I'm making a library that uses Ktor Client in the ...

# ktor

[Martin Gaens]

I'm making a library that uses Ktor Client in the background, but for some reason when I use it (when I use the .jar), I get a NoClassDefFoundError. This is the full stack trace:

Exception in thread "main" java.lang.NoClassDefFoundError: io/ktor/client/engine/cio/CIO
	at com.gitlab.djsushi123.kotlintelegrambotmother.Bot.<init>(bot.kt:22)
	at com.gitlab.djsushi123.kotlintelegrambotmother.BotKt.buildBot(bot.kt:57)
	at MainKt.main(Main.kt:7)
	at MainKt$main$2.invoke(Main.kt)
	at MainKt$main$2.invoke(Main.kt)
	at kotlin.coroutines.intrinsics.IntrinsicsKt__IntrinsicsJvmKt$createCoroutineUnintercepted$$inlined$createCoroutineFromSuspendFunction$IntrinsicsKt__IntrinsicsJvmKt$1.invokeSuspend(IntrinsicsJvm.kt:205)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlin.coroutines.ContinuationKt.startCoroutine(Continuation.kt:115)
	at kotlin.coroutines.jvm.internal.RunSuspendKt.runSuspend(RunSuspend.kt:19)
	at MainKt.main(Main.kt)
Caused by: java.lang.ClassNotFoundException: io.ktor.client.engine.cio.CIO
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
	... 10 more

What am I doing wrong? The library uses Gradle. This is my `build.gradle.kts`:

plugins {
    id("org.jetbrains.kotlin.jvm") version "1.7.0"
    kotlin("plugin.serialization") version "1.7.0"

    `java-library`
}

version = "0.0.1-alpha"

repositories {
    // Use Maven Central for resolving dependencies.
    mavenCentral()
}

dependencies {
    implementation(platform("org.jetbrains.kotlin:kotlin-bom"))

    implementation("org.jetbrains.kotlin:kotlin-stdlib")

    api("io.ktor:ktor-client-core:2.0.2")
    api("io.ktor:ktor-client-cio:2.0.2")

    api("io.ktor:ktor-client-content-negotiation:2.0.2")
    api("io.ktor:ktor-serialization-kotlinx-json:2.0.2")

    api("io.ktor:ktor-client-resources:2.0.2")

    // Use the Kotlin test library.
    testImplementation("org.jetbrains.kotlin:kotlin-test")

    // Use the Kotlin JUnit integration.
    testImplementation("org.jetbrains.kotlin:kotlin-test-junit")
}

[Aleksei Tirman [JB]]

Hey. How do you build a JAR file?

[Martin Gaens]

@Aleksei Tirman [JB] I run the build gladle task

[Martin Gaens]

The JAR file gets output into lib/build/libs

[Aleksei Tirman [JB]]

As far as I know, this command builds only your artifact. So to run you application you need add all the dependencies to the classpath.

[Aleksei Tirman [JB]]

Alternatively, you can use something like ShadowJar to pack your application/library with all dependencies in a single JAR.

[Martin Gaens]

So you have some useful links on how to add the dependencies to the classpath? I couldn't find any resources on how to properly create Kotlin JVM (not multiplatform) libraries through Gradle.

[Aleksei Tirman [JB]]

You may find this useful https://docs.oracle.com/javase/tutorial/essential/environment/paths.html#classpath

[Martin Gaens]

Thank you very much!