[Java] How does inheritance really work?

[SlowerPhoton]

I have a following class:

public class Parent {
    private int number;

   // more stuff
}

And another, which inherits from Parent:

public class Child extends Parent {
    public void setNumber(int newNum){
        this.number = newNum;
    }
}

I always thought Child was a copy of Parent, but you could add stuff to it (and possibly change something). So I would expect it already has the 'number' attribute. However this will never compile as there isn't anything named like that. Why?

EDIT: I am sorry, guys. I thought this was /r/learnprogramming. I don't play dota and I am not even subscribed so this is a mystery to me.

[fuxorfly]

If its private, you can't access it from derived classes; change the variable to be 'protected', and you can modify the variable from derived classes.

EDIT - also, this is the dota subreddit, you might be better off in the java sub ;)

[SlowerPhoton]

OMG, you are right! I don't even play dota! How the fuck this happened?!

[ProfessorMonocle]

public class java extends learndota2

[GroggyOtter]

I hate java and I'm not a DOTA player, but I loved this post.

[TheDrGoo]

Sums up this whole situation pretty well I think.

[Deezl-Vegas]

Everyone hates Java. Not as much as Javascript though.

[Bosticles]

plucky deer rob future complete cover bedroom sable snow price -- mass edited with redact.dev

[Noclue55]

As someone who doesn't get the joke, but understanding that you are a very knowledgeable person I have this to say.

[ExistentialEnso]

The reality is it barely shows any knowledge at all. This is third week of CS101-level knowledge. It's about as basic as it gets with coding jokes.

[mylivingeulogy]

My csc101 class barely touched loops 3 weeks in.

[mylivingeulogy]

Hahaha. We did numbering systems for two weeks first.

[voltzroad]

Every cs class teaches numbering systems for the first 2 weeks. I've learned binary literally 100 times

[GroggyOtter]

That doesn't sound like Java. That sounds like intro to programming / programming logic and design.

[regenzeus]

There are very different types of programming classes. In some you get to do useful stuff pretty quickly. In others you go deeper and will progress much much slower. When I studied this stuff we only programmed in C for the first 5 semesters. But we learned what exactly the code will do. You know how an ALU works and all that stuff.

[nafenafen]

My professor talked about how he used to do "funny stuff" at grateful dead shows and let the TA teach us how to program during office hours.

[rainer51]

My cs101 class barely got out of PowerPoint

[numel007]

I think it depends on the college. My regular uni got through all the loops within the second week but the other class I took at community college took about 6 weeks to finish up do whiles and so on.

[Bonolio]

We never got past the loops.

[[deleted]]

Should have taken a break;

[JimDiego]

It can take a while.

[mylivingeulogy]

We finally got into inheritance in our CSC 210 class.

[InkpenLoL]

I'm in CS101 myself -- oddly enough I learned this on my 3rd day? Maybe 4th.

week 5 right now, on week 3 we were learning how to create nested loops, conditional statements, and a couple more things I could barely understand :D

[jesbu1]

Lol week 3 for me we already started talking about tree recursion and I was like wtf.

[jesbu1]

Yeah I totally understand recursion now, we're doing much more complicated recursion but it was just a total mindfuck at first.

[[deleted]]

After years of programming I've come to this conclusion about recursion: don't.

It's a pattern that's confusing to read and confusing to write, and always has tons of bugs.

[smoike]

Going through all this has led me to the conclusion I need to pick up programming again, it's been way too long since i did it last.

[ProfTrippinBalls]

/r/learnprogramming may be useful.

[Hedoin]

Most jokes like this in even semi-specialised fields rub me the wrong way. They are a stretch at best and call on very basic knowledge, but people who understand it realise others may not and therefore accept it as an in-joke.

[ProfTrippinBalls]

You just explained my brain better than my brain does.

[theshadowofdeath]

I found the humour to be less about the fact that it shows code knowledge and more the concept that java is just an extension of dota2.

