The ElevatedButton isn't changing the text value

Question

I'm trying to change the value of the text in the button whenever I press it, but it stays the same. Tried using Naviagation.push but I kept getting errors from it so I deleted it off.

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

int myVariableNumber = 0;

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Hello World"),
        backgroundColor: Colors.black,
      ),
      backgroundColor: Colors.black,
      body: Scaffold(
        body: Container(
          alignment: Alignment.center,
          width: 300,
          height: 300,
          color: Colors.white,
          child: SizedBox(
            width: 140,
            height: 70,
            child: ElevatedButton(
              onPressed: () {
                myVariableNumber = myVariableNumber + 1;
                Navigator.push(context, -)
                
              },
              
              child: Text('Hello $myVariableNumber'),
            ),
          ),

        ),
      ),
    );
  }
}

Tried navigation.push and I expected it to refresh and change numbers, but it only gave me errors.

Answer 1

Use setState() method for myVariableNumber.

Answer 2

To update value of this button, you need to rebuild your widget by calling setState method. And move your state into State subclass (in this case is _MyHomePageState).

import 'package:flutter/material.dart';

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int myVariableNumber = 0; // move your state here

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Hello World"),
        backgroundColor: Colors.black,
      ),
      backgroundColor: Colors.black,
      // body: Scaffold( // remove this unnecessary Scaffold
      body: Container(
        alignment: Alignment.center,
        width: 300,
        height: 300,
        color: Colors.white,
        child: SizedBox(
          width: 140,
          height: 70,
          child: ElevatedButton(
            onPressed: () => setState(() { // this will update your widget with new myVariableNumber value
              myVariableNumber = myVariableNumber + 1;
            }),
            child: Text('Hello $myVariableNumber'),
          ),
        ),
      ),
      // ),
    );
  }
}