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What is the role of the 'by lazy' property in Kotlin and in what scenarios is its use appropriate?

sobes.tech AI

Answer from AI

In Kotlin, a property with the by lazy modifier is initialized lazily — that is, the value is computed only upon the first access to the property, not when the object is created. This is useful when initialization is resource-intensive or not always needed.

Example usage:

val heavyResource by lazy {
    println("Initialization")
    "Result"
}

fun main() {
    println("Before access")
    println(heavyResource) // Initialization occurs here
    println(heavyResource) // Re-initialization does not occur
}

Use cases:

  • Deferred initialization of objects that are not always needed.
  • Performance optimization.
  • Safe initialization in a multithreaded environment (by default, lazy is thread-safe).