Book Image

Oracle Certified Associate, Java SE 7 Programmer Study Guide

By : Richard M. Reese
Book Image

Oracle Certified Associate, Java SE 7 Programmer Study Guide

By: Richard M. Reese

Overview of this book

<p>Java SE 7 Associate Programmer certification adds to your qualification as a Java developer. Knowledge of Java is important, but knowing how to write an efficient and productive code adds to your skills and gives you an edge when you are planning to give the certification exam. Coverage of the objectives goes beyond a simple review of certification objectives.</p> <p>"Oracle Certified Associate, Java SE 7 Programmer Study Guide" addresses certification exam objectives and provides discussion and examples to show the best ways of applying Java language features in real world programming. You will gain in-depth understanding of Java by examining how objects are allocated in the heap and how methods are managed in the program stack.<br /><br />"Oracle Certified Associate, Java SE 7 Programmer Study Guide" covers all of the Java SE 7 Associate Programmer certification objectives. It starts with a high level overview of an application’s structure to provide a framework for subsequent chapters. Chapters are organized around common themes with emphasis on memory usage. You will get an in-depth and complete understanding of the run-time Java environment using the illustrations that show the impact of class and method usage on the program stack and heap. <br /><br />Augmenting the coverage of certification objectives are examples of how you can use the classes, methods, and techniques in a productive and sound manner. In addition, sample exam questions are given in each chapter.</p>
Table of Contents (16 chapters)
Oracle Certified Associate, Java SE 7 Programmer Study Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface

Constructors


Constructors are used to initialize the member variables of a class. When an object is created, memory is allocated for the object and the constructor for the class is executed. This typically occurs using the new keyword.

Initialization of an object's instance variables is important. One of the developer's responsibilities is making sure that the state of an object is always valid. To assist in this process, constructors are executed whenever an object is created.

An alternate approach, which is not used by Java, is to use an initialization method that the programmer should call after an object is created. However, the use of such an initialization method is not a foolproof technique. The programmer may not be aware that the method exists, or may forget to call the method. To avoid these types of problems, a constructor is automatically invoked when an object is created.

The important characteristics of constructors include:

  • Constructors have the same name as the class

  • Constructor...