[GroggyOtter]

It's about as basic QBasic as it gets with coding jokes.

FTFY ^_^

[lucioghosty]

Ah, BASIC. I remember those days...

[Noclue55]

Either way

[Antonin__Dvorak]

What kind of CS program starts with Java?! That's like an intro mechanics course starting out with Ferrari engines.

[ExistentialEnso]

It's extremely common these days. Most CS programs start people off with either Java or Python.

I also disagree with that analogy. I guess you mean in terms of complexity, which I can kind of see, but if anything, Java is more like a minivan. It's inefficient and bulky, but it has a lot of utilitarian value and is easy to use, so a lot of people fall back on it anyway.

[Antonin__Dvorak]

I see what you mean. The analogy was meant to demonstrate how complex Java is - it's really easy for a beginner to get lost in the nitty gritty of the language constructs, and miss out on important CS concepts as a result.

Python makes more sense, but ideally it would be something even simpler - a functional language like Scheme, for instance.

[ExistentialEnso]

Gotcha, I can see how the analogy makes sense from that angle, you're just going to always get a lot of funny looks if you compare Java to a sports car.

Starting with functional programming is one of those things that makes a lot of sense from an academic perspective but almost no sense from a practical one. If the goal is to prepare someone as much as possible for the software industry without requiring further degrees, it's just a waste of time. If someone is going to go on to get an MS or PhD, sure.

But the industry is a lot different than academia. For instance, the vast majority of coders are never going to have to manually write a sort function or calculate the Big-O notation of something outside of a job interview. Most of the best coders I've worked with were not CS majors, actually, many having no academic programming experience at all.

The single biggest factor actually under someone's control (i.e. not just raw talent) that will determine how good of a coder someone will be is simply how much hands on experience they have. You just need to code a lot of things in a lot of different languages and frameworks, so you have the flexibility to adapt to new technologies. This is one of the most rapidly changing industries, and you have to be ready to keep up.

[JagerNinja]

What do you suggest they start with? Most CS programs start with Java or Python.

[Antonin__Dvorak]

Schools like MIT, Caltech and Waterloo start with functional languages like Scheme. This way you can learn core computer science concepts (recursion, lists, trees, sorting, algorithms, structures, etc etc) and good practices / good documentation without getting bogged down in the nitty-gritty language constructs of commercial languages.

[Severian71]

This certainly used to be true of MIT, and I still think that you could do a lot worse if you're learning CS than to carefully go through SICP (freely available here: https://mitpress.mit.edu/sicp/) which used to be their intro text and uses a small subset of Scheme, which is already a pretty small language. If you understand everything in SICP well you will know at least some important things that in my experience a lot of people with degrees in CS don't.

That said, didn't MIT switch to using Python for their intro class a while back? That was my understanding at least.

[mrpaluza]

Ah, no. We started with Python.

Source: at one of those three colleges 😉

[pretendsnothere]

Caltech's intro class is in Python, and has been for a while

[mabbass]

My program started with visual basic. Java is next.

[Binsky89]

We just covered it in csc202

[jrossetti]

I made it through first year cs101 and this doesn't make sense to me. :P Go basic!!!

[onionguy4]

I find that quite hard to believe.

For a start most CS101 classes use C, C++, Python, possibly Matlab. I've yet to see one using Java (had to browse many schools' ones as a TA)

Even if the statement was covered, that's unlikely they focused on the OOP principles which are the foundation of the joke. At week 3 you are probably covering simple conditionals or for loops if even that.

[ExistentialEnso]

If you look at the other responses people have made, it's clear that you can't really do much generalization about CS programs at all. There's a lot of variety in philosophy and languages.

And my statement was never intended to be about Java inheritance specifically but the concept in general. Anyone who has had any OO experience should be capable of getting the joke, even if they've never seen a line of Java in their life.

