A - the possibly successful expression resultpublic abstract class Try<A> extends Object implements MonadError<Throwable,A,Try<?>>, MonadRec<A,Try<?>>, Traversable<A,Try<?>>, CoProduct2<Throwable,A,Try<A>>
Monad of the evaluation outcome of an expression that might throw. Try/catch/finally semantics map to
trying/catching/ensuring, respectively.Either| Modifier and Type | Method and Description |
|---|---|
Try<A> |
catchError(Fn1<? super Throwable,? extends Monad<A,Try<?>>> recoveryFn)
|
<S extends Throwable> |
catching(Class<S> throwableType,
Fn1<? super S,? extends A> recoveryFn)
Catch any instance of
throwableType and map it to a success value. |
Try<A> |
catching(Fn1<? super Throwable,? extends Boolean> predicate,
Fn1<? super Throwable,? extends A> recoveryFn)
Catch any thrown
T satisfying predicate and map it to a success value. |
<B> Try<B> |
discardL(Applicative<B,Try<?>> appB)
Sequence both this
Applicative and appB, discarding this Applicative's
result and returning appB. |
<B> Try<A> |
discardR(Applicative<B,Try<?>> appB)
Sequence both this
Applicative and appB, discarding appB's result and
returning this Applicative. |
Try<A> |
ensuring(SideEffect sideEffect)
Run the provided runnable regardless of whether this is a success or a failure (the
Try analog to
finally. |
static <A> Try<A> |
failure(Throwable t)
Static factory method for creating a failure value.
|
<B> Try<B> |
flatMap(Fn1<? super A,? extends Monad<B,Try<?>>> f)
Chain dependent computations that may continue or short-circuit based on previous results.
|
<B> Try<B> |
fmap(Fn1<? super A,? extends B> fn)
Covariantly transmute this functor's parameter using the given mapping function.
|
Throwable |
forfeit(Fn1<? super A,? extends Throwable> fn)
If this is a failure, return the wrapped value.
|
<B> Lazy<Try<B>> |
lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,Try<?>>> lazyAppFn)
Given a
lazy instance of this applicative over a mapping function, "zip" the two instances together
using whatever application semantics the current applicative supports. |
<T extends Throwable> |
orThrow()
If this is a success value, return it.
|
abstract <T extends Throwable> |
orThrow(Fn1<? super Throwable,? extends T> fn)
If this is a success value, return it.
|
<B> Try<B> |
pure(B b)
Lift the value
b into this applicative functor. |
static Pure<Try<?>> |
pureTry()
|
A |
recover(Fn1<? super Throwable,? extends A> fn)
If this is a success, return the wrapped value.
|
static <A> Try<A> |
success(A a)
Static factory method for creating a success value.
|
Try<A> |
throwError(Throwable throwable)
Throw an error value of type
E into the monad. |
Either<Throwable,A> |
toEither()
If this is a success, wrap the value in a
Either.right(R) and return it. |
<L> Either<L,A> |
toEither(Fn1<? super Throwable,? extends L> fn)
If this is a success, wrap the value in a
Either.right(R) and return it. |
Maybe<A> |
toMaybe()
If this is a success, wrap the value in a
Maybe.just(A) and return it. |
<B> Try<B> |
trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,Try<?>>> fn)
Given some operation yielding a
RecursiveResult inside this MonadRec, internally trampoline the
operation until it yields a termination instruction. |
<B,App extends Applicative<?,App>,TravB extends Traversable<B,Try<?>>,AppTrav extends Applicative<TravB,App>> |
traverse(Fn1<? super A,? extends Applicative<B,App>> fn,
Fn1<? super TravB,? extends AppTrav> pure)
Apply
fn to each element of this traversable from left to right, and collapse the results into
a single resulting applicative, potentially with the assistance of the applicative's pure function. |
static <A> Try<A> |
trying(Fn0<? extends A> supplier)
|
static Try<Unit> |
trying(SideEffect sideEffect)
|
static <A extends AutoCloseable,B extends AutoCloseable,C extends AutoCloseable,D> |
withResources(Fn0<? extends A> fn0,
Fn1<? super A,? extends B> bFn,
Fn1<? super B,? extends C> cFn,
Fn1<? super C,? extends Try<? extends D>> fn)
Convenience overload of
withResources that
cascades
two dependent resource creations via nested calls. |
static <A extends AutoCloseable,B extends AutoCloseable,C> |
withResources(Fn0<? extends A> fn0,
Fn1<? super A,? extends B> bFn,
Fn1<? super B,? extends Try<? extends C>> fn)
Convenience overload of
withResources that cascades dependent resource
creation via nested calls. |
static <A extends AutoCloseable,B> |
withResources(Fn0<? extends A> fn0,
Fn1<? super A,? extends Try<? extends B>> fn)
Given a
aSupplier and an Fn1
fn, apply fn to the result of aSupplier, ensuring that the result has its
close method invoked, regardless of the outcome. |
<B> Try<B> |
zip(Applicative<Fn1<? super A,? extends B>,Try<?>> appFn)
Given another instance of this applicative over a mapping function, "zip" the two instances together using
whatever application semantics the current applicative supports.
