How to fix 'Text is null' in flutter

Question

I want to create an app which has a TabBarView with two tabs. On the first Tab there is a Textfield and on the other tab there is a text widget which should display the text which you entered into Textfield but I always get an error because text is null.( I'm new in programming with flutter)

I tried to initialize the variable in TextOutput class but it didn't work because the variable is final.

TabBarView(
      children: <Widget>[
        TextCreatePage(), TextOutput()
      ],




class TextCreatePageState extends State<TextCreatePage> {
String textvalue;
@override
Widget build(BuildContext context) {
  return Center(child: TextField(
    onChanged: (String value) {
    setState(() {
       textvalue = value;
       TextOutput(textvalue: textvalue,);
            });





class TextOutput extends StatelessWidget {
final String textvalue;

TextOutput({this.textvalue});
@override
Widget build(BuildContext context) {
    return Text(textvalue); 
}
}

Hector Aguero · Answer 1 · 2021-03-27T17:16:12.510

So, for anyone that search this and got here, I'm using this to manage null String variables.

1. Show Empty Text

String nullText; //for null-safety change to: String? nullText;

//now, inside of your widget build
Text(nullText ?? '');

2. Not show Text Widget

String nullText;

//now, inside of your widget build
if(nullText != null)
 Text(nullText);

with null-safety

String? nullText;

//now, inside of your widget build
if(nullText != null)
 Text(nullText!);

Also you can show like this, but this show the null word

String nullText; //for null-safety change to String? nullText;

//now, inside of your widget build
Text('$nullText');

Live Example https://dartpad.dev/faab5bc3c2df9573c0a75a5ce3d4b4b9

score 3 · Answer 2 · answered Jan 27 '19 at 13:21

3

It's not clear from the information your provided in your question what code causes the error, but I guess it is this line:

return Text(textvalue);

If you change it to

return textvalue != null ? Text(textvalue) : Container();

your error should go away.

answered Jan 27 '19 at 13:21

Günter Zöchbauer

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I think it is a problem with the textvalue variable in Textoutput and the constructor because textvalue always is null. – Cl_Rtg08 Jan 27 '19 at 20:07
Dorsn't look this way. – Günter Zöchbauer Jan 27 '19 at 20:08
Hard to tell from here. – Günter Zöchbauer Jan 28 '19 at 15:02
Ok, i tested some things and now I know where the error is but I don't know how to fix it. The error is probably at the constructor in the TextCreatePageState class. – Cl_Rtg08 Jan 28 '19 at 15:36
The code in your question doesn't contain such a constructor. – Günter Zöchbauer Jan 28 '19 at 15:37
I meant the TextOutput(textvalue: textvalue); – Cl_Rtg08 Jan 28 '19 at 15:47
I don't see anything wrong with it. Should be easy to debug though. – Günter Zöchbauer Jan 28 '19 at 15:49
When I use Navigator.push(context, MaterialPageRoute(builder: (BuildContext context) => TextOutput(textvalue: textvalue2,))); everything works ? – Cl_Rtg08 Jan 29 '19 at 06:04

score 0 · Answer 3 · answered Feb 17 '22 at 03:14

Hector Aguero's answer is what I've been doing to workaround the error.

I use this everywhere:

Text(nullText ?? '');

But I wonder what's stopping Flutter team to make Text() widget support null value?

// This should be acceptable and simply not rendering any text
// why they don't allow this is beyond me
Text(nullText);

How to fix 'Text is null' in flutter

3 Answers3