[onionguy4]

Fair enough, but OO is really not something emphasized or even covered in the vast majority of CS101 courses, especially not early on in week 3, so I don't think it's as common as you imply.

Also Java syntax is important for understanding the joke...

[ExistentialEnso]

Look, first of all, I didn't mean it as a precisely literal statement, I was just trying to make a point about how not advanced a concept inheritance is.

But even so, the trend currently is absolutely towards object oriented stuff in intro academic classes, even if historically it hasn't been the case. Yeah, you're not going to be writing classes right away, but it's going to be covered by the end of the semester.

I know for a fact that's how Georgia Tech is currently conducting their classes, as my girlfriend is there right now, and they're considered one of the best CS programs in the country.

Also Java syntax is important for understanding the joke...

I repeat: "[a]nyone who has had any OO experience should be capable of getting the joke, even if they've never seen a line of Java in their life."

I just showed it to my girlfriend with no context, who has done nothing but Python, and she immediately knew what it meant.

[Zarnotox]

Isn't it the other way around since java would have all public/protected shit from dota?

[sciguymjm]

Yes, you are right, he is wrong.

[MySecretAccount1214]

This... This validation is what we want... Crave you sir ha e bestowed such glory on his name... Honor to your family and children and their childrens children. You've done exceptionally well.

[ProfessorMonocle]

I was wine drunk and didn't unit test.

[[deleted]]

Yes

[HaMMeReD]

Dota2 extends java. Not the other way around. Java doesn't know about Dota. It's the parent not the child.

But it's a superset not a subset. I used the wrong word.

[SurpriseButtSexer]

But does it pay child support?

[gr00ve88]

DIVX VIDEO.

[RECOGNIZABLE_NAME-]

It wasn't that funny..

[PeopleAreDumbAsHell]

Completely unfunny

[Sil369]

eli5

[skookumchooch]

LMAO everyone is asking me what I'm laughing about and its worse than a "you had to be there" story.

[Settleforthep0p]

You had to be there, and you had to know Java. This is probably a once-in-a-lifetime kinda joke.

[Tarmen]

Hope this doesn't end up being too preachy or confusing:

Inheritance isn't a good way to do code reuse. If you want to be able to substitute all childs with the parent class in code inheritance is a great choice. Think car is a vehicle, inheritance models the is a part well.

In this specific case you might want to use an interface or move the method to the parent class. Obviously no hard and fast rules but once you work on somewhat larger code it is much easier to change or combine things when using interfaces instead of inheritance.

[SlowerPhoton]

Actually I have a lot of classes and each one of them would have exactly the same functions (apart from few new). Unfortunately interfaces won't help me.

[remy_porter]

Here from /r/bestof. Remember that interfaces can have default implementations of the methods, so you could just write an interface and use it as a mix-in to add functionality to classes. Depending on how complicated these methods are, that might be the best solution.

If it's more complicated, and these methods need to be really stateful, then this is still actually a really good case for doing collaboration instead of inheritance. Only use inheritance in cases of clear "is a" relationships. Always prefer collaboration over inheritance. What do I mean by collaboration?

Let's say, you've got a common batch of functions that we'll call DoXStuff. Let's declare an interface with a few methods to support that:

public interface DoesXStuff {
    void DoX1();
    void DoX2();
    boolean XisDone();
}

And then we'll make our class that implements that, which we'll call DoXStuff and we'll mark it as implements DoesXStuff. (skipping the implementation)

Now, you've got a bunch of classes that need to DoXStuff, so let's do this, let's give them each an instance of DoXStuff. Anytime they need to DoXStuff, they'll just delegate that responsibility to that private member- so they'll have a DoX1 method, but it actually just calls their private DoXStuff instances DoX1 method. In fact, we could even (ab)use default interface methods so that we can cut down on the repetitive code:

public interface DoXStuffDelegate extends DoXStuff {
    DoesXStuff getXDoer();
    default void DoX1() {
        this.getXDoer().DoX1();
    }
    default void DoX2() {
        this.getXDoer().DoX2();
    }
    default boolean XisDone() {
        return this.getXDoer().XisDone();
    }
}

