In Flutter, a button is disabled if both its onPressed and onLongPress callbacks are null. This concise article shows you how to disable a button after it has been pressed (this will be useful in cases where you want the user to be able to interact with a button only once).
Overview
The steps:
1. Create a variable called _isPressed to hold the button condition. In the beginning, _isPressed = false (make sure you’re using a stateful widget).
2. If _isPressed = false, set the button’s onPressed property to a callback function, otherwise, set onPressed to null:
onPressed: _isPressed == false ? _myCallback : null,Because the onLongPress property is null by default, you don’t have to do anything with it in this case.
3. When the button is pressed, call:
setState(() {
      _isPressed = true;
});These steps can be hard to imagine for developers who haven’t worked with Flutter for long. Consider the following complete example for better understanding.
Example
App preview:

The code:
import 'package:flutter/material.dart';
void main() {
  runApp(const MyApp());
}
class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      // Hide the debug banner
      debugShowCheckedModeBanner: false,
      title: 'Kindacode.com',
      home: HomePage(),
    );
  }
}
class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);
  @override
  State<HomePage> createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
  // This variable determines whether the button is disable or not
  bool _isPressed = false;
  // This function is called when the button gets pressed
  void _myCallback() {
    setState(() {
      _isPressed = true;
    });
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Kindacode.com'),
        ),
        body: Center(
            child: ElevatedButton(
          onPressed: _isPressed == false ? _myCallback : null,
          child: const Text('I Am A Button'),
        )));
  }
}That’s it. Further reading:
- Flutter: Creating Custom Back Buttons
 - Working with ElevatedButton in Flutter
 - Flutter: Text with Read More / Read Less Buttons
 - Flutter: Create a Button with a Loading Indicator Inside
 - Working with OutlinedButton in Flutter
 - 4 Ways to Create Full-Width Buttons in Flutter
 
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