OCA

Name: OCA | Oracle Certified Associate Java SE 8 Programmer I Study Guide: Exam 1Z0-808
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Oracle Certified Associate Java SE 8 Programmer I Study Guide: Exam 1Z0-808

Jeanne Boyarsky Scott Selikoff(Autor*in)

Sybex (Verlag)

Erschienen am 11. Dezember 2014

432 Seiten

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Introduction xxi Assessment Test xxxi Chapter 1 Java Building Blocks 1 Understanding the Java Class Structure 2 Fields and Methods 2 Comments 4 Classes vs. Files 5 Writing a main() Method 6 Understanding Package Declarations and Imports 9 Wildcards 10 Redundant Imports 11 Naming Conflicts 12 Creating a New Package 13 Code Formatting on the Exam 16 Creating Objects 16 Constructors 17 Reading and Writing Object Fields 18 Instance Initializer Blocks 18 Order of Initialization 19 Distinguishing Between Object References and Primitives 20 Primitive Types 20 Reference Types 24 Key Differences 25 Declaring and Initializing Variables 25 Declaring Multiple Variables 26 Identifiers 27 Understanding Default Initialization of Variables 29 Local Variables 29 Instance and Class Variables 30 Understanding Variable Scope 31 Ordering Elements in a Class 34 Destroying Objects 36 Garbage Collection 36 finalize() 38 Benefits of Java 39 Summary 40 Exam Essentials 41 Review Questions 42 Chapter 2 Operators and Statements 51 Understanding Java Operators 52 Working with Binary Arithmetic Operators 53 Arithmetic Operators 53 Numeric Promotion 55 Working with Unary Operators 57 Logical Complement and Negation Operators 57 Increment and Decrement Operators 58 Using Additional Binary Operators 60 Assignment Operators 60 Compound Assignment Operators 62 Relational Operators 63 Logical Operators 64 Equality Operators 65 Understanding Java Statements 66 The if-then Statement 67 The if-then-else Statement 68 The switch Statement 72 The while Statement 76 The do-while Statement 78 The for Statement 80 Understanding Advanced Flow Control 86 Nested Loops 87 Adding Optional Labels 87 The break Statement 88 The continue Statement 90 Summary 92 Exam Essentials 92 Review Questions 94 Chapter 3 Core Java APIs 101 Creating and Manipulating Strings 102 Concatenation 102 Immutability 104 The String Pool 105 Important String Methods 105 Method Chaining 110 Using the StringBuilder Class 111 Mutability and Chaining 112 Creating a StringBuilder 113 Important StringBuilder Methods 114 StringBuilder vs. StringBuffer 117 Understanding Equality 117 Understanding Java Arrays 119 Creating an Array of Primitives 119 Creating an Array with Reference Variables 121 Using an Array 123 Sorting 124 Searching 125 Varargs 126 Multidimensional Arrays 126 Understanding an ArrayList 129 Creating an ArrayList 129 Using an ArrayList 130 Wrapper Classes 134 Autoboxing 136 Converting Between array and List 136 Sorting 138 Working with Dates and Times 138 Creating Dates and Times 138 Manipulating Dates and Times 142 Working with Periods 145 Formatting Dates and Times 148 Parsing Dates and Times 151 Summary 151 Exam Essentials 152 Review Questions 153 Chapter 4 Methods and Encapsulation 165 Designing Methods 166 Optional Specifiers 168 Return Type 169 Method Name 170 Parameter List 171 Optional Exception List 171 Method Body 171 Working with Varargs 172 Applying Access Modifiers 173 Private Access 173 Default (Package Private) Access 175 Protected Access 176 Public Access 180 Designing Static Methods and Fields 181 Calling a Static Variable or Method 182 Static vs. Instance 183 Static Variables 185 Static Initialization 186 Static Imports 187 Passing Data Among Methods 188 Overloading Methods 191 Creating Constructors 196 Default Constructor 197 Overloading Constructors 199 Final Fields 202 Order of Initialization 202 Encapsulating Data 205 Creating Immutable Classes 207 Writing Simple Lambdas 208 Lambda Example 209 Lambda Syntax 211 Predicates 214 Summary 215 Exam Essentials 216 Review Questions 218 Chapter 5 Class Design 233 Introducing Class Inheritance 234 Extending a Class 235 Applying Class Access Modifiers 237 Creating Java Objects 237 Defining Constructors 238 Calling Inherited Class Members 244 Inheriting Methods 246 Inheriting Variables 257 Creating Abstract Classes 259 Defining an Abstract Class 260 Creating a Concrete Class 262 Extending an Abstract Class 263 Implementing Interfaces 266 Defining an Interface 267 Inheriting an Interface 269 Interface Variables 273 Default Interface Methods 274 Static Interface Methods 278 Understanding Polymorphism 279 Object vs. Reference 281 Casting Objects 282 Virtual Methods 284 Polymorphic Parameters 285 Polymorphism and Method Overriding 287 Summary 288 Exam Essentials 289 Review Questions 291 Chapter 6 Exceptions 299 Understanding Exceptions 300 The Role of Exceptions 300 Understanding Exception Types 302 Throwing an Exception 304 Using a try Statement 305 Adding a finally Block 307 Catching Various Types of Exceptions 309 Throwing a Second Exception 311 Recognizing Common Exception Types 313 Runtime Exceptions 314 Checked Exceptions 317 Errors 317 Calling Methods That Throw Exceptions 318 Subclasses 319 Printing an Exception 321 Summary 323 Exam Essentials 324 Review Questions 325 Appendix A Answers to Review Questions 333 Chapter 1: Java Building Blocks 334 Chapter 2: Operators and Statements 336 Chapter 3: Core Java APIs 339 Chapter 4: Methods and Encapsulation 342 Chapter 5: Class Design 346 Chapter 6: Exceptions 349 Appendix B Study Tips 353 Studying for the Test 354 Creating a Study Plan 354 Creating and Running Sample Applications 355 Taking the Test 359 Understanding the Question 359 Applying Process of Elimination 362 Optimizing Your Time 364 Getting a Good Night's Rest 366 Index 367