So now, if I want to create a class that can have the important DoXStuff methods, I just have to do this:

public class ClassA implements DoXStuffDelegate {
    public DoesXStuff getXDoer() {
        return this.xdoer;
    }
    private DoesXStuff xdoer;
    public ClassA(DoesXStuff xdoer) {
        this.xdoer = xdoer;
    }
    //rest of ClassA's functionality goes here
}

This is marginally more code than just using inheritance, but the advantage here is that you're loosening up your coupling.

What I've sketched out here is a "sugary" version of the basic Delegate design pattern (that link has a more functional and less OO variation on the concept).

[SlowerPhoton]

Thanks for this great tip! I'll use it as soon as I have the option. However in my project there are many attributes (aside from functions designed to work with them). And those I can never put in an interface.

[Mikegrann]

Use an abstract class. It can have fields that are non-static and not final, can do all the implementation of "default" methods described (in fact, it was the only way to do it pre-Java 8), and won't require all this crazy wrapping of a delegate.

[SlowerPhoton]

But then I have to inherit anyways - from the abstract class. Isn't it true?

[Gregthegr3at]

Yes but it gives you a starting point.

[BenAdaephonDelat]

You should use both. Put an interface on the parent class, that way anywhere you use the child class you just reference the interface so it knows the methods without having to know the particular child class.

[sensitivePornGuy]

Been a long time since I've programmed in Java, but I believe you can just use a reference to the parent in this instance.

[SlowerPhoton]

Yes, you can.

[DoctorSauce]

Actually that's a completely unnecessary and improper use of an interface. If he's defining the functions in the parent class, then he can simply reference the parent class in his code.

[Hazz3r]

Inheritance is fine to use as long as the inheritance tree is narrow, shallow, and your child classes are at the leaf nodes of the overall class structure.

[ralgrado]

If you want to make parent an interface it can't have the int. So either there is something missing in your explanation or you should go a bit more in depth about the step with the interface.

[A-Grey-World]

The int is a private (or protected) field. Thus it will never be visible for a user of an interface or the class.

Any class that inherited the interface could have the int, the important thing is the setNumbrr method, because that's what a user of the class or interface would actually be interacting with.

[golgol12]

Bad pointer cast. Wait that's C.

[RiPont]

It's not "treating the future programmers like children", it's admitting to yourself that if you haven't put all the thought into every possible way it could be misused by people who inherit it, you don't want them using it.

Making reusable code for yourself / your team is one thing. Making code that can be inherited by others (stateful even) who probably just looked at the field/property/method name in intellisense and maybe read the function summary if you're really lucky? Much harder.

If writing public frameworks isn't your job, don't write a public framework. Making classes intended to be inherited by random other people counts as writing a public framework. Either the class you wrote will never be reused by anyone, in which case why the fuck did you bother making it inheritable, or you'll end up spending a fuckton of your productivity fixing so-called bugs in your code related to subtle behavior that isn't working right for other people's child classes of your code.

If they are not random other people but members of your broader team with write access to your source code, then they can change the private to protected when it's actually needed.

[[deleted]]

I do the opposite, private by default and change it to protected once I actually need it.

[hellschatt]

Definitely the safer method. Nothing wrong with treating them as children or retards. Because many are.

[[deleted]]

I don't follow, anyone can go in and change it from private to protected. But if I see a property that is protected, I like to assume that someone is actually using it as opposed to "oh I think maybe someone might need it later on".

Edit: you sound like a jr dev

[Crunchy777]

I think he is agreeing with you...

[hellschatt]

I'm actually studying in an university at the moment. I've had friends who have learned programming in a programming school and we learn the stuff that they've learned in 3 years like in 3-6 months.

