Flutter vs React Native comparison - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Performance difference between Flutter and React Native

Which statement best describes the performance difference between Flutter and React Native apps?

A Flutter apps generally have better performance because they compile to native ARM code and use a rendering engine.

B React Native apps always perform better because they use native UI components directly without any extra rendering layer.

C Flutter apps perform worse because they rely on JavaScript bridge for UI updates.

D React Native apps perform better because Flutter uses web views internally.

💡 Hint

Think about how each framework renders UI and compiles code.

Flutter compiles Dart code to native ARM code and uses its own rendering engine, which often results in smoother animations and faster UI updates. React Native uses a JavaScript bridge to communicate with native components, which can introduce some overhead.

❓ ui_behavior

intermediate

UI consistency across platforms

Which framework provides more consistent UI appearance across Android and iOS by default?

A React Native, because it uses native UI components on each platform.

B Flutter, because it uses native platform widgets automatically.

C React Native, because it uses web technologies for UI rendering.

D Flutter, because it draws its own UI components using Skia engine.

💡 Hint

Consider how each framework renders UI elements.

Flutter uses its own rendering engine (Skia) to draw UI components, so the app looks the same on both Android and iOS. React Native uses native UI components, so the appearance can differ between platforms.

❓ lifecycle

advanced

Hot reload behavior difference

What is a key difference in hot reload behavior between Flutter and React Native during development?

A React Native's hot reload updates UI instantly preserving state, Flutter requires full restart.

B Flutter's hot reload updates UI instantly preserving state, React Native's fast refresh updates UI preserving state but may lose some state in complex cases.

C Flutter's hot reload updates UI instantly without losing state, React Native reloads entire app losing state.

D Both Flutter and React Native require full app restart to see UI changes.

💡 Hint

Think about how each framework handles code changes during development.

Flutter's hot reload is very fast and preserves the app state. React Native uses fast refresh which also preserves state but can sometimes lose it in complex scenarios.

❓ navigation

advanced

Navigation libraries comparison

Which statement correctly compares navigation handling in Flutter and React Native?

A Both Flutter and React Native require third-party libraries for navigation.

B React Native has a built-in Navigator component, Flutter requires third-party packages for navigation.

C Flutter has a built-in Navigator widget for navigation, React Native relies on third-party libraries like React Navigation.

D Flutter uses native platform navigation APIs directly, React Native uses a Navigator widget.

💡 Hint

Consider what is included by default in each framework.

Flutter includes a Navigator widget in its core framework to manage navigation stack. React Native does not include navigation by default and developers use popular libraries like React Navigation.

📝 Syntax

expert

State management syntax difference

Given the following state update code snippets, which one correctly updates state in React Native using hooks?

Flutter

const [count, setCount] = useState(0);

// Update count by incrementing by 1

A setCount(prevCount => prevCount + 1);

B this.setState({count: count + 1});

C count = count + 1;

D setCount(count + 1);

💡 Hint

Think about the safest way to update state when it depends on previous state.

Using the functional form setCount(prevCount => prevCount + 1) ensures the update uses the latest state value, avoiding bugs in asynchronous updates. Option A works but can cause bugs if multiple updates happen quickly. Option A is class component syntax. Option A directly mutates state which is incorrect.

Practice

1. Which programming language does Flutter primarily use for app development?

easy

A. Kotlin

B. JavaScript

C. Swift

D. Dart

Solution

1. Step 1: Identify Flutter's language

   Flutter uses Dart as its main programming language for building apps.

2. Step 2: Compare with other options

   JavaScript is used by React Native, Kotlin and Swift are for native Android and iOS development respectively.

