How to use this Book: Intro

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In this section, we answer the burning question: “So why DID they put that in an OOA&D book?”

Who is this book for?

If you can answer “yes” to all of these:

  1. Do you know Java? (You don’t need to be a guru.)


    You’ll probably be okay if you know C# instead.

  2. Do you want to learn, understand, remember, and apply object-oriented analysis and design to real world projects, and write better software in the process?

  3. Do you prefer stimulating dinner party conversation to dry, dull, academic lectures?

this book is for you.

Who should probably back away from this book?

If you can answer “yes” to any one of these:

  1. Are you completely new to Java? (You don’t need to be advanced, and even if you don’t know Java, but you know C#, you’ll probably understand almost all of the code examples. You also might be okay with just a C++ background.)

  2. Are you a kick-butt OO designer/developer looking for a reference book?

  3. Are you afraid to try something different? Would you rather have a root canal than mix stripes with plaid? Do you believe that a technical book can’t be serious if programming concepts are anthropomorphized?

this book is not for you.

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[note from marketing: this book is for anyone with a credit card.]

We know what you’re thinking

“How can this be a serious programming book?”

“What’s with all the graphics?”

“Can I actually learn it this way?”

And we know what your brain is thinking

Your brain craves novelty. It’s always searching, scanning, waiting for something unusual. It was built that way, and it helps you stay alive.

So what does your brain do with all the routine, ordinary, normal things you encounter? Everything it can to stop them from interfering with the brain’s real job—recording things that matter. It doesn’t bother saving the boring things; they never make it past the “this is obviously not important” filter.

How does your brain know what’s important? Suppose you’re out for a day hike and a tiger jumps in front of you, what happens inside your head and body?

Neurons fire. Emotions crank up. Chemicals surge.

And that’s how your brain knows...

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This must be important! Don’t forget it!

But imagine you’re at home, or in a library. It’s a safe, warm, tiger-free zone. You’re studying. Getting ready for an exam. Or trying to learn some tough technical topic your boss thinks will take a week, ten days at the most.

Just one problem. Your brain’s trying to do you a big favor. It’s trying to make sure that this obviously non-important content doesn’t clutter up scarce resources. Resources that are better spent storing the really big things. Like tigers. Like the danger of fire. Like how you should never again snowboard in shorts.

And there’s no simple way to tell your brain, “Hey brain, thank you very much, but no matter how dull this book is, and how little I’m registering on the emotional Richter scale right now, I really do want you to keep this stuff around.”

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Metacognition: thinking about thinking

If you really want to learn, and you want to learn more quickly and more deeply, pay attention to how you pay attention. Think about how you think. Learn how you learn.

Most of us did not take courses on metacognition or learning theory when we were growing up. We were expected to learn, but rarely taught to learn.

But we assume that if you’re holding this book, you really want to learn object-oriented analysis and design. And you probably don’t want to spend a lot of time. And since you’re going to develop software, you need to remember what you read. And for that, you’ve got to understand it. To get the most from this book, or any book or learning experience, take responsibility for your brain. Your brain on this content.

The trick is to get your brain to see the new material you’re learning as Really Important. Crucial to your well-being. As important as a tiger. Otherwise, you’re in for a constant battle, with your brain doing its best to keep the new content from sticking.

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So just how DO you get your brain to think object-oriented analysis and design is a hungry tiger?

There’s the slow, tedious way, or the faster, more effective way. The slow way is about sheer repetition. You obviously know that you are able to learn and remember even the dullest of topics if you keep pounding the same thing into your brain. With enough repetition, your brain says, “This doesn’t feel important to him, but he keeps looking at the same thing over and over and over, so I suppose it must be.”

The faster way is to do anything that increases brain activity, especially different types of brain activity. The things on the previous page are a big part of the solution, and they’re all things that have been proven to help your brain work in your favor. For example, studies show that putting words within the pictures they describe (as opposed to somewhere else in the page, like a caption or in the body text) causes your brain to try to makes sense of how the words and picture relate, and this causes more neurons to fire. More neurons firing = more chances for your brain to get that this is something worth paying attention to, and possibly recording.

