If this is the case, any developer ( whoever is using your library) can misuse your library. Both were marked as internal members still I was able to access them from the Java source. I modified the value of count and invoked the function. In the following image, you can see IntelliJ IDEA gives a warning but still I can successfully build and execute the application. Now imagine if I'm using Java as the primary programming language for the development of my application then see what happens if I try to access Librar圜lass 👇ĭid you notice it 😲? From the Java code, I'm able to access internal members of the Kotlin class. Why I’m writing an article on that? Let’s see the real problem. When I tried to access the instance, I can just access doSomething() method and nothing other than that since other members are declared with an internal visibility modifier. If I’m using Kotlin as a primary language for the development of my application and If I try to use Librar圜lass in the application, it’ll look like this 👇Īs you can see, I’ve declared libClass as an instance of Librar圜lass. Now let’s say I’m using your library in some application (here it’s SampleApp). Now imagine that you’ve published this library. The only function doSomething() is invoking a call to the internal member function. Your library has a public class Librar圜lass.Īs you can see, this class has an internal member field count and member function doSomethingInternally() which can’t be directly accessed. Let's assume that you're developing a library in Kotlin. This feature of Kotlin is helpful in a way such that you can easily access, modify and test the internal functionalities or properties of a module.īut this can lead to issues if not handled properly while developing library projects. This means other Kotlin modules can’t access classes/members marked with an internal modifier. Gradle module, IntelliJ IDEA module, etc). internal modifier means that the member is visible within the same module (For e.g.

Kotlin has the following visibility modifiers: public, protected, private and internal. If you are developing a library or SDK then it’s obvious that you don’t want to expose some classes or don’t want any member function or field of a class visible to the module which is going to implement your library. Hello developers, in this article we’ll explore some things which need attention if you’re developing a library/SDK using Kotlin programming language which targets JVM or you want to make it interoperable with Java.

Kotlin internal modifier