builder property Null safety

InteractiveViewerWidgetBuilder? builder
final

Builds the child of this widget.

Passed with the InteractiveViewer.builder constructor. Otherwise, the child parameter must be passed directly, and this is null.

link
This example shows how to use builder to create a Table whose cell contents are only built when they are visible. Built and remove cells are logged in the console for illustration.
To create a local project with this code sample, run:
flutter create --sample=widgets.InteractiveViewer.builder.1 mysample

See also:

Implementation

final InteractiveViewerWidgetBuilder? builder;