Rename MaterialState to WidgetState

What changed?

`MaterialState`, and its related APIs, have been moved out of the Material library and renamed to `WidgetState`.

Will this affect my application?

Who is affected: Applications and packages relying on the previous behaviour or signature. Code that uses MaterialState, WidgetState, MaterialStatePropertyResolver and related APIs.
Practical impact: Behaviour or API differences that can break builds or change runtime behaviour.
What action should I take?: Follow the official migration guide below, update affected call sites, run `dart fix --apply` where a fix is available, then run your tests.

APIs mentioned:MaterialState WidgetState MaterialStatePropertyResolver WidgetStatePropertyResolver MaterialStateColor WidgetStateColor MaterialStateMouseCursor WidgetStateColorMouseCursor MaterialStateBorderSide WidgetStateBorderSide MaterialStateOutlinedBorder WidgetStateOutlinedBorder

How do I migrate safely?

Before and after (from the official guide)

dart+7−7

Before

1	−	MaterialState selected = MaterialState.selected;
2
3	−	final MaterialStateProperty<Color> backgroundColor;
4
5	−	class _MouseCursor extends MaterialStateMouseCursor{
6		const _MouseCursor(this.resolveCallback);
7
8	−	final MaterialPropertyResolver<MouseCursor?> resolveCallback;
9
10		@override
11	−	MouseCursor resolve(Set<MaterialState> states) => resolveCallback(states) ?? MouseCursor.uncontrolled;
12		}
13
14	−	BorderSide side = MaterialStateBorderSide.resolveWith((Set<MaterialState> states) {
15	−	if (states.contains(MaterialState.selected)) {
16		return const BorderSide(color: Colors.red);
17		}
18		return null;
19		});

After

1	+	WidgetState selected = WidgetState.selected;
2
3	+	final WidgetStateProperty<Color> backgroundColor;
4
5	+	class _MouseCursor extends WidgetStateMouseCursor{
6		const _MouseCursor(this.resolveCallback);
7
8	+	final WidgetPropertyResolver<MouseCursor?> resolveCallback;
9
10		@override
11	+	MouseCursor resolve(Set<WidgetState> states) => resolveCallback(states) ?? MouseCursor.uncontrolled;
12		}
13
14	+	BorderSide side = WidgetStateBorderSide.resolveWith((Set<WidgetState> states) {
15	+	if (states.contains(WidgetState.selected)) {
16		return const BorderSide(color: Colors.red);
17		}
18		return null;
19		});

Raw before / after

MaterialState selected = MaterialState.selected;

final MaterialStateProperty<Color> backgroundColor;

class _MouseCursor extends MaterialStateMouseCursor{
  const _MouseCursor(this.resolveCallback);

  final MaterialPropertyResolver<MouseCursor?> resolveCallback;

  @override
  MouseCursor resolve(Set<MaterialState> states) => resolveCallback(states) ?? MouseCursor.uncontrolled;
}

BorderSide side = MaterialStateBorderSide.resolveWith((Set<MaterialState> states) {
  if (states.contains(MaterialState.selected)) {
    return const BorderSide(color: Colors.red);
  }
  return null;
});

WidgetState selected = WidgetState.selected;

final WidgetStateProperty<Color> backgroundColor;

class _MouseCursor extends WidgetStateMouseCursor{
  const _MouseCursor(this.resolveCallback);

  final WidgetPropertyResolver<MouseCursor?> resolveCallback;

  @override
  MouseCursor resolve(Set<WidgetState> states) => resolveCallback(states) ?? MouseCursor.uncontrolled;
}

BorderSide side = WidgetStateBorderSide.resolveWith((Set<WidgetState> states) {
  if (states.contains(WidgetState.selected)) {
    return const BorderSide(color: Colors.red);
  }
  return null;
});

Official migration guide (excerpt, © The Flutter Authors, CC BY 3.0)

A [Flutter fix][] is available to help migrate the MaterialState classes to WidgetState.

To migrate, replace MaterialState with WidgetState.

Code before migration:

MaterialState selected = MaterialState.selected;

final MaterialStateProperty&#x3C;Color> backgroundColor;

class _MouseCursor extends MaterialStateMouseCursor{
  const _MouseCursor(this.resolveCallback);

  final MaterialPropertyResolver&#x3C;MouseCursor?> resolveCallback;

  @override
  MouseCursor resolve(Set&#x3C;MaterialState> states) => resolveCallback(states) ?? MouseCursor.uncontrolled;
}

BorderSide side = MaterialStateBorderSide.resolveWith((Set&#x3C;MaterialState> states) {
  if (states.contains(MaterialState.selected)) {
    return const BorderSide(color: Colors.red);
  }
  return null;
});

Code after migration:

WidgetState selected = WidgetState.selected;

final WidgetStateProperty&#x3C;Color> backgroundColor;

class _MouseCursor extends WidgetStateMouseCursor{
  const _MouseCursor(this.resolveCallback);

  final WidgetPropertyResolver&#x3C;MouseCursor?> resolveCallback;

  @override
  MouseCursor resolve(Set&#x3C;WidgetState> states) => resolveCallback(states) ?? MouseCursor.uncontrolled;
}

BorderSide side = WidgetStateBorderSide.resolveWith((Set&#x3C;WidgetState> states) {
  if (states.contains(WidgetState.selected)) {
    return const BorderSide(color: Colors.red);
  }
  return null;
});

Migration assistantAI-generated · grounded in cited sources

AI explanations are not configured

Set AI_PROVIDER (for example to openai-compatible with a local Ollama or LM Studio endpoint) to enable grounded explanations. Everything else on this page works without an AI provider.

Evidence & verification

Official migration guide·Verified classification (95%)

Listed in the official breaking-changes index (docs.flutter.dev/release/breaking-changes).

An official announcement or migration guide documents an intended behaviour or API change. A verified source change (git diff) shows code changed but does not by itself prove a public API is breaking. AI interpretations are labelled and never used to classify a change.

Validation warnings

api-symbols: {"reason":"no referenced symbol found in the current API index","unresolved":["MaterialState","WidgetState","MaterialStatePropertyResolver","WidgetStatePropertyResolver","MaterialStateColor","WidgetStateColor","MaterialStateMouseCursor","WidgetStateColorMouseCursor","MaterialStateBorderSide","WidgetStateBorderSide","MaterialStateOutlinedBorder","WidgetStateOutlinedBorder","MaterialStateTextStyle","WidgetStateTextStyle","MaterialStateProperty","WidgetStateProperty","MaterialStatePropertyAll","WidgetStatePropertyAll","MaterialStatesController","WidgetStatesController","MaterialStateOutlineInputBorder","MaterialStateUnderlineInputBorder"]}

Source commit: b3045439b7c0
Source last updated: Oct 21, 2026
Last synchronized: Oct 21, 2026
Publication status: published

Publication history

Oct 21, 2026, 8:31 PM: new → published (ingestion) — Backed by an official breaking-change/migration guide.

AI explanationAI-generated · grounded in cited sources

AI explanations are not configured

Set AI_PROVIDER (for example to openai-compatible with a local Ollama or LM Studio endpoint) to enable grounded explanations. Everything else on this page works without an AI provider.

Was this useful?

RemovedHigh impact3.22.0