Package com.guinetik.rr.result

Class Result<T,​E>

  • Type Parameters:
    T - the type of the success value
    E - the type of the error value
    public class Result<T,​E>
extends Object
    A container object representing either a successful result or an error.

    Inspired by Rust's Result<T, E> and Scala's Either[L, R], this class provides a functional approach to error handling without exceptions. It forces explicit handling of both success and failure cases, leading to more robust code.

    Creating Results

    
 // Success case
 Result<User, ApiError> success = Result.success(new User("John"));

 // Failure case
 Result<User, ApiError> failure = Result.failure(new ApiError(404, "Not found"));

    Checking and Extracting Values

    
 Result<User, ApiError> result = client.fluent().get("/users/1", User.class);

 if (result.isSuccess()) {
     User user = result.getValue();
     System.out.println("Found: " + user.getName());
 } else {
     ApiError error = result.getError();
     System.err.println("Error: " + error.getMessage());
 }

    Pattern Matching with match()

    
 result.match(
     user -> System.out.println("Success: " + user.getName()),
     error -> System.err.println("Failed: " + error.getMessage())
 );

    Functional Transformations

    
 // Transform the success value
 Result<String, ApiError> nameResult = result.map(user -> user.getName());

 // Transform the error
 Result<User, String> stringError = result.mapError(err -> err.getMessage());

 // Chain operations
 String name = result
     .map(User::getName)
     .map(String::toUpperCase)
     .getOrElse("Unknown");

    Safe Value Extraction

    
 // With default value
 User user = result.getOrElse(User.anonymous());

 // With lazy default
 User user = result.getOrElseGet(() -> loadDefaultUser());

 // Throw on failure
 User user = result.getOrElseThrow(() -> new UserNotFoundException());

 // Unwrap (throws RuntimeException on failure)
 User user = result.unwrap();

 // Convert to Optional
 Optional<User> optional = result.toOptional();
    Since:
    1.0.0
    Author:
    guinetik <guinetik@gmail.com>
    See Also:
    RocketRest.FluentApi, ApiError

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static <T,​E>
      Result<T,​E>      		 failure​(E error)
      Creates a failed Result containing the given error.
      E getError()
      Gets the error contained in this Result.
      T getOrElse​(T defaultValue)
      Gets the value contained in this Result or the given default value if this Result is a failure.
      T getOrElseGet​(Supplier<? extends T> supplier)
      Gets the value contained in this Result or the value supplied by the given Supplier if this Result is a failure.
      <X extends Throwable>
      T      		 getOrElseThrow​(Supplier<? extends X> exceptionSupplier)
      Gets the value contained in this Result or throws the given exception if this Result is a failure.
      T getValue()
      Gets the value contained in this Result.
      Result<T,​E> ifFailure​(Consumer<? super E> consumer)
      Executes the given consumer if this Result is a failure.
      Result<T,​E> ifSuccess​(Consumer<? super T> consumer)
      Executes the given consumer if this Result is a success.
      boolean isFailure()
      Returns whether this Result is a failure.
      boolean isSuccess()
      Returns whether this Result is a success.
      <U> Result<U,​E> map​(Function<? super T,​? extends U> mapper)
      Maps the value of this Result if it's a success, using the given mapping function.
      <F> Result<T,​F> mapError​(Function<? super E,​? extends F> mapper)
      Maps the error of this Result if it's a failure, using the given mapping function.
      Result<T,​E> match​(Consumer<? super T> successConsumer, Consumer<? super E> errorConsumer)
      Pattern-matches over this Result, executing one of the consumers depending on success/failure.
      static <T,​E>
      Result<T,​E>      		 success​(T value)
      Creates a successful Result containing the given value.
      Optional<T> toOptional()
      Converts this Result to an Optional containing the value if this Result is a success, or an empty Optional if this Result is a failure.
      String toString()  
      T unwrap()
      Returns the value if this Result is a success, or unwraps the error by throwing an exception.

