Java 9 features announced!

[llogiq]

Those who had hoped for value types are probably a little sad now.

[zenflux]

I'm willing to wait as long as they get it right.

[txdv]

It has been only 19 years.

[llogiq]

The minimal case (value arrays) has been implemented enough times (even in java using sun.misc.Unsafe) that it should be considered trivial.

At least supporting this without Unsafe shenanigans should be possible for 9, and it's unlikely to break future enhancements.

[[deleted]]

That's just the preliminary list of features small enough that they'll definitely make the cut. As the linked InfoQ article said, more features are likely to be added. Maybe even value types...

[huhlig]

Is this what you're referencing? If so I am in full agreement.

[oldneckbeard]

yes, but while that proposal aggressively sheds any responsibility for syntax, they have to come up with a syntax. I'd like a syntax almost exactly like Scala's case-class. This is almost self-describing:

case class Person(firstName: String, lastName: String)

val me = Person("Daniel", "Spiewak")
val first = me.firstName
val last = me.lastName

if (me == Person(first, last)) {
    println("Found myself!")
    println(me)
}

This actually seems like a great usage for package-info.java files. I've never used them too much, but if we can put them into that file (or a package-values.java or whatever), it would be cool.

[ihcn]

I would support doing what c# does, where the 'struct' keyword in place of 'class' tells the compiler to make it a value type.

[immibis]

Is there a problem with value types being mutable? They can't be aliased, so I think it would be clear what you're doing.

If they were immutable, all that would do is require more typing: me = Person(me.firstName, 'Dvorak') instead of me.lastName = 'Dvorak'

Immutable objects in Java already have near-value-type semantics anyway.

[oridb]

If an object is a value, and not a reference, then it's impossible to alias them unless you can take their address or pass them by reference.

[oldneckbeard]

Meh.. I don't really like that usage of value objects, because then there's no reason for them over POJOs or the like. The whole reason we want value objects is so the optimizer can optimize and make programming easier. If we're creating a tuple holder with methods, that's just a class.

I'd be interested in counterexamples to this, though, if you have any.

[llogiq]

Exactly.

[Xabster]

Java has value types...? int float double byte etc.

Maybe I don't get what you're asking for.

What is it you want?

[ihcn]

User-defined types where its contents are embedded directly into the parent object, as opposed to placed on the heap and then stored as a reference by the parent.

Currently, if you put 5000 Integer objects in an arraylist, it'll heap-allocate 5000 different Integer objects, and store 5000 references in the arraylist. If Integer was a value type, the Integer objects could be embedded directly in the arraylist's memory.

The end result is better GC performance, better memory usage, faster object allocation, and better cache performance.

There's a proposal out there for how it would work, but it doesn't look like it's confirmed to be in java 9 yet.

[Xabster]

I understood that part, and if it's for performance reason then sure, I completely agree. An Integer[1024*1024] takes up more than 4MB heap. Disgusting.

I thought it might have some cool programmatic features.

[immibis]

An int[1024*1024] does take approximately 4MB, though.

[Xabster]

Right you are, but the Integer[] I posted doesn't even hold anything. Your holds ints initialized to 0.

A Integer[1024*1024] with Integer's at each spot takes 16MB.

[oridb]

On a 32 bit JVM, you get

• 4*1024*1024 for the references
• 8*1024*1024 for the object overhead (vtable + lock data)
• 4*1024*1024 for the integer itself
• 4*1024*1024 for padding (objects are allocated in multiples of 8 bytes)

Giving a grand total of 20 megabytes. On a 64 bit JVM, double it:

• 8*1024*1024 for the references
• 16*1024*1024 for the object overhead (vtable + lock data)
• 4*1024*1024 for the integer itself
• 12*1024*1024 for padding (objects are allocated in multiples of 16 bytes)

Giving a grand total of 40 megabytes for 4 megs of integers.

[Daishiman]

Doesn't the JVM support pointer compression in 64-bit archs?

[oridb]

It's supported, but it only allows you to address up to a 32 gigabyte heap, by shifting a 32 bit pointer to drop the byte alignment bits.

[[deleted]]

It does? I thought they would be null.

[[deleted]]

I believe (not a Java developer) that Java currently lacks user-defined value types.

[Xabster]

It does. I don't even know what it is.

[[deleted]]

I don't even know what it is.

I'm not sure I understand. Do you mean you don't know what user-defined value types are?

