Summary - Packages

Combine package, import and internal to set up a module structure.

Summary - Packages

In this group you learned declaring a namespace with package, importing types with import, module visibility with internal, build management with Gradle and the kotlinx extension libraries.

Now you will combine them: put package and import in a file to use File, then define an internal class. This structure is the organizational foundation of Kotlin projects. Later, modular architecture and version catalogs build on it.

Exercise Combine package and import

At the top write package com.example.app. Then add import java.io.File. In main create a File with val f = File("kayit.txt") and print it with println(f).

Show example solution

package com.example.app

import java.io.File

fun main() {
    val f = File("kayit.txt")
    println(f)
}

Exercise Combine internal class and package

At the top write package com.example.tools. Then add import java.io.File. Define internal class Helper; inside it add fun info(f: File): String = f.toString(). In main create an instance with val h = Helper() and print the result with println(h.info(File("kayit.txt"))).

Show example solution

package com.example.tools

import java.io.File

internal class Helper {
    fun info(f: File): String = f.toString()
}

fun main() {
    val h = Helper()
    println(h.info(File("kayit.txt")))
}

Test yourself

Which provides module-level visibility?
- internal
- protected
- public
- private
Show answer

internal — internal restricts a definition to the same module.
Match the package concepts

package

Namespace
import

Bringing in
internal

Module visibility
kotlinx

Extension libraries

Next lesson: JUnit

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies