Hot Reload vs Hot Restart in Flutter: Explained in Simple Words
Hot Reload vs Hot Restart in Flutter: Explained in Simple Words
Flutter is known for its fast development.
One of its best features is the ability to quickly see changes in your app without restarting it fully.
This is where Hot Reload and Hot Restart come in.
Both sound similar but work differently — and are used in different situations.
Let’s break it down step-by-step.
🚀 What Is Hot Reload?
Hot Reload quickly injects new code into your running app without losing the current app state.
It’s fast and helps developers test UI changes instantly.
🔧 What Happens Behind the Scenes?
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Flutter compiles the updated Dart code
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It injects changes into the running app
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The widget tree is rebuilt, but the app state is preserved
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You don’t go back to the start screen
✅ When to Use Hot Reload?
Use Hot Reload when you:
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Change UI design (e.g., text, color, layout)
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Add new widgets or modify existing ones
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Fix small bugs in your code
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Want to test without losing form inputs or navigation state
🧠 Example
Let’s say you changed the button color from blue to red.
Hot Reload:
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Press
rin terminal or click "Hot Reload" in IDE -
App updates instantly — button turns red
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You stay on the same screen with same data
♻️ What Is Hot Restart?
Hot Restart stops the app and starts it again without recompiling the whole app.
It clears all app state, but keeps all code changes.
🔧 What Happens Behind the Scenes?
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Flutter destroys the app state
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Reloads the app from the main() function
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Useful when your changes don’t show up with hot reload
✅ When to Use Hot Restart?
Use Hot Restart when you:
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Change app state-related code (like provider, variables, logic)
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Add new variables that need initialization
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Modify constructors or global state
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Want to reset the app to starting state
🧠 Example
Say you changed a default value in a variable:
Hot Reload:
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App won’t reflect the new default (old value is still in memory)
Hot Restart:
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App restarts and shows
counter = 10as default
🔥 Which One Should You Use?
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For quick changes to UI or layout → Use Hot Reload
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For resetting everything or changing state/logic → Use Hot Restart
💻 How to Perform Hot Reload and Hot Restart
In Terminal:
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r→ Hot Reload -
R→ Hot Restart
In Android Studio or VS Code:
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Click the Hot Reload lightning icon
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Click the Hot Restart circular arrow icon
⚠️ What Hot Reload Can’t Do
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Update initial values of variables
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Apply changes in constructors
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Modify main.dart behavior
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Change state-management logic (like Bloc/Provider setup)
In such cases, use Hot Restart.
👨💻 Real-World Example
Suppose you have a form with user inputs and you're testing UI layout:
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You change the text box color → Use Hot Reload
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You change how the form data is stored or processed → Use Hot Restart
This helps save time during development.
📌 Important Notes
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Neither hot reload nor hot restart clears your codebase
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They’re development tools, not for production builds
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If changes don’t reflect, try a full App Restart or Rebuild
🧪 Bonus Tip: Full App Restart
If all else fails or plugins don’t work right:
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Stop the app and re-run with
flutter run
This is called a Full Restart, and takes longer but resets everything fully.
💬 Final Thoughts
Hot Reload and Hot Restart are powerful tools that make Flutter development fast and fun.
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Use Hot Reload to tweak and test designs without losing progress.
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Use Hot Restart when your code changes need a fresh app launch.
Knowing when to use each will save time and improve your coding workflow.
Build. Reload. Restart. Repeat. That’s Flutter magic for faster development. 🚀
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