Error handling patterns in Android Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

Handling Null Pointer Exception in Kotlin Android

What will be the output when this Kotlin Android code runs and the nullable variable is null?

Android Kotlin

val userName: String? = null
val displayName = userName!!.length
println("Length: $displayName")

A Throws KotlinNullPointerException at runtime

B Prints: Length: 0

C Prints: Length: null

D Compilation error due to null safety

💡 Hint

The double exclamation mark (!!) forces a non-null assertion.

Using !! on a null value causes KotlinNullPointerException at runtime.

🧠 Conceptual

intermediate

Try-Catch Block Behavior in Kotlin Android

What is the output of this Kotlin code snippet in Android when an exception occurs inside the try block?

Android Kotlin

try {
  val result = 10 / 0
  println("Result: $result")
} catch (e: ArithmeticException) {
  println("Caught division by zero")
} finally {
  println("Finally block executed")
}

A Result: 0\nFinally block executed

B Only Finally block executed

C Caught division by zero\nFinally block executed

D Runtime crash without any output

💡 Hint

Division by zero throws ArithmeticException.

The exception is caught and handled, then finally block runs.

❓ lifecycle

advanced

Exception Handling in Android Activity Lifecycle

If an exception is thrown inside onCreate() of an Android Activity and not caught, what happens?

A Exception is logged but app continues normally

B Exception is silently ignored and activity continues

C Activity restarts automatically without user notice

D App crashes and shows a crash dialog

💡 Hint

Uncaught exceptions in lifecycle methods cause app crashes.

Android does not catch uncaught exceptions in lifecycle methods; app crashes.

📝 Syntax

advanced

Correct Kotlin Syntax for Catching Multiple Exceptions

Which Kotlin code snippet correctly catches both IOException and NumberFormatException in Android?

Android Kotlin

fun parseData() {
  try {
    // code that may throw exceptions
  } catch (e: IOException, e: NumberFormatException) {
    println("Exception caught")
  }
}

A catch (e: IOException) { println("Exception caught") } catch (e: NumberFormatException) { println("Exception caught") }

B catch (e: IOException | NumberFormatException) { println("Exception caught") }

C catch (e: Exception) { if (e is IOException || e is NumberFormatException) println("Exception caught") }

D catch (e: IOException, e: NumberFormatException) { println("Exception caught") }

💡 Hint

Kotlin does not support multiple exception types in one catch clause.

Kotlin requires separate catch blocks for different exception types.

🔧 Debug

expert

Diagnosing Silent Failure in Coroutine Exception Handling

In this Kotlin coroutine code, why does the exception not crash the app or print the error message?

Android Kotlin

GlobalScope.launch {
  try {
    throw IllegalStateException("Error in coroutine")
  } catch (e: Exception) {
    // empty catch block
  }
}
println("Coroutine launched")

A GlobalScope.launch requires explicit supervisor to catch exceptions

B Exception is caught but ignored due to empty catch block

C Coroutine does not support exceptions so it fails silently

D Exception is thrown on main thread causing crash before catch

💡 Hint

Empty catch blocks swallow exceptions silently.

The exception is caught but nothing is done, so no error is shown.