kotlin-stdlib/kotlin/Result

Result

@JvmInline
value class Result<out T> : Serializable(source)

A discriminated union that encapsulates a successful outcome with a value of type T or a failure with an arbitrary Throwable exception.

Since Kotlin

1.3

Types

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object Companion

Companion object for Result class that contains its constructor functions success and failure.

Functions

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fun exceptionOrNull(): Throwable?

Returns the encapsulated Throwable exception if this instance represents failure or null if it is success.

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inline fun getOrNull(): T?

Returns the encapsulated value if this instance represents success or null if it is failure.

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open override fun toString(): String

Returns a string Success(v) if this instance represents success where v is a string representation of the value or a string Failure(x) if it is failure where x is a string representation of the exception.

Properties

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val isFailure: Boolean

Returns true if this instance represents a failed outcome. In this case isSuccess returns false.

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val isSuccess: Boolean

Returns true if this instance represents a successful outcome. In this case isFailure returns false.

Extensions

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inline fun <R, T> Result<T>.fold(onSuccess: (value: T) -> R, onFailure: (exception: Throwable) -> R): R

Returns the result of onSuccess for the encapsulated value if this instance represents success or the result of onFailure function for the encapsulated Throwable exception if it is failure.

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inline fun <R, T : R> Result<T>.getOrDefault(defaultValue: R): R

Returns the encapsulated value if this instance represents success or the defaultValue if it is failure.

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inline fun <R, T : R> Result<T>.getOrElse(onFailure: (exception: Throwable) -> R): R

Returns the encapsulated value if this instance represents success or the result of onFailure function for the encapsulated Throwable exception if it is failure.

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inline fun <T> Result<T>.getOrThrow(): T

Returns the encapsulated value if this instance represents success or throws the encapsulated Throwable exception if it is failure.

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inline fun <R, T> Result<T>.map(transform: (value: T) -> R): Result<R>

Returns the encapsulated result of the given transform function applied to the encapsulated value if this instance represents success or the original encapsulated Throwable exception if it is failure.

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inline fun <R, T> Result<T>.mapCatching(transform: (value: T) -> R): Result<R>

Returns the encapsulated result of the given transform function applied to the encapsulated value if this instance represents success or the original encapsulated Throwable exception if it is failure.

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inline fun <T> Result<T>.onFailure(action: (exception: Throwable) -> Unit): Result<T>

Performs the given action on the encapsulated Throwable exception if this instance represents failure. Returns the original Result unchanged.

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inline fun <T> Result<T>.onSuccess(action: (value: T) -> Unit): Result<T>

Performs the given action on the encapsulated value if this instance represents success. Returns the original Result unchanged.

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inline fun <R, T : R> Result<T>.recover(transform: (exception: Throwable) -> R): Result<R>

Returns the encapsulated result of the given transform function applied to the encapsulated Throwable exception if this instance represents failure or the original encapsulated value if it is success.

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inline fun <R, T : R> Result<T>.recoverCatching(transform: (exception: Throwable) -> R): Result<R>

Returns the encapsulated result of the given transform function applied to the encapsulated Throwable exception if this instance represents failure or the original encapsulated value if it is success.