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# Null safety Flutter example
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This folder contains a demonstration of the upcoming Dart feature, sound null
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safety. For additional information about this feature, see
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https://dart.dev/null-safety.
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The folder contains two sample Flutter apps:
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* `null_unsafe_app`: This contains a small weather app, which has three null
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errors in its rendering code as a result of not using null safety.
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Try running the app (`flutter run` in a terminal, or the Run action in
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VSCode/Android Studio), and see if the UI works. The null errors are
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sporadic, so try hot reloading a bunch of times and experience the app
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sometimes working and sometimes failing.
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* `null_safe_app`: This contains the same weather app, but this time using
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null safety. There are two copies of the source code:
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`lib/badapp.dart`: This is the same source code as in the unsafe app. Try
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uncommenting the two commented lines of null-unsafe code, and notice how the
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Dart analyzer with null safety immediately flags the lines as unsafe.
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`lib/goodapp.dart`: This a safe version of the unsafe app, with the null
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errors fixed. Read through the comments to see illustrations of how to resolve
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null errors with null safety.
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## Running the example code
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This sample is
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[experimental](https://github.com/flutter/samples/tree/master/experimental), and
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requires using a **beta channel** Flutter SDK. You can change to the beta
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channel with `flutter channel beta` followed by `flutter upgrade` (don't forget
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to change back to `flutter channel stable` for production use.
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