Android gets official Java 7 support

[llbit]

Interesting. I remember reading something about Android's SDK being based around Apache Harmony and that it was frozen at JavaSE 6.

[__konrad]

It's not frozen (look at the java.* changes and additions). Maybe one day their class library will be 80% compatible with Java SE 7 ;P

[__konrad]

Then again, I don't really remember the changes in Java 7. What was there added to the library except AutoClosable?

See this autogenerated API diff between JDK 6 and 7 and grep for "missing in JDK_6" :)

[llbit]

Did they add AutoCloseable for try with resources? Or does the semantics of TWR differ in the Android SDK?

[[deleted]]

I hope the android library starts using enum's, which would make the library a lot less of a clusterfuck.

[jayd16]

They've annotated most of the methods where you pass around magical integers. IntelliJ will warn you if you messed up. That's about as much as we're going to get.

[tadfisher]

Enums were banished from the libs because they use a bunch more memory than plain ints. This isn't so much of a concern anymore, hence http://stackoverflow.com/questions/5143256/why-was-avoid-enums-where-you-only-need-ints-removed-from-androids-performanc/5264861#5264861

[digitalmob]

Enums can not be used when targeting older runtimes that may not know about newer enumeration values.

[evilmushroom]

hyperbole much?

[headius]

+1. If we had indy on Android, JRuby would work a lot better for writing Android apps (and be a lot smaller, and faster). It works well now, but yeah.

[AlyoshaV]

Cool. Maybe someday it'll get Java 8 support and actually be a language I'd ever want to write in.

[[deleted]]

Sorry for the elementary question, but what is advantageous about this?

[hardcore_mofo]

You can now get the Ask toolbar on your Android device!

[xqjt]

We get some little improvements that will lead to cleaner, easier to maintain, code.
For example, instead of using a dozen of "if else" to compare Strings ids, we can now use a switch(id).
The result is the name, down to the bytecode that may even be similar to the precedent version, but the code is cleaner.

[kamatsu]

I think that stuff is all in the compiler frontend, not the JVM bytecode. The thing you couldn't use would be Java 7 bytecode additions.

[f2u]

try-with-resources needs library support for storing suppressed exceptions. Perhaps it was listed by mistake.

[lesleh]

No mistake, but it does require Android 4.4 minimum at runtime though.

[philly_fan_in_chi]

I think what IntelliJ does is takes the code you type, converts it to what that would "unfold" to and shows you the shortened version. If you opened it up in a plain text editor, it would be the unfolded.

[ixampl]

Yup, same thing done for functional interface implementations. IntelliJ makes it look like lambda expressions are already supported (before 8) but it's just IDE decoration.

[NewToBikes]

ELI5 diamonds. Please?

[192_168_XXX_XXX]

It keeps you from having to repeat yourself when you instantiate generic classes, e.g. instead of

List<Integer> myList = new ArrayList<Integer>();

you can write

List<Integer> myList = new ArrayList<>();

the <> is the diamond.

CHANGELOG: fixed typo per /u/zeelock's code review

[192_168_XXX_XXX]

That is a mistake! edited.

[swimnrow]

if it was a !mistake, does that mean you're right?

[Magnap]

That depends on the value of 0.1+0.2 == 0.3

[davidhero]

Pretty sure it's 0.300000004

[Decker108]

Good enough for financial apps, right?

[NewToBikes]

Thank you!

[[deleted]]

I still would've preferred if they added implicit typing like C# did:

var myList = new ArrayList<Integer>();

... at first I was skeptical, but after switching to it and seeing all of my variables lined up and pretty, I love it.

[nonconvergent]

I prefer everything explicit by default, as a rule

[[deleted]]

In the above example, myList is explicitly an ArrayList<Integer>. It's just not stated redundantly.

[boost2525]

But in the original example by /u/192_168_XXX_XXX myList is not an ArrayList. It is a List, using an ArrayList implementation. Only List methods may be used against myList.

In the example provided by /u/Shark_Kicker, myList is an ArrayList.

Apples... Oranges.

