(#) Creating an Animatable during composition without using `remember` !!! ERROR: Creating an Animatable during composition without using `remember` This is an error. Id : `UnrememberedAnimatable` Summary : Creating an Animatable during composition without using `remember` Severity : Error Category : Correctness Platform : Any Vendor : Jetpack Compose Identifier : androidx.compose.animation.core Feedback : https://issuetracker.google.com/issues/new?component=612128 Min : Lint 8.0 and 8.1 Compiled : Lint 8.7+ Artifact : [androidx.compose.animation:animation-core-android](androidx_compose_animation_animation-core-android.md.html) Since : 1.5.0 Affects : Kotlin and Java files and test sources Editing : This check runs on the fly in the IDE editor Implementation : [Source Code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/compose/animation/animation-core-lint/src/main/java/androidx/compose/animation/core/lint/UnrememberedAnimatableDetector.kt) Tests : [Source Code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/compose/animation/animation-core-lint/src/test/java/androidx/compose/animation/core/lint/UnrememberedAnimatableDetectorTest.kt) Copyright Year : 2021 Animatable instances created during composition need to be `remember`ed, otherwise they will be recreated during recomposition, and lose their state. Either hoist the Animatable to an object that is not created during composition, or wrap the Animatable in a call to `remember`. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/test/{.kt:12:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable = Animatable<Boolean, Any>(false) ---------- src/test/{.kt:13:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable2 = Animatable(0f) ---------- src/test/{.kt:15:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable3 = Animatable(Color.Red) ---------- src/test/{.kt:20:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable = Animatable<Boolean, Any>(false) ---------- src/test/{.kt:21:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable2 = Animatable(0f) ---------- src/test/{.kt:23:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable3 = Animatable(Color.Red) ---------- src/test/{.kt:28:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable = Animatable<Boolean, Any>(false) ---------- src/test/{.kt:29:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable2 = Animatable(0f) ---------- src/test/{.kt:31:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable3 = Animatable(Color.Red) ---------- src/test/{.kt:41:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable = Animatable<Boolean, Any>(false) ---------- src/test/{.kt:42:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable2 = Animatable(0f) ---------- src/test/{.kt:44:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable3 = Animatable(Color.Red) ---------- src/test/{.kt:48:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable = Animatable<Boolean, Any>(false) ---------- src/test/{.kt:49:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable2 = Animatable(0f) ---------- src/test/{.kt:51:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable3 = Animatable(Color.Red) ---------- src/test/{.kt:58:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable = Animatable<Boolean, Any>(false) ---------- src/test/{.kt:59:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable2 = Animatable(0f) ---------- src/test/{.kt:61:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable3 = Animatable(Color.Red) ---------- src/test/{.kt:66:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable = Animatable<Boolean, Any>(false) ---------- src/test/{.kt:67:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable2 = Animatable(0f) ---------- src/test/{.kt:69:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable3 = Animatable(Color.Red) ---------- src/test/{.kt:77:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable = Animatable<Boolean, Any>(false) ---------- src/test/{.kt:78:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable2 = Animatable(0f) ---------- src/test/{.kt:80:Error: Creating an Animatable during composition without using remember [UnrememberedAnimatable] val animatable3 = Animatable(Color.Red) ---------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `src/test/{.kt`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers package test import androidx.compose.animation.* import androidx.compose.animation.core.* import androidx.compose.runtime.* import androidx.compose.ui.graphics.