This lets Android Studio know that the kotlin directory is a source root, so when the project model is loaded into the IDE it will be properly recognized. Alternatively, you can put Kotlin classes in the Java source directory, typically located in src/main/java.
Android Studio
使用 Gradle Kotlin DSL 構(gòu)建腳本后，將源代碼根目錄java修改為kotlin。
Kotlin 版本 build.gradle.kts：
android {
...
sourceSets["main"].java.srcDir("src/main/kotlin")
}
對應(yīng)的 Groovy 版本 build.gradle：
android {
...
sourceSets {
main.java.srcDirs += 'src/main/kotlin'
}
}
