Overview
Result<F, S> is a sealed interface that represents either a successful outcome (Success<F, S>) or a failure (Failure<F, S>). It provides a functional approach to error handling without exceptions.
Package: com.softwarearchetypes.common
Source: /common/src/main/java/com/softwarearchetypes/common/Result.java:14
Type Parameters
The type of the failure value
The type of the success value
Creating Results
success
static <F, S> Result<F, S> success(S value)
The success value to wrap
A Result in success state
Result<String, Integer> result = Result.success(42);
assert result.success(); // true
assert result.getSuccess() == 42;
failure
static <F, S> Result<F, S> failure(F value)
The failure value to wrap
A Result in failure state
Result<String, Integer> result = Result.failure("Error occurred");
assert result.failure(); // true
assert result.getFailure().equals("Error occurred");
State Checking
success
default boolean success()
true if success, false if failure
failure
default boolean failure()
true if failure, false if success
getSuccess
Extracts the success value.
Throws: IllegalStateException if called on a failure Result.
getFailure
Extracts the failure value.
Throws: IllegalStateException if called on a success Result.
default <R> Result<F, R> map(Function<? super S, ? extends R> mapper)
mapper
Function<? super S, ? extends R>
required
Function to transform the success value. Must not be null.
Result with transformed success value, or original failure
Result<String, Integer> result = Result.<String, Integer>success(10)
.map(val -> "Value: " + (val * 2));
assert result.getSuccess().equals("Value: 20");
mapFailure
default <L> Result<L, S> mapFailure(Function<? super F, ? extends L> mapper)
mapper
Function<? super F, ? extends L>
required
Function to transform the failure value. Must not be null.
Result with transformed failure value, or original success
Result<String, Integer> result = Result.<Integer, Integer>failure(404)
.mapFailure(code -> "Error " + code + ": Not Found");
assert result.getFailure().equals("Error 404: Not Found");
default <L, R> Result<L, R> biMap(
Function<? super S, ? extends R> successMapper,
Function<? super F, ? extends L> failureMapper
)
successMapper
Function<? super S, ? extends R>
required
Function to transform the success value. Must not be null.
failureMapper
Function<? super F, ? extends L>
required
Function to transform the failure value. Must not be null.
Result with transformed value
Result<Integer, Integer> result = Result.success(1);
Result<String, String> mapped = result.biMap(
val -> String.valueOf(val * 2),
val -> ""
);
assert mapped.getSuccess().equals("2");
flatMap
default <R> Result<F, R> flatMap(Function<S, Result<F, R>> mapping)
mapping
Function<S, Result<F, R>>
required
Function that returns a new Result. Must not be null.
Result from the mapping function, or original failure
Result<String, Integer> result = Result.<String, Integer>success(5)
.flatMap(val -> Result.success(val * 2));
assert result.getSuccess() == 10;
// With failure
Result<String, Integer> failed = Result.<String, Integer>success(5)
.flatMap(val -> Result.failure("Validation failed"));
assert failed.failure();
Side Effects
default Result<F, S> peek(
Consumer<? super S> successConsumer,
Consumer<? super F> failureConsumer
)
successConsumer
Consumer<? super S>
required
Consumer to execute on success. Must not be null.
failureConsumer
Consumer<? super F>
required
Consumer to execute on failure. Must not be null.
peekSuccess
default Result<F, S> peekSuccess(Consumer<? super S> successConsumer)
successConsumer
Consumer<? super S>
required
Consumer to execute on success. Must not be null.
peekFailure
default Result<F, S> peekFailure(Consumer<? super F> failureConsumer)
failureConsumer
Consumer<? super F>
required
Consumer to execute on failure. Must not be null.
Folding and Combining
default <U> U fold(
Function<? super F, ? extends U> leftMapper,
Function<? super S, ? extends U> rightMapper
)
leftMapper
Function<? super F, ? extends U>
required
Function to apply to failure value. Must not be null.
rightMapper
Function<? super S, ? extends U>
required
Function to apply to success value. Must not be null.
The result of applying the appropriate mapper
Integer result = Result.<String, Integer>success(10)
.fold(error -> -1, val -> val * 3);
assert result == 30;
Integer failureResult = Result.<String, Integer>failure("Error")
.fold(String::length, val -> val * 3);
assert failureResult == 5;
ifSuccessOrElse
default <R> R ifSuccessOrElse(
Function<S, R> successMapping,
Function<F, R> failureMapping
)
Function to apply on success. Must not be null.
Function to apply on failure. Must not be null.
The result of applying the appropriate mapping function
combine
default <FAILURE, SUCCESS> Result<FAILURE, SUCCESS> combine(
Result<F, S> secondResult,
BiFunction<F, F, FAILURE> failureCombiner,
BiFunction<S, S, SUCCESS> successCombiner
)
The Result to combine with. Must not be null.
failureCombiner
BiFunction<F, F, FAILURE>
required
Function to combine failure values. Must not be null.
successCombiner
BiFunction<S, S, SUCCESS>
required
Function to combine success values. Must not be null.
Result<Integer, Integer> first = Result.success(5);
Result<Integer, Integer> second = Result.success(10);
Result<Integer, Integer> combined = first.combine(
second,
(val1, val2) -> val1 - val2,
Integer::sum
);
assert combined.getSuccess() == 15;
Composite Results
composite
static <F, S> CompositeResult<F, S> composite()
accumulate() to progressively build up a Result containing multiple values.
CompositeResult with empty list
compositeSet
static <F, S> CompositeSetResult<F, S> compositeSet()
accumulate() to progressively build up a Result containing multiple unique values.
CompositeSetResult with empty set
CompositeResult
Helper class for accumulating multiple Results into a List with fail-fast semantics.
accumulate
public CompositeResult<F, S> accumulate(Result<F, S> newResult)
The Result to accumulate. Must not be null.
CompositeResult with accumulated values or failure
Result<String, List<Integer>> result = Result.<String, Integer>composite()
.accumulate(Result.success(1))
.accumulate(Result.success(2))
.accumulate(Result.success(3))
.toResult();
assert result.success();
assert result.getSuccess().equals(List.of(1, 2, 3));
// Fail-fast behavior
Result<String, List<Integer>> failed = Result.<String, Integer>composite()
.accumulate(Result.success(1))
.accumulate(Result.failure("Error occurred"))
.accumulate(Result.success(3))
.toResult();
assert failed.failure();
assert failed.getFailure().equals("Error occurred");
success
Checks if this composite is in success state.
true if success, false if failure
failure
Checks if this composite is in failure state.
true if failure, false if success
toResult
public Result<F, List<S>> toResult()
Result containing either a list of all successes or the first failure
CompositeSetResult
Helper class for accumulating multiple Results into a Set with fail-fast semantics. Automatically removes duplicates.
accumulate
public CompositeSetResult<F, S> accumulate(Result<F, S> newResult)
The Result to accumulate. Must not be null.
CompositeSetResult with accumulated values or failure
Result<String, Set<Integer>> result = Result.<String, Integer>compositeSet()
.accumulate(Result.success(1))
.accumulate(Result.success(2))
.accumulate(Result.success(1)) // Duplicate removed
.accumulate(Result.success(3))
.toResult();
assert result.success();
assert result.getSuccess().equals(Set.of(1, 2, 3));
success
Checks if this composite is in success state.
true if success, false if failure
failure
Checks if this composite is in failure state.
true if failure, false if success
toResult
public Result<F, Set<S>> toResult()
Result containing either a set of all successes or the first failure