* @Composable fun Test() { // Float function and constructor from androidx.compose.animation.core val animatable = Animatable(false) val animatable2 = Animatable(0f) // Color function from androidx.compose.animation val animatable3 = Animatable(Color.Red) } val lambda = @Composable { // Float function and constructor from androidx.compose.animation.core val animatable = Animatable(false) val animatable2 = Animatable(0f) // Color function from androidx.compose.animation val animatable3 = Animatable(Color.Red) } val lambda2: @Composable () -> Unit = { // Float function and constructor from androidx.compose.animation.core val animatable = Animatable(false) val animatable2 = Animatable(0f) // Color function from androidx.compose.animation val animatable3 = Animatable(Color.Red) } @Composable fun LambdaParameter(content: @Composable () -> Unit) {} @Composable fun Test2() { LambdaParameter(content = { // Float function and constructor from androidx.compose.animation.core val animatable = Animatable(false) val animatable2 = Animatable(0f) // Color function from androidx.compose.animation val animatable3 = Animatable(Color.Red) }) LambdaParameter { // Float function and constructor from androidx.compose.animation.core val animatable = Animatable(false) val animatable2 = Animatable(0f) // Color function from androidx.compose.animation val animatable3 = Animatable(Color.Red) } } fun test3() { val localLambda1 = @Composable { // Float function and constructor from androidx.compose.animation.core val animatable = Animatable(false) val animatable2 = Animatable(0f) // Color function from androidx.compose.animation val animatable3 = Animatable(Color.Red) } val localLambda2: @Composable () -> Unit = { // Float function and constructor from androidx.compose.animation.core val animatable = Animatable(false) val animatable2 = Animatable(0f) // Color function from androidx.compose.animation val animatable3 = Animatable(Color.Red) } } @Composable fun Test4() { val localObject = object { // Float function and constructor from androidx.compose.animation.core val animatable = Animatable(false) val animatable2 = Animatable(0f) // Color function from androidx.compose.animation val animatable3 = Animatable(Color.Red) } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [source code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/compose/animation/animation-core-lint/src/test/java/androidx/compose/animation/core/lint/UnrememberedAnimatableDetectorTest.kt) for the unit tests for this check to see additional scenarios. The above example was automatically extracted from the first unit test found for this lint check, `UnrememberedAnimatableDetector.notRemembered`. To report a problem with this extracted sample, visit https://issuetracker.google.com/issues/new?component=612128. (##) Including !!! This is not a built-in check. To include it, add the below dependency to your project. ``` // build.gradle.kts implementation("androidx.compose.animation:animation-core-android:1.8.0-alpha07") // build.gradle implementation 'androidx.compose.animation:animation-core-android:1.8.0-alpha07' // build.gradle.kts with version catalogs: implementation(libs.animation.core.android) # libs.versions.toml [versions] animation-core-android = "1.8.0-alpha07" [libraries] # For clarity and text wrapping purposes the following declaration is # shown split up across lines, but in TOML it needs to be on a single # line (see https://github.com/toml-lang/toml/issues/516) so adjust # when pasting into libs.versions.toml: animation-core-android = { module = "androidx.compose.animation:animation-core-android", version.ref = "animation-core-android" } ``` 1.8.0-alpha07 is the version this documentation was generated from; there may be newer versions available. NOTE: These lint checks are **also** made available separate from the main library. You can also use `androidx.compose.animation:animation-core-lint:1.8.0-alpha07`. [Additional details about androidx.compose.animation:animation-core-android](androidx_compose_animation_animation-core-android.md.html). (##) Suppressing You can suppress false positives using one of the following mechanisms: * Using a suppression annotation like this on the enclosing element: ```kt // Kotlin @Suppress("UnrememberedAnimatable") fun method() { problematicStatement() } ``` or ```java // Java @SuppressWarnings("UnrememberedAnimatable") void method() { problematicStatement(); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection UnrememberedAnimatable problematicStatement() ``` * Using a special `lint.xml` file in the source tree which turns off the check in that folder and any sub folder. A simple file might look like this: ```xml <?xml version="1.0" encoding="UTF-8"?> <lint> <issue id="UnrememberedAnimatable" severity="ignore" /> </lint> ``` Instead of `ignore` you can also change the severity here, for example from `error` to `warning`. You can find additional documentation on how to filter issues by path, regular expression and so on [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html). * In Gradle projects, using the DSL syntax to configure lint. For example, you can use something like ```gradle lintOptions { disable 'UnrememberedAnimatable' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore UnrememberedAnimatable ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).