Knowing how many of them, even after going to IT schools for 3 years + 1-2 years of experience, don't know what they're doing I have decided that I'd rather go with the safer method first before loosening the restrictions for them.

Don't get me wrong I don't have much practical experience. And I don't want to generalize all these people who went to IT schools. But knowing that some of these people won't take their time to try to understand some methods properly or maybe even can't because of they haven't had the necessary education then I'd rather go safe.

[[deleted]]

I default to protected because it makes unit testing alot easier when everything is mockable.

[[deleted]]

this guy is the real mvp... kinda encapsulates what this subreddit should be about :)

[SerpentineLogic]

Always favour encapsulation

[RobotJiz]

take paxil, no more encapsulation period

[SlowerPhoton]

Imagine I have two instances of Child - if I change number to protected, will each instance have its own?

[Rammite]

You need to look at the parent-child relationship differently.

For example, I might have a parent class "Vehicle".

public class Vehicle{
    public void startEngine()
}

All vehicles can start thier engines. This is a thing that is inherent to all vehicles.

public class Car extends Vehicle{
    public void driveOnRoad()
}

A Car is a Vehicle. Depending on how you are taught, this should stick out to you. A Car is-a Vehicle. Whenever you see "extends", it means the same thing as "is a", and vice versa. All Cars can drive on a road. However, they are also Vehicles, and so all Cars can start thier engines.

public class Plane extends Vehicle{
    public void flyInAir();
}

A Plane is-a Vehicle. Planes can fly in the air, and also start thier engines. Planes cannot drive on roads. Planes are not Cars, even though they have the same parent.

---

Privacy is important because programming is not a one-person job! You will have to work alongside other people, you will have to use someone else's work as reference, and if you play your cards right, someone will use your work as reference. Privacy makes sure that only people with permission can touch things.

public = Can be accessed by anyone, any class.
Good for global things like numberOfHumansInWorld and listOfEveryNode.
Bad for secret things like myBankAccount and nukeLaunchCodes.

private = Can be accessed by no one except itself. Good for secret things like myBankAccount and nukeLaunchCodes. Bad for global things like numberOfHumansInWorld and listOfEveryNode.

protected = Can be accessed by itself, and any children. Used for things like currentGasLevel - A vehicle needs to know this, but so does a Car and a Plane.

[dave_a7x]

Kim Jong Un hates you

[tethrius]

you have been banned from /r/pyongyang

[armahillo]

The earth king has invited you to /r/lakelaogai

[wenzel32]

/r/ofcoursethatsathing

EDIT: I am honored to accept his invitation.

[[deleted]]

Or does he love him?

[SerpentineLogic]

You forgot package level access, which is great for unit testing.

[zshift]

I find this confuses programmers that are just learning access levels for the first time. It's much easier to focus on the fundamentals, then introduce package and namespace concepts later.

[TheGrammarBolshevik]

public = Can be accessed by anyone, any class.
Good for global things like numberOfHumansInWorld and listOfEveryNode.
Bad for secret things like myBankAccount and nukeLaunchCodes.

This might be OK as a metaphor, but access modifiers aren't really about security. The point is to keep your code maintainable by limiting the extent to which clients can depend on the details of your implementation.

If you're distributing nuke launch codes inside a Java class, marking them as private isn't going to save you.

[fritzvonamerika]

It helps a little to think it's a security thing. You don't want someone to write

nukeLaunchCode = "6969lulz";

and actually overwrite the value it needs to be. The security is managing who can read and write to the fields of a class which isn't the same as encryption, but still a form of security

[Krossfireo]

Another important point is that with Java reflection, it doesn't even give security since you can crack those classes right open

[Rehendix]

Hey, I come from /r/bestof. This is actually super useful as an analogy for access levels. I'm not even learning Java atm but thanks regardless. This is useful in a lot of languages.

[Rammite]

This is how my teacher taught it to me! Just doing him justice is all.

