hi, I'm stuck with a weird problem. as you can see, I used IDEA to create a new project with gradle...

# getting-started

[xun su]

hi, I'm stuck with a weird problem. as you can see, I used IDEA to create a new project with gradle to learn kotlin
if I add the line

package com.xun.kotlin

to the file, notice the error beside the build button. what's wrong with that ? if I comment the line, the error disappear.
I used to be a frontend developer, In javascript, there is no need to add the line like this.

[ephemient]

The reference to MainKt was to the package-less name. Now that you've added a package name, that needs to change.

[ephemient]

You can either edit the run configuration or remove it and use the "run" action again, which will recreate the run configuration

[xun su]

Hi, why you say MainKt , but not Main.kt ?
anyway I removed that line, Yes, now I could build and run the code via IDEA
but how about use command line ?

java -jar path/to/build/libs/result.jar

just show me a error:

then I searched a similar question and get a answer like this

so I add a line to my build.gradle.kts ,:

tasks.withType<Jar> { manifest { attributes["Main-Class"] = "com.xun.kotlin.MainKt" } }

but I got a another error:

xun@xun-Yoga-14sIHU-2021:~/Desktop/kotlin-basic/build/libs$ java -jar kotlin-basic-1.0-SNAPSHOT.jar 
Error: Could not find or load main class com.xun.kotlin.MainKt
Caused by: java.lang.ClassNotFoundException: com.xun.kotlin.MainKt

[xun su]

anyway, I just wanna run the project with the command line, what is wrong?

[xun su]

I mean, we can use IDEA to run the project, but I'd prefer to use command line

[ephemient]

Kotlin wraps top-level elements of file.kt in a FileKt class for Java compatibility by default (you can choose a different name with @file:JVM name("..."))

[ephemient]

to run from the command line, it would be better to use the Gradle application plugin. running as an individual jar like that will result in missing dependencies

[ephemient]

plugins {
    application
}

application {
    mainClass.set("com.xun.kotlin.MainKt")
}

this will allow you to use ./gradlew run

[xun su]

I thought the file kotlin-basic-1.0-SNAPSHOT.jar is in build directory so it has all it's dependencies bundled

[ephemient]

or ./gradlew installDist which will create a directory build/install containing everything needed, or ./gradlew distZip or ./gradlew distTar which will create that bundle in build/distributions

[ephemient]

no, dependencies are not bundled in the jar

[xun su]

thank you , I've never learn java before so I just code like javascript way😄. thanks again

[xun su]

but I really wanna know why the solution I mentioned didn't get work in my project😀

[Stephan Schroeder]

if you want all dependencies to be included into the jar - a so called "fat jar" - you can use the shadow-plugin: https://plugins.gradle.org/plugin/com.github.johnrengelman.shadow

[ephemient]

you can but don't. https://product.hubspot.com/blog/the-fault-in-our-jars-why-we-stopped-building-fat-jars

[xun su]

Hi, actually I'm follow the graalvm doc(https://www.graalvm.org/22.3/guides/#run-java-applications-on-graalvm-from-the-cli) , it says "If your Java project is built with Gradle, run ./gradlew build to build the project and then run it from a JAR file as usual (java -jar <JAR file>)."
I thought the builded jar file is in build/libs/, so I went there but still got error: