How to check if a "lateInit" variable has been initialized in Kotlin?

Any variable which is initialized after its declaration is known as a "late initialized variable". In conventional programming languages, any non-NULL type of variable need to be initialized in the constructor. But sometimes, by mistake, developers forget to do these NULL checks which causes a programming error. In order to avoid this situation, Kotlin introduced a new modifier called as "lateInit". Along with this modifier, Kotlin provides a couple of methods to check whether this variable is initialized or not.

In order to create a "lateInit" variable, we just need to add the keyword "lateInit" as an access modifier of that variable. Following are the couple of conditions that need to be followed in order to use "lateInit" in Kotlin −

• Use "lateInit" with a mutable variable. That means, we need use "var" keyword with "lateInit".

• "lateInit" is only allowed with non-NULLable data types.

• "lateInit" does not work with primitive data types.

• "lateInit" can be used when the variable property does not have any getter and setter methods.

Example

In this example, we will declare a variable as a "lateInit" variable and we will be using our Kotlin library function to check whether the variable is initialized or not.

class Tutorial {

   lateinit var name : String

   fun checkLateInit(){
      println(this::name.isInitialized)
      // it will print false as the value is not initialized

      // initializing name
      name = "www.tutorialspoint.com/"
      println(this::name.isInitialized)
      // It will return true
   }
}

fun main() {
   var obj=Tutorial();
   obj.checkLateInit();
}

Output

Once you execute the code, it will generate the following output −

false
true

In the second case, the variable name is initialized, hence it returns True.