Cookbooks
Kotlin
Chapter 5. Good Coding Practices
Handling errors

Kotlin:
Handling errors

How to:

Kotlin provides try, catch, finally, and throw to manage errors. Here’s how you use them:

fun main() {
    val numerator = 10
    val denominator = 0

    try {
        val result = numerator / denominator
        println("Result: $result")
    } catch (e: ArithmeticException) {
        println("Can't divide by zero, buddy.")
    } finally {
        println("This happens no matter what.")
    }
}

Output:

Can't divide by zero, buddy.
This happens no matter what.

If something goes wrong in the try block, execution zips to the catch. It catches the specific error thrown (ArithmeticException in this case). The finally block runs after—no matter the outcome.

Deep Dive

The try-catch block has been a thing since early programming days—it’s like a safety net. Kotlin also offers throw for manually tossing an exception into the ring, and there’s finally for code that’s gotta run—clean-up work, often.

Alternatives include the Result type and Kotlin’s try as an expression.

val result: Result<Int> = try {
    Result.success(numerator / denominator)
} catch (e: ArithmeticException) {
    Result.failure(e)
}

This approach returns a Result object—you get either a success or a failure without the drama of an unhandled exception.

Implementation in Kotlin is neat because you can use try like an expression, meaning it returns a value. Choices like these make error handling in Kotlin pretty versatile. It’s about choosing the right tool for the job, just like you would in a workshop.

See Also

  • Kotlin docs on Exceptions: Kotlin Exception Handling
  • Kotlin Result type docs: Kotlin Result
  • Effective Java, 3rd Edition, by Joshua Bloch—great insights on exceptions, though it’s Java-specific.
Logging