorite.
Download it Free: Thinking in Java
2. The Java Tutorials (From Oracle/SUN)
Straight from the stable of Oracle/SUN. The best free tutorials for Java beginners. We can learn Java at our own pace comfortable using these free tutorials. As it is from Oracle, can be considered a good choice. It has multiple tutorial trails covering basics to advanced lessons.
Learn Free: The Java Tutorials – Free
3. The Java Language Specification
This is a cool option for a serious Java learner. This is the most authoritative it can get. It gives you the rules of engagement. My personal best choice for learning Java. Available as a free PDF for download. SE 7 Edition is written by James Gosling, Bill Joy, Guy Steele, Gilad Bracha, Alex Buckley. After seeing this names, do you still want further recommendation? Go ahead dive deep into it.
Download PDF: The Java Language Specification
Other Choices for Free Java Tutorials:
4. Java Application Development on Linux
Yes Java is platform independent and no doubt about it. As described by the authors of the book, "…to cover development and deployment of a Java application that has command-line, GUI, servlet, and enterprise components on a Linux platform. We’re going to show you a simplistic enterprise application, “from cradle
to grave,” but along the way cover issues of design process, production environment, setup, administration, and maintenance…"
Download PDF: Java Application Development on Linux
5. Introduction to Programming Using Java
This Java Ebook by David J Eck is a popular choice and will serve good as a Java tutorial. It is free and comes is different format including a PDF format for download. For a beginner programmer in Java, this will be a good choice.
Free Ebook: Introduction to Programming Using Java
6. Think Java
This Java Ebook is based on How to think like a Computer Scientist original text. It can be read online and downloaded as a PDF book for free. It is written by author Allen B Downey. This can be used as reference tutorial for Java beginners.
Download Free: Think Java
7. Data Structures and Algorithms with Object-Oriented Design Patterns in Java
Good tutorial for learning data structures using Java. It is written by Bruno R. Preiss. It is available free as an online resource and Java source code can be downloaded.
Free Online Tutorial: Data Structures and Algorithms with OOD Patterns in Java