T
- The value type associated with this Promise.@ProviderType public interface Promise<T>
A Promise represents a future value. It handles the interactions for
asynchronous processing. A Deferred
object can be used to create a
Promise and later resolve the Promise. A Promise is used by the caller of an
asynchronous function to get the result or handle the error. The caller can
either get a callback when the Promise is resolved with a value or an error,
or the Promise can be used in chaining. In chaining, callbacks are provided
that receive the resolved Promise, and a new Promise is generated that
resolves based upon the result of a callback.
Both callbacks
and
chaining
can be repeated any number of times,
even after the Promise has been resolved.
Example callback usage:
Promise<String> foo = foo(); foo.onResolve(() -> System.out.println("resolved"));Example chaining usage;
Success<String,String> doubler = p -> Promises .resolved(p.getValue() + p.getValue()); Promise<String> foo = foo().then(doubler).then(doubler);
Modifier and Type | Method and Description |
---|---|
Promise<T> |
delay(long milliseconds)
Delay after the resolution of this Promise.
|
Promise<T> |
fallbackTo(Promise<? extends T> fallback)
Fall back to the value of the specified Promise if this Promise fails.
|
Promise<T> |
filter(Predicate<? super T> predicate)
Filter the value of this Promise.
|
<R> Promise<R> |
flatMap(Function<? super T,Promise<? extends R>> mapper)
FlatMap the value of this Promise.
|
java.lang.Throwable |
getFailure()
Returns the failure of this Promise.
|
T |
getValue()
Returns the value of this Promise.
|
boolean |
isDone()
Returns whether this Promise has been resolved.
|
<R> Promise<R> |
map(Function<? super T,? extends R> mapper)
Map the value of this Promise.
|
Promise<T> |
onFailure(Consumer<? super java.lang.Throwable> failure)
Register a callback to be called with the failure for this Promise when
this Promise is resolved with a failure.
|
Promise<T> |
onResolve(java.lang.Runnable callback)
Register a callback to be called when this Promise is resolved.
|
Promise<T> |
onSuccess(Consumer<? super T> success)
Register a callback to be called with the result of this Promise when
this Promise is resolved successfully.
|
Promise<T> |
recover(Function<Promise<?>,? extends T> recovery)
Recover from a failure of this Promise with a recovery value.
|
Promise<T> |
recoverWith(Function<Promise<?>,Promise<? extends T>> recovery)
Recover from a failure of this Promise with a recovery Promise.
|
<R> Promise<R> |
then(Success<? super T,? extends R> success)
Chain a new Promise to this Promise with a Success callback.
|
<R> Promise<R> |
then(Success<? super T,? extends R> success,
Failure failure)
Chain a new Promise to this Promise with Success and Failure callbacks.
|
Promise<T> |
thenAccept(Consumer<? super T> consumer)
Chain a new Promise to this Promise with a Consumer callback that
receives the value of this Promise when it is successfully resolved.
|
Promise<T> |
timeout(long milliseconds)
Time out the resolution of this Promise.
|
boolean isDone()
This Promise may be successfully resolved or resolved with a failure.
true
if this Promise was resolved either successfully or
with a failure; false
if this Promise is unresolved.T getValue() throws java.lang.reflect.InvocationTargetException, java.lang.InterruptedException
If this Promise is not resolved
, this method must block
and wait for this Promise to be resolved before completing.
If this Promise was successfully resolved, this method returns with the
value of this Promise. If this Promise was resolved with a failure, this
method must throw an InvocationTargetException
with the
failure exception
as the cause.
java.lang.reflect.InvocationTargetException
- If this Promise was resolved with a
failure. The cause of the InvocationTargetException
is
the failure exception.java.lang.InterruptedException
- If the current thread was interrupted while
waiting.java.lang.Throwable getFailure() throws java.lang.InterruptedException
If this Promise is not resolved
, this method must block
and wait for this Promise to be resolved before completing.
If this Promise was resolved with a failure, this method returns with the
failure of this Promise. If this Promise was successfully resolved, this
method must return null
.
null
if this
Promise was successfully resolved.java.lang.InterruptedException
- If the current thread was interrupted while
waiting.Promise<T> onResolve(java.lang.Runnable callback)
The specified callback is called when this Promise is resolved either successfully or with a failure.
