Explain how the 'lateinit' property works in Kotlin.

lateinit is used for declaring non-nullable properties that will be initialized later, before their first use.

• It applies only to mutable properties (var).
• It cannot be used with primitive data types (like Int, Boolean, Float) because they cannot be null.
• The compiler does not require immediate initialization of the property upon declaration.
• If the property is used before initialization, an UninitializedPropertyAccessException will be thrown.

Example:

class MyClass {
    lateinit var myProperty: String // Property will be initialized later

    fun initializeProperty(value: String) {
        myProperty = value
    }

    fun useProperty() {
        println(myProperty) // Safe after initialization
    }
}

fun main() {
    val obj = MyClass()
    // obj.useProperty() // Will throw UninitializedPropertyAccessException here
    obj.initializeProperty("Hello")
    obj.useProperty() // Will print "Hello"

    // Check if initialized
    if (obj::myProperty.isInitialized) {
        println("Property is initialized")
    }
}

You can check if a lateinit property has been initialized using reflection: ::propertyName.isInitialized.

The use of lateinit is common in frameworks where properties are injected (dependency injection) after object creation (for example, in Android with UI elements or dependency injection).