Activity results in Android Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What is the output when returning a result from an Activity?

Consider an Android app where Activity A starts Activity B for a result. Activity B sets the result as Intent with key "user_name" and value "Alice" before finishing. What will Activity A receive in onActivityResult?

Android Kotlin

val intent = Intent()
intent.putExtra("user_name", "Alice")
setResult(Activity.RESULT_OK, intent)
finish()

A Activity A receives RESULT_OK and intent with "user_name" = "Alice"

B Activity A receives RESULT_CANCELED and no data

C Activity A receives RESULT_OK but intent is null

D Activity A crashes due to missing data

💡 Hint

Remember that setResult passes data back to the calling Activity.

When Activity B calls setResult with RESULT_OK and an Intent containing extras, Activity A receives that Intent in onActivityResult with the same extras.

❓ lifecycle

intermediate

What happens if you call finish() without setResult()?

In an Android app, Activity B is started for result by Activity A. Activity B calls finish() without calling setResult(). What result does Activity A receive?

A Activity A receives null Intent and crashes

B Activity A receives RESULT_OK with no data

C Activity A receives RESULT_OK with default data

D Activity A receives RESULT_CANCELED with no data

💡 Hint

If setResult is not called, what is the default result code?

If setResult is not called, the default result code is RESULT_CANCELED and no data is sent back.

📝 Syntax

advanced

Which code snippet correctly starts an Activity for result using the new Activity Result API?

Android introduced a new Activity Result API replacing startActivityForResult. Which snippet correctly registers and launches an Activity for result?

Android Kotlin

val getContent = registerForActivityResult(ActivityResultContracts.GetContent()) { uri: Uri? ->
    // handle the returned Uri
}

// To launch:
getContent.launch("image/*")

A

val launcher = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result -> if (result.resultCode == Activity.RESULT_OK) { val data = result.data } }
launcher.launch(intent)

B

startActivityForResult(intent, REQUEST_CODE)
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) { }

C val launcher = startActivityForResult(intent, REQUEST_CODE)

D

registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result -> /* no parameters */ }
launcher.launch(intent)

💡 Hint

Look for the correct use of registerForActivityResult with a lambda receiving a result parameter.

Option A correctly uses registerForActivityResult with StartActivityForResult contract and handles the result in the lambda.

🔧 Debug

advanced

Why does onActivityResult not get called after starting an Activity for result?

An app uses startActivityForResult to launch Activity B from Activity A. But onActivityResult in Activity A is never called after Activity B finishes. What is the most likely cause?

A Activity B calls finish() without setResult()

B Activity B is launched with startActivity instead of startActivityForResult

C Activity A overrides onActivityResult but forgets to call super.onActivityResult

D Activity A uses the new Activity Result API but also overrides onActivityResult

💡 Hint

Check how Activity B is started.

If Activity B is started with startActivity instead of startActivityForResult, onActivityResult will not be called.

🧠 Conceptual

expert

What is the advantage of the new Activity Result API over startActivityForResult?

Android introduced the Activity Result API to replace startActivityForResult and onActivityResult. Which is the main advantage of the new API?

A It allows multiple Activities to run simultaneously in the background

B It automatically saves and restores Activity state without extra code

C It simplifies result handling by using lifecycle-aware callbacks and avoids deprecated methods

D It removes the need to create Intents for starting Activities

💡 Hint

Think about lifecycle and code clarity improvements.

The new Activity Result API uses lifecycle-aware components and callbacks, making result handling cleaner and avoiding deprecated methods.