How to Handle Errors in Kotlin: Try-Catch and More

In Kotlin, you handle errors using try-catch blocks to catch exceptions and prevent crashes. You can also use throw to raise exceptions intentionally and finally to run code regardless of errors.

Why This Happens

Errors happen when your program tries to do something invalid, like dividing by zero or accessing a missing file. Without handling these errors, your program will crash and stop working.

kotlin

fun divide(a: Int, b: Int): Int {
    return a / b
}

fun main() {
    println(divide(10, 0))
}

Output

Exception in thread "main" java.lang.ArithmeticException: / by zero
	at MainKt.divide(Main.kt:2)
	at MainKt.main(Main.kt:6)

The Fix

Use a try-catch block to catch the error and handle it gracefully. This way, your program can continue running or show a friendly message instead of crashing.

kotlin

fun divide(a: Int, b: Int): Int {
    return try {
        a / b
    } catch (e: ArithmeticException) {
        println("Cannot divide by zero.")
        0
    }
}

fun main() {
    println(divide(10, 0))
}

Output

Cannot divide by zero.
0

Prevention

Always anticipate possible errors and use try-catch blocks around risky code. Validate inputs before using them, and use Kotlin's require or check functions to catch invalid states early. Avoid catching generic exceptions; catch specific ones to handle errors properly.

Related Errors

Other common errors include NullPointerException when accessing null values and IndexOutOfBoundsException when accessing invalid list indexes. Use Kotlin's null safety features and check list sizes before access to avoid these.

Key Takeaways

Use try-catch blocks to handle exceptions and prevent crashes.

Catch specific exceptions to respond correctly to different errors.

Validate inputs before processing to avoid errors.

Use Kotlin's null safety to prevent null-related errors.

Use finally blocks to run cleanup code regardless of errors.