How to loop over a list and reset in Dart?

Question

I have a simple question. I have a list of three integers. In my app, I have a floating action button. Each time when button is pressed the 'next' element of list is displayed. I have to reset to the first element once the looping is completed. I achieved this in a hard way;

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  List nums = [1, 2, 3];

  void _incrementCounter() {
    if (_counter <= 1) {
      setState(() {
        _counter++;
      });
    } else {
      setState(() {
        _counter = 0;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Text('${nums[_counter]}'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        child: Icon(Icons.add),
      ),
    );
  }
}

I wish to know if there are some easier ways to achieve this. Thanks in advance for any help.

Mobina · Accepted Answer · 2020-08-17 16:02:07Z

3

You can use remainder (%) to get back to the first index after a loop:

  void _incrementCounter() {
      setState(() {
        _counter = (_counter + 1) % nums.length;
      });
  }

answered Aug 17, 2020 at 16:02

Mobina

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