Why stateless is mostly used than stateful widget in software development?

Question

I wanted to make a commercial app. Everyone suggest me to make the whole app is stateless. Why we use a stateless widget instead of the stateful widget for making heavy software?

Answer 1

StatefulWidget requires a State class. This means one thing the user can look at is 2 classes the developer writes. Maintaining more code is more work.

Each StatefulWidget can do any work. It can create an HTTP Client and make a network request. It can open a file and read it. Widget code should not be doing things like that. When you challenge yourself to write StatelessWidget code, you avoid the temptation to put "business-logic" in Widget code.

It makes your life hard when you put logic in widgets. You have to test that code, and now you have to read each individual widget when there is a bug, or when your teammate writes new widget code that has logic.

This also means a widget has more than one reason to change. A StatefulWidget will change if the logic is not right, or if the user doesn't like the look of the UI. Whereas a StatelessWidget will only change the appearance of the UI.

Heavy software can only be made if the pieces that make it are light, otherwise you will get stuck when adding new features. StatelessWidget is lighter than StatefulWidget.

Answer 2

There is no such thing as a "stateless app". Calling something an "app" already establishes the fact that it has a state, compared to say a picture.

The problem is, you asked someone a question with context and they gave you an explanation in that context. And when you did not understand that explanation, you did not ask them for clarification, but instead decided to come here and ask your question here, without any of the context you had before. We cannot possibly guess that context. I'm sure they were right in the context you had, but with the context gone, the plain statement of fact that is left is simply wrong. Next time, ask for clarification when you do not understand something immediately to preserve the context.

Maybe you meant why you should not use a StatefulWidget as your first Widget in the tree?

You can find an explanation here: runApp throws an exception with stateful widget

Maybe you wanted to know the difference between Stateful and Stateless Widgets?

You can find an explanation here: What is the relation between stateful and stateless widgets in Flutter?