The filename, directory name or volume label syntax is incorrect - Kotlin - Maven

Question

I get this error when I start my packaged jar. When I run it from my IDE it does not give the error and run.

java.io.FileNotFoundException: file:\C:\Development\Kotlin\AccountTool\target\AccountTool-1.0-SNAPSHOT-jar-with-dependencies.jar!\accounts.json (The filename, directory name or volume label syntax is incorrect)
    at java.io.FileInputStream.open0(Native Method)
    at java.io.FileInputStream.open(Unknown Source)
    at java.io.FileInputStream.<init>(Unknown Source)
    at java.io.FileInputStream.<init>(Unknown Source)
    at java.io.FileReader.<init>(Unknown Source)
    at com.martacus.accounttool.ToolView$handler.readData(Tool.kt:41)
    at com.martacus.accounttool.ToolView.<init>(Tool.kt:56)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at java.lang.Class.newInstance(Unknown Source)
    at tornadofx.FXKt.find(FX.kt:238)
    at tornadofx.App.start(App.kt:27)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(Unknown Source)
    at com.sun.javafx.application.LauncherImpl$$Lambda$52/31866147.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$45/2900468.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$170(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$48/4210449.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$47/24077489.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$145(Unknown Source)
    at com.sun.glass.ui.win.WinApplication$$Lambda$36/1828305.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

Code and file hierarchy in the ide:

fun readData(){
    accounts.clear()
    var readFile = ToolView::class.java.classLoader.getResource("accounts.json").file
    println(readFile)
    FileReader(readFile).use{
        var account = gson.fromJson(it, Array<Account>::class.java) ?: return
        for(i in account){
            accounts.add(i)
        }
    }

}

.jar root:

I have no idea what is going wrong and why it is giving me the error. Searching on stackoverflow and google didnt provide me with the right answer. I hope someone here can help me, if you need any more info please say so.

Thanks!

Answer 1

When a resource is packed into a jar, it is not available as a file in filesystem anymore. Therefore you cannot use standard API for working with filesystem as File() or FileReader() to access the contents of the resource.

Instead you should open resource stream with Class.getResourceAsStream or ClassLoader.getResourceAsStream methods and read the content from that stream:

val stream = ToolView::class.java.classLoader.getResourceAsStream("accounts.json")

stream.reader().use {
    println(it.readText())
}