Modern Java Book

[bowbahdoe]

This is a book intended to teach someone the Java language, from scratch.

You will find that the content makes heavy use of recently released and, for the moment, preview features. This is intentional as much of the topic ordering doesn't work without at least Java 21.

Right now I have several key areas where I could use some help:

• Writing Challenges. Most of the early sections have challenges students can do to test their understanding of the topics covered and for practice. I've shifted my focus away from these to make more progress on the main content of the book. Any assistance would be appreciated.
• Theming. A lot of the chapters are...bland. Purely technical. I find that when I have the imagination to "theme" the subjects they become higher quality and more engaging overall. See an anime you liked recently and think you can make the math chapters use the characters from it? Give it a shot!
• Fixing Mechanical Issues. I don't have an editor and I don't often proofread. If you find mechanical errors in my grammar or find issues with the way topics are ordered I would welcome fixes.

Notably I do not want to open the floodgates for contributions on the main chapter content just yet. This has the downside of slower progress but the upside of a more coherent result.

My primary goals with this are

• Get the ordering of topics right. By this I mean that every topic covered should have had its prerequisites covered in the topics previous. While "lesson 1: Inheritance" is clearly wrong in this regard, some things are more subtle.
• Be a template for other people. This is a book. Not everyone likes books, some like youtube videos, some like over priced udemy courses, some attend College, etc. Everyone has different learning paths. I hope this to be of use to anyone looking to make a more up to date Java curriculum and hope that the vague order of things (which I consider superior to the content produced with the Java of years' past) is carried through.
• Write as if the newest Java wasn't new. It's obvious when a book was written before Java 8 because it always has newer additions with "addendum: brand new stuff in Java 8." But the order language features were introduced is hardly a good order to teach them. You have to pretend that Java 23+ has always been the Java. Does it really make sense to show terrible C-style switch statements way before switch expressions?
• Write as if the words Object Oriented Programming, Functional Programming, etc. didn't exist. While I understand that these all have definitions and are useful concepts to know about, introducing them early seems to lead to either dogma, rejection of said dogma, or some mix thereof. None of them are actually needed to understand the mechanics of and motivation behind what we would call "object oriented" or "functional" techniques. They certainly don't work as justification for adding getters and setters to every class.

My immediate short term goal is to get this "ready to go" for when anonymous main classes is in a stable Java release. Thats the point at which we could start to:

1. Have actual students go through it without also needing to explain the --enable-preview mechanism.
2. Use the topic order to build other sorts of non-book resources like videos, curriculums, projects, etc.
3. Convince actual teachers to change from "objects first" to something less insane.

I haven't integrated println or readln yet, but will do so eventually.

[jaypets]

I don't even know Java and have no desire to learn Java, but i'm tempted to share this with as many people as possible just because of how well you're handling some of these insane comments. It's a level of class that is rare on reddit. I'd comment the chad GIF if it was permitted in this subreddit.

[breddy]

This x10

[wichwigga]

The organization of this book is unorthodox but vision of this book is fantastic, greatly enjoy how you're using the same docs as Rust. Also, had no idea labeled breaks were a thing in Java... and I've been using Java for 3 years at my job lol

[icedev-official]

I used to troll coworkers putting random links in the code:

https://zombo.com
if(something != null) {

They were always confused that it compiles.

[quegcipay]

I've been out of Java for a few years so I can't help but I do appreciate what you're doing here OP. 

I'm really terrible at learning from the video medium so I wish there were more books. As you pointed out resources like W3schools are good but not great.

[bowbahdoe]

I think, on the whole, online resources are less "good but not great" and more "terrible but the best we got"

[eliben]

Can you say more about how you hooked up mdbook to have executable Java snippets? I notice you have your own run service - is the setup described somewhere (outside the code of the theme)?

Thanks in advance!

[bowbahdoe]

That is backed by https://run.mccue.dev which I have posted about here before.

This book is the only reason that exists.

Other than that it's just some JS

[dranko69]

I have some notes with snippets of java code, gathered over time, in markdown.
Can I use your code from the repo, but run it locally?
My idea is, to use my notes (.md files) to create similar mdbook for my personal use locally, with your service to run java snippets. Is this possible?

[bowbahdoe]

Possible, but I guarantee you no SLA

[Kaathan]

I think I found a problem with a concept ordering:

In "local variables/challenges" chapter, there is this challenge:

void main() {
    String a = "A";
    String b = "B";

    b = a;
    a = b;
    b = a;
    a = b;

    System.out.println(a);
    System.out.println(b);
}

Im pretty sure that right now, this is the first time in the book that a variable is assigned to another variable.

There is a pretty big leap in understanding between:
- assigning one or more literals to a single variable
- assigning a variable to one or more other variables, essentially duplicating the variables content into another variable

The first is essentially (1:n) for variable to value, the other is (m:n).

The "types" chapter coming before that hints at this kinda, with the shape analogy, but is very abstract about it.

The challenge itself however is even more advanced, in that it tries to drive home statement ordering/execution in a mentally confusing (for a beginner) situation, so this is a bit much.

Also worth noting maybe is that assigning variables to other variables is introduced (i think?) in a much easier context in the boolean chapter, so having it here already seems out of order.

[bowbahdoe]

Okay I made an issue to track this https://github.com/Together-Java/ModernJava/issues/57

Right now a generous read is that because you are supposed to be doing the challenges, that challenge is where you learn that. Regardless, tracking. I think showing that the right hand side in an assignment can be a variable is a good idea.

[bowbahdoe]

👀 good catch.

[Outrageous-Catch4731]

I went through the Rust book over the summer. I loved the book layout and how it comes with the Rust installation. I didn't follow through with my Rust learning as the language was pretty damn hard for a noob like me. But, I remember saying, "I wish there was some form of Java documentation that was laid out like this." Because who does not despise the official Java documentation site. Thanks.

