Either (jnoaber 0.0.3 API)

java.lang.Object
- eu.hanskruse.noaber.Either<E,T>

Type Parameters:

E - {code left} type parameter, typically used for errors.

T - right type parameter, typically used for the value if there is no error.
```
public final class Either<E,T>
extends Object
```
Represents a value of one of two possible types. (a disjoint union.) Instances of Either are either an instance of left or right. This implementation of Either also allows for an empty value, where neither left or @code{right} are set. A common use of Either is as an alternative to exception handling. Convention in other languages, such as Scala, is that left is used for the exception and right for the success.

Author:

kruse@hanskruse.eu

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`static <E1,T1> Either<E1,T1>`	`empty()` Creates an empty `Either`.
`boolean`	`equals(Object obj)`
`Optional<E>`	`filterLeft(Predicate<? super E> predicate)` If a `left` value is present, and the value matches the given predicate, return an `Optional` describing the value, otherwise return an `Optional.empty`.
`Optional<T>`	`filterRight(Predicate<? super T> predicate)` If a `right` value is present, and the value matches the given predicate, return an `Optional` describing the value, otherwise return an `Optional.empty`.
`E`	`getLeft()` Gets the `left` value.
`T`	`getRight()` Gets the right value.
`int`	`hashCode()`
`E`	`ifLeftNotPresent(E other)` Returns provided `other` value if `left` is not present.
`E`	`ifLeftNotPresentGet(Supplier<? extends E> other)` Returns value provided by a `Provider` if `left` is not present.
`<X extends Throwable> E`	`ifLeftNotPresentThrow(Supplier<? extends X> other)` Throw a `Throwable` of type `X` provided by a `Provider` if {code left} is not present.
`void`	`ifLeftPresent(Consumer<? super E> consumer)` If {code left} has a value apply the `Consumer` to the {code left} value.
`T`	`ifRightNotPresent(T other)` Returns provided `other` value if `right` is not present.
`T`	`ifRightNotPresentGet(Supplier<? extends T> other)` Returns value provided by a `Provider` if `right` is not present.
`<X extends Throwable> T`	`ifRightNotPresentThrow(Supplier<? extends X> other)` Throw a `Throwable` of type `X` provided by a `Provider` if {code right} is not present.
`void`	`ifRightPresent(Consumer<? super T> consumer)` If {code right} has a value apply the `Consumer` to the {code right} value.
`boolean`	`isEmpty()` True if neither `left` or `right` are present.
`boolean`	`isLeftPresent()` True if the `left` value is present.
`boolean`	`isRightPresent()` True if the `right` value is present.
`<U> Optional<? extends U>`	`mapLeft(Function<? super E,? extends U> mapper)` If a `left` value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result.
`<U> Optional<? extends U>`	`mapRight(Function<? super T,? extends U> mapper)` If a `right` value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result.
`static <E1,T1> Either<E1,T1>`	`ofLeft(E1 left)` Creates an `Either` with the `left` value set.
`static <E1,T1> Either<E1,T1>`	`ofNullableLeft(E1 left)` Creates an `Either` with the `left` value set.The `left` value may be null.
`static <E1,T1> Either<E1,T1>`	`ofNullableRight(T1 right)` Creates an `Either` with the right value set.
`static <E1,T1> Either<E1,T1>`	`ofRight(T1 right)` Creates an `Either` with the right value set.
`Either<T,E>`	`swap()` Gets a new `Either` with `left` and `right` swapped.
`String`	`toString()`

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait

- Method Detail
  - empty
```
public static <E1,T1> Either<E1,T1> empty()
```
    Creates an empty Either.
    
    Type Parameters:
    
    E1 - left type parameter
    
    T1 - right type parameter
    
    Returns:
    
    Empty Either.
  - ofLeft
```
public static <E1,T1> Either<E1,T1> ofLeft(E1 left)
```
    Creates an Either with the left value set. The left value may not be null.
    
    Type Parameters:
    
    E1 - left type parameter
    
    T1 - right type parameter
    
    Parameters:
    
    left - left value
    
    Returns:
    
    Either with left value set
    
    Throws:
    
    NullPointerException - if left is null
  - ofNullableLeft
```
public static <E1,T1> Either<E1,T1> ofNullableLeft(E1 left)
```
    Creates an Either with the left value set.The left value may be null.
    
    Type Parameters:
    
    E1 - left type parameter.
    
    T1 - right type parameter.
    
    Parameters:
    
    left - left value
    
    Returns:
    
    Either with left value set
  - ofNullableRight
```
public static <E1,T1> Either<E1,T1> ofNullableRight(T1 right)
```
    Creates an Either with the right value set. Right may be null.
    
    Type Parameters:
    
    E1 - left type parameter
    
    T1 - right type parameter
    
    Parameters:
    
    right - right value
    
    Returns:
    
    Either with right value set
  - ofRight
```
public static <E1,T1> Either<E1,T1> ofRight(T1 right)
```
    Creates an Either with the right value set. The right value may not be null.
    
    Type Parameters:
    
    E1 - left type parameter
    
    T1 - right type parameter
    
    Parameters:
    
    right - right value
    
    Returns:
    
    Either with right value set
    
    Throws:
    
    NullPointerException - if right is null
  - equals
```
public boolean equals(Object obj)
```
    Overrides:
    
    equals in class Object
  - filterLeft
```
public Optional<E> filterLeft(Predicate<? super E> predicate)
```
    If a left value is present, and the value matches the given predicate, return an Optional describing the value, otherwise return an Optional.empty.
    
    Parameters:
    
    predicate - Predicate to apply to the left value, if present
    
    Returns:
    
    an Optional describing filtered left value, if a left value is present and the left value matches the given predicate, otherwise an empty Optional
    
    Throws:
    
    NullPointerException - if the predicate is null throw a NullPointerException
  - filterRight
```
public Optional<T> filterRight(Predicate<? super T> predicate)
```
    If a right value is present, and the value matches the given predicate, return an Optional describing the value, otherwