Android SDK and API levels in Android Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Android SDK Versions

Which Android SDK version introduced the Material Design guidelines?

A API level 23 (Marshmallow)

B API level 19 (KitKat)

C API level 21 (Lollipop)

D API level 18 (Jelly Bean)

💡 Hint

Material Design was a big visual update introduced around 2014.

Material Design was introduced in Android 5.0 Lollipop, which corresponds to API level 21.

❓ ui_behavior

intermediate

API Level and Runtime Permissions

From which Android API level did apps need to request dangerous permissions at runtime instead of install time?

A API level 22 (Lollipop MR1)

B API level 21 (Lollipop)

C API level 24 (Nougat)

D API level 23 (Marshmallow)

💡 Hint

This change improved user control over app permissions.

Starting with API level 23 (Marshmallow), apps must request dangerous permissions at runtime.

❓ lifecycle

advanced

Behavior Change in Background Execution

Which API level introduced restrictions on background services to improve battery life?

A API level 26 (Oreo)

B API level 25 (Nougat)

C API level 28 (Pie)

D API level 24 (Nougat)

💡 Hint

This change limited apps running in the background starting around 2017.

Android Oreo (API level 26) introduced background execution limits to save battery.

❓ navigation

advanced

API Level and Navigation Component

Which minimum API level is required to use the Android Jetpack Navigation Component?

A API level 16 (Jelly Bean)

B API level 19 (KitKat)

C API level 14 (Ice Cream Sandwich)

D API level 21 (Lollipop)

💡 Hint

Navigation Component supports most devices from Jelly Bean onward.

The Navigation Component requires a minimum API level of 16 (Jelly Bean).

📝 Syntax

expert

Checking API Level at Runtime

What is the correct Kotlin code snippet to check if the device is running at least API level 23 before executing a block?

Android Kotlin

if (/* condition here */) {
  // execute code
}

A if (Build.VERSION.SDK_INT == Build.VERSION_CODES.M) { }

B if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { }

C if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) { }

D if (Build.VERSION.SDK_INT > Build.VERSION_CODES.M) { }

💡 Hint

You want to include API level 23 and above.

Checking with >= ensures the code runs on API 23 and any higher version.

Practice

1. What does the minSdk version specify in an Android app?

easy

A. The latest Android version available

B. The Android version you compile your app against

C. The Android version your app is optimized for

D. The oldest Android version your app can run on

Solution

1. Step 1: Understand minSdk meaning

   minSdk defines the minimum Android version that can run the app.

2. Step 2: Differentiate from other SDK versions

   compileSdk is for building, targetSdk is optimization, but minSdk is the oldest supported version.

3. Final Answer:

   The oldest Android version your app can run on -> Option D

4. Quick Check:

   minSdk = oldest supported version [OK]

Hint: minSdk means minimum Android version supported [OK]

Common Mistakes:

• Confusing minSdk with compileSdk
• Thinking minSdk is the target optimization version
• Assuming minSdk is the latest Android version

2. Which of the following is the correct way to set the compileSdk version to 33 in a Kotlin DSL Gradle file?

easy

A. compileSdkVersion 33

B. compileSdkVersion = 33

C. compileSdk = 33

D. compileSdk(33)

Solution

1. Step 1: Identify Kotlin DSL syntax for compileSdk

   In Kotlin DSL, compileSdk is assigned directly with =.

2. Step 2: Compare options

   compileSdkVersion 33 is Groovy syntax without assignment, compileSdkVersion = 33 uses the wrong property name, and compileSdk(33) is invalid function call syntax. Only compileSdk = 33 is correct.

3. Final Answer:

   compileSdk = 33 -> Option C

4. Quick Check:

   Kotlin DSL uses compileSdk = 33 [OK]

Hint: Kotlin DSL uses equals sign for assignments [OK]

Common Mistakes:

• Using Groovy syntax in Kotlin DSL
• Omitting equals sign
• Using method call syntax incorrectly

3. Given this Gradle configuration snippet:

android {
  compileSdk = 31
  minSdk = 21
  targetSdk = 30
}

What is the highest Android version your app is optimized for?

medium

A. 30

B. 21

C. 31

D. Cannot determine from this

Solution

1. Step 1: Identify meaning of targetSdk

   targetSdk is the Android version the app is optimized for and tested against.

2. Step 2: Check given values

   Here, targetSdk is 30, so the app is optimized for Android 30.

3. Final Answer:

   30 -> Option A

4. Quick Check:

   targetSdk = 30 means optimized for Android 30 [OK]

Hint: targetSdk shows optimization version, not compileSdk [OK]

Common Mistakes:

• Confusing compileSdk with targetSdk
• Thinking minSdk is optimization version
• Choosing compileSdk as optimization version

4. You set minSdk = 30 but want your app to run on Android 21 devices. What is the problem in this Gradle config?

android {
  compileSdk = 33
  minSdk = 30
  targetSdk = 33
}

medium

A. compileSdk must be lower than minSdk

B. minSdk is too high, app won't run on Android 21

C. targetSdk must be equal to minSdk

D. No problem, app runs on all versions

Solution

1. Step 1: Understand minSdk role

   minSdk sets the lowest Android version the app supports.

2. Step 2: Check compatibility with Android 21

   Since minSdk is 30, devices with Android 21 cannot run the app.

3. Final Answer:

   minSdk is too high, app won't run on Android 21 -> Option B

4. Quick Check:

   minSdk = 30 excludes Android 21 devices [OK]

Hint: minSdk must be ≤ lowest Android version supported [OK]

Common Mistakes:

• Thinking compileSdk affects device compatibility
• Assuming targetSdk limits device support
• Believing app runs on all versions regardless of minSdk

5. You want to use a new Android feature introduced in API level 31 but still support devices running API level 21. How should you configure your Gradle file to safely use this feature?

hard

A. Set minSdk = 21, targetSdk = 31, and use runtime checks for API 31 features

B. Set minSdk = 21 and targetSdk = 21

C. Set minSdk = 31 and targetSdk = 31

D. Set compileSdk = 21 and minSdk = 31

Solution

1. Step 1: Understand minSdk and targetSdk roles

   minSdk is the oldest supported version; targetSdk is the optimized version.

2. Step 2: Use runtime checks for new features

   To support API 21 devices but use API 31 features, keep minSdk = 21, set targetSdk = 31, and check API level at runtime before using new features.

3. Step 3: Evaluate options

   Set minSdk = 21, targetSdk = 31, and use runtime checks for API 31 features correctly sets minSdk and targetSdk and mentions runtime checks. Others either restrict support or use wrong compileSdk.

4. Final Answer:

   Set minSdk = 21, targetSdk = 31, and use runtime checks for API 31 features -> Option A

5. Quick Check:

   minSdk low + targetSdk high + runtime checks = safe feature use [OK]

Hint: Use runtime API checks to support older devices safely [OK]

Common Mistakes:

• Raising minSdk and losing older device support
• Not using runtime checks for new APIs
• Setting compileSdk lower than targetSdk