hu.akarnokd.reactive4java.base

Class Option<T>

java.lang.Object

hu.akarnokd.reactive4java.base.Option<T>

Type Parameters:

T - the type of the contained object

Direct Known Subclasses:

Option.Error, Option.None, Option.Some

public abstract class Option<T>
extends java.lang.Object

A class representing a value, an exception or nothing. These classes are used by materialize and dematerialize operators.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Option.Error<T> Class representing an error option.
static class	Option.None<T> The helper class representing an option holding nothing.
static class	Option.Some<T> A helper class representing an option holding something of T.

Constructor Summary

Constructors

Constructor and Description
Option()

Method Summary

Modifier and Type	Method and Description
static <T> Option.Error<T>	error(java.lang.Throwable t) Create an error instance with the given Throwable.
static java.lang.Throwable	getError(Option<?> o) Extracts the error value from the option.
boolean	hasError()
boolean	hasValue()
static boolean	isError(Option<?> o) Returns true if the option is of type Error.
boolean	isNone()
static boolean	isNone(Option<?> o) Returns true if the option is of type None.
static boolean	isSome(Option<?> o) Returns true if the option is of type Some.
static <T> Option.None<T>	none() Returns a none of T.
static <T> Option.Some<T>	some(T value) Create a new Some instance with the supplied value.
abstract T	value()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Option

public Option()

Method Detail

value

public abstract T value()

Returns:

query for the value.

hasValue

public boolean hasValue()

Returns:

true if this option has a value (not error).

Since:

0.97

hasError

public boolean hasError()

Returns:

true if this option has an error (not value).

Since:

0.97

isNone

public boolean isNone()

Returns:

true if this option is empty.

Since:

0.97

none

@Nonnull
public static <T> Option.None<T> none()

Returns a none of T.

Type Parameters:

T - the type of the T

Returns:

the None of T

some

@Nonnull
public static <T> Option.Some<T> some(T value)

Create a new Some instance with the supplied value.

Type Parameters:

T - the value type

Parameters:

value - the initial value

Returns:

the some object

error

@Nonnull
public static <T> Option.Error<T> error(@Nonnull
                                                  java.lang.Throwable t)

Create an error instance with the given Throwable.

Type Parameters:

T - the element type, irrelevant

Parameters:

t - the throwable

Returns:

the error instance

isError

public static boolean isError(@Nullable
                              Option<?> o)

Returns true if the option is of type Error.

Parameters:

o - the option

Returns:

true if the option is of type Error.

isNone

public static boolean isNone(@Nullable
                             Option<?> o)

Returns true if the option is of type None.

Parameters:

o - the option

Returns:

true if the option is of type None.

isSome

public static boolean isSome(@Nullable
                             Option<?> o)

Returns true if the option is of type Some.

Parameters:

o - the option

Returns:

true if the option is of type Some.

getError

@Nonnull
public static java.lang.Throwable getError(Option<?> o)

Extracts the error value from the option. It throws an IllegalArgumentException if o is not an Error instance.

Parameters:

o - the option to get the error from

Returns:

the inner throwable