Why IntelliJ take a bit of time to build my main function even if it is just contain one println statement? I use Kotlin.
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I have used Kotlin with latest version of Eclipse for 2 months without any performance problem on my Windows 10 computer.
Now I would like to do a live coding session about Kotlin with intelliJ (since it's the JetBrains language...) ultimate edition that I just installed and never used before, on a recent OSX computer. The two computers have good hardware and are no limiting my tests.
My problem is that each time there is a modification in my Kotlin code, the compilation time is between 8 seconds and 35 seconds. I did my tests on minimalist code:
class TestKotlin {
var a = 1
}
If I change the variable "a" and so need to build again, it always need 8 seconds in the best cases to complete the compilation.
Since I want to do a live coding session with a lot of small functions and compilations, this kind of delay is way too much significative.
The viewers will need to wait a lot before to see the results at each compilation, they are logically expecting good performance from IntelliJ tool.
In the same project, I tried to do the same kind of Java class (with a single attribute) and modify its attribute in order to trigger the compilation, and it takes less than 1 second to compile.
I tried to manually compile the code in command line with that:
kotlinc hello.kt -include-runtime -d hello.jar
java -jar hello.jar
I had some decent compilation times, even if it was near to 3 seconds.
When I look at the "Messages" screen in IntelliJ while it is compiling Kotlin code, I can see this:
Information:Kotlin: Kotlin JPS plugin version 1.0.6-release-127
Information:Kotlin: Using kotlin-home = /Users/myUsername/Library/Application Support/IntelliJIdea2016.3/Kotlin/kotlinc
It stops here for all the compilation time, and then do almost instantaneously the next steps:
Information:Kotlin: Kotlin Compiler version 1.0.6-release-127
Information:17/01/17 11:38 - Compilation completed successfully in 11s 639ms
Maybe there is a problem in the configuration of IntelliJ or something like this. I had a hard time at searching for something that could improve the performances but nothing helped me...
I would be very grateful if someone can help me to have some realistic compilation time with Kotlin in Intellij like in Eclipse!
This seems similar to the problem KT-15491.
To ensure that it's your case too, try to execute the following simple Kotlin program:
import java.io.File
import kotlin.system.measureNanoTime
fun main(args: Array<String>) {
val elapsedNs = measureNanoTime { File.createTempFile("tmp", "", null).deleteOnExit() }
println(elapsedNs.toDouble() / 1000000000)
}
If the printed elapsed time is significantly greater than a fraction of a second, than that is the reason.
This issue affects not only Kotlin compiler but every JVM program that tries to create a temporary file, or to do any other action involving SecureRandom class.
I've experienced the same slowdown on each JPS build on my Windows 7 notebook. I've tried the workaround with security providers order described in this question and it helped.
Make sure you have checked those boxes in settings:
Incremental Kotlin compilation
Kotlin compiler daemon (keeps the kotlinc process alive)
I'm in the process of learning Kotlin as an Android developer!
Out of curiosity, why didn't the JetBrains guys follow the Java style syntax (where they could have), and made it easier on developers to learn Kotlin?
For example, defining a simple function in Kotlin:
fun simpleFunc(x: Int): Int {
// do stuff
}
Why didn't they do:
fun Int simpleFunc(Int x) {
// do stuff
}
I would appreciate hearing your opinion on this
As mentioned in the Kotlin FAQ, Kotlin's syntax makes it more natural to omit type declarations when they can be inferred by the compiler (which isn't supported by Java). Also, from our experience with Kotlin, we see no evidence that Kotlin's type declaration syntax presents a difficulty for people learning Kotlin.
(Note that your suggested syntax is also different from Java, so it's not clear why you think it would be easier to learn.)
Java is like a coffee, and Kotlin means that coffee with a little bit sugar in there. In some cases, Kotlin does increase the efficiency and make the programming more enjoyable.
Comparing with Java, Kotlin is more effective and actually can work with Java pretty well.
Check the example in that picture here about Safe Calls on the official kotlinlang.org,
In Chains, when there's a null value，you need to use if function to determine whether the value is null，but there's only one sentence method needed for Kotlin.
Plus, when you are using Gradle daemon and Smart Compilation，Kotlin shows a faster compile speed than Java.
the horizontal axis means ten consecutive incremental builds with one core file changed.
You can see that the Gradle daemon still takes two or three runs to warm up, but after that the performance of both languages is very similar. With no changes, Java takes 4.6 seconds per warm build, while Kotlin averages 4.5 seconds. When we change a file that isn’t used by any other files, Java requires an average of 7.0 seconds to do a warm build, and Kotlin clocks in at 6.1. And finally, when we change a file that is imported by many other files in the project, Java requires 7.1 seconds to do an incremental build once the Gradle daemon is warmed up, while Kotlin averages 6.0 seconds.
Citations: 1. https://kotlinlang.org/docs/reference/null-safety.html
https://medium.com/#johnkorly/kotlin-vs-java-performance-drill-down-which-to-choose-2514bdf91916
The kotlin team describes here why the type declarations (like in your example) are on the right:
Why have type declarations on the right?
