Which access modifier ensures that a class or object can only be used within the same file?

In Android (Java/Kotlin), there is no access modifier that restricts the use of a class or object to a single file, as in some other languages.

In Java, there is the package-private access modifier (absence of an explicit modifier), which restricts access to a class or class members within the same package, but not within a single file.

In Kotlin, you can use the internal modifier, which limits visibility within a module (e.g., a Gradle module), but not to a single file.

If you need to restrict usage within a single file, in Kotlin, you can declare functions and properties with the private modifier at the file level, but classes cannot be restricted this way.

Thus, in Android, there is no modifier that restricts a class or object to only one file. The closest are package-private in Java and private at the file level for functions/properties in Kotlin.