Exceptions

To throw an exception object, use the throw keyword:

throw Exception("Exception in Kotlin.")

Note: Whenever an exception is thrown, the execution of the function is interrupted until the exception is caught or propagates to the caller.

To catch an exception, use the try and catch expression:

try {
    // Code that may throw an exception
} catch (exception: Exception) {
    // Exception handling
    println("An error occurred: ${exception.message}")
}

Note: There can be more than one catch block, which lets you handle different types of exceptions separately.

try {
    // Code that may throw multiple types of exceptions
} catch (exception: IOException) {
    // Specific handling for IOException
    println("I/O error:  ${exception.message}")
} catch (exception: Exception) {
    // Generic handling for other exceptions
    println("Unexpected error: ${exception.message}")
} finally {
    // Optional block that always runs, with or without an exception
    println("Operation finished.")
}

The finally block runs regardless of whether an exception is thrown, and can be used to release resources or perform cleanup actions.

Kotlin lets you create your own exception classes, inheriting from Throwable or from any of its subclasses, such as Exception or RuntimeException:

class CustomException(message: String) : Exception(message)

throw CustomException(message = "This is a custom exception.")

Custom exceptions are used to represent errors specific to your application’s domain.