尝试从Java实例化Kotlin类时出错 [英] Error trying to instantiate a Kotlin class from Java

问题描述

我试图从Java实例化Kotlin类，但是每次尝试用Maven编译时，都会出现错误cannot find symbol:

I am trying to instantiate a Kotlin class from Java but every time I try to compile with Maven I get the error cannot find symbol:

class ConfigCommand(private val game: Game) : Command("config", "") {

  init {
    addAliases("cfg")
  }

  override fun getRequiredRank(): Rank? {
    return null
  }

  override fun getDescription(): String {
    return "Shows the config for the game"
  }

  @Throws(CommandException::class)
  override fun execute(sender: CommandSender, args: Array<String>): Boolean {

    if (args.isEmpty()) {
        if (sender !is Player)
            throw NoConsoleAccessException()
        sender.openInventory(ConfigGUI(game).build())
        return true
    }

    return false
  }
}

不确定为什么格式不正确，但是无论如何，在将其转换为可以正常工作的Kotlin类之前，我需要在我的主类Java类中注册此命令.当我尝试从Java类实例化Kotlin类时，IDE中没有错误，但是当我编译它时，Maven发出了尖叫声

Not sure why that didn't format correctly but anyway before I converted it to a Kotlin class it worked but I need to register this command in my main class which is a Java class. When I try to instantiate a Kotlin class from a Java class there are no errors in the IDE but when I go to compile it maven screams

cannot find symbol
[ERROR] symbol:   class ConfigCommand

推荐答案

我仍在弄清楚Kotlin，但我尝试根据您的示例尝试一些排列.我很容易根据您的Hastebin pom来创建您的问题.

I'm still figuring out Kotlin, but I tried to work through a few permutations based on your example. I was easily able to create your problem based on your Hastebin pom.

您是对的，将<phase>更改为process-sources可以使我的测试代码在Maven中进行编译，但是(诚实地)我无法永远记住所有Maven阶段，因此我不会个人无需进行更多研究就可以轻松地转换为过程源，特别是因为IntelliJ工具依赖于compile阶段.

You were right that changing the <phase> to process-sources got my test code to compile in Maven, but I (honestly) can't always remember all the Maven phases off the top of my head so I wouldn't personally be comfortable with changing to process-sources without more research -- especially since the IntelliJ tooling relies on the compile phase.

在研究了我自己的互操作示例之后，关键的部分(并且在工具默认设置中缺少)似乎是<sourceDirectory>元素，它是<build>的顶级子元素，如下所示:

After playing around with my own interop examples, it seems like the critical (and missing from the tooling defaults) piece is the <sourceDirectory> element as a top-level child of <build> as in:

<build>
    <sourceDirectory>src/main/java</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin.version}</version>
                <executions>
                    <execution>
                        <id>compile</id>

在运行mvn compile终端命令时，将<sourceDirectory>作为顶级元素添加到<build>下，使我的Java到Kotlin互操作代码得以编译.当我在"java"目录中混合源文件以同时包含Java和Kotlin文件时，确实如此.

Adding the <sourceDirectory> as a top-level element under <build> made my Java to Kotlin interop code compile when I ran the mvn compile terminal command. That was true when I mixed the source files in the "java" directory to contain both Java and Kotlin files.

作为旁注(我不明白为什么写这篇文章)，当我将"Kotlin"作为类名的一部分添加到Kotlin源中时，我不需要添加<sourceDirectory>元素...

As a side note (and I don't I understand why as I write this), when I added "Kotlin" as part of my class name to my Kotlin source I didn't need to add the <sourceDirectory> element...

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