Introduction

Java, "born" in 1995, is now just about 20 years old. As with anything 20 years old, there is a good amount of history and variation between versions of Java. Over the years, the certification exams have changed to cover different topics. The names of the exams have even changed. This book covers the Java 8 Oracle Certified Associate (OCA) exam.

If you read about "the exam" on the Web, you may see information about the older names for the exam. We've showed the changes in name. Here's what happened. Sun Microsystems used to have two exams. The SCJP (Sun Certified Java Programmer) was meant for programmers and the SCJA (Sun Certified Java Associate) was meant for those who wanted broader knowledge. When Oracle bought Sun Microsystems, they changed all the names from Sun to Oracle, giving us the OCJP and OCJA.

Then Oracle made two strategic decisions with Java 7. They decided to stop updating the OCJA exam. They also decided to cover more on in the programmer space and split it into two exams. Now you first take the OCAJP (Oracle Certified Associate Java Programmer), also known as Java Programmer I, or OCA. That's what this book is about. Then you take the OCPJP (Oracle Certified Professional Java Programmer), also known as Java Programmer II, or OCP. There's also an upgrade exam in case you took an older version of the SCJP or OCPJP and want to upgrade. Most people refer to the current exams as OCA 8, OCP 8, and the Java 8 upgrade exam. We mention when a topic is split between the OCA and OCP so you know which parts are more advanced.

We try to keep the history to a minimum in this book. There are some places on the exam where you need to know both an "old way" and a "new way" of doing things. When that happens, we will be sure to tell you what version of Java introduced it. We will also let you know about topics that are not on the exam anymore in case you see questions in the older free online mock exams.

The OCA Exam

All you need to do to earn the Oracle Certified Associate Java SE 8 Programmer certification is to pass the exam! That's it.

Oracle has a tendency to fiddle with the length of the exam and the passing score once it comes out. Since it's pretty much a guarantee that whatever we tell you here will become obsolete, we will give you a feel for the range of variation. The OCA exam has varied between 60 and 90 questions since it was introduced. The score to pass has varied between 60 percent and 80 percent. The time allowed to take the exam has varied from two hours to two-and-a-half hours.

Oracle has a tendency to "tweak" the exam objectives over time as well. They do make minor additions and removals from what is covered on the exam. Although this tends to affect the OCP exam more than the OCA exam, there are a few topics that were added to the OCA for Java 8. It wouldn't be a surprise for Oracle to make changes.

Although there will likely be minor changes to the scope of the exam, it certainly isn't a secret. We've created a book page on our blog: www.selikoff.net/oca. If there are any changes to the topics on the exam after this book is published, we will note them there.

That book page also contains a link to the official exam page so that you can check the length and passing score that Oracle has chosen for the moment.

