Pagecontroller.page cannot be accessed before a pageview is built with it

When encountering the error “pagecontroller.page cannot be accessed before a pageview is built with it,” it usually means that you are trying to access properties or methods of a PageController instance before it has been initialized or before the associated PageView has been created.

In Flutter, the PageController class is commonly used to control navigation and page scrolling in a PageView. To properly access pagecontroller.page, you need to ensure that the PageController is initialized and a PageView associated with it has been created.

Here’s an example to demonstrate the usage of PageController:

  import 'package:flutter/material.dart';

  class MyPage extends StatefulWidget {
    @override
    _MyPageState createState() => _MyPageState();
  }

  class _MyPageState extends State {
    PageController _pageController;
    int _currentPage = 0;

    @override
    void initState() {
      super.initState();
      _pageController = PageController(initialPage: _currentPage);
    }

    @override
    void dispose() {
      _pageController.dispose();
      super.dispose();
    }

    @override
    Widget build(BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: Text('Example Page'),
        ),
        body: PageView(
          controller: _pageController,
          onPageChanged: (int page) {
            setState(() {
              _currentPage = page;
            });
          },
          children: [
            Container(
              color: Colors.red,
              child: Center(
                child: Text('Page 1'),
              ),
            ),
            Container(
              color: Colors.blue,
              child: Center(
                child: Text('Page 2'),
              ),
            ),
            Container(
              color: Colors.green,
              child: Center(
                child: Text('Page 3'),
              ),
            ),
          ],
        ),
      );
    }
  }

  void main() {
    runApp(MaterialApp(
      home: MyPage(),
    ));
  }
  

In this example, we create a simple Flutter application with a PageView that contains three pages. The PageController is initialized in the ‘initState’ method and associated with the PageView. The current page is stored in the ‘_currentPage’ variable, which is updated whenever the page changes using the ‘onPageChanged’ callback.

This ensures that the PageController is properly initialized and that pagecontroller.page can be safely accessed within the context of the PageView.

Remember to dispose of the PageController in the ‘dispose’ method to avoid any memory leaks.

I hope this explanation helps you understand how to resolve the “pagecontroller.page cannot be accessed before a pageview is built with it” error in Flutter.