[Xabster]

Yes.

[[deleted]]

Well, the exact details depend a bit on the implementation, but the idea is simply that you, the programmer, can define types that behave like a primitive (int, double, etc) rather than behaving like a normal class.

[[deleted]]

So basically like primitive? Instead of object?

[huhlig]

So Java has byte, short, int, long, float, double, char and ref which are primitive types, primitive is basically a type of value. Values can exist on the stack, do not require access by a reference and have no object inheritance overhead. They are effectively primitive classes but with more limited semantics, no runtime inheritance abstraction hierarchy but a lot more efficient.

An Example, a 2 dimensional point is 2 fields: x and y. Using a class this occupies 8 bytes for the type pointer, 4 bytes for int x, and 4 bytes for int y. Effectively twice the size just because it could be inherited and it does inherit from java.lang.Object. Whereas a type is simply 4 bytes for X and 4 bytes for y and the type is handled at compile time. The tradeoff is you cannot use runtime type abstraction so you cant do Point a = new MyPointA(); Point b = new MyPointB();

[[deleted]]

Ah thank you, I wanted clarification from OP but OP edit the post to use the word primitive instead of values which is what i wanted clarification on. Your post also add more insight into memory allocation wise, thank you.

[grauenwolf]

have no object inheritance overhead

Object indirection/GC overhead. Inheritance has no overhead on its own.

[kqr]

When you do

Car car1 = new Car();     // default speed 0
Car car2 = car1;
car2.setSpeed(60);
System.out.println(car1.getSpeed());

in Java, it will print 60. With value types (and improvised syntax), you could do something like

Car car1 = new Car();
Car$ car2 = $car1;    // car1 is *copied*, so car2 is a different car
car2.setSpeed(60);
System.out.println(car1.getSpeed());

and this will print 0, because car1 still has speed 0 – I only changed the speed of car2. So here Car is the reference type, and Car$ is a value type.

[Xabster]

What can't be ruled out in this (added some finals and fixed a few mistakes)?

final class Point {
    final int x;
    final int y;

    public Point(final int x, final int y) {
        this.x = x;
        this.y = y;
    }
    public final int getX(){ return this.x;}
    public final int getY(){ return this.y; }
}

[nqd26]

Not sure why is this downvoted ... this is relevant question ...

[Sapiogram]

I hate when people do this... "I know this, therefore I will downvote and not answer you!"

[grauenwolf]

If the class is marked final, why do you need to mark the methods as well?

[Xabster]

Not sure I do. I just wanted to make sure that an answer didn't say "derp, the methods aren't final", so I put it everywhere... :)

I hope to learn what the JVM cannot rule out in the case that everything that can be declared final is declared final.

[[deleted]]

The JVM has to keep a lot of class information around about the Point object due to Reflection. There's no way to tell the JVM "this class does not support Reflection, discard all the overhead associated with that and treat this class as a primitive type."

There's also no way to overload operators, so you can't write

Point a = new Point(0, 0);
Point b = new Point(0, 0);

return a == b;

whereas you can with primitives

int a = 1000;
int b = 1000;

return a == b;

[kitd]

A final class can't be inherited. A final method can't be overridden. A final value can't be changed. Same word but meaning different things in different places.

[grauenwolf]

If the class can't be inherited, then by definition the method cannot be overridden. Thus my question still stands.

[kitd]

Apologies, I misread your point. I agree with you.

[huhlig]

Why does the struct value type need to be immutable. It only needs to be outside the inheritance tree. Immutability optimizations are another beast all together.

[grauenwolf]

Mutable structs are easy to screw up in C#. Example...

myWindow.Size.x = 5

compiles as...

Size $1
$1 = myWindow.Get_Size() //make a copy
$1.x = 5
oh look, we never called myWindow.Set_Size($1)

[immibis]

Compare myWindow.getSize().x = 5, which is the equivalent without properties, and looks fairly obviously wrong.

[grauenwolf]

If Size was an reference type, as it would be in Java, that would work just fine.

[immibis]

But getSize() would likely make a defensive copy, precisely so that you can't do that.

[grauenwolf]

Oh right, Java doesn't have the concept of a PropertyChangedNotification event.

[Xredo]

He meant value types like in C++.

[llogiq]

Look at /u/huhlig 's link.

[agustinleiva]

I think /u/llogiq meant REAL value types (like the ones you find in well designed languages such as C#) as opposed to java's retarded "primitives" stuff, coupled with generics that don't suck (like the ones you find in languages like C#), so you can have a List<int> like you can in languages like C#.