Scheduling the Exam

The exam is administered by Pearson VUE and can be taken at any Pearson VUE testing center. To find a testing center or register for the exam, go to www.pearsonvue.com. Choose IT and then Oracle. If you haven't been to the test center before, we recommend visiting in advance. Some testing centers are nice and professionally run. Others stick you in a closet with lots of people talking around you. You don't want to be taking the test with someone complaining about their broken laptop nearby!

At this time, you can reschedule the exam without penalty until up to 24 hours before. This means that you can register for a convenient time slot well in advance, knowing that you can delay if you aren't ready by that time. Rescheduling is easy and can be done on the Pearson VUE website. This may change, so check the rules before paying.

The Day of the Exam

When you go to take the exam, remember to bring two forms of ID, including one that is government issued. See Pearson's list of what is acceptable ID at http://www.pearsonvue.com/policies/1S.pdf. Try not to bring too much extra with you as it will not be allowed into the exam room. While you will be allowed to check your belongings, it is better to leave extra items at home or in the car.

You will not be allowed to bring paper, your phone, and so forth into the exam room with you. Some centers are stricter than others. At one center, tissues were even taken away from us! Most centers allow keeping your ID and money. They watch you taking the exam, though, so don't even think about writing notes on money.

The exam center will give you writing materials to use during the exam. These are used as scratch paper during the exam to figure out answers and keep track of your thought process. The exam center will dispose of them at the end. Notice how we said "writing materials" rather than "pen and paper." Some centers still give pen and paper. Most give a small erasable board and a dry erase marker. If you have a preference to which you receive, call the testing center in advance to inquire.

Finding Out Your Score

In the past, you would find out right after finishing the exam if you passed. Now you have to wait nervously until you can check your score online.

If you go onto the Pearson VUE website, it will just have a status of "Taken" rather than your result. Oracle uses a separate system for scores. You'll need to go to http://certview.oracle.com to find out whether you passed and your score. It doesn't update immediately upon taking the test, but we haven't heard of it taking more than an hour. In addition to your score, you'll also see objectives for which you got a question wrong and instructions on how to get a hardcopy certificate.

At some point, you'll get an electronic certificate and some more time after that you'll receive your printed certificate. Sound vague? It is. The times reported to receive certificates vary widely.

Exam Questions

The OCA exam consists of multiple-choice questions. There are typically five or six possible answers. If a question has more than one answer, the question specifically states exactly how many correct answers there are. This book does not do that. We say "choose all that apply" to make the questions harder. This means the questions in this book are generally harder than those on the exam. The idea is to give you more practice so you can spot the correct answer more easily on the real exam.

Note that exam questions will sometimes have line numbers that begin with numbers higher than 1. This is to indicate that you are looking at a code snippet rather than a complete class. We follow this convention as well to get you used to it.

If you read about older versions of the exam online, you might see references to drag-and-drop questions. These questions had you do a puzzle on how to complete a piece of code. There was also a bug in the exam software that caused your answers to get lost if you reviewed them again. Luckily, these are no longer on the exam.

Getting Started

We recommend reading Appendix B, "Study Tips," before diving into the technical material in this book. Knowing how to approach studying will help you make better use of your study time.

Next, make sure you have downloaded version 8 of the JDK. If you learned Java some time ago, you might have version 7 or even earlier. There have been both big and small changes to the language. You could get a question wrong if you study with the wrong version.

Also, please check our book page to make sure Oracle hasn't changed the objectives. For example, if Oracle decided that lambdas weren't on the exam, you'd want to know that before studying. We will post any updates that you should know about at www.selikoff.net/oca.

Getting Help

Both of the authors are moderators at CodeRanch.com. CodeRanch.com is a very large and active programming forum that is very friendly toward Java beginners. It has a forum just for this exam called OCAJP. It also has a forum called Beginning Java for non-exam-specific questions. As you read the book, feel free to ask your questions in either of those forums. It could be you are having trouble compiling a class or that you are just plain confused about something. You'll get an answer from a knowledgeable Java programmer. It might even be one of us.

Who Should Buy This Book

If you want to become certified as a Java programmer, this book is definitely for you. If you want to acquire a solid foundation in Java and your goal is to prepare for the exam, this book is also for you. You'll find clear explanations of the concepts you need to grasp and plenty of help to achieve the high level of professional competency you need in order to succeed in your chosen field.

This book is intended to be understandable to...

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