Flutter Spacer

Summary: in this tutorial, you’ll learn how to use the flutter Spacer widget to create an adjustable and empty spacer between widgets in a flex container.

Introduction to the Flutter Spacer widget

A Spacer widget creates an adjustable and empty spacer for tuning spacing between child widgets in a flex container like Row and Column.

Because a Spacer widget takes up all available space, setting mainAxisAlignment property on a flex container that contains a Spacer widget to one of the following values will not take any effect:

• spaceAround
• spaceBetween
• spaceEvenly

If a flex container contains multiple Spacer widgets, you can use a flex factor to determine how much space each Spacer can take up. The flex factor is 1 by default.

Flutter Spacer widget example

The following example shows how to use the Row widget to arrange three child widgets in a horizontal array:

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(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: SafeArea(
          child: Row(
            children: [
              Container(
                color: Colors.redAccent,
                height: 50,
                width: 50,
              ),
              Container(
                color: Colors.greenAccent,
                height: 50,
                width: 50,
              ),
              Container(
                color: Colors.blueAccent,
                height: 50,
                width: 50,
              ),
            ],
          ),
        ),
      ),
    );
  }
}
Code language: Dart (dart)

To keep the first widget at the start of the row and push the second and third widgets to the end of the row, you can add a Spacer widget between the first and the second widgets like this:

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(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: SafeArea(
          child: Row(
            children: [
              Container(
                color: Colors.redAccent,
                height: 50,
                width: 50,
              ),
              const Spacer(),
              Container(
                color: Colors.greenAccent,
                height: 50,
                width: 50,
              ),
              Container(
                color: Colors.blueAccent,
                height: 50,
                width: 50,
              ),
            ],
          ),
        ),
      ),
    );
  }
}
Code language: Dart (dart)

To make the space between the first and second widgets twice as the space between the second and the third widgets, you follow these steps:

• First, add another Spacer between the second and third widgets.
• Second, set the flex property of the first Spacer located between the first and second widgets to 2.

For example:

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(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: SafeArea(
          child: Row(
            children: [
              Container(
                color: Colors.redAccent,
                height: 50,
                width: 50,
              ),
              const Spacer(flex: 2),
              Container(
                color: Colors.greenAccent,
                height: 50,
                width: 50,
              ),
              const Spacer(),
              Container(
                color: Colors.blueAccent,
                height: 50,
                width: 50,
              ),
            ],
          ),
        ),
      ),
    );
  }
}
Code language: Dart (dart)

Summary

• Use Flutter Spacer to create an empty and adjustable spacer between the widgets of a flex container.