[Solved][Flutter] This requires the 'non-nullable' language feature to be enabled. Try updating your pubspec.yaml to set the minimum SDK constraint to 2.12.0 or higher, and running 'pub get'.

Last Updated on 2021-10-15 by Clay

The code after the dart version upgrade needs to enable the so-called Null-Safety to compile. If the code disable Null-Safety, the following error will occur:

Last Updated on 2021-10-14 by Clay

If you have a requirement for plotting a pie chart when you developing via Flutter, I can recommend a useful plotting package: fl_chart.

Last Updated on 2021-10-14 by Clay

The Row and Column in Flutter can make our components display a horizontal or vertical layout, which are very important layout forms.