Lateinit vs Lazy in Kotlin

I am Naimish Trivedi, I have a far experience in native and hybrid programming. I have presented the programming concept here in a simple and easy way from my experience. This will be very useful for native Developers.

In this Article, we will learn about the lateinit vs lazy properties in Kotlin.

In Kotlin for Android development, lateinit and lazy are both mechanisms used to delay the initialization of properties. However, they serve different purposes and have different use cases.

lateinit

lateinit is a modifier that is used for non-null properties. It allows you to declare a property without initializing it immediately, but you must initialize it before using it, otherwise, it will throw a LateInitializationException.

for example :

In this example, message is declared with lateinit, but it must be initialized before calling printMessage().

lazy

lazy is a function that takes a lambda and returns an instance of Lazy<T>, which has a value that will be computed only upon the first access. It is useful when the initialization of a property is computationally expensive or you want to defer its initialization until it's actually needed.

for example :

In this example, studentModel will be initialized upon the first access to it via printProperty(). The lambda provided to lazy will be executed only once.

Differences

• Initialization: lateinit properties must be initialized before use, whereas lazy properties are initialized lazily, upon the first access.
• Nullable vs Non-nullable: lateinit can only be used with non-nullable properties, while lazy can be used with both nullable and non-nullable properties.
• Performance: lateinit initialization happens immediately when the property is accessed, while lazy initialization occurs only once, upon the first access, making it more suitable for heavy initialization operations.

In summary, use lateinit when you have a non-nullable property that must be initialized before use, and use lazy when you want lazy initialization for properties, especially when the initialization is expensive or can be deferred.

That's it for now.

Thanks

Happy Coding..!!