CompletionStage

public interface CompletionStage

java.util.concurrent.CompletionStage<T>

Known indirect subclasses

CompletableFuture<T> A Future that may be explicitly completed (setting its value and status), and may be used as a CompletionStage, supporting dependent functions and actions that trigger upon its completion.

A stage of a possibly asynchronous computation, that performs an action or computes a value when another CompletionStage completes. A stage completes upon termination of its computation, but this may in turn trigger other dependent stages. The functionality defined in this interface takes only a few basic forms, which expand out to a larger set of methods to capture a range of usage styles:

The computation performed by a stage may be expressed as a Function, Consumer, or Runnable (using methods with names including apply, accept, or run, respectively) depending on whether it requires arguments and/or produces results. For example:
```
 stage.thenApply(x -> square(x))
      .thenAccept(x -> System.out.print(x))
      .thenRun(()
```