Exception Handling Best Practices in Kotlin

Introduction

Exception Handling Best Practices is a fundamental concept every Kotlin developer should understand. Exceptions signal that something went wrong at runtime. Kotlin treats checked exceptions differently from Java, encouraging explicit error handling where it matters.

Catch specific exceptions instead of generic Exception when possible. In this tutorial you will learn the syntax, walk through a complete example program, study the sample output, and review best practices so you can apply the concept confidently in your own projects.

Definition

• Catch specific exceptions instead of generic Exception when possible.
• Do not use exceptions for normal control flow.
• Provide meaningful error messages to help debugging.

Syntax

catch (e: IOException) { ... }

Exception Handling Best Practices in Kotlin Example Program in Kotlin

fun readValue(text: String): Int? {
    return try {
        text.toInt()
    } catch (e: NumberFormatException) {
        println("Please enter a valid number")
        null
    }
}

fun main(args: Array<String>) {
    println(readValue("25"))
    println(readValue("XYZ"))
}

Sample Output

25
Please enter a valid number
null

When to use

Use try/catch when calling code that can fail — file access, network calls, parsing — and you need a controlled recovery path.

How it works

1. The program starts with a main function — the entry point that runs when you execute the file.

2. The println("Please enter a valid number") statement writes a line to the console — this produces part of the sample output below.

3. The println(readValue("25")) statement writes a line to the console — this produces part of the sample output below.

4. The println(readValue("XYZ")) statement writes a line to the console — this produces part of the sample output below.

5. Catch specific exceptions instead of generic Exception when possible.

6. Run the program in IntelliJ IDEA, Android Studio, or with the Kotlin command-line compiler (kotlinc / kotlin). Compare your console output with the sample output shown below.

Best Practices

Common Mistakes

Key Points

• Catch specific exceptions instead of generic Exception when possible.
• Do not use exceptions for normal control flow.
• Provide meaningful error messages to help debugging.
• Test the example locally and verify the output matches the sample.
• Experiment by changing input values to see how behaviour changes.

Notes

• Semicolons at the end of statements are optional in Kotlin.