📌 Exception Handling in Kotlin

Exception Handling in Kotlin is a mechanism to handle runtime errors, preventing the application from crashing. It allows you to manage and respond to unexpected issues effectively.

✅ 1. What is an Exception?

An exception is an unwanted or unexpected event that occurs during program execution, disrupting the normal flow. Examples include:

• Division by zero

• Accessing an invalid index in an array

• Null pointer references

✅ 2. Try-Catch Block

Kotlin uses try-catch blocks to catch and handle exceptions.

📌 Syntax:

kotlin
fun () {    try {        val result = 10 / 0        println(result)    } catch (e: ArithmeticException) {        println("Exception caught: ${e.message}")    } Exception caught: / by zeroExecution completed.

✅ 3. Multiple Catch Blocks

You can use multiple catch blocks to handle different types of exceptions.

📌 Example:

kotlin
fun () {    val str: String? = null        try {        println(str!!.length) // Throws NullPointerException    } catch (e: NullPointerException) {        println("Null Pointer Exception: ${e.message}")    } Null Pointer Exception: null

• Kotlin executes the appropriate catch block based on the exception.

✅ 4. Finally Block

The finally block always executes, whether an exception occurs or not. It is typically used for cleanup operations like closing files or releasing resources.

📌 Example:

kotlin
fun () {    try {        val data = arrayOf(1, 2, 3)        println(data[5]) // ArrayIndexOutOfBoundsException    } catch (e: Exception) {        println("Exception: ${e.message}")    } Exception: Index 5 out of bounds for length 3This will always execute.

✅ 5. Throwing Exceptions

You can throw exceptions using the throw keyword.

📌 Example:

kotlin
fun (age: Int) {    fun () {    try {        validateAge(16)    } catch (e: IllegalArgumentException) {        println("Exception: ${e.message}")    }}

Output:

makefile
class InvalidUserException(message: String) : Exception(message)fun (username: String) {    fun () {    try {        login("user123")    } catch (e: InvalidUserException) {        println("Exception: ${e.message}")    }}

Output:

makefile
Exception: Invalid username: user123

✅ 7. Conclusion

• Use try-catch-finally to handle exceptions.

• Handle specific exceptions using multiple catch blocks.

• Use the finally block for cleanup operations.

• Throw exceptions using throw.

• Create custom exceptions by extending the Exception class.