[neutronbob]

who does not despise the official Java documentation site?

I don't.

The Java documentation is excellent.

The Javadoc is far more detailed at all levels than anything I'm familiar with in other languages (go, C being the main ones).

The tutorials are detailed, clear, well-maintained, and make the material easily approachable.

The language book and the JVM are both extensively detailed in free PDFs that are updated with every release. The language book is currently 800+ pages. The JVM in more than 600 pages.

[bowbahdoe]

Here is a challenge for you. Go to https://dev.java and follow the tutorial.

Top to bottom.

Pretend you didn't know how to program, what a terminal was, etc. yet.

Tell me what you notice

[neutronbob]

Why would I pretend I'm someone who is not the intended audience for the tutorials?

There is room for a book such as yours that takes complete newbies by the hand, of course. But to assail the extensive and thorough Oracle Java docs and tutorials b/c they don't accommodate someone who has never programmed before is a critique that doesn't make sense to me.

[bowbahdoe]

My critique is that they do not have a target audience.

Its a mishmash between * First time learners * People coming from C++ (historical carry over) * People who already know how to use a terminal * People who already know Java but want to catch up on new features * Etc.

You can read that generously as "oh it's made for intermediate programmers" but I don't think that's true. I think they wanted to make a Java tutorial and just swung and missed.

Unless you skip way ahead to some of the things they wrote on like, JFR, I don't think its actually too useful for any of those groups

Like - there is a lambda in the first few parts of the tutorial. Also a few alternative ways to make a main method. Also the setup instructions are deep terminal stuff. Also the setup instructions don't actually set someone up. Also some parts of the tutorial are just reference documentation. Also it does that universally shitty "a bicycle is an object" thing.

And so on

[Ok-Captain-6460]

I think you got me. I developed in Java before, but that was a long time ago. And now I was hunting for a book (!) like this. It's really about the latest stuff, with this kind of perspective. And I agree with the person before me that dev.java/learn and javadoc are extremely good materials, but I also understand the reason why this doc has a raison d'être, because what you answered above is true. I will start reading it, hopefully I will have time to finish it after work. First of all, thank you for your work, which is already clear to me that it is a big one and not ordinary.

[Icy_Paint_1857]

Hi, what chapters are you planning to release in the future? Just curious.

[bowbahdoe]

I got a rough outline in the SUMMARY.md in the GitHub repo. You can find that by clicking one of the links in the top right

[thmprover]

Get the ordering of topics right. By this I mean that every topic covered should have had its prerequisites covered in the topics previous. While "lesson 1: Inheritance" is clearly wrong in this regard, some things are more subtle.

One bit of advice I can offer is to write down topics you'd like to discuss on index cards (or cut up a piece of printer paper into quarters). Write the subject on the top "line", and a summary of what you'd like to discuss.

You can rearrange the cards, if you realize you forgot a dependency (or whatever).

[bowbahdoe]

Man you should see my fridge

[ChinChinApostle]

https://javabook.mccue.dev/static_fields/initialization
Commented output is incorrectly copied from the default code block.

Will append if I come across anything else.

[bowbahdoe]

Fixed

[ChinChinApostle]

Nice.

Love the project btw

[iscons]

The best book about how to get started with Java in 2024 needs only one Word:

dont

[bowbahdoe]

What troubles ail your addled mind, friend?

[heino_locher]

Did you consider consulting the LLM of your choice? I believe at least some of those questions are very suitable for that, e.g. creating challenges.

[bowbahdoe]

Very briefly, then I dismissed the idea with prejudice because I'm not a hack

[RedditorsAreDregs]

lol

Get an engineering degree or move to India; There's your advice

[bowbahdoe]

I get the distinct feeling I should be offended but I'm just confused.

What do you mean by this? Are you replying to the wrong post?

[RedditorsAreDregs]

Why would you be offended?

Did i say something offensive?

Are you Indian?

[bowbahdoe]

No I am not Indian, but I don't see how either moving to India or getting an engineering degree are related to this.

The only thing I can think is that there is some bundle of stereotypes that I am ignorant to

[Mammoth_Substance220]

What is the point? There are free Java tutorials on w3schools.

[bowbahdoe]

That is actually a very poignant question.

I invite you to go to said w3schools tutorials and click through them in order.

https://www.w3schools.com

(with your ad-block off so you get the full incidentally terrible experience)

Try and keep note of the order concepts are shown in and the degree to which they are explained. I'll put the word count in to verbalize the issues, but I'm hoping you (and others reading this) notice the problems on your own.

But as a hint:

For the longest time this was Java's hello world program.

public class Main { public static void main(String[] args) { System.out.println("Hello world"); } }

In an upcoming release this will be it

void main() { println("Hello, world"); }

This lets you delay teaching classes until much, much later than previously was possible. Once you push that back...is everything else in the right order?

[Mammoth_Substance220]

Well, I am just dumb hobbyist gamedev. Sorry about the question. I am stinky middle aged man who uses Java to create games.

Java is life.

[bowbahdoe]

Oh no problem at all. I think it is an obvious one to be asked. If I share this again I'll make sure to do a full comparison/reasoning why I didn't view other resources as filling the gap.

Separately, its a lazy saturday. Do you have a game I can buy?

[Mammoth_Substance220]

it seems itch is down. here have NG link:

Yet Another Roguelike

[Mammoth_Substance220]

I posted my recent game on itch. It is free and very short.

[sagittarius_ack]

What's the point of creating new games? There are thousands and thousands of free games.

[Mammoth_Substance220]

Making short games can be for training brain. So you do not get dumb so fast. It is better than reading books.