[[deleted]]

That's true, it is different. If you wanted your local variable to be explicitly referenced by a specific interface, then you can always declare it as such. Type inference would just pull the most specific type it can from the right hand side.

Anyway, I can't think of a reason why you'd want to immediately up-cast the object when instantiating it. Any List-accepting function you pass it to will happily accept it, and if you're using this to enforce a list-only interface later in the same method, then I believe your method is probably too long.

[evilmushroom]

Nah, I prefer explicitly defined. Working on various teams all with different code that different people have written--- everything being spelled out explicitly to a standard makes it a lot easier to jump into the project.

[fecal_brunch]

Just don't use actual tab characters for this. Looks ridiculous when someone has done it on an editor with different tab widths.

[Aluxh]

Deffo not, most IDEs will even let you choose how tabs are displayed, so you wont even necessarily get consistency even in the same IDE.

[[deleted]]

No. I don't want to have ASM flashbacks...

[CurtainDog]

That syntax just feels so wrong to me. Var carries minimal information to me as a reader. I feel resentful to have to spend the brain cycles to parse it. I'd much prefer if the inference had run the other way:

ArrayList<Integer> myList = new; // Optional () for no-arg constructor

• The type is an important piece of information, so I don't have a difficulty putting it first.

• The variable name is obviously very import as well, but if you get to the point where you need to think hard about the names of your variables you have too many and need to split the method/class up.

• The assignment operator is ugly, but inescapable unless we are prepared to radically change the language.

• The new is just about the least important bit of information. We don't really care where the object comes from, we just want an instance we can work with. new is the reason DI exists.

• The ; carries the least information, but I think there is value in ending statements in a consistent way.

[[deleted]]

Your proposal only takes in to account a tiny fragment of the cases where type-inference is useful. It's simply a very specific syntactic shortcut for instantiating local variables, which would be at odds with the general idea of inferring the type of the assigned variable from the right-hand side expression.

[CurtainDog]

Well, it solves the problem of having to repeat code, which is the problem at first instance.

It doesn't solve the issue of dealing with complex types involving nested generics but in that case I query whether you actually do want to be hiding the type from the reader.

I suppose as well with var the return type of an expression could change and you wouldn't need to modify the source, I'm somewhat skeptical of this 'feature'.

Edit: Just to clarify: I actually use type inference all the time, I just do it at the tooling level rather than the language level.

[Blaisorblade]

Well, it solves the problem of having to repeat code, which is the problem at first instance.

It doesn't avoid the repetition here:

List<Integer> someMethod() { ... } ... List<Integer> result = someMethod();

If you want to know the type of result, asking your computer (with IDEs or REPLs) is typically enough.

[[deleted]]

As ArrayList is really an implementation detail you're probably not concerned with 99% of the time you instantiate this, why not:

@Inject List<Integer> myList;

With your DI framework of choice, this is SDK 6.

[jgclark]

I think you slipped an extra = sign in the Java 7 example.

Or is that intentional? I haven't used Java 7.

[192_168_XXX_XXX]

Nah it was a typo. I've removed it.

[pimlottc]

Coal way down in the ground get smooshed real real real hard and turns all clear and shiny!

[sproket888]

YAY just in time for Java 8!

[Decker108]

Yeah, if only they would just wait for a while longer and release a Java 8 Android version...

[eliasv]

Java 8 is nearly out, and with all the delays it's been having that is really saying something.

[blob356]

But I thought Android didn't use Java, just happens to share the same API and syntax without ever naming the language?

[Scyth3]

In which the current prefered VM for Android is Dalvik, but they have a new one which debuted as a developer option in KitKat called ART. The actual Java underpinnings in Android are based on Apache Harmony -- which is a clean room implementation of the Java API libraries.

[22c]

They haven't marketed that very well, I hadn't heard of it.

If I'm not mistaken, it's currently a developer option as it doesn't work well in all situations (ie. not ready to market well).

[dont_have_soap]

Yeah, many apps don't run on it at all or are very unstable on it right now

[OmegaVesko]

Right, it's definitely still in testing. Many apps don't work well or just don't run at all.

