Flutter: showDialog: build function returned null
1
I have a StatefulWidget. Then when I click a button, it shows an alert dialog. When I implement:
onTap: () {
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Text("Hello"),
);
}
}
Everything works fine. But when I transfered the things inside the builder to a different StatefulWidget, then this error occurs:
A build function returned null.
I/flutter ( 3647): The offending widget is: Builder
I/flutter ( 3647): Build functions must never return null. To return an empty space that causes the building widget to
I/flutter ( 3647): fill available room, return "new Container()". To return an empty space that takes as little room as
I/flutter ( 3647): possible, return "new Container(width: 0.0, height: 0.0)".
Here is the code:
Here is the calling StatefulWidget:
onTap: () {
showDialog(
context: context,
builder: (BuildContext context) {
LastVacDialog(
currentDose: currDose,
currentDate: currDate,
currentIndex: i,
setValue: changeDoseValueAndDate,
);
},
);
},
Here is the new StatefulWidget:
class LastVacDialog extends StatefulWidget {
LastVacDialog({
this.currentDose,
this.currentDate,
this.setValue,
this.currentIndex,
});
final int currentDose;
final DateTime currentDate;
final void Function(int, DateTime, int) setValue;
final currentIndex;
@override
LastVacDialogState createState() => new LastVacDialogState();
}
class LastVacDialogState extends State<LastVacDialog> {
int _dose;
DateTime _today;
@override
Widget build(BuildContext context) {
return AlertDialog(
title: Text("Last Dose"),
);
}
}
Is there something wrong with my code? I just omitted some variables for simplicity.
dart
flutter asked Nov 27 '18 at 11:16
nypoginypogi
12414
add a comment |
1
I have a StatefulWidget. Then when I click a button, it shows an alert dialog. When I implement:
onTap: () {
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Text("Hello"),
);
}
}
Everything works fine. But when I transfered the things inside the builder to a different StatefulWidget, then this error occurs:
A build function returned null.
I/flutter ( 3647): The offending widget is: Builder
I/flutter ( 3647): Build functions must never return null. To return an empty space that causes the building widget to
I/flutter ( 3647): fill available room, return "new Container()". To return an empty space that takes as little room as
I/flutter ( 3647): possible, return "new Container(width: 0.0, height: 0.0)".
Here is the code:
Here is the calling StatefulWidget:
onTap: () {
showDialog(
context: context,
builder: (BuildContext context) {
LastVacDialog(
currentDose: currDose,
currentDate: currDate,
currentIndex: i,
setValue: changeDoseValueAndDate,
);
},
);
},
Here is the new StatefulWidget:
class LastVacDialog extends StatefulWidget {
LastVacDialog({
this.currentDose,
this.currentDate,
this.setValue,
this.currentIndex,
});
final int currentDose;
final DateTime currentDate;
final void Function(int, DateTime, int) setValue;
final currentIndex;
@override
LastVacDialogState createState() => new LastVacDialogState();
}
class LastVacDialogState extends State<LastVacDialog> {
int _dose;
DateTime _today;
@override
Widget build(BuildContext context) {
return AlertDialog(
title: Text("Last Dose"),
);
}
}
Is there something wrong with my code? I just omitted some variables for simplicity.
dart
flutter asked Nov 27 '18 at 11:16
nypoginypogi
12414
add a comment |
1
1
1
1
I have a StatefulWidget. Then when I click a button, it shows an alert dialog. When I implement:
onTap: () {
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Text("Hello"),
);
}
}
Everything works fine. But when I transfered the things inside the builder to a different StatefulWidget, then this error occurs:
A build function returned null.
I/flutter ( 3647): The offending widget is: Builder
I/flutter ( 3647): Build functions must never return null. To return an empty space that causes the building widget to
I/flutter ( 3647): fill available room, return "new Container()". To return an empty space that takes as little room as
I/flutter ( 3647): possible, return "new Container(width: 0.0, height: 0.0)".
Here is the code:
Here is the calling StatefulWidget:
onTap: () {
showDialog(
context: context,
builder: (BuildContext context) {
LastVacDialog(
currentDose: currDose,
currentDate: currDate,
currentIndex: i,
setValue: changeDoseValueAndDate,
);
},
);
},
Here is the new StatefulWidget:
class LastVacDialog extends StatefulWidget {
LastVacDialog({
this.currentDose,
this.currentDate,
this.setValue,
this.currentIndex,
});
final int currentDose;
final DateTime currentDate;
final void Function(int, DateTime, int) setValue;
final currentIndex;
@override
LastVacDialogState createState() => new LastVacDialogState();
}
class LastVacDialogState extends State<LastVacDialog> {
int _dose;
DateTime _today;
@override
Widget build(BuildContext context) {
return AlertDialog(
title: Text("Last Dose"),
);
}
}
Is there something wrong with my code? I just omitted some variables for simplicity.
dart
flutter asked Nov 27 '18 at 11:16
nypoginypogi
12414
I have a StatefulWidget. Then when I click a button, it shows an alert dialog. When I implement:
onTap: () {
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Text("Hello"),
);
}
}
Everything works fine. But when I transfered the things inside the builder to a different StatefulWidget, then this error occurs:
A build function returned null.