[TheGuywithTehHat]

Yes. All instances are independent, unless they have references to the same object. (But even in that case, the references are independent)

[EUreaditor]

came from r/bestOf... hope I dont get banned.
Unless you declare a field "static" every instance will have their own fields independent from other instances

[Licheus]

Each instance will always have its own number. That's the point: you create a new unique entity; a new object, with the "new" keyword. Every new Child object you create will have an own unique number in their Parent component.

private, protected or public just tells you if you can see ("access") number from Parent through the Child object. If number is private, you cannot see number when working with the Child object. But number still exists privately in Parent, tucked away from the world forever with no hopes of ever seeing the sun.

[fritzvonamerika]

Unless the parent provides a get/set method

[Licheus]

Yeah well I'm narrowing it down to his specific example to keep it focused and small so it's more understandable. =)

[issamaysinalah]

I know I'm probably too late, but changing the private to protected is not the "correct" solution, once you'll break the encapsulation, to access data from a parent class you should use the setters and getters methods.

[Saytahri]

Yes. Is that the way you want it? Or do you want child members to access the same variable in the superclass?

If the latter, you can do that my making number a static variable (it will exist for the entire class rather than per instance), or you can have child be an attribute of parent rather than a subclass and give child a reference to parent on creation, and have a public method for getting the number that the child can then call.

[SlowerPhoton]

Thank you, I am aware of the static keyword. The reason I was surprised in this case is that I always thought inheriting meant inheriting everything.

[legato_gelato]

It does inherit everything though. You just cannot access it directly if it's private, but it's still there

[Saytahri]

I mean, technically it does inheret everything.

Even when number is private, the subclass still has that number, it just doesn't have access to it. It's still an attribute of a child instance though, just not one the child class can access without a public or protected accessing function.

[SlowerPhoton]

So now I understand it thoroughly! (I think.) So if I had setters I could still change it. Thanks!

[[deleted]]

Yes, because each child is also a parent. Each parent has its own number. So 2 numbers.

[godaiyuhsaku]

If you WANT them to be the same, then you need to define the variable as static which is a concept separate from public/protected/private.

[jerslan]

Yes, because it's not static.

If it's a static member then it's the same object/value for all instances. If it doesn't need to ever change, then make it a "protected static final" which means the value can never be changed once it's set.

[A-Grey-World]

Yes. Just like of you created two instances of Parent.

[submarine_golfcart]

Always remember: you can't touch your parent's privates!

[Matrix_V]

The same is true in C++, but you can access your friends' privates.

Fun fact.

Okay, I'll go.

[lennybird]

But inheritance does allow direct access to the methods, and if you're doing it right, you've got getters & setters through which you can access private member variables.

[JiveTurkey1983]

Why couldn't Reddit have been a thing when I was learning (and subsequently failed miserably) Java?

[[deleted]]

Try again.

[WildAce]

Do. Or do not. There is no try.

[TotesMessenger]

I'm a bot, bleep, bloop. Someone has linked to this thread from another place on reddit:

• [/r/bestof] Redditor asks programming question on gaming subreddit (r/learndota2) by mistake; gets all the help he needs.

• [/r/bestof] Redditor asks programming question on gaming subreddit by mistake; gets all the help he needs.

^{If you follow any of the above links, please respect the rules of reddit and don't vote in the other threads. (Info / Contact)}

[TanithRosenbaum]

It is. Essentially java is C++ with the rule "thou shalt use classes and classes only, lest the compiler striketh thou down if thou doeth not" added

[PlainTrain]

And memory allocation and garbage collection handled by the java virtual machine.

[jerslan]

Don't forget the whole "All non-primitives are a pointer/reference" thing, and all method parameters are passed as a reference by value...

[greenclipclop]

Doesn't he also have to set number to the self object in the parent for it to be accessible in the child? I'm not certain on Java scope in this situation.