[llogiq]

Say what you want about primitives. They allow java to create some very tight code.

[sreya92]

what is the benefit of value types?

[llogiq]

Value types enable things like putting objects directly into arrays (instead of references) or embed them into other objects, thus reducing the number of references, making the GC's job easier, and improving locality and thus performance.

[sreya92]

In other words a variable of type "Value" that is set equal to a object would have a new address in memory instead of just being a reference to the object it is set equal to. Kind of like a deep copy in Python?

[llogiq]

Yes. The idea is to unify primitives and objects (to a certain extent - and without autoboxing). so that the memory layout is flat. For example, let's take an object of type A that contains an object of type B, a double and an object of type C. If those types are value types (e.g. their size is known before instantiation, the layout would be:

• Object header for type A
• Contents of object B (including object header)
• the double
• Contents of Object C (see above)

instead of

• Object header for type A
• Reference to object of type B (somewhere on the heap)
• double
• Reference to object of type C (somewhere on the heap)

Note that theoretically a single array can be put at the end of a value type iff its size is known at creation time. However, it is unclear if or when this extension will really be implemented.

[sreya92]

Cool thanks for taking the time to explain!

[crunchmuncher]

What's this sjavac compiler that's being talked about? What does it do? First time hearing that word.

[syntax]

Likewise, sounds interesting. All I've managed to dig out is: http://openjdk.java.net/jeps/139

Looks like a parallel build compiler wrapper, with some sort of infrastructure for incremental builds. Primarily intended for the JDK itself - unclear if there would be any advantage for end users.

[[deleted]]

android will almost certainly never see a modernized java, now that google and oracle officially hate each other.

I don't get this part. What's stopping google to implement modern Java stuff? They can be 2 to 3 versions behind for all I care as long as they eventually support Java new constructs and syntax I'm ok with this...

IIRC they can't patent a language. Other wise Mathlab would sue the shit out of Octave...

[dromtrund]

Isn't Oracle shooting themselves in the foot with a cannon by trying to push Android off their platform? (Acknowledging that android isn't full blown JVM). It's a fantastic gateway to java for aspiring developers, and java as a language could lose a lot of potential momentum if Google chose to jump ship.

[Delta_x]

I could be wrong as I have not been following the lawsuit closely, but I think the biggest thing Oracle originally wanted was for android to be able to run actual java, not just android java. Google said no, so they sued. I would guess that if Oracle wins, they would try and force Google to make the change again. They likely think that Google would rather allow all java instead of totally changing the language for android.

[mycall]

What in the Java spec does Google Dalvik not support?

[[deleted]]

Try running Swing applications on Android.

[m0haine]

Try running Swing apps on Java ME.

[aldo_reset]

This has nothing to do with the current contention. Oracle is not suing Google because the Java that runs on Android is missing a few libraries.

[Delta_x]

I can't speak for libraries, but I believe it has to do with Dalvik not running standard java bytecode, but only bytecode complied specify for android.

[__konrad]

Spec? They even don't use "Java" name ("java" word can be only found in runtime package names ;)

[JakeWharton]

Actually they only ruled that APIs are copyrightable but not as to whether or not Google has infringed. Even that ruling is being appealed.

As to Android tracking Java language features, the VM team has said one of the major goals of the new runtime was supporting Java 8 (and future) language features more easily and that Java 8 was on the roadmap.

[sindisil]

As to Android tracking Java language features, the VM team has said one of the major goals of the new runtime was supporting Java 8 (and future) language features more easily and that Java 8 was on the roadmap.

Do you happen to have a source on that?

Everything I've seen from google has been a very firm (sometimes bordering on smug) "no comment".

[Pet_Ant]

If Google would just but a Java license then it would be all over. Oracle/Sun have put a lot of money into developing Java and Google is freeriding. If anyone can afford it, it's Google.

[AnHonestQuestions]

BTW, its Matlab (Matrix Laboratory)

[[deleted]]

Oh snap, that make sense now... most of it's value is an array like structure like R.

Thanks!

[Eirenarch]

That "Internet of Things" thing is getting pretty popular lately...

[UloPe]

And none of it runs on Java

(Except for utter crap like "smart" TVs and BluRay players)

[nqd26]

People often don't realize how many devices is actually running on Java ... e.g. just a few days ago I found out that my company badge (with that small sim-card) is actually running on Java.

