The Object of Java fully embraces the object-oriented paradigm by taking an "objects-centric" approach to presenting problem solving and programming. This book focuses on the skills and discipline of software engineering that are needed for good programming. Since specifications are critical for conveying code behavior in the object-oriented model, discussions of method preconditions and postconditions, and class invariants are used consistently to document examples and to define example classes. The Unified Modeling Language (UML) is used as the specification language. The book also uses the notion of patterns to identify numerous expressions, instructions, algorithms and designs that serve to pattern program segments. This book is designed for those who are programming with the BlueJ IDE. Readers begin with four complete chapters focusing on objects, classes and methods. The presentation of primitive data occurs in Chapter 5, ensuring the necessary prior exposure to object declaration, object instantiation, assignment, method calling, parameter passage, class diagrams and object diagrams. In order to accommodate this placement of topics, control structures are covered later than in other books. The book also emphasizes the importance of testing with special sections devoted to ensure that readers develop basic debugging skills, and knowledge of simple path testing and black-box testing. This book is designed for readers without prior programming experience, and is also appropriate for those with knowledge of other languages who are looking for a true object-oriented introduction to Java.