Passing data between activities in Android Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What will be displayed after passing data between activities?

Consider two activities: MainActivity sends a string "Hello" to SecondActivity using Intent extras. SecondActivity displays the received string in a TextView. What text will the TextView show?

Android Kotlin

val intent = Intent(this, SecondActivity::class.java)
intent.putExtra("message", "Hello")
startActivity(intent)

// In SecondActivity onCreate:
val message = intent.getStringExtra("message")
textView.text = message

A Hello

B null

C message

D Empty TextView

💡 Hint

Check how the string extra is passed and retrieved using the same key.

The string "Hello" is put into the Intent with key "message" and retrieved in SecondActivity with the same key, so the TextView shows "Hello".

📝 Syntax

intermediate

Which code correctly passes an integer between activities?

You want to send an integer value 42 from MainActivity to DetailActivity. Which option correctly puts the integer into the Intent extras?

A intent.putExtra("number")

B intent.putExtra("number", "42")

C intent.putExtra(42, "number")

D intent.putExtra("number", 42)

💡 Hint

Remember putExtra needs a key and a value.

Option D correctly uses putExtra with a key "number" and an integer value 42. Option D sends a string, not integer. Option D reverses key and value. Option D misses the value.

❓ lifecycle

advanced

What happens if you try to retrieve data from Intent in onCreate after configuration change?

If SecondActivity receives data via Intent extras and you retrieve it in onCreate, what happens when the device rotates causing a configuration change?

A The Intent extras are lost and data becomes null.

B The data is still available in Intent extras and can be retrieved again.

C The activity crashes due to missing Intent data.

D The data is saved automatically in savedInstanceState.

💡 Hint

Think about what happens to the Intent during activity recreation.

The Intent that started the activity remains the same after configuration change, so extras are still available in onCreate.

🔧 Debug

advanced

Why does retrieving data from Intent extras return null?

You passed a string extra with key "username" from MainActivity but in SecondActivity, intent.getStringExtra("user") returns null. Why?

A The key used to retrieve data does not match the key used to put data.

B The Intent extras are cleared automatically after startActivity.

C The data type must be Parcelable to pass between activities.

D You must cast the extra to String explicitly.

💡 Hint

Check the exact key strings used in putExtra and getStringExtra.

Intent extras are stored as key-value pairs. If keys don't match exactly, retrieval returns null.

🧠 Conceptual

expert

What is the best way to pass a complex object between activities?

You want to pass a custom data object with multiple fields from one activity to another. Which approach is correct and efficient?

A Convert the object to JSON string and pass it as a string extra.

B Store the object in a static variable and access it from the other activity.

C Make the object implement Parcelable and pass it via Intent extras.

D Serialize the object to a file and pass the file path via Intent.

💡 Hint

Android recommends a specific interface for passing objects efficiently.

Parcelable is the Android-recommended way to pass complex objects efficiently between activities via Intent extras.