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kotlinlang

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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.

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

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

error1.png

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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&lt;Jar&gt; { 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```

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

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

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("...")`)

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

```plugins {
    application
}

application {
    mainClass.set("com.xun.kotlin.MainKt")
}
```
this will allow you to use `./gradlew run`

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

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`

no, dependencies are not bundled in the jar

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

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

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>

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

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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 &lt;JAR file&gt;`)."
I thought the builded jar file is in `build/libs/`, so I went there but still got error: