How To Change Flutter Textformfield Focused Border Width [Easy Flutter Guide]

In this tutorial, we’ll learn what Flutter textformfield focused border width is and how to properly change it. We’ll be using practical Flutter code examples for better understanding.

Introduction: Flutter Textformfield Focused Border Width

It specifies the thickness/height of border line of Flutter textformfield widget when the textformfield is focused. In our post, we’ll use the word ‘width‘ to specify the thickness/height of border line. Let’s first see its default width/thickness and after that, we’ll customize it practically.

Default Focused Border Width

For that, we’ll implement a simple Flutter textformfield widget. By default, the textformfield is assigned with underline border which we’ll see in the below image after our code gets executed. See below code:

TextFormField()

The above image shows the default Flutter textformfield focused border width. Let’s now see how to changes its width/thickness.

Change Flutter Textformfield Focused Border Width

• In order to do that, we’ve to use the decoration constructor of textformfield widget class and pass it input decoration.
• After that, we’ll use the focused border constructor of input decoration and pass it underline input border as we are currently customizing the underline border width.
• Finally, we’ve to use the border side constructor of underline input border and pass it border side widget and then by using its width constructor, we can easily customize its width. This constructor takes a double(decimal) value but passing it integer will also work just fine. For demonstration, we’ve passed it a value 3. See below code:

TextFormField(
        decoration: InputDecoration(
            focusedBorder: UnderlineInputBorder(
                borderSide: BorderSide(
                     width: 3))),
      )

As we can see that Flutter textformfield focused border width is successfully customized.

See below code if you want to change the outline border width of textformfield.

TextFormField(
      decoration: InputDecoration(
          focusedBorder: OutlineInputBorder(
              borderSide: BorderSide(
                   width: 4))),
      )

So this is how we can easily change Flutter textformfield focused border width.

Click here if you are interested in learning the color customization of Flutter textfield focused border width.

The complete source code of custom focused border width is given in the below section.

Custom Flutter Textformfield Focused Border Width Source Code

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: Homepage(),
    );
  }
}
class Homepage extends StatefulWidget {
  @override
  State<Homepage> createState() => _HomepageState();
}
class _HomepageState extends State<Homepage> {
  @override
  Widget build(BuildContext context) {
    return SafeArea(
        child: Scaffold(
            body: Center(
                child: Padding(
      padding: const EdgeInsets.all(20),
      child: TextFormField(
        decoration: InputDecoration(
            focusedBorder: UnderlineInputBorder(
                borderSide: BorderSide( width: 3))),
      ),
    ))));
  }
}