Flutter - Changing the border color of the OutlineInputBorder

I'm trying to change the border color of the OutlineInputBorder but tried inumerous ways and failed.

I created the whole Theme configuration through the buildDarkTheme() function but I can not change the border color to yellow

Below is the image and the code:

import 'package:flutter/material.dart';

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

const kBlackHalf = const Color(0xFF212121);
const kBlackLight = const Color(0xFF484848);
const kBlack = const Color(0xFF000000);
const kYellow = const Color(0xFFffd600);
const kYellowLight = const Color(0xFFffff52);
const kYellowDark = const Color(0xFFc7a500);
const kWhite = Colors.white;

ThemeData buildDarkTheme() {
  final ThemeData base = ThemeData();
  return base.copyWith(
    primaryColor: kBlack,
    accentColor: kYellow,
    scaffoldBackgroundColor: kBlackHalf,
    primaryTextTheme: buildTextTheme(base.primaryTextTheme, kWhite),
    primaryIconTheme: base.iconTheme.copyWith(color: kWhite),
    buttonColor: kYellow,
    textTheme: buildTextTheme(base.textTheme, kWhite),    
    inputDecorationTheme: InputDecorationTheme(
      border: OutlineInputBorder(
        borderSide: BorderSide(color: kYellow)
      ),
      labelStyle: TextStyle(
        color: kYellow,
        fontSize: 24.0
      ),
    ),
  );
}

TextTheme buildTextTheme(TextTheme base, Color color) {
  return base.copyWith(
    body1: base.headline.copyWith(color: color, fontSize: 16.0),
    caption: base.headline.copyWith(color: color),
    display1: base.headline.copyWith(color: color),
    button: base.headline.copyWith(color: color),
    headline: base.headline.copyWith(color: color),
    title: base.title.copyWith(color: color),
  );
}

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

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => new _HomePageState();
}

class _HomePageState extends State<HomePage> {
  String xp = '0';

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        actions: <Widget>[
          new IconButton(
            icon: Icon(Icons.ac_unit),
            onPressed: () {},
          )
        ],
      ),
      body: new Container(
        padding: new EdgeInsets.only(top: 16.0),
        child: new ListView(
          children: <Widget>[
            new InkWell(
              onTap: () {},
              child: new InputDecorator(
                decoration: new InputDecoration(          
                  labelText: 'XP',
                  border: OutlineInputBorder()
                ),
                child: new Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  mainAxisSize: MainAxisSize.min,
                  children: <Widget>[
                    new Text(this.xp),
                  ],
                ),
              ),
            )
          ],
        ),
      )
    );
  }
}

For more references:

Not able to change TextField Border Color

https://github.com/flutter/flutter/issues/17592

Since July you can now use enabledBorder:

new TextField(
  decoration: new InputDecoration(
    enabledBorder: const OutlineInputBorder(
      // width: 0.0 produces a thin "hairline" border
      borderSide: const BorderSide(color: Colors.grey, width: 0.0),
    ),
    border: const OutlineInputBorder(),
    labelStyle: new TextStyle(color: Colors.green),
    ...
  ),
)

See the full documentation for the new decorators

Add hintColor to your theme like this and it should change the OutlineInputBorder color.

ThemeData buildDarkTheme() {
  final ThemeData base = ThemeData();
  return base.copyWith(
    primaryColor: kBlack,
    accentColor: kYellow,
    scaffoldBackgroundColor: kBlackHalf,
    primaryTextTheme: buildTextTheme(base.primaryTextTheme, kWhite),
    primaryIconTheme: base.iconTheme.copyWith(color: kWhite),
    buttonColor: kYellow,
    hintColor: YOUR_COLOR,
    textTheme: buildTextTheme(base.textTheme, kWhite),    
    inputDecorationTheme: InputDecorationTheme(
      border: OutlineInputBorder(),
      labelStyle: TextStyle(
        color: kYellow,
        fontSize: 24.0
      ),
    ),
  );
}

This is the solution for the mentioned problem use enabledBorder if the TextField is not clicked by the user and use focusedBorder if the TextField is clicked by the user.

 enabledBorder: new OutlineInputBorder(
        borderRadius: new BorderRadius.circular(25.0),
        borderSide:  BorderSide(color: Colors.pinkAccent ),

      ),
      focusedBorder: new OutlineInputBorder(
        borderRadius: new BorderRadius.circular(25.0),
        borderSide:  BorderSide(color: Colors.pinkAccent ),

      ),