3. Final Answer:

   Dart -> Option D

4. Quick Check:

   Flutter = Dart [OK]

Hint: Flutter always uses Dart language for coding apps [OK]

Common Mistakes:

• Confusing Flutter's Dart with React Native's JavaScript
• Thinking Flutter uses native languages like Kotlin or Swift

2. Which of the following is the correct way to create a simple button in React Native?

easy

A. alert('Hello')}>Click me

B. ElevatedButton(onPressed: () => print('Hello'), child: Text('Click me'))

C. alert('Hello')} />

D. Button('Click me', onPress: () => alert('Hello'))

Solution

1. Step 1: Recognize React Native button syntax

   React Native uses JSX syntax with <Button> component and props like title and onPress.

2. Step 2: Eliminate other options

   ElevatedButton(onPressed: () => print('Hello'), child: Text('Click me')) is Flutter syntax, C is HTML, D is invalid syntax.

3. Final Answer:

   <Button title='Click me' onPress={() => alert('Hello')} /> -> Option C

4. Quick Check:

   React Native button uses <Button title=... onPress=... /> [OK]

Hint: React Native buttons use JSX with title and onPress props [OK]

Common Mistakes:

• Using Flutter button syntax in React Native
• Confusing HTML button with React Native
• Incorrect event handler names

3. What is a key difference in UI rendering between Flutter and React Native?

medium

A. Flutter uses native UI components; React Native uses custom widgets.

B. Flutter uses a single rendering engine with widgets; React Native uses native platform components.

C. Both Flutter and React Native use native UI components directly.

D. React Native uses a custom rendering engine; Flutter uses native components.

Solution

1. Step 1: Understand Flutter's rendering

   Flutter draws UI using its own rendering engine and widgets, not native components.

2. Step 2: Understand React Native's rendering

   React Native uses native platform UI components for rendering.

3. Final Answer:

   Flutter uses a single rendering engine with widgets; React Native uses native platform components. -> Option B

4. Quick Check:

   Flutter = custom engine; React Native = native components [OK]

Hint: Flutter draws widgets itself; React Native uses native UI elements [OK]

Common Mistakes:

• Thinking Flutter uses native UI components
• Confusing React Native with Flutter rendering
• Assuming both use same rendering method

4. You wrote this Flutter code but the app crashes on start:

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Text('Hello World')
      )
    );
  }
}

What is the likely cause?

medium

A. No error; code runs fine

B. Text widget must be inside a Center widget in Scaffold body

C. StatelessWidget requires a const constructor

D. Missing a MaterialApp widget around Scaffold

Solution

1. Step 1: Analyze Scaffold body usage

   Scaffold body can accept a Text widget directly; it does not cause a crash.

2. Step 2: Confirm no crash

   The code runs fine as is; wrapping Text in Center is optional for layout but not required to prevent crash.

3. Final Answer:

   No error; code runs fine -> Option A

4. Quick Check:

   Scaffold body accepts Text widget directly [OK]

Hint: Text widget can be used directly in Scaffold body without crash [OK]

Common Mistakes:

• Assuming MaterialApp is missing
• Thinking StatelessWidget needs const constructor
• Incorrectly assuming Text alone causes crash

5. You want your app to look exactly the same on Android and iOS with smooth animations and consistent UI. Which framework is better suited and why?

hard

A. Flutter, because it uses its own rendering engine and widgets for consistent UI

B. Flutter, because it uses JavaScript for faster development

C. React Native, because it compiles to native code for performance

D. React Native, because it uses native components for each platform

Solution

1. Step 1: Understand UI consistency needs

   To have identical UI on Android and iOS, a single rendering engine controlling UI is best.

2. Step 2: Match framework to need

   Flutter uses its own rendering engine and widgets, ensuring consistent UI and smooth animations across platforms.

3. Step 3: Eliminate wrong options

   React Native uses native components, so UI differs per platform; Flutter does not use JavaScript.

4. Final Answer:

   Flutter, because it uses its own rendering engine and widgets for consistent UI -> Option A

5. Quick Check:

   Consistent UI = Flutter's custom rendering [OK]

Hint: For identical UI on all platforms, choose Flutter [OK]

Common Mistakes:

• Choosing React Native for consistent UI
• Thinking Flutter uses JavaScript
• Confusing native components with consistent UI