|
public final <S extends Throwable> Try<A> catching(Class<S> throwableType, Fn1<? super S,? extends A> recoveryFn)
throwableType and map it to a success value.public final Try<A> catching(Fn1<? super Throwable,? extends Boolean> predicate, Fn1<? super Throwable,? extends A> recoveryFn)
T satisfying predicate and map it to a success value.public final Try<A> ensuring(SideEffect sideEffect)
Try analog to
finally.
If the runnable runs successfully, the result is preserved as is. If the runnable itself throws, and the result
was a success, the result becomes a failure over the newly-thrown Throwable. If the result was a failure
over some Throwable t1, and the runnable throws a new Throwable t2, the
result is a failure over t1 with t2 added to t1 as a suppressed exception.
public final A recover(Fn1<? super Throwable,? extends A> fn)
Throwable to fn and
return the result.fn - the function mapping the potential Throwable T to Apublic final Throwable forfeit(Fn1<? super A,? extends Throwable> fn)
fn and return
the result.fn - the function mapping the potential A to Tpublic final <T extends Throwable> A orThrow() throws T extends Throwable
T - a declarable exception type used for catching checked exceptionsT - anything that the call site may want to explicitly catch or indicate could be thrownT extends Throwablepublic abstract <T extends Throwable> A orThrow(Fn1<? super Throwable,? extends T> fn) throws T extends Throwable
fn and throw
the result.public final Maybe<A> toMaybe()
Maybe.just(A) and return it. Otherwise, return Maybe.nothing().Maybe the success valuepublic final Either<Throwable,A> toEither()
Either.right(R) and return it. Otherwise, return the Throwable in an Either.left(L).public final <L> Either<L,A> toEither(Fn1<? super Throwable,? extends L> fn)
Either.right(R) and return it. Otherwise, apply the mapping
function to the failure Throwable, re-wrap it in an Either.left(L), and return it.public Try<A> throwError(Throwable throwable)
E into the monad.throwError in interface MonadError<Throwable,A,Try<?>>throwable - the error typemonadpublic Try<A> catchError(Fn1<? super Throwable,? extends Monad<A,Try<?>>> recoveryFn)
catchError in interface MonadError<Throwable,A,Try<?>>recoveryFn - the catch functionMonadpublic <B> Try<B> fmap(Fn1<? super A,? extends B> fn)
fmap in interface Applicative<A,Try<?>>fmap in interface Functor<A,Try<?>>fmap in interface Monad<A,Try<?>>fmap in interface MonadError<Throwable,A,Try<?>>fmap in interface MonadRec<A,Try<?>>fmap in interface Traversable<A,Try<?>>B - the new parameter typefn - the mapping functionpublic <B> Try<B> flatMap(Fn1<? super A,? extends Monad<B,Try<?>>> f)
flatMap in interface Monad<A,Try<?>>flatMap in interface MonadError<Throwable,A,Try<?>>flatMap in interface MonadRec<A,Try<?>>B - the resulting monad parameter typef - the dependent computation over Apublic <B> Try<B> pure(B b)
b into this applicative functor.pure in interface Applicative<A,Try<?>>pure in interface Monad<A,Try<?>>pure in interface MonadError<Throwable,A,Try<?>>pure in interface MonadRec<A,Try<?>>B - the type of the returned applicative's parameterb - the valuepublic <B> Try<B> zip(Applicative<Fn1<? super A,? extends B>,Try<?>> appFn)
zip in interface Applicative<A,Try<?>>zip in interface Monad<A,Try<?>>zip in interface MonadError<Throwable,A,Try<?>>zip in interface MonadRec<A,Try<?>>B - the resulting applicative parameter typeappFn - the other applicative instancepublic <B> Lazy<Try<B>> lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,Try<?>>> lazyAppFn)
lazy instance of this applicative over a mapping function, "zip" the two instances together
using whatever application semantics the current applicative supports. This is useful for applicatives that
support lazy evaluation and early termination.lazyZip in interface Applicative<A,Try<?>>lazyZip in interface Monad<A,Try<?>>lazyZip in interface MonadError<Throwable,A,Try<?>>lazyZip in interface MonadRec<A,Try<?>>B - the resulting applicative parameter typelazyAppFn - the lazy other applicative instanceMaybe,
Eitherpublic <B> Try<B> discardL(Applicative<B,Try<?>> appB)
Applicative and appB, discarding this Applicative's
result and returning appB. This is generally useful for sequentially performing side-effects.discardL in interface Applicative<A,Try<?>>discardL in interface Monad<A,Try<?>>discardL in interface MonadError<Throwable,A,Try<?>>discardL in interface MonadRec<A,Try<?>>B - the type of the returned Applicative's parameterappB - the other Applicativepublic <B> Try<A> discardR(Applicative<B,Try<?>> appB)
Applicative and appB, discarding appB's result and
returning this Applicative. This is generally useful for sequentially performing side-effects.discardR in interface Applicative<A,Try<?>>discardR in interface Monad<A,Try<?>>discardR in interface MonadError<Throwable,A,Try<?>>discardR in interface MonadRec<A,Try<?>>B - the type of appB's parameterappB - the other Applicativepublic <B> Try<B> trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,Try<?>>> fn)
RecursiveResult inside this MonadRec, internally trampoline the
operation until it yields a termination instruction.