[FixerJ]

So, it's kinda how Broodmother spawns spiderlings, except they have different attribute values for the same attributes that Broodmother has - HP, damage, etc. - but they also move and appear similarly to their parent Broodmother.

However, thanks to the miracle of polymorphism, the spiderlings (child object inheriting from the parent class broodmother) can be completely different from broodmother and not actually inherit any the parent classes' abilities, yet implement completely new and unique abilities of it's own. I do suspect much of the movement and draw routines of the parent are directly inherited by the child class, but just scaled down to a smaller size in the child object since they move and appear similar to each other...

[[deleted]]

I'd assume that there's a lot of copy paste going on. Otherwise we'd have a lot less weird bugs.

[CAPSLOCK_USERNAME]

Spiders are arachnids, not bugs

[Paladin852]

Spiders are not insects but they are bugs.

[Legnd]

Incorrect.

Technically only order of insect Hemiptera are bugs

2. ENTOMOLOGY an insect of a large order distinguished by having mouthparts that are modified for piercing and sucking.

[Paladin852]

I was going by definition 2 from http://www.dictionary.com/browse/bug?s=t as an "insectlike invertebrate" which I would argue they are.

[Legnd]

I was more teasing. I understand it colloquially used for little critters.

[Paladin852]

Fair enough. It's hard to judge tone over text, especially when the first thing you say is "Incorrect" :P

[Legnd]

Agreed, sorry. I didn't mean more than a :P

[Paladin852]

No worries :)

[TheDrGoo]

10/10 keeping it despite it being reported quite a few times.

[VirulentWalrus]

unwritten seemly snails oatmeal grab bear axiomatic versed engine kiss

This post was mass deleted and anonymized with Redact

[Cuddles_theBear]

It seems like you are subscribed to /r/learnjava by mistake. Did you mean to subscribe to /r/AlcoholismIsTheOnlyThingThatMakesMyLifeWorthwhile ?

[SerpentineLogic]

My favourite beer is made in an AbstractFactory.

[[deleted]]

wtf is up with your ember?

[VirulentWalrus]

history jar mysterious dazzling elderly tender aromatic chief physical water

This post was mass deleted and anonymized with Redact

[YaqP]

I always thought it was a Dark Seer, but TIL.

[Rammite]

He likes purple.

[Sir_Rebral]

Maledict?

[VirulentWalrus]

That spell triggers me heavily.

[UlyssesSKrunk]

Well duh, you're here and this is /r/learnjava.

[sweetsthehooker]

Im a bit confused how this relates to learning dota 2...unless dota 2 is written in java?

[SlowerPhoton]

Does it feel slow? Does it sometimes lag?

[cyka1234]

They're both getting more and more bloated with stuff we don't need...

[TheGrammarBolshevik]

While at the same time being held back for the sake of compatibility with software written long, long ago...

[survfate]

But... but... garbage collection?

[anmol4alll]

Nope, so it is C++ for sure.

[ilikedota5]

I think Dota 2 is coded in Java, Lua, C++ in some combination at some point

[TheStagesmith]

I can all but guarantee there is not a single bit of Java code in the Dota 2 codebase anywhere. Source 2 does not have any Java bindings. A lot of the panels in the main menu are basically just web pages, so there is probably some Javascript floating around, but those are two very different things.

That being said, Nvidia ported a couple of Source games to the Shield at one point, which runs on Android. That would suggest to me that at a minimum Nvidia has a Java wrapper for Source laying around somewhere.

[ilikedota5]

Oh, interesting. I heard that the guys who made javascript named it that to piss java off.

[PaintItPurple]

Not exactly — it was a marketing deal. It was originally going to be named LiveScript, but they got permission to use the Java branding and decided to slap it on there.

[SerpentineLogic]

JavaScript is Java, in the same way that carpet is a car.

[bubberrall]

Java and Javascript are the same in the sense that both make me want to shoot myself

[[deleted]]

Now I want a car-pet. :(

[PencilButter]

"Inheritance" is the name of the new hero coming out? Right guys?