We believe it makes the code more readable. Besides, it enables some nice syntactic features. For instance, it is easy to leave type annotations out. Scala has also proven pretty well this is not a problem.
I'm trying to create a Kotlin Vert.x language support module and I need a way to compile Kotlin files and load the results with a ClassLoader. I've tried using kotlin-compiler library and found K2JVMCompiler class, but it seems to support only command-line-style arguments with its exec method. Is there a way to compile a Kotlin file in runtime (possibly without having to save and read .class files) and immediately load the generated classes? (Kind of like Groovy does.) If not, do you have any useful compiler arguments suggestions or pretty much any advices?
This feels like an XY Problem. You want to know how to compile Kotlin on the fly so that you can more easily use Vert.x by running from Kotlin source files instead of compiled code. But really the recommended path for Vert.x usage is to create a simple bit of code that deploys your verticle within compiled code.
In the question, your link for language support says Vert.x 2 in the path "vertx.io/vertx2/language_support.html"; which is different than how it is now done in Vert.x 3. I think you are merging two thoughts into one. First that Vert.x 3 wants you to run Java/Kotlin files from source (it doesn't really; that was a Vert.x 2 thing they moved away from for compiled languages), and second that you need custom language support (you don't).
You should try to use Vert.x 3 by running compiled code. To do so, build your classes and run your own main() that deploys a verticle programatically. Your code would be simple as:
import io.vertx.core.Vertx
fun main(args: Array<String>) {
val vertx = Vertx.vertx()
vertx.deployVerticle(SomeVerticleOfMine())
}
Alternatively, the docs for running and deploying from the command-line say:
Vert.x will compile the Java source file on the fly before running it. This is really useful for quickly prototyping verticles and great for demos. No need to set-up a Maven or Gradle build first to get going!
And really it is indeed just for prototyping and quick testing, and it isn't any faster than letting your IDE do the same and running from the compiled classes. You also then have debugging features of the IDE which are infinitely valuable.
For a few helper libraries for using Kotlin with Vert.x, view these options:
Vert.x 3 module for Klutter - I am the author, one of my libraries
Vert.x 3 helpers for Kotlin - by Cy6erGn0m
Kovert, a REST framework for Vert.x 3 - I am the author, one of my libraries
Vert.x nubes - not Kotlin specific, but makes Vert.x-Web friendlier for JVM languages.
There is a full sample project of running Vert.x + Kovert (specifically start with the App class). You can look at the code of Kovert to do your own similar work of starting and running Vert.x nicely, with Promises or however you wish. The docs for Kovert have links to code for starting Vertx and also starting a Verticle to use Vert.x-Web, so more sample code you can read. But it helps to understand Injekt (light-weight dependency registry), Kovenant (promises library), and Klutter configuration injection to understand the complete sample.
Other quick note, Vert.x has codegen support for other languages, but since you can call all of the Java version directly, it does not need to support Kotlin either.
Kotlin 1.1 comes with javax.script (JSR-223) support, which means you can use it as scripting engine similarly to JavaScript with Nashorn.
I've been asked to debug a prototype iPad app (written in Objective C). I thought a good approach would be to write a series of unit tests (IDing bugs and helping me familiarise myself with the code). Though I have written unit tests before I've never used xcode, Objective C; or a Mac for that matter.
The problem being that the code as it stands won't currently build - there are a large number of errors. I'm wondering if there is a way to unit test certain parts of the code using xcode without having to build the entire project; or do I need to ID what's causing all or the errors and eliminate these first?
I would say it depends on how deeply linked the components are, if the error producing components are separate enough (i.e they only communicate/are used by themselves), then you could simply remove them from the build.
However, if the components are also necessary for the remainder of the app (the parts you want to test), then you would need to fix the errors first, as otherwise you couldn't really test the full functionality in your unit tests.
I have a simple question. Coming from a java background and having worked extensively with eclipse, netbeans or any other java IDE, is quite nice to have the possibility to add a main method to a class and execute it within the IDE, with just a click, and see the output.
I was looking for the same possibility within xcode4/objective-c but I couldn't find a way. From time to time, I like testing small piece of software, without compiling and running the whole project.
As I am still "thinking" in Java, could you suggest the proper way to achieve this with xcode4 from an "objective-c developer point of view" ?
thanks
There's not really a lightweight way to do this, but you have two options that I can think of depending on whether you want to keep the harness code you've written.
If you do, then you'd need to make a new target in your project for each class you drive with a harness, and have that target build just the class you are driving and a simple file with just the main code to drive that class.
If you don't, then you could make a target with a main, and each time you want to drive a different class, change which files are built, change the code in main, and rebuild.
This is assuming that you want to avoid both running and compiling the rest of your code. If you don't mind compiling everything, you could have one test-harness target that builds all of your classes, and either change main on the fly, or use #ifdefs or a runtime argument to decide which helper code to run.