无法运行 jar 文件。 （错误：无法找到或加载主类 co.pissarra.Mainkt）

Question

I was trying to create a small webserver using spark and kotlin.

But I am stuck at the step where I should be able to create a jar of the project and run it from the command line. But I get the following error on running java -jar pissarra-core-all-1.0-SNAPSHOT.jar

Error: Could not find or load main class co.pissarra.Mainkt

I tried using intellij idea's artifact creation without success, and moved on to creating jar using build.gradle . Following is the code for the same

task fatJar(type: Jar) {
    manifest {
        attributes 'Implementation-Version': version,
                'Main-Class': 'co.pissarra.Mainkt'
    }
    baseName = project.name + '-all'
    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
    with jar
} 

After running ./gradlew clean followed by ./gradlew fatJar , I am able to create jar file in build/libs/ directory. This jar also gives the same error.

On extracting the jar file, I am able to see the directory structure co/pissarra/ with the Mainkt.class file inside it. Also it has the META-INF directory with MANIFEST.MF file whose content are as follows

Manifest-Version: 1.0
Implementation-Version: 1.0-SNAPSHOT
Main-Class: co.pissarra.Mainkt

Since stackoverflow does not allows to upload files, you can find the jar file here . You can also build the jar file from the github project here .

Answer 1

Check your MANIFEST file. The class name should be "MainKt" and not "Mainkt"