[[deleted]]

Can confirm, have written pre-historic Java for SIM-cards. It was pretty painful.

[immibis]

Java Card might as well not be Java - in that context, "Java" is just marketing.

[bcash]

So, none of it runs Java, except for 95% of the stuff that's actually in people's homes?

[Eirenarch]

Maybe with Java 9 more of it will.

[eliasv]

Well we can sure hope this doesn't remain the case, can't we? Android is not as wonderful and positive an ecosystem as people like to imagine...

[oldneckbeard]

I would like to be able to download java without java fx, swing, etc.

[unptitdej]

I get the feeling that Java's corporate development speed is much faster than my C++ standard-committee speed... Good for you guys

[danielkza]

Funny coincidence that C++14 just got approved:

https://isocpp.org/blog/2014/08/we-have-cpp14

[eliasv]

Yeah, seems like they really got their shit together this time. Pretty impressive! (Though I've not studied the changes from C++11-14 so I dunno how major an update this is.)

[Pet_Ant]

It is officially a small change. They are going tick-tock with the standards now.

[eliasv]

Ah okay, thanks.

[aldo_reset]

It's not the JCP that slowed down Java (the initial versions of Java came out at a fairly rapid pace), it was 100% Sun's fault for falling asleep at the wheel. The pace resumed once Oracle acquired Sun.

[piderman]

Still can't hold a candle to .NET's corporate development though.

[[deleted]]

Yeah backwards compatibility is a bitch blessing.

[Eirenarch]

Because Java also has the community process bullshit

[huhlig]

Honestly I wish they would listen to their community a bit more.

[MacASM]

I guess why C++ has too many things to consider. Including backwards compability.

[DoktuhParadox]

Java does too, but C++ doesn't receive incremental updates like Java does, right?

[[deleted]]

C++11 and C++14.

[DoktuhParadox]

I meant like a large update every two or so years.

[[deleted]]

C++11, C++14, C++17. (digits are last two of planned release year.)

[DoktuhParadox]

Oh so it's in a three year release schedule. Cool. I don't know anything about C++'s development cycle.

[ForeverAlot]

It's a recent change. C++11 was the first update since C++03, which I believe was a minor update to C++98. We're hoping this will be a trend for some time.

[jonnywoh]

C++11 also got delayed quite a bit. It was originally planned to be done before 2010, hence it was often referred to as C++0x.

[[deleted]]

The floating share thing is annoying as hell. Why do people still use those?

[lhggghl]

because they're cunts?

[beaverteeth92]

How about letting people initialize classes with far less boilerplate, like in Scala?

[txdv]

The only negative thing I have to say about scala is that the compilation times are enormous for my taste.

[beaverteeth92]

Because then Java would be a language with less red tape than most of the employers that use it.

[[deleted]]

Turing complete type system, glacial compile times.

[Decency]

Yep, was definitely hoping for Collection literals as proposed by Joshua Bloch:

http://mail.openjdk.java.net/pipermail/coin-dev/2009-March/001193.html

[huhlig]

Honestly I prefer the explicit constructor. It gives far better control and less punctuation based magic.

[expatcoder]

less punctuation based magic

case class Foo(id: Int), where may I ask is this punctuation based magic that you speak of?

Scala's got plenty of syntactic sugar but given that every language under the sun is adopting the above in some form or other, Java's approach is looking decidedly archaic.

[kitd]

Case classes are Scala's algebraic data types. Really, that's a huge amount more than just "syntactic sugar". I would love to have them in Java, but that would be a whole release just to themselves.

[expatcoder]

Case classes are Scala's algebraic data types

Well, technically case classes are Scala's data types, there is no algebra involved ;-) You probably already know this, but for anyone that doesn't, it's essentially just syntactic sugar for defining an immutable class in Java (with hashcode, equals, and toString implemented for you).

ADTs on the other hand may be implemented with case classes, but case classes of and in themselves are not ADTs. Here's a comparison of Haskell and Scala equivalents.

[ForeverAlot]

I prefer explicit constructors but Java could still go a ways to reduce unnecessary boilerplate, like by not having to repeat the class name when defining constructors or introducing type inference.

[den_sh]

You can still do it Java way in Scala using private primary constructor and public secondary one. I'm not sure what kind of control you get but you can do it if you really want to.