This method may be called at any time including before and after this Promise has been resolved.
Resolving this Promise happens-before any registered callback is
called. That is, in a registered callback, isDone()
must return
true
and getValue()
and getFailure()
must not
block.
A callback may be called on a different thread than the thread which registered the callback. So the callback must be thread safe but can rely upon that the registration of the callback happens-before the registered callback is called.
callback
- The callback to be called when this Promise is resolved.
Must not be null
.Promise<T> onSuccess(Consumer<? super T> success)
This method may be called at any time including before and after this Promise has been resolved.
Resolving this Promise happens-before any registered callback is
called. That is, in a registered callback, isDone()
must return
true
and getValue()
and getFailure()
must not
block.
A callback may be called on a different thread than the thread which registered the callback. So the callback must be thread safe but can rely upon that the registration of the callback happens-before the registered callback is called.
success
- The Consumer callback that receives the value of this
Promise. Must not be null
.Promise<T> onFailure(Consumer<? super java.lang.Throwable> failure)
This method may be called at any time including before and after this Promise has been resolved.
Resolving this Promise happens-before any registered callback is
called. That is, in a registered callback, isDone()
must return
true
and getValue()
and getFailure()
must not
block.
A callback may be called on a different thread than the thread which registered the callback. So the callback must be thread safe but can rely upon that the registration of the callback happens-before the registered callback is called.
failure
- The Consumer callback that receives the failure of this
Promise. Must not be null
.<R> Promise<R> then(Success<? super T,? extends R> success, Failure failure)
The specified Success
callback is called when this Promise is
successfully resolved and the specified Failure
callback is
called when this Promise is resolved with a failure.
This method returns a new Promise which is chained to this Promise. The returned Promise must be resolved when this Promise is resolved after the specified Success or Failure callback is executed. The result of the executed callback must be used to resolve the returned Promise. Multiple calls to this method can be used to create a chain of promises which are resolved in sequence.
If this Promise is successfully resolved, the Success callback is executed and the result Promise, if any, or thrown exception is used to resolve the returned Promise from this method. If this Promise is resolved with a failure, the Failure callback is executed and the returned Promise from this method is failed.
This method may be called at any time including before and after this Promise has been resolved.
Resolving this Promise happens-before any registered callback is
called. That is, in a registered callback, isDone()
must return
true
and getValue()
and getFailure()
must not
block.
A callback may be called on a different thread than the thread which registered the callback. So the callback must be thread safe but can rely upon that the registration of the callback happens-before the registered callback is called.
R
- The value type associated with the returned Promise.success
- The Success callback to be called when this Promise is
successfully resolved. May be null
if no Success
callback is required. In this case, the returned Promise must
be resolved with the value null
when this Promise is
successfully resolved.failure
- The Failure callback to be called when this Promise is
resolved with a failure. May be null
if no Failure
callback is required.<R> Promise<R> then(Success<? super T,? extends R> success)
This method performs the same function as calling
then(Success, Failure)
with the specified Success callback and
null
for the Failure callback.
R
- The value type associated with the returned Promise.success
- The Success callback to be called when this Promise is
successfully resolved. May be null
if no Success
callback is required. In this case, the returned Promise must
be resolved with the value null
when this Promise is
successfully resolved.then(Success, Failure)
Promise<T> thenAccept(Consumer<? super T> consumer)
The specified Consumer
is called when this Promise is resolved
successfully.
This method returns a new Promise which is chained to this Promise. The returned Promise must be resolved when this Promise is resolved after the specified callback is executed. If the callback throws an exception, the returned Promise is failed with that exception. Otherwise the returned Promise is resolved with the success value from this Promise.
This method may be called at any time including before and after this Promise has been resolved.
Resolving this Promise happens-before any registered callback is
called. That is, in a registered callback, isDone()
must return
true
and getValue()
and getFailure()
must not
block.
A callback may be called on a different thread than the thread which registered the callback. So the callback must be thread safe but can rely upon that the registration of the callback happens-before the registered callback is called.
consumer
- The Consumer callback that receives the value of this
Promise. Must not be null
.Promise<T> filter(Predicate<? super T> predicate)
If this Promise is successfully resolved, the returned Promise must
either be resolved with the value of this Promise, if the specified
Predicate accepts that value, or failed with a
NoSuchElementException
, if the specified Predicate does not
accept that value. If the specified Predicate throws an exception, the
returned Promise must be failed with the exception.
