Читать книгу OCP Oracle Certified Professional Java SE 17 Developer Study Guide - Jeanne Boyarsky - Страница 57

OCP EXAM OBJECTIVES COVERED IN THIS CHAPTER:

 Handling date, time, text, numeric and boolean valuesUse primitives and wrapper classes including Math API, parentheses, type promotion, and casting to evaluate arithmetic and boolean expressions

 Utilizing Java Object-Oriented ApproachDeclare and instantiate Java objects including nested class objects, and explain the object life-cycle including creation, reassigning references, and garbage collectionUnderstand variable scopes, use local variable type inference, apply encapsulation, and make objects immutable

Welcome to the beginning of your journey to achieve a Java 17 certification. We assume this isn't the first Java programming book you've read. Although we do talk about the basics, we do so only because we want to make sure you have all the terminology and detail you need for the exam. If you've never written a Java program before, we recommend you pick up an introductory book on Java 8 or higher. Examples include Head First Java, 3rd Edition (O'Reilly Media, 2022) and Beginning Programming with Java for Dummies (For Dummies, 2021). Then come back to this certification study guide.

As the old saying goes, you have to learn how to walk before you can run. Likewise, you have to learn the basics of Java before you can build complex programs. In this chapter, we present the basics of Java packages, classes, variables, and data types, along with the aspects of each that you need to know for the exam. For example, you might use Java every day but be unaware that you cannot create a variable called 3dMap or this. The exam expects you to know and understand the rules behind these principles. While most of this chapter should be review, there may be aspects of the Java language that are new to you since they don't come up in practical use often.