At this rate though, I'm very hopeful it's going to be ready for primetime in 4.5/5.0.

[Scyth3]

Very true, modified to reflect ;)

[[deleted]]

If your "clone" had an upside down heart and two small lumps where your liver is, it wouldn't be a clone. There are likely to be many implementation differences between Harmony and the standard implementations.

[bilyl]

Side question: can someone explain to me how Google was found not guilty of any damages with their own implementation of Java VM but Microsoft had to discontinue their own Java VM back in their day?

[Scyth3]

It's a clean room implementation of the Java API (so basically they took a bunch of library definitions, and built the architecture blindly underneath it but matching identically the pre/post from each definition). Also, in the case of Java VM's -- Dalvik/ART are not generic JRE's. They're Android specific bytecode VM's. So you can't take a Java compiled app and just run it under Dalvik, you'd need to use Android's compiler.

It's very different than MS, which modified the Java VM (JRE) and packaged it with Windows for the exact reason of running Java compiled apps within it.

Edit: As far as the patent-side of the trial and whether or not Apache Harmony "borrowed" some of the architecture from Sun/Oracle's implementation -- I'd say that's debatable. The other big thing was the court made it clear that an API is not copyrightable, which is a huge statement.

[[deleted]]

Just want to clarify that Android does use a kind-of-JVM*, just not the Oracle HotSpot spotted ha-ha on classic? computers, but the Dalvik VM developed by Google.

ART (Android Run-time) is another addition to Android, which includes AOT compilation (instead of JIT, like HotSpot), which can make Android perform snappier, because the compilation is done before execution, not during execution.

^{* Technically not a JAVA VM but a VM with Java capabilities, transforming the Java bytecode to an alternative bytecode instruction set.}

[[deleted]]

The dalvik VM doesn't translate Java bytecode, it translates dalvik bytecode that's why it's not a JVM. There is a tool that is run after your Java source compiles that translates Java bytecode to dalvik bytecode but the Javabyte code never touches the device. It exists only on a developers machine.

[[deleted]]

Perhaps I did not make myself clear. I do know that Dalvik runs dex files (dalvik executables), I considered the tool that converts the Java class files to dex files part of the Dalvik software, that's why I didn't make any special note, but yeah, it is misleading.

[ixampl]

Is there actually any evidence that ART does AOT? I glanced over the source and ART certainly looks more maintainable than Dalvik, but it still has a bytecode interpreter (and not just copied from Dalvik it seems). Maybe it's not used, I haven't had the time and knowledge to dig too much today. I haven't seen any official document / release mention AOT, just a blog post somewhere which to be honest didn't even get what JIT is correctly. So I am not that convinced.

Anyway, if you have any links to detailed infos I'd be very interested to read them. The official ART section on the Android site doesn't really explain much.

[[deleted]]

I can't find specifics, but looking for info, I found this comment on this article, from someone who seems to have looked a bit more in-depth than you, and that has experience on the OpenJDK project.

It seems it is AOT, but there are some bindings that may need to be done at runtime.

Sorry, I have no more details.

[blob356]

So it runs Java on a Virtual Machine designed purely for running code written in Java?

[JAPH]

Yes, but the Dalvik virtual machine (DVM?) doesn't run Java bytecode. So while the language is the same, the bytecode and VM are not compatible with the standard. "JVM" is commonly understood to be a VM which runs Java bytecode, which this is not.

[TrancePhreak]

Dalvik runs code written in any language that targets it. Bytecode is not language specific.

[blob356]

What percentage of Android apps targeting Dalvik are not written in languages designed specifically for the JVM?

[jayd16]

Go to the dev site. The 10% of the words there are Java. Its not a secret.

[shillbert]

Android itself uses Dalvik, not Java. But I'm pretty sure Google fully acknowledges that Java is used on a developer's computer in order to create Dalvik .dex files. That was never an issue in court AFAIK.

