kotlinx.coroutines.android

Class HandlerDispatcher

kotlinx.coroutines.android.HandlerDispatcher

public class HandlerDispatcher

Dispatches execution onto Android Handler.

This class provides type-safety and a point for future extensions.

See Also:

Handler

Method Summary

Modifier and Type	Method and Description
HandlerDispatcher	getImmediate() Returns dispatcher that executes coroutines immediately when it is already in the right context (current looper is the same as this handler's looper) without an additional re-dispatch. This dispatcher does not use Handler.post when current looper is the same as looper of the handler.

Method Detail

getImmediate

public HandlerDispatcher getImmediate()

Returns dispatcher that executes coroutines immediately when it is already in the right context (current looper is the same as this handler's looper) without an additional re-dispatch. This dispatcher does not use Handler.post when current looper is the same as looper of the handler.

Immediate dispatcher is safe from stack overflows and in case of nested invocations forms event-loop similar to Dispatchers.Unconfined. The event loop is an advanced topic and its implications can be found in Dispatchers.Unconfined documentation.

Example of usage:

suspend fun updateUiElement(val text: String) {
  /*
   * If it is known that updateUiElement can be invoked both from the Main thread and from other threads,
   * `immediate` dispatcher is used as a performance optimization to avoid unnecessary dispatch.
   */
  withContext(Dispatchers.Main.immediate) {
    uiElement.text = text
  }
  // Do context-independent logic such as logging
}

See Also:

re-dispatch, Handler.post, Dispatchers.Unconfined, Dispatchers.Unconfined