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

Understanding how Java handles data


The core of programming is code that manipulates data. As programmers we are interested in the organization of data and code. The organization of data is referred to as data structures . These structures can be static or dynamic in nature. For example, the ages of a population can be stored in consecutive locations in a data structure known as an array . While the array data structure has a fixed size, the contents may or may not change. Arrays are discussed in detail in Chapter 4, Using Arrays and Collections.

In this section, we will examine several different aspects of variables including:

  • How they are declared

  • Primitive data types versus objects

  • Where they reside in memory

  • How they are initialized

  • Their scope and lifetime

Java identifiers, objects, and memory

Variables are defined to be of a specific type and are allocated memory. When an object is created, instance variables that make up the object are allocated on the heap. The static variables of an object...