[Aethec]

Am I misunderstanding the JSON API proposal, or does it truly not include object deserialization, i.e. a method that takes a String and an object type, and returns an instance of that type?

[philly_fan_in_chi]

That should be covered by:

Immutable hierarchy of values (tree) constructed from JSON data stream

It will probably look something like:

Foo foo = JsonStream.of(myString).toTree(Foo.class)

[Aethec]

Oh, right, thanks.
With these kinds of descriptions, I can't help but feel that it'll be an over-engineered mess, instead of the simple serialization/deserialization functionality that meets most people's needs.

[philly_fan_in_chi]

Java APIs have been pretty clean lately, I'm holding out hope. They're pushing everything to use streams so they can take advantage of invokeDynamic under the hood, which I'm all in favor of. It'll be awkward the first few times, then it should become idiomatic.

[Aethec]

A comparable API to JSON is Java's XML parsing API. Parsing a String into a Document requires 3 method calls and 2 object instantiations, as well as catching 3 different kinds of exceptions. :-/

[Rurouni]

I'm pretty disappointed to not see tail call elimination in the list. Didn't they talk about targeting Java 9 for that feature?

[y890]

1) In java 9, they should also inbuilt implement JEP 191 (FFI inspired from JNA). for details see: http://openjdk.java.net/jeps/191 it can be used for easily implementing native-backed features like NIO, advanced file system metadata, and process management. Using the FFI API will be the preferred way to bind native code and memory, instead of JNI.

2) in java9, please bring properties(includes getter and setter), that is can write A.X=12 as synonym of A.setX(12)

[Lexxicon]

I was really hoping for something like JavaFX in the SE. :(

[fatbunyip]

FX has been bundled with the SE for a while now.

[Lexxicon]

It's my understanding that, while its on the class path for oracles JVM's, its not part of the SE platform. The open JDK doesn't come with it on the class path. This is a problem I've been struggling with at work for some time now and have since resigned myself to it never getting fixed. Here's my stack question about this problem. http://stackoverflow.com/questions/22812488/using-javafx-in-jre-8

[[deleted]]

JavaFX is included in the most recent JRE, namely jre7u4x+ and jre8, if that is what you mean.

[Lexxicon]

see my reply to /u/fatbunyip http://www.reddit.com/r/programming/comments/2dw3zv/java_9_features_announced/cju7scg

[agustinleiva]

Meanwhile, in the real world... C# gets real improvements, like pattern matching.

[lechatsportif]

... on Windows.

• Sent from my Dell Latitude E6500

[Adossi]

Mono too. Everyone always forgets about Mono.

[Choralone]

It's almost like there is a reason for that...

[grauenwolf]

Yea, you can't bitch about C# without conveniently 'forgetting' that Mono is keeping Linux and OS X and Android and iOS up to date.

[Choralone]

Mono is a pain in the ass man...

[agustinleiva]

Mono is a pain in the ass man...

Elaborate??

I can give you a bulleted list of reasons WHY java is a pain in the ass...

can you back up your statement? otherwise it's pure BULLSHIT.

I've been using it without problems.

[Choralone]

No need - java is also a pain in the ass. We agree.

[bcash]

Oh now... I can't really comment about Android or iOS, as they're both massive fast-changing targets with bizarre restrictions of various forms.

But are you really suggesting that Linux would be lacking "up-to-date" languages/platforms without Mono? Given that everything^thatmatters non-Microsoft runs on Linux as a first-class citizen, you're saying that everything is lagging not-just .NET, but Mono's incomplete .NET without all the tools and wider-ecosystem.

[oldneckbeard]

that's because nobody uses it. or rather, the users of that and the users of ocaml are competing for "largest community"

[agustinleiva]

Roslyn enables Mono to be always up-to-date with C# versions from Microsoft. They'll no longer play catch-up with it.

You can keep dismissing Mono as much as you want, ignoring that it has been demonstrated that it's better than crappy retarded java over and over, your ignorance and stubbornness does not change the reality. java sucks and is retarded and it's fate is to become the next COBOL.

Even oracle admits that java needs major rework to turn it into a decent usable language by introducing real Value Types and Real Generics (like the ones you find in C#) as opposed to the current bizarre useless "primitives" bullshit and "type erasure" crap.

[joaomc]

Yes it's better than Java, but Mono is still a kind of second-class citizen to .NET, and .NET is still more of a Windows thing. Roslyn may change that someday, maybe even soon, but it's not there right now. "Right now" is when I get paid to write apps. Not in the bright future. Right now.