If this Promise is resolved with a failure, the returned Promise must be failed with that failure.
This method may be called at any time including before and after this Promise has been resolved.
predicate
- The Predicate to evaluate the value of this Promise.
Must not be null
.<R> Promise<R> map(Function<? super T,? extends R> mapper)
If this Promise is successfully resolved, the returned Promise must be resolved with the value of specified Function as applied to the value of this Promise. If the specified Function throws an exception, the returned Promise must be failed with the exception.
If this Promise is resolved with a failure, the returned Promise must be failed with that failure.
This method may be called at any time including before and after this Promise has been resolved.
R
- The value type associated with the returned Promise.mapper
- The Function that must map the value of this Promise to the
value that must be used to resolve the returned Promise. Must not
be null
.<R> Promise<R> flatMap(Function<? super T,Promise<? extends R>> mapper)
If this Promise is successfully resolved, the returned Promise must be resolved with the Promise from the specified Function as applied to the value of this Promise. If the specified Function throws an exception, the returned Promise must be failed with the exception.
If this Promise is resolved with a failure, the returned Promise must be failed with that failure.
This method may be called at any time including before and after this Promise has been resolved.
R
- The value type associated with the returned Promise.mapper
- The Function that must flatMap the value of this Promise to
a Promise that must be used to resolve the returned Promise. Must
not be null
.Promise<T> recover(Function<Promise<?>,? extends T> recovery)
If this Promise is successfully resolved, the returned Promise must be resolved with the value of this Promise.
If this Promise is resolved with a failure, the specified Function is applied to this Promise to produce a recovery value.
null
, the returned Promise must
be resolved with the recovery value.null
, the returned Promise must be
failed with the failure of this Promise.
To recover from a failure of this Promise with a recovery value of
null
, the recoverWith(Function)
method must be used. The
specified Function for recoverWith(Function)
can return
Promises.resolved(null)
to supply the desired null
value.
This method may be called at any time including before and after this Promise has been resolved.
recovery
- If this Promise resolves with a failure, the specified
Function is called to produce a recovery value to be used to
resolve the returned Promise. Must not be null
.Promise<T> recoverWith(Function<Promise<?>,Promise<? extends T>> recovery)
If this Promise is successfully resolved, the returned Promise must be resolved with the value of this Promise.
If this Promise is resolved with a failure, the specified Function is applied to this Promise to produce a recovery Promise.
null
, the returned Promise
must be resolved with the recovery Promise.null
, the returned Promise must be
failed with the failure of this Promise.This method may be called at any time including before and after this Promise has been resolved.
recovery
- If this Promise resolves with a failure, the specified
Function is called to produce a recovery Promise to be used to
resolve the returned Promise. Must not be null
.Promise<T> fallbackTo(Promise<? extends T> fallback)
If this Promise is successfully resolved, the returned Promise must be resolved with the value of this Promise.
If this Promise is resolved with a failure, the successful result of the specified Promise is used to resolve the returned Promise. If the specified Promise is resolved with a failure, the returned Promise must be failed with the failure of this Promise rather than the failure of the specified Promise.
This method may be called at any time including before and after this Promise has been resolved.
fallback
- The Promise whose value must be used to resolve the
returned Promise if this Promise resolves with a failure. Must not
be null
.Promise<T> timeout(long milliseconds)
If this Promise is successfully resolved before the timeout, the returned
Promise is resolved with the value of this Promise. If this Promise is
resolved with a failure before the timeout, the returned Promise is
resolved with the failure of this Promise. If the timeout is reached
before this Promise is resolved, the returned Promise is failed with a
TimeoutException
.
milliseconds
- The time to wait in milliseconds. Zero and negative
time is treated as an immediate timeout.Promise<T> delay(long milliseconds)
Once this Promise is resolved, resolve the returned Promise with this Promise after the specified delay.
milliseconds
- The time to delay in milliseconds. Zero and negative
time is treated as no delay.Copyright © 2010 - 2020 Adobe. All Rights Reserved