JavaFX + Kotlin coroutine without android OS, is it possible?

Question

I have a runnable jar that has a UI made with javafx fxml and the class code in kotlin with some database operations done with spring jpa.

Everything works great, except that I would like to not block the main thread while doing the work. Coming from C# I saw that in kotlin you can use coroutine like async await.


import javafx.fxml.FXML
import javafx.scene.control.Button
import kotlinx.coroutines.*

class appGui{
    @FXML
    private var buttonExecute: Button? = null

    @FXML
    fun buttonExecuteClick() {
       buttonExecute!!.isDisable = true

       CoroutineScope(Dispatchers.Main).launch {
           withContext(Dispatchers.IO){
               work()
           }

           buttonExecute!!.isDisable = false
       }
    }

    private suspend fun work() {
       println("corotine starting...")
       delay(5000);
       //springMain.applyChanges()
       println("corotine finished...")
    }
}

So I have added the coroutine call, but I got an exception Module with the Main dispatcher is missing. Add dependency providing the Main dispatcher

Looking at this exception, I found that you have to import the coroutines-android instead of the core, so I change my pom to it

        <dependency>
            <groupId>org.jetbrains.kotlinx</groupId>
            <artifactId>kotlinx-coroutines-android</artifactId>
            <version>1.4.2</version>
        </dependency>

which cause other exception ClassNotFoundException: android.os.Looper Now I'm confused, is the coroutine intended to be used in android app? I'm running a jar on windows. Or do I need to go back to runnable task and do things like it was done in swing?

If you are not running on Android you should not use the Android dependency. Maybe this helps: github.com/Kotlin/kotlinx.coroutines/blob/master/ui/… — mipa
mipa, that is it! So simple, I have just changed the import from kotlinx-coroutines-android to kotlinx-coroutines-javafx thanks! — P. Waksman

P. Waksman P. Waksman · Accepted Answer · 2020-12-22T13:38:22

Thank to mipa (comment) for the tip.

just change the pom to import the javafx instead android.

        <dependency>
            <groupId>org.jetbrains.kotlinx</groupId>
            <artifactId>kotlinx-coroutines-javafx</artifactId>
            <version>1.4.2</version>
        </dependency>

simple and easy.

There is 3 main imports in the doc right now https://github.com/Kotlin/kotlinx.coroutines/blob/master/ui/coroutines-guide-ui.md

kotlinx-coroutines-android -- Dispatchers.Main context for Android applications.
kotlinx-coroutines-javafx -- Dispatchers.JavaFx context for JavaFX UI
applications. kotlinx-coroutines-swing -- Dispatchers.Swing context for Swing UI applications.

I just need to use the right one

JavaFX + Kotlin coroutine without android OS, is it possible?

1 Answers