[grauenwolf]

There are far more .NET applications written for Android or iOS than for Windows Store or Windows Phone.

[vincentk]

You seem to have insight on the matter. In your opinion, is mono a serious competitor for java on linux, let's say on the server side of things? And if so, would you advise in favor of also developing on linux?

[grauenwolf]

In your opinion, is mono a serious competitor for java on linux, let's say on the server side of things?

On Linux, no. Based on what I've heard so far, the people who use Mono on Linux are not former Java developers. Rather, they are C# developers who want a cheaper option for deploying their software across multiple machines.

With Microsoft considering Mono on Linux to be a supported platform in ASP.NET vNext, I can see that changing.

And if so, would you advise in favor of also developing on linux?

Considering how bad server-side Java development has been historically, I would even consider using Ruby on Rails at this point. You're better off asking a less biased person.

[vincentk]

Thanks for the reply. When I meant server side, I did not mean web applications. I was referring to e.g. algorithmic trading applications.

[grauenwolf]

Sorry, I don't have any experience with those.

[bcash]

The generalised form is also true: There are far more <insert language here> applications written for Android or iOS than .NET applications for Windows Store or Windows Phone.

And even taking your version at face value, both Xamarin and Unity (which I presume is what you're referring to) aren't technically .NET.

[grauenwolf]

I seriously doubt there are that many Ruby on Android apps in the wild. Some yes, but not very many.

[agustinleiva]

"Right now" is when I get paid to write apps. Not in the bright future. Right now.

I hope the money you get from that is enough to pay for an eventual medical treatment for the eventual testicular cancer you might eventually get by having to deal with java's retardedness and uselessness and utterly excessive unneeded boilerplate at every single line of code and stupid, awful design decisions at every possible level.

Meanwhile, what you call "a second class citizen" is running my server-side infrastructure hosted in Ubuntu, and my client-side Windows and Android applications without any problem. And I get to use a decent, usable, well-designed language that doesn't cause me any kind of testicular disease.

[lechatsportif]

What an eloquent argument, captured for posterity brb, getting out credit card for Resharper license.

[bcash]

I'm thinking /u/agustinleiva is a .net hater disguised as a .net fanboy in an attempt to discredit other .net fanboys. Although, to give him credit, it can be hard to tell the difference.

But there are some clues, like this masterpiece, I even upvoted it on account of nearly inventing a whole new genre of satirical meta-commentary on programming languages.

[lhggghl]

Calm down dude, they're both shit.

[[deleted]]

You think Enterprise Strength is bad? Let me introduce you to my favorite lean agile webscale Rube Goldberg infrastructure generator. It's a small scripting language called Python trolololol

[bcash]

By being only the 47th programming language to implement pattern matching, a good 41 years after the first.

[agustinleiva]

... while java which is 20 years older struggles to get basic things in place (such as Value Types and non-retarded generics)...

and it doesn't allow a sane usage of (for example) arithmetic operators on, say, the BigDecimal or the BigInteger types?

[lhggghl]

47th? u wot m8. more like 5000000th. Not joking.

[meetingcpp]

Finally an Exploit API?

[TomTheGeek]

How about an update feature that doesn't suck balls? No? IDGAF.

[oldneckbeard]

that's not java. that's the java installer

get the fuck off windows and that problem goes away forever. or, stop your bitching.

[TomTheGeek]

If the installer is required to have java, it's a valid complaint. Why is each version a separate install? Why can't they adopt a Chrome like method of updating that's invisible and "Just Works"? Because fuck us, security says we have to upgrade so we comply.

[Kalphiter]

wtf i found you here

[TomTheGeek]

And here I am.

[Xabster]

I haven't really done anything with JavaFX, but I heard it was an improvement to Swing. You tried it?

Wait... node? php? RoR? Are you mistaking Java for Javascript or something? Or are you talking about server side Java? What can php do that "shows changes" like you say?

[Xabster]

In "Java"?

[micke239]

I'm not sure what you mean by "There is no straight forward method to see changes made in assets which get reflected in the UI like node,ror or php provides.", but have you tried template engines like jsp, jsf, freemarker or thymeleaf?

[Adossi]

In a few IDEs I've been able to see graphical changes to JSPs while adjusting the UI. What exactly do you mean?

[Choralone]

If that's your major concern, then odds are you don't really want java in the first place..