# Runnable Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) # Runnable ``` @FunctionalInterface interface Runnable ``` |------------------------------------------------------------------------------------------| | [java.lang.Runnable](https://developer.android.com/reference/kotlin/java/lang/Runnable#) | 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| Known Direct Subclasses [AnimationDrawable](https://developer.android.com/reference/kotlin/android/graphics/drawable/AnimationDrawable.html#),[CookieSyncManager](https://developer.android.com/reference/kotlin/android/webkit/CookieSyncManager.html#),[RenderScript.RSErrorHandler](https://developer.android.com/reference/kotlin/android/renderscript/RenderScript.RSErrorHandler.html#),[RenderScript.RSMessageHandler](https://developer.android.com/reference/kotlin/android/renderscript/RenderScript.RSMessageHandler.html#),[RunnableFuture](https://developer.android.com/reference/kotlin/java/util/concurrent/RunnableFuture.html#),[Thread](https://developer.android.com/reference/kotlin/java/lang/Thread),[TimerTask](https://developer.android.com/reference/kotlin/java/util/TimerTask.html#) |------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [AnimationDrawable](https://developer.android.com/reference/kotlin/android/graphics/drawable/AnimationDrawable.html#) | An object used to create frame-by-frame animations, defined by a series of Drawable objects, which can be used as a View object's background. | | [CookieSyncManager](https://developer.android.com/reference/kotlin/android/webkit/CookieSyncManager.html#) | The CookieSyncManager is used to synchronize the browser cookie store between RAM and permanent storage. | | [RenderScript.RSErrorHandler](https://developer.android.com/reference/kotlin/android/renderscript/RenderScript.RSErrorHandler.html#) | The runtime error handler base class. | | [RenderScript.RSMessageHandler](https://developer.android.com/reference/kotlin/android/renderscript/RenderScript.RSMessageHandler.html#) | The base class from which an application should derive in order to receive RS messages from scripts. | | [RunnableFuture](https://developer.android.com/reference/kotlin/java/util/concurrent/RunnableFuture.html#) | A[Future](https://developer.android.com/reference/kotlin/java/util/concurrent/Future.html#)that is[Runnable](https://developer.android.com/reference/kotlin/java/lang/Runnable#). | | [Thread](https://developer.android.com/reference/kotlin/java/lang/Thread) | A*thread*is a thread of execution in a program. | | [TimerTask](https://developer.android.com/reference/kotlin/java/util/TimerTask.html#) | A task that can be scheduled for one-time or repeated execution by a[Timer](https://developer.android.com/reference/kotlin/java/util/Timer.html#). | | 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| Known Indirect Subclasses [ForkJoinWorkerThread](https://developer.android.com/reference/kotlin/java/util/concurrent/ForkJoinWorkerThread.html#),[FutureTask](https://developer.android.com/reference/kotlin/java/util/concurrent/FutureTask.html#),[HandlerThread](https://developer.android.com/reference/kotlin/android/os/HandlerThread.html#),[RunnableScheduledFuture](https://developer.android.com/reference/kotlin/java/util/concurrent/RunnableScheduledFuture.html#) |------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [ForkJoinWorkerThread](https://developer.android.com/reference/kotlin/java/util/concurrent/ForkJoinWorkerThread.html#) | A thread managed by a[ForkJoinPool](https://developer.android.com/reference/kotlin/java/util/concurrent/ForkJoinPool.html#), which executes[ForkJoinTask](https://developer.android.com/reference/kotlin/java/util/concurrent/ForkJoinTask.html#)s. | | [FutureTask](https://developer.android.com/reference/kotlin/java/util/concurrent/FutureTask.html#) | A cancellable asynchronous computation. | | [HandlerThread](https://developer.android.com/reference/kotlin/android/os/HandlerThread.html#) | A[Thread](https://developer.android.com/reference/kotlin/java/lang/Thread)that has a[Looper](https://developer.android.com/reference/kotlin/android/os/Looper.html#). | | [RunnableScheduledFuture](https://developer.android.com/reference/kotlin/java/util/concurrent/RunnableScheduledFuture.html#) | A[ScheduledFuture](https://developer.android.com/reference/kotlin/java/util/concurrent/ScheduledFuture.html#)that is[Runnable](https://developer.android.com/reference/kotlin/java/lang/Runnable#). | | The`Runnable`interface should be implemented by any class whose instances are intended to be executed by a thread. The class must define a method of no arguments called`run`. This interface is designed to provide a common protocol for objects that wish to execute code while they are active. For example,`Runnable`is implemented by class`Thread`. Being active simply means that a thread has been started and has not yet been stopped. In addition,`Runnable`provides the means for a class to be active while not subclassing`Thread`. A class that implements`Runnable`can run without subclassing`Thread`by instantiating a`Thread`instance and passing itself in as the target. In most cases, the`Runnable`interface should be used if you are only planning to override the`run()`method and no other`Thread`methods. This is important because classes should not be subclassed unless the programmer intends on modifying or enhancing the fundamental behavior of the class. ## Summary | Public methods || |--------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | abstract[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [run](https://developer.android.com/reference/kotlin/java/lang/Runnable#run())`()` When an object implementing interface`Runnable`is used to create a thread, starting the thread causes the object's`run`method to be called in that separately executing thread. | ## Public methods ### run Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` abstract fun run(): Unit ``` When an object implementing interface`Runnable`is used to create a thread, starting the thread causes the object's`run`method to be called in that separately executing thread. The general contract of the method`run`is that it may take any action whatsoever. **See Also** - [java.lang.Thread#run()](https://developer.android.com/reference/kotlin/java/lang/Thread#run())