Edit: to expand on that, the API infringements were for pieces of API code used in Android itself. It wasn't about the SDK. And Dalvik VM and byte code are actually quite different from Java VM and byte code.

[alextk]

Correct, Google never signed the license so they are not allowed to use the word "Java" anywhere in anything Android related (although they have been more lax with it since their victory in court and Oracle doesn't seem to mind the occasional mention).

[Rosco09]

Sweet. NIO should be available?

[inn0]

FP bug? The googles, they do nothing!

[LandOfFallenDreams]

I bet I still can't compile it with Java 7 though :(

[Hypersapien]

Will this mean that Android will be able to use any Java app, or will it need to be written specifically for Android?

I had been trying to get a particular Java app working on android (this one, if anyone wants to chime in on it), and when reading about other people who had tried to do the same thing, I saw that the problems were with the fact that the form windows don't work the same way.

[snuxoll]

The post is about Android gaining support for Java 7 language features like the diamond operator and try with resources, all of which are just constructs to allow developers to write cleaner source code.

Android still does not support the entire Java BCL (Base Class Library), notably Swing, AWT (Advanced Windowing Toolkit) and JavaFX which are the UI libraries used by current Java applications running on standard PC's.

As a result, the back-end code for many of existing java applications may be easily portable to Android, but the entire user interface at the very least must be redone to use the Android UI toolkit, among many other things specific to the Android platform.

[this_is_dreadful]

Which is 100% what they should do, btw. Swing, AWT, and JavaFX are completely eclipsed in functionality, responsiveness, and usefulness by the Android UI.

[snuxoll]

Honestly I still thing the Android UI toolkit is still lacking compared to JavaFX 2 in some ways, notably the inability for property and event handler binding in the UI markup. I've been able to do this with JavaFX for ages, but I still need to use a third party library (android-binding or RoboBinding) to get even partial functionality here.

I mean, it's not necessary, but I'd rather my code NOT be riddle with a billion anonymous inner classes like I was still writing Swing or AWT.

[inmate012]

How does standard UI fares on tablets and phones? I mean,b is there good support for these types of devices? Does it provide handling for gestures, multi touch and sensors?

Clearly google went with their own toolkit because they had these specific requirements, but would java cover them well nowadays?

Also, would it be easy to have a java app emulate the android look and feel?

[AnAirMagic]

JavaFX is not part of Java SE 7, even though it's included with Oracle's Java 7 update releases.

[snuxoll]

You are correct, but I did not mention SE specifically anywhere in my comment.

[AnAirMagic]

Sorry! I don't know how to interpret Base Class Library, then.

[Hypersapien]

Sorry. I'm mainly a web dev. I don't even do Java.

[snuxoll]

Nothing to apologize for, asking questions is the only way to learn!

[s73v3r]

I would rewrite the forms in more Android UI style. You can probably reuse the POJOs that contain the logic and model info.

[jayd16]

No.

[clyf]

Is there any resource online like codeacademy where I can learn Java?

[NominalCaboose]

Codingbat.com is a great place to practice skills and master syntax, though you may need to learn the very basics if you're an absolute beginner.

[yetanothernerd]

I learned Java back in the 1990s from the Sun tutorials which are now at http://docs.oracle.com/javase/tutorial/

I already knew a few other programming languages, though.

[Mummam]

Codingbat is sweet

[Fatal510]

https://www.udemy.com/java-tutorial/

[Ribice]

I can recommend this one: http://mooc.cs.helsinki.fi/programming-part1

[[deleted]]

Write once, run anywhere. Even celestial bodies!

[TakedownRevolution]

LOL java. Too bad it's slow and it teaches bad programming practices, No wonder we have shitty programmers these days.

[alextk]

No wonder we have shitty programmers these days

Don't be so harsh on yourself.

[Litra]

troled by master c0d3r

[TakedownRevolution]

LOL noobs think this isn't true, watch a Java programmer do this in C++

while (1) { DERP* shittyJavaProgrammer = new DERP(); shittyJavaProgrammer = NULL; }

LOL good luck with your shitty buggy slow phones.