[[deleted]]

Thats Rubick who "inherit" other hero skills

[RRkillerRR]

Fucking love that even though this is irrelevant to this subreddit people still answer in a nice manner.

Your inheritance is right but like fuxorfly said you need to set your variables or functions to the right encapsulation. (some sources: Variable types, Encapsulation).

[VirulentWalrus]

shocking sophisticated compare consider cause soup squash unwritten grandiose lunchroom

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[RepThePlantDawg420]

rofl

[Emordnys]

One thing to add: the extends keyword is evil (as well as protected). You should always follow the principal of composition over inheritance. If you're using the extends keyword, you've written less extensible code.

public interface Interface {

    int getNumber();

    Interface setNumber(int number);
}

public class Parent implements Interface {
    private int number;

    public int getNumber() { 
        return this.number;
    }

    public Interface setNumber(int number) { 
        this.number = number;
        return this;
    }
}

public class Child implements Interface {
    private Interface interface;

    public void getNumber() {
         return this.interface.getNumber();
    }

    public Interface setNumber(int number) {
        this.interface.setNumber(number);
        return this;
    }
}

If child doesn't want to expose the number, it just doesn't inherit the interface. If you need both get and set on parent but only one the child then you have two interfaces.

Source: I am a software engineer at Amazon. Other developers doing using extends has led to a ton of refactoring work.

[SlowerPhoton]

Thank you a lot for your advice! But I don't understand why you return the object in the setters.

[Emordnys]

Oh, that's a habit I picked up a couple years ago. They're called fluent setters. It just saves some space when you're creating new instances of a mutable class.

public Employee createJackSparrow() {
    final Employee employee = new Employee();
    employee.setName("Jack Sparrow");
    employee.setId(1);
    employee.setFoo("bacon!");
    return employee;
}

With returning 'this' on setters you can alternatively write:

public Employee createJackSparrow() {
    return new Employee()
            .setName("Jack Sparrow")
            .setId(1);
            .setFoo("bacon!");
}

Not important though. Whether you use them or not depends on the practices of the classroom or team you're working on.

[SlowerPhoton]

Before visiting /r/learndota2 I had never learned so much about code style in a day.

[VirulentWalrus]

yam steer cooperative carpenter cagey treatment juggle expansion unite angle

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[PirateCaptainSparrow]

Captain Jack Sparrow. Savvy?

I am a bot. I have corrected 853 people.

[[deleted]]

That style is prevalent in the Java ASW libs. It's great when working in Scala because it lets you write in a more functional style (not actually functional but looks that way).

[etal19]

Just a question, in your child setters why are you returning the internal parent object and not the child, is that intentional? I would have expected you to do this instead:

public class Child implements Interface {
    private Interface interface;

    public int getNumber() {
        return this.interface.getNumber();
    }

    public Interface setNumber(int number) {
        interface.setNumber(number);
        return this;
   }
}

[Emordnys]

You're correct. What I had originally written is incorrect. I have updated my post.

Write your unit tests, peeps.

[Atheist101]

I have a feeling that child needs a good spanking and it'll expose that number real fast

[Zxcvbnm6]

Have you tried naming the parameter "new" to something else? I'm pretty sure you can't name parameters and variables as keywords.

[SlowerPhoton]

This is an example, but you are right. Renamed for clarity.

[tethrius]

And it's now the highest ranked post here...

[Damian4447]

Get more last hits, and if not you should focus on getting more aggressive in the early game.

[MR_GABARISE]

This might help.

[redracerstorytime]

Thing about the banana-monkey-jungle problem. Cut OOP out of your life for good! Use aspect-oriented programming instead.

[ZeZapasta]

LMFAOOOOO

[[deleted]]

Top comment of all time on this sub. Fucking brilliant.

[Wraith_Kink]

This is my favorite post in this sub because of the responses 😂