A conversational style helps because people tend to pay more attention when they perceive that they’re in a conversation, since they’re expected to follow along and hold up their end. The amazing thing is, your brain doesn’t necessarily care that the “conversation” is between you and a book! On the other hand, if the writing style is formal and dry, your brain perceives it the same way you experience being lectured to while sitting in a roomful of passive attendees. No need to stay awake.

But pictures and conversational style are just the beginning.

Here’s what WE did

We used pictures, because your brain is tuned for visuals, not text. As far as your brain’s concerned, a picture really is worth 1,024 words. And when text and pictures work together, we embedded the text in the pictures because your brain works more effectively when the text is within the thing the text refers to, as opposed to in a caption or buried in the text somewhere.

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We used redundancy, saying the same thing in different ways and with different media types, and multiple senses, to increase the chance that the content gets coded into more than one area of your brain.

We used concepts and pictures in unexpected ways because your brain is tuned for novelty, and we used pictures and ideas with at least some emotional content, because your brain is tuned to pay attention to the biochemistry of emotions. That which causes you to feel something is more likely to be remembered, even if that feeling is nothing more than a little humor, surprise, or interest.

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We used a personalized, conversational style, because your brain is tuned to pay more attention when it believes you’re in a conversation than if it thinks you’re passively listening to a presentation. Your brain does this even when you’re reading.

We included more than 80 activities, because your brain is tuned to learn and remember more when you do things than when you read about things. And we made the exercises challenging-yet-do-able, because that’s what most people prefer.

We used multiple learning styles, because you might prefer step-by-step procedures, while someone else wants to understand the big picture first, and someone else just wants to see a code example. But regardless of your own learning preference, everyone benefits from seeing the same content represented in multiple ways.

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We include content for both sides of your brain, because the more of your brain you engage, the more likely you are to learn and remember, and the longer you can stay focused. Since working one side of the brain often means giving the other side a chance to rest, you can be more productive at learning for a longer period of time.

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And we included stories and exercises that present more than one point of view, because your brain is tuned to learn more deeply when it’s forced to make evaluations and judgements.

We included challenges, with exercises, and by asking questions that don’t always have a straight answer, because your brain is tuned to learn and remember when it has to work at something. Think about it—you can’t get your body in shape just by watching people at the gym. But we did our best to make sure that when you’re working hard, it’s on the right things. That you’re not spending one extra dendrite processing a hard-to-understand example, or parsing difficult, jargon-laden, or overly terse text.

We used people. In stories, examples, pictures, etc., because, well, because you’re a person. And your brain pays more attention to people than it does to things.

We used an 80/20 approach. We assume that if you’re going for a PhD in software design, this won’t be your only book. So we don’t talk about everything. Just the stuff you’ll actually need.

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Here’s what YOU can do to bend your brain into submission

So, we did our part. The rest is up to you. These tips are a starting point; listen to your brain and figure out what works for you and what doesn’t. Try new things.

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Cut this out and stick it on your refrigerator.

  1. Slow down. The more you understand, the less you have to memorize.

    Don’t just read. Stop and think. When the book asks you a question, don’t just skip to the answer. Imagine that someone really is asking the question. The more deeply you force your brain to think, the better chance you have of learning and remembering.

  2. Do the exercises. Write your own notes.

    We put them in, but if we did them for you, that would be like having someone else do your workouts for you. And don’t just look at the exercises. Use a pencil. There’s plenty of evidence that physical activity while learning can increase the learning.

  3. Read the “There are No Dumb Questions”

    That means all of them. They’re not optional side-bars—they’re part of the core content! Don’t skip them.

