I am new in Flutter. I want to change the value using setState but it doesn't work.

I would appreciate any help.

CodePudding user response：

Make sure the value that you want to change is outside the Widget.

CodePudding user response：

According to docs setState() defination is

Calling setState notifies the framework that the internal state of this object has changed in a way that might impact the user interface in this subtree, which causes the framework to schedule a build for this State object.

So if the state of the widget changes you have to call setState to trigger a rebuild of the view and see immediatly the changes implied by the new state.

For example:

class _MyHomePageState extends State<MyHomePage> {
 int _counter = 0;

 void _incrementCounter() {

   setState(() {
  _counter  ;
  });
 }

so the abovesetState() is called telling the flutter framwork that something has changed , which causes the rerun the build method and the updated part is reflected on the screen.If we change the _counter without calling setstate() than the changes wont be reflected.