Returns whether the promise has already been completed with a value or an exception.
Note: Using this method may result in non-deterministic concurrent programs.
true
if the promise is already completed, false
otherwise
Tries to complete the promise with either a value or the exception.
Note: Using this method may result in non-deterministic concurrent programs.
If the promise has already been completed returns false
, or true
otherwise.
Test two objects for inequality.
true
if !(this == that), false otherwise.
Equivalent to x.hashCode
except for boxed numeric types and null
. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null
returns a hashcode where null.hashCode
throws a NullPointerException
.
a hash value consistent with ==
The expression x == that
is equivalent to if (x eq null) that eq null else x.equals(that)
.
true
if the receiver object is equivalent to the argument; false
otherwise.
Cast the receiver object to be of type T0
.
Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String]
will throw a ClassCastException
at runtime, while the expression List(1).asInstanceOf[List[String]]
will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.
the receiver object.
ClassCastException
if the receiver object is not an instance of the erasure of type T0
.
Create a copy of the receiver object.
The default implementation of the clone
method is platform dependent.
a copy of the receiver object.
Completes the promise with either an exception or a value.
Either the value or the exception to complete the promise with. If the promise has already been fulfilled, failed or has timed out, calling this method will throw an IllegalStateException.
Completes this promise with the specified future, once that future is completed.
This promise
Tests whether the argument (that
) is a reference to the receiver object (this
).
The eq
method implements an equivalence relation on non-null instances of AnyRef
, and has three additional properties:
x
and y
of type AnyRef
, multiple invocations of x.eq(y)
consistently returns true
or consistently returns false
.For any non-null instance x
of type AnyRef
, x.eq(null)
and null.eq(x)
returns false
.
null.eq(null)
returns true
. When overriding the equals
or hashCode
methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2
), they should be equal to each other (o1 == o2
) and they should hash to the same value (o1.hashCode == o2.hashCode
).
true
if the argument is a reference to the receiver object; false
otherwise.
The equality method for reference types. Default implementation delegates to eq
.
See also equals
in scala.Any.
true
if the receiver object is equivalent to the argument; false
otherwise.
Completes the promise with an exception.
The throwable to complete the promise with. If the throwable used to fail this promise is an error, a control exception or an interrupted exception, it will be wrapped as a cause within an ExecutionException
which will fail the promise. If the promise has already been fulfilled, failed or has timed out, calling this method will throw an IllegalStateException.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize
method is invoked, as well as the interaction between finalize
and non-local returns and exceptions, are all platform dependent.
Returns string formatted according to given format
string. Format strings are as for String.format
(@see java.lang.String.format).
Returns the runtime class representation of the object.
a class object corresponding to the runtime type of the receiver.
The hashCode method for reference types. See hashCode in scala.Any.
the hash code value for this object.
Test whether the dynamic type of the receiver object is T0
.
Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String]
will return false
, while the expression List(1).isInstanceOf[List[String]]
will return true
. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.
true
if the receiver object is an instance of erasure of type T0
; false
otherwise.
Equivalent to !(this eq that)
.
true
if the argument is not a reference to the receiver object; false
otherwise.
Wakes up a single thread that is waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Wakes up all threads that are waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Completes the promise with a value.
The value to complete the promise with. If the promise has already been fulfilled, failed or has timed out, calling this method will throw an IllegalStateException.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
a String representation of the object.
Tries to complete the promise with an exception.
Note: Using this method may result in non-deterministic concurrent programs.
If the promise has already been completed returns false
, or true
otherwise.
Tries to complete the promise with a value.
Note: Using this method may result in non-deterministic concurrent programs.
If the promise has already been completed returns false
, or true
otherwise.
© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala/concurrent/Promise.html
Promise is an object which can be completed with a value or failed with an exception.
A promise should always eventually be completed, whether for success or failure, in order to avoid unintended resource retention for any associated Futures' callbacks or transformations.