Question 75294 in Flutter Question posted in
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Flutter: The screen is not updating

I have a problem in flutter when I add a new element to the list and I call setState, the list is updated but the screen is not.
I tried calling the setState after addText() but it doesn’t work also.

This is my code:

import 'package:flutter/material.dart';

class TestScreen extends StatefulWidget {
  @override
  _TestScreenState createState() => _TestScreenState();
}

class _TestScreenState extends State<TestScreen> {
  List<Widget> testList = [
    Text('data'),
  ];

  void addText() {
    setState(() {
      testList.add(
        Text('data'),
      );
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      resizeToAvoidBottomInset: true,
      body: SafeArea(
        child: Column(
          children: [
            Expanded(
              child: ListView(
                children: testList,
              ),
            ),
            ElevatedButton(
                onPressed: () {
                  setState(() {
                    addText();
                  });
                },
                child: Text('Click'))
          ],
        ),
      ),
    );
  }
}
Tags:

2

Answers


  1. 0

    You can use listView like this

    ListView.builder(
  shrinkWrap: true,
  itemCount: testList.length,
  itemBuilder(context, index) {
    return testList[index];
  }
)

void addText() {
      testList.add(
        Text('data'),
      );
  }
    Login or Signup to reply.
  2. 0

    Your bug is because of calling setState twice, there is no need to call it in addText():

    import 'package:flutter/material.dart';

class TestScreen extends StatefulWidget {
  @override
  _TestScreenState createState() => _TestScreenState();
}

class _TestScreenState extends State<TestScreen> {
  List<Widget> testList = [
    Text('data'),
  ];

  void addText() {
    testList.add(
      Text('data'),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      resizeToAvoidBottomInset: true,
      body: SafeArea(
        child: Column(
          children: [
            Expanded(
              child: ListView(
                children: testList,
              ),
            ),
            ElevatedButton(
              onPressed: () {
                setState(() {
                  addText();
                });
              },
              child: Text('Click'),
            ),
          ],
        ),
      ),
    );
  }
}

    happy coding…

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