Mastering Kotlin

Implementing the Singleton pattern in Kotlin

To create thread-safe Singletons in Kotlin, we can rely on object declarations, as we discovered in Chapter 5, Modeling Real-World Data. To create a Kotlin equivalent implementation of our ThreadSafeSingleton example from the previous section, we can write the following Kotlin code:

object ThreadSafeSingleton

With this single line, we can now access ThreadSafeSingleton from anywhere in our code base in a thread-safe manner. Adding the object keyword rather than class ensures that the compiler will generate bytecode that enforces the Singleton pattern for us.

We can now add a property to our ThreadSafeSingleton object to demonstrate how to access properties of an object declaration. Consider the ...