I/flutter ( 3647): The offending widget is: Builder
I/flutter ( 3647): Build functions must never return null. To return an empty space that causes the building widget to
I/flutter ( 3647): fill available room, return "new Container()". To return an empty space that takes as little room as
I/flutter ( 3647): possible, return "new Container(width: 0.0, height: 0.0)".
Here is the code:
Here is the calling StatefulWidget:
onTap: () {
showDialog(
context: context,
builder: (BuildContext context) {
LastVacDialog(
currentDose: currDose,
currentDate: currDate,
currentIndex: i,
setValue: changeDoseValueAndDate,
);
},
);
},
Here is the new StatefulWidget:
class LastVacDialog extends StatefulWidget {
LastVacDialog({
this.currentDose,
this.currentDate,
this.setValue,
this.currentIndex,
});
final int currentDose;
final DateTime currentDate;
final void Function(int, DateTime, int) setValue;
final currentIndex;
@override
LastVacDialogState createState() => new LastVacDialogState();
}
class LastVacDialogState extends State<LastVacDialog> {
int _dose;
DateTime _today;
@override
Widget build(BuildContext context) {
return AlertDialog(
title: Text("Last Dose"),
);
}
}
Is there something wrong with my code? I just omitted some variables for simplicity.
dart
flutter dart
flutter asked Nov 27 '18 at 11:16
nypoginypogi
12414
asked Nov 27 '18 at 11:16
nypoginypogi
12414
asked Nov 27 '18 at 11:16
nypoginypogi
12414
asked Nov 27 '18 at 11:16
nypoginypogi
12414
asked Nov 27 '18 at 11:16
nypoginypogi
12414
12414
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
2
Add the Word Return in Front of - LastVacDialog
builder: (BuildContext context) {
return LastVacDialog(
...
As Error is Stating Build function must never return null. So return your LastVacDialog Widget by adding return in front of it.
answered Nov 27 '18 at 11:24
anmol.majhailanmol.majhail
4,1232320
Thanks! Why does it need the return?
– nypogi
Nov 27 '18 at 11:30
Build Method is a function that creates a widget, & we need to return a value to that which can't be null.
– anmol.majhail
Nov 27 '18 at 11:46
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
draft saved
draft discarded
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53498470%2fflutter-showdialog-build-function-returned-null%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
2
Add the Word Return in Front of - LastVacDialog
builder: (BuildContext context) {
return LastVacDialog(
...
As Error is Stating Build function must never return null. So return your LastVacDialog Widget by adding return in front of it.
answered Nov 27 '18 at 11:24
anmol.majhailanmol.majhail
4,1232320
Thanks! Why does it need the return?
– nypogi
Nov 27 '18 at 11:30
Build Method is a function that creates a widget, & we need to return a value to that which can't be null.
– anmol.majhail
Nov 27 '18 at 11:46
add a comment |
2
Add the Word Return in Front of - LastVacDialog
builder: (BuildContext context) {
return LastVacDialog(
...
As Error is Stating Build function must never return null. So return your LastVacDialog Widget by adding return in front of it.
answered Nov 27 '18 at 11:24
anmol.majhailanmol.majhail
4,1232320
Thanks! Why does it need the return?
– nypogi
Nov 27 '18 at 11:30
Build Method is a function that creates a widget, & we need to return a value to that which can't be null.
– anmol.majhail
Nov 27 '18 at 11:46
add a comment |
2
2
2
Add the Word Return in Front of - LastVacDialog
builder: (BuildContext context) {
return LastVacDialog(
...
As Error is Stating Build function must never return null. So return your LastVacDialog Widget by adding return in front of it.
answered Nov 27 '18 at 11:24
anmol.majhailanmol.majhail
4,1232320
Add the Word Return in Front of - LastVacDialog
builder: (BuildContext context) {
return LastVacDialog(
...
As Error is Stating Build function must never return null. So return your LastVacDialog Widget by adding return in front of it.
answered Nov 27 '18 at 11:24
anmol.majhailanmol.majhail
4,1232320
answered Nov 27 '18 at 11:24
anmol.majhailanmol.majhail
4,1232320
answered Nov 27 '18 at 11:24
anmol.majhailanmol.majhail
4,1232320
answered Nov 27 '18 at 11:24
anmol.majhailanmol.majhail
4,1232320
4,1232320
Thanks! Why does it need the return?
– nypogi
Nov 27 '18 at 11:30
Build Method is a function that creates a widget, & we need to return a value to that which can't be null.
– anmol.majhail
Nov 27 '18 at 11:46
add a comment |
Thanks! Why does it need the return?
– nypogi
Nov 27 '18 at 11:30
Build Method is a function that creates a widget, & we need to return a value to that which can't be null.
– anmol.majhail
Nov 27 '18 at 11:46
Thanks! Why does it need the return?
– nypogi
Nov 27 '18 at 11:30
Thanks! Why does it need the return?
– nypogi
Nov 27 '18 at 11:30
Build Method is a function that creates a widget, & we need to return a value to that which can't be null.
– anmol.majhail
Nov 27 '18 at 11:46
Build Method is a function that creates a widget, & we need to return a value to that which can't be null.
– anmol.majhail
Nov 27 '18 at 11:46
add a comment |
draft saved
draft discarded
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
draft saved
draft discarded
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53498470%2fflutter-showdialog-build-function-returned-null%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
