layout

Use Expanded when a child must fill its share of a Row or Column, and Flexible when it may be smaller than its share. Measured layouts on Flutter 3.44 show where the leftover space goes, why loose children never donate it to siblings, and when only Flexible survives unbounded constraints.

A widget asked for height: double.infinity inside a parent with no height limit, like a Column or ListView. Use Expanded, a finite height, LimitedBox, or SliverFillRemaining instead.

The official google_mobile_ads sample renders nothing until onAdLoaded, so your content jumps by 150 dp seconds after the screen appears. Ask for the anchored adaptive size first, reserve it with a SizedBox, persist the height across launches, and only then load the ad. Measured on Flutter 3.44.8 with google_mobile_ads 9.1.0.

Targeting Android SDK 35 puts your Flutter app in edge-to-edge mode, so the Scaffold body draws behind the navigation bar. Consume the insets with SafeArea and MediaQuery padding instead of opting out, because the opt-out is already dead on Android 16.

The keyboard shrinks your Scaffold body's max height, so a Column that just fit now overflows. Wrap the body in a scrollable instead of turning resizeToAvoidBottomInset off.

For a long list, never use shrinkWrap. Use Expanded when the list is the only scrollable, and slivers (CustomScrollView) when it shares a scroll with other sections. Here is why, with a build-count benchmark.

Move the color inside the decoration: use decoration: BoxDecoration(color: ...) instead of passing both color and decoration to the same Container.

This error means an Expanded or Flexible is not a direct child of a Row, Column, or Flex. Move it directly under the flex widget, or drop Expanded if the parent is not a flex.

The slivers list of a CustomScrollView only accepts slivers. Wrap box widgets in SliverToBoxAdapter, or swap ListView/Padding/Column for SliverList and SliverPadding.

Put a list and a grid in a single continuous scroll without nested scrollables. Use CustomScrollView with SliverList and SliverGrid, and skip the shrinkWrap trap that quietly kills performance.