  4. Make this the last thing you read before bed. Or at least the last challenging thing.

    Part of the learning (especially the transfer to long-term memory) happens after you put the book down. Your brain needs time on its own, to do more processing. If you put in something new during that processing time, some of what you just learned will be lost.

  5. Drink water. Lots of it.

    Your brain works best in a nice bath of fluid. Dehydration (which can happen before you ever feel thirsty) decreases cognitive function.

  6. Talk about it. Out loud.

    Speaking activates a different part of the brain. If you’re trying to understand something, or increase your chance of remembering it later, say it out loud. Better still, try to explain it out loud to someone else. You’ll learn more quickly, and you might uncover ideas you hadn’t known were there when you were reading about it.

  7. Listen to your brain.

    Pay attention to whether your brain is getting overloaded. If you find yourself starting to skim the surface or forget what you just read, it’s time for a break. Once you go past a certain point, you won’t learn faster by trying to shove more in, and you might even hurt the process.

  8. Feel something!

    Your brain needs to know that this matters. Get involved with the stories. Make up your own captions for the photos. Groaning over a bad joke is still better than feeling nothing at all.

  9. Design something!

    Apply what you read to something new you’re designing, or rework an older project. Just do something to get some experience beyond the exercises and activities in this book. All you need is a problem to solve... a problem that might benefit from one or more techniques that we talk about.

Read Me

This is a learning experience, not a reference book. We deliberately stripped out everything that might get in the way of learning whatever it is we’re working on at that point in the book. And the first time through, you need to begin at the beginning, because the book makes assumptions about what you’ve already seen and learned.

We assume you are familiar with Java.

It would take an entire book to teach you Java (in fact, that’s exactly what it took: Head First Java). We chose to focus this book on analysis and design, so the chapters are written with the assumption that you know the basics of Java. When intermediate or advanced concepts come up, they’re taught as if they might be totally new to you, though.

If you’re completely new to Java, or coming to this book from a C# or C++ background, we strongly recommend you turn to the back of the book and read Appendix B before going on. That appendix has some intro material that will help you start this book off on the right foot.

We only use Java 5 when we have to.

Java 5.0 introduces a lot of new features to the Java language, ranging from generics to parameterized types to enumerated types to the foreach looping construct. Since many professional programmers are just moving to Java 5, we didn’t want you getting hung up on new syntax while you’re trying to learn about OOA&D. In most cases, we stuck with pre-Java 5 syntax. The only exception is in Chapter 1, when we needed an enumerated type—and we explained enums in that section in some detail.

If you’re new to Java 5, you should have no trouble with any of the code examples. If you’re already comfortable with Java 5, then you will get a few compiler warnings about unchecked and unsafe operations, due to our lack of typed collections, but you should be able to update the code for Java 5 on your own quite easily.

The activities are NOT optional.

The exercises and activities are not add-ons; they’re part of the core content of the book. Some of them are to help with memory, some are for understanding, and some will help you apply what you’ve learned. Don’t skip the exercises. The crossword puzzles are the only things you don’t have to do, but they’re good for giving your brain a chance to think about the words and terms you’ve been learning in a different context.

The redundancy is intentional and important.

One distinct difference in a Head First book is that we want you to really get it. And we want you to finish the book remembering what you’ve learned. Most reference books don’t have retention and recall as a goal, but this book is about learning, so you’ll see some of the same concepts come up more than once.

The examples are as lean as possible.

Our readers tell us that it’s frustrating to wade through 200 lines of an example looking for the two lines they need to understand. Most examples in this book are shown within the smallest possible context, so that the part you’re trying to learn is clear and simple. Don’t expect all of the examples to be robust, or even complete—they are written specifically for learning, and aren’t always fully-functional.

In some cases, we haven’t included all of the import statements needed, but we assume that if you’re a Java programmer, you know that ArrayList is in java.util, for example. If the imports are not part of the normal core J2SE API, we mention it. We’ve also placed all the source code on the web so you can download it. You’ll find it at

Also, for the sake of focusing on the learning side of the code, we did not put our classes into packages (in other words, they’re all in the Java default package). We don’t recommend this in the real world, and when you download the code examples from this book, you’ll find that all classes are in packages.