Stack-safety depends on implementations guaranteeing that the growth of the call stack is a constant factor independent of the number of invocations of the operation. For various examples of how this can be achieved in stereotypical circumstances, see the referenced types.
trampolineM in interface MonadRec<A,Try<?>>B - the ultimate resulting carrier typefn - the function to internally trampolineMonadRecfor a basic implementation,
for a {@link CoProduct2 coproduct} implementation,
for an implementation leveraging an already stack-safe {@link Monad#flatMap(Fn1)},
for a {@link MonadT monad transformer} implementationpublic <B,App extends Applicative<?,App>,TravB extends Traversable<B,Try<?>>,AppTrav extends Applicative<TravB,App>> AppTrav traverse(Fn1<? super A,? extends Applicative<B,App>> fn, Fn1<? super TravB,? extends AppTrav> pure)
fn to each element of this traversable from left to right, and collapse the results into
a single resulting applicative, potentially with the assistance of the applicative's pure function.traverse in interface Traversable<A,Try<?>>B - the resulting element typeApp - the result applicative typeTravB - this Traversable instance over BAppTrav - the full inferred resulting type from the traversalfn - the function to applypure - the applicative pure functionpublic static <A> Try<A> success(A a)
A - the success parameter typea - the wrapped valuepublic static <A> Try<A> failure(Throwable t)
A - the success parameter typet - the Throwablepublic static Try<Unit> trying(SideEffect sideEffect)
public static <A extends AutoCloseable,B> Try<B> withResources(Fn0<? extends A> fn0, Fn1<? super A,? extends Try<? extends B>> fn)
Fn0<AutoCloseable>aSupplier and an Fn1
fn, apply fn to the result of aSupplier, ensuring that the result has its
close method invoked, regardless of the outcome.
If the resource creation process throws, the function body throws, or the
close method throws, the result is a failure. If both the function body and the
close method throw, the result is a failure over the function body
Throwable with the close method Throwable added as a
suppressed Throwable. If only the
close method throws, the result is a failure over that Throwable.
Note that withResources calls can be nested, in which case all of the above specified exception
handling applies, where closing the previously created resource is considered part of the body of the next
withResources calls, and Throwables are considered suppressed in the same manner.
Additionally, close methods are invoked in the inverse order of resource creation.
This is Try's equivalent of
try-with-resources, introduced in Java 7.
A - the resource typeB - the function return typefn0 - the resource supplierfn - the function bodyTry representing the result of the function's application to the resourcepublic static <A extends AutoCloseable,B extends AutoCloseable,C> Try<C> withResources(Fn0<? extends A> fn0, Fn1<? super A,? extends B> bFn, Fn1<? super B,? extends Try<? extends C>> fn)
withResources that cascades dependent resource
creation via nested calls.A - the first resource typeB - the second resource typeC - the function return typefn0 - the first resource supplierbFn - the dependent resource functionfn - the function bodyTry representing the result of the function's application to the dependent resourcepublic static <A extends AutoCloseable,B extends AutoCloseable,C extends AutoCloseable,D> Try<D> withResources(Fn0<? extends A> fn0, Fn1<? super A,? extends B> bFn, Fn1<? super B,? extends C> cFn, Fn1<? super C,? extends Try<? extends D>> fn)
withResources that
cascades
two dependent resource creations via nested calls.A - the first resource typeB - the second resource typeC - the final resource typeD - the function return typefn0 - the first resource supplierbFn - the second resource functioncFn - the final resource functionfn - the function bodyTry representing the result of the function's application to the final dependent resource