TaskCompletionSource

Kotlin |Java

class TaskCompletionSource<TResult>

Provides the ability to create Task-based APIs.

Use a TaskCompletionSource to set a result or exception on a Task returned from an asynchronous API:

public class MarcoPolo {
  public static Task<String> marco(int delay) {
    TaskCompletionSource<String> taskCompletionSource = new TaskCompletionSource<>();

    new Handler().postDelayed(() -> taskCompletionSource.setResult("polo"), delay);

    return taskCompletionSource.getTask();
  }
}

And then your APIs can be used as any other Task-consuming APIs:

public class MyActivity extends Activity {
  @Override
  public void onStart() {
    super.onStart();

    marco(1000).addOnCompleteListener(
        task -> Log.d(TAG, "got message after one second: " + task.getResult()));
  }
}

Summary

Public constructors
`TaskCompletionSource()` Creates an instance of `TaskCompletionSource`.
`TaskCompletionSource(cancellationToken: CancellationToken)` Creates an instance of `TaskCompletionSource` with a `CancellationToken` so that the Task can be set to canceled when `CancellationToken` is canceled.

Public functions
`Task<TResult!>`	`getTask()` Returns the Task.
`Unit`	`setException(e: Exception)` Completes the Task with the specified exception.
`Unit`	`setResult(result: TResult?)` Completes the Task with the specified result.
`Boolean`	`trySetException(e: Exception)` Completes the Task with the specified exception, unless the Task has already completed.
`Boolean`	`trySetResult(result: TResult?)` Completes the Task with the specified result, unless the Task has already completed.

Public constructors

TaskCompletionSource

TaskCompletionSource()

Creates an instance of TaskCompletionSource.

TaskCompletionSource

TaskCompletionSource(cancellationToken: CancellationToken)

Creates an instance of TaskCompletionSource with a CancellationToken so that the Task can be set to canceled when CancellationToken is canceled.

Public functions

getTask

fun getTask(): Task<TResult!>

Returns the Task.

setException

fun setException(e: Exception): Unit

Completes the Task with the specified exception.

Throws
`java.lang.IllegalStateException`	if the Task is already complete

setResult

fun setResult(result: TResult?): Unit

Completes the Task with the specified result.

Throws
`java.lang.IllegalStateException`	if the Task is already complete

trySetException

fun trySetException(e: Exception): Boolean

Completes the Task with the specified exception, unless the Task has already completed. If the Task has already completed, the call does nothing.

Returns
`Boolean`	`true` if the exception was set successfully, `false` otherwise

trySetResult

fun trySetResult(result: TResult?): Boolean

Completes the Task with the specified result, unless the Task has already completed. If the Task has already completed, the call does nothing.

Returns
`Boolean`	`true` if the result was set successfully, `false` otherwise