[android-components](../index.md) / [mozilla.components.lib.state](index.md) / [Observer](./-observer.md)

# Observer

`typealias Observer<S> = (`[`S`](-observer.md#S)`) -> `[`Unit`](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) [(source)](https://github.com/mozilla-mobile/android-components/blob/master/components/lib/state/src/main/java/mozilla/components/lib/state/Store.kt#L25)

Listener called when the state changes in the [Store](-store/index.md).

