Is it possible to listen for changes, and upon a change, get those new values from a separate class and update variable in current class?

user_13029516 0
Viewed 7123

So, I am in my home_screen dart file and I have a Text in it where I want it to display the live value from another class's properties value. When I update the class's properties value from another script I want my home_screen Text to update to that new value. My class in a separate file is the following (simplified) :

class MyClass {

  static int myNumber = 10;

}

I want the following Text to update with the value of myNumber in another file:

Text('iWantThisToDisplayLiveMyNumber'),

When I change the value of myNumber from yet another random script how do I get the Text to update in live time to always be myNumber?

dart flutter
2 Answers

Look into Providers.

class MyClass with ChangeNotifier {
        
   static int myNumber = 10;
    
   void changeNumber(){
       myNumber = 1;
       notifyListeners();
   }

 }

In your Widget class you can set up a "listener" like this:

int updatedNumber = Provider.of<MyClass>(context, listen: true).myNumber;

This is a basic and bad way of doing this. Please check out the "ChangeNotifier" "ChangeNotifierProvider" and "Provider.of" Sections in the docs here.

https://flutter.dev/docs/development/data-and-backend/state-mgmt/simple

Its pretty easy to get started with. Good luck

user_109194910

You can make use of the getter and setter functions.

In the example below we are printing happy birthday when the person's age changes:

class Person {
  int _age;

  Person(this._age);

  int get age => _age;
  
  set age(int newValue) {
    print("Happy birthday! You have a new Age.");
    //do some awsome things here when the age changes
    _age = newValue;
  }
}

The usage is exactly as you are used to:

final newPerson = Person(20);
  
print(newPerson.age); //20
newPerson.age = 21; //prints happy birthday
print(newPerson.age); //21
user_110034970
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