Continuation

public interface Continuation

A function that is called to continue execution after completion of a Task.

Public Method Summary

abstract R
then(Task<T> task)
Returns the result of applying this Continuation to task.

Public Methods

public abstract R then (Task<T> task)

Returns the result of applying this Continuation to task.

To propagate failure from the completed Task call getResult() and allow the RuntimeExecutionException to propagate. The RuntimeExecutionException will be unwrapped such that the Task returned by continueWith(Continuation) or continueWithTask(Continuation) fails with the original exception.

To suppress specific failures call getResult(Class) and catch the exception types of interest:

 task.continueWith(new Continuation<String, String>() {
 @Override
 public String then(Task<String> task) {
 try {
 return task.getResult(IOException.class);
 } catch (FileNotFoundException e) {
 return "Not found";
 } catch (IOException e) {
 return "Read failed";
 }
 }
 }
 

To suppress all failures guard any calls to getResult() with isSuccessful():

 task.continueWith(new Continuation<String, String>() {
 @Override
 public String then(Task<String> task) {
 if (task.isSuccessful()) {
 return task.getResult();
 } else {
 return DEFAULT_VALUE;
 }
 }
 }
 

Parameters
task the completed Task. Never null
Throws
Exception if the result couldn't be produced

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