Flutter: How to Fully Print a Long String/List/Map

If you’re running a Flutter with an iOS simulator or an Android emulator by using the following command:

flutter run

Then you’ll notice that whenever you print out a long string, list, map, or JSON data to the terminal with the print() or debugPrint() function, the output is truncated to 1000 character length and is followed by <>, like this:

So how do we print the full string/list/map without trimming anything? The solution is to print out each chunk of 1000 characters sequentially until the end. We can define a reusable function for this by using a loop in combination with the substring() method, as follows:

// kindacode.com
void myLongPrint(input) {
  String str = input.toString();

  // print out each chunk of 1000 characters sequentially
  while (str.length > 1000) {
    debugPrint(str.substring(0, 1000));

    // remove the first 1000 characters
    str = str.substring(1000);
  }

  // print the remaining characters
  debugPrint(str);
}

Full example:

// main.dart
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 MaterialApp(
      // Remove the debug banner
      debugShowCheckedModeBanner: false,
      title: 'KindaCode.com',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
        useMaterial3: true,
      ),
      home: const HomeScreen(),
    );
  }
}

class HomeScreen extends StatefulWidget {
  const HomeScreen({Key? key}) : super(key: key);

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

// define our reusable function
void myLongPrint(input) {
  String str = input.toString();

  // print out each chunk of 1000 characters sequentially
  while (str.length > 1000) {
    debugPrint(str.substring(0, 1000));

    // remove the first 1000 characters
    str = str.substring(1000);
  }

  // print the remaining characters
  debugPrint(str);
}

class _HomeScreenState extends State<HomeScreen> {
  final List _dummyList = List.generate(10000, (index) => "Item $index");

  @override
  void initState() {
    myLongPrint(_dummyList);
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('KindaCode.com')),
    );
  }
}

Screenshot:

Note that if you want to print out a big thing, it’ll take time.

Further reading:

• Flutter BottomAppBar: Tutorial & Examples
• Flutter and Firestore Database: CRUD example
• Flutter + Firebase Storage: Upload, Retrieve, and Delete files
• Flutter: Creating Transparent/Translucent App Bars
• Flutter SliverAppBar Example (with Explanations)
• Working with ListWheelScrollView in Flutter (2 Examples)

You can also tour around our Flutter topic page or Dart topic page for the most recent tutorials and examples.