Navigation drawer in Android Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What happens when the navigation drawer is opened?

In an Android app using a navigation drawer, what is the typical behavior when the drawer is opened?

A The drawer appears over the main content without moving it.

B The main content slides to the right and the drawer appears from the left.

C The main content fades out and the drawer replaces it completely.

D The drawer slides from the bottom covering the main content.

💡 Hint

Think about how the main screen moves when the drawer opens.

The navigation drawer typically slides in from the left, pushing the main content to the right to reveal the drawer.

❓ lifecycle

intermediate

When should you close the navigation drawer?

In an Android app with a navigation drawer, when is the best time to close the drawer programmatically?

A When the app is paused or stopped.

B Only when the user presses the back button.

C Immediately after the user selects a menu item from the drawer.

D Never close it programmatically; let the user close it manually.

💡 Hint

Think about user experience after selecting an option.

Closing the drawer right after a menu item is selected improves user experience by showing the new content clearly.

❓ navigation

advanced

Which code snippet correctly sets up a navigation drawer toggle?

Given an Activity with a DrawerLayout and a Toolbar, which Kotlin code correctly sets up the ActionBarDrawerToggle to sync the drawer icon?

Android Kotlin

val drawerLayout: DrawerLayout = findViewById(R.id.drawer_layout)
val toolbar: Toolbar = findViewById(R.id.toolbar)

A

val toggle = ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.open, R.string.close)
drawerLayout.addDrawerListener(toggle)
toggle.syncState()

B

val toggle = ActionBarDrawerToggle(this, drawerLayout, toolbar)
drawerLayout.addDrawerListener(toggle)
toggle.syncState()

C

val toggle = ActionBarDrawerToggle(drawerLayout, this, toolbar, R.string.open, R.string.close)
drawerLayout.setDrawerListener(toggle)
toggle.syncState()

D

val toggle = ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.open, R.string.close)
drawerLayout.addDrawerListener(toggle)
toggle.sync()

💡 Hint

Check the constructor parameters and method names carefully.

Option A uses the correct constructor parameters and method names to set up the toggle properly.

📝 Syntax

advanced

What error does this code produce?

Consider this Kotlin code snippet inside an Activity: val drawerLayout = findViewById(R.id.drawer_layout) val toggle = ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.open, R.string.close) drawerLayout.addDrawerListener(toggle) // Missing toggle.syncState() call What is the likely result when running the app?

A The drawer works perfectly with no issues.

B The app crashes with a NullPointerException.

C The drawer opens but the icon animates incorrectly.

D The drawer icon does not appear or respond to clicks.

💡 Hint

Think about what syncState() does for the toggle.

Without calling syncState(), the drawer toggle icon is not properly synced with the drawer state, so it won't appear or respond.

🔧 Debug

expert

Why does the navigation drawer not close on back press?

An Android app uses a navigation drawer. The developer overrides onBackPressed() as follows: override fun onBackPressed() { super.onBackPressed() if (drawerLayout.isDrawerOpen(GravityCompat.START)) { drawerLayout.closeDrawer(GravityCompat.START) } } What is the problem with this code?

A Calling super.onBackPressed() first closes the activity before the drawer can close.

B The drawerLayout.isDrawerOpen() method is used incorrectly and always returns false.

C The drawerLayout.closeDrawer() method requires a delay to work properly.

D The GravityCompat.START constant is not the correct gravity for the drawer.

💡 Hint

Consider the order of operations in onBackPressed().

Calling super.onBackPressed() first causes the activity to handle back press and possibly finish before the drawer can close, so the drawer never closes.