The ‘Brain Power’ exercises don’t have answers.

For some of them, there is no right answer, and for others, part of the learning experience of the Brain Power activities is for you to decide if and when your answers are right. In some of the Brain Power exercises you will find hints to point you in the right direction.

The Technical Team

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Technical Reviewers:

Huge thanks to our amazing trio of technical reviewers. These guys caught mistakes that we missed, let us know when we were moving too fast (or too slow), and even let us know when our jokes sucked. Several times, they turned chapters around in a matter of hours... we’re not sure if that means they’re really helpful, or need to get away from software development a little more. Hannibal in particular made our week when he let us know that the big OOA&D arrow in Chapter 10 was “Hot!” Thanks guys, this book wouldn’t be nearly as solid without your hard work.

Kathy Sierra and Bert Bates:

We continue to be amazed at the insight and expertise that Bert Bates has about cliffs, and that Kathy Sierra has about dog doors. If that doesn’t make much sense, don’t be surprised—everything you know about almost everything gets turned on its head when you meet this pair, and yet we all came out much for the better because of their help.

Bert and Kathy did a ton of review at the eleventh hour, and we’re thankful they did. Their help and guidance continues to be the heart of Head First.

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My co-authors:

Because I’m doing the typing, I get to step out of “we” mode for a moment and say thanks to my co-authors, Dave West and Gary Pollice. Neither of these guys knew what they were signing up for when they came on board, but I’ve never been so impressed by a couple of guys willing to explain, defend, and even change their opinions and knowledge about software design, requirements and analysis, and lift shafts. They were simply incredible, writing up until the very last day, and even got me to relax and laugh until I cried on several occasions.

Our editor:

This book wouldn’t be in your hands if not for Mary O’Brien. I think it’s fair to say she fought more battles and paved the way for us to work without interruption more times than any of us really are aware of. Most importantly, she made this the single most enjoyable project we’ve worked on in our careers. Frankly, she kicked our asses a number of times, and it made all the difference. She really doesn’t realize how much of an effect she has on the people she works with, because we don’t tell her enough how much we respect her and value her opinions. So there, now you know, Mary. If we could put your name on the cover, we would (oh, wait... we did!).

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The O’Reilly team:

These books are a team effort, never more so than on this one. Mike Hendrickson and Laurie Petrycki oversaw this project at various times, and took heated phone calls more than once. Sanders Kleinfeld cut his Head First teeth on this project, and managed to come out alive; better yet, he did a great job, improving the book, and we all are excited that this is just the first of many Head First books he’ll be working on. Mike Loukides found Bert and Kathy way back when, and Tim O’Reilly had the foresight to turn their crazy idea into a series. As always, Kyle Hart is instrumental in getting these books “out there”, and Edie Freedman’s beautiful cover design continues to amaze us all.

A particularly special thanks goes out to Louise Barr, the Head First Design Editor. Lou pulled several 12- and 14-hour days to help us with graphics in this book, and put together the amazing Objectville Subway Map in Chapter 10. Lou, your work has improved the learning quality of this book, and we can’t thank you enough for your contributions.

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Special thanks

Near the completion of this book, Laura Baldwin, the CFO of O’Reilly, encountered some personal tragedy. It’s hard to know what to say in these situations, especially because Laura has really become the backbone of O’Reilly in many ways. Laura, we are thinking and praying for you and your family, and we wish you all the very, very best in the days to come. We know you’d want nothing more than to see everyone at O’Reilly working harder than ever while you’re away.

This book is certainly a testament to the people at O’Reilly continuing to deliver, and in many of our conversations, your name came up as someone we wanted to support, and not let down in any way. Your effect on this company is extraordinary, and O’Reilly and the Head First series will all be much better for the day you can return to us in full swing.

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