    • Method Detail

      • success

        public static <T,​E> Result<T,​E> success​(T value)
        Creates a successful Result containing the given value.
        Type Parameters:
        T - the type of the value
        E - the type of the error
        Parameters:
        value - the value
        Returns:
        a successful Result containing the value

      • failure

        public static <T,​E> Result<T,​E> failure​(E error)
        Creates a failed Result containing the given error.
        Type Parameters:
        T - the type of the value
        E - the type of the error
        Parameters:
        error - the error
        Returns:
        a failed Result containing the error

      • isSuccess

        public boolean isSuccess()
        Returns whether this Result is a success.
        Returns:
        true if this Result is a success, false otherwise

      • isFailure

        public boolean isFailure()
        Returns whether this Result is a failure.
        Returns:
        true if this Result is a failure, false otherwise

      • getValue

        public T getValue()
        Gets the value contained in this Result.
        Returns:
        the value
        Throws:
        NoSuchElementException - if this Result is a failure

      • getError

        public E getError()
        Gets the error contained in this Result.
        Returns:
        the error
        Throws:
        NoSuchElementException - if this Result is a success

      • getOrElse

        public T getOrElse​(T defaultValue)
        Gets the value contained in this Result or the given default value if this Result is a failure.
        Parameters:
        defaultValue - the value to return if this Result is a failure
        Returns:
        the value if this Result is a success, otherwise the default value

      • getOrElseGet

        public T getOrElseGet​(Supplier<? extends T> supplier)
        Gets the value contained in this Result or the value supplied by the given Supplier if this Result is a failure.
        Parameters:
        supplier - the Supplier to provide the default value
        Returns:
        the value if this Result is a success, otherwise the value from the supplier

      • getOrElseThrow

        public <X extends Throwable> T getOrElseThrow​(Supplier<? extends X> exceptionSupplier)
                                       throws X extends Throwable
        Gets the value contained in this Result or throws the given exception if this Result is a failure.
        Type Parameters:
        X - the type of the exception to throw
        Parameters:
        exceptionSupplier - the Supplier to provide the exception to throw
        Returns:
        the value if this Result is a success
        Throws:
        X - if this Result is a failure
        X extends Throwable

      • unwrap

        public T unwrap()
        Returns the value if this Result is a success, or unwraps the error by throwing an exception. This is similar to Rust's unwrap() method.
        Returns:
        the contained value
        Throws:
        RuntimeException - if this is a failure, with the error toString() as the message

      • map

        public <U> Result<U,​E> map​(Function<? super T,​? extends U> mapper)
        Maps the value of this Result if it's a success, using the given mapping function.
        Type Parameters:
        U - the type of the result of the mapping function
        Parameters:
        mapper - the function to apply to the value
        Returns:
        a new Result with the mapped value if this Result is a success, otherwise a new Result with the same error

      • mapError

        public <F> Result<T,​F> mapError​(Function<? super E,​? extends F> mapper)
        Maps the error of this Result if it's a failure, using the given mapping function.
        Type Parameters:
        F - the type of the result of the mapping function
        Parameters:
        mapper - the function to apply to the error
        Returns:
        a new Result with the mapped error if this Result is a failure, otherwise a new Result with the same value

      • ifSuccess

        public Result<T,​E> ifSuccess​(Consumer<? super T> consumer)
        Executes the given consumer if this Result is a success.
        Parameters:
        consumer - the consumer to execute
        Returns:
        this Result

      • ifFailure

        public Result<T,​E> ifFailure​(Consumer<? super E> consumer)
        Executes the given consumer if this Result is a failure.
        Parameters:
        consumer - the consumer to execute
        Returns:
        this Result

      • toOptional

        public Optional<T> toOptional()
        Converts this Result to an Optional containing the value if this Result is a success, or an empty Optional if this Result is a failure.
        Returns:
        an Optional containing the value if this Result is a success, otherwise an empty Optional

      • match

        public Result<T,​E> match​(Consumer<? super T> successConsumer,
                               Consumer<? super E> errorConsumer)
        Pattern-matches over this Result, executing one of the consumers depending on success/failure. 
         result.match(value -> System.out.println(value), err -> log.error(err));
        Parameters:
        successConsumer - runs if this result is a success (receives the value)
        errorConsumer - runs if this result is a failure (receives the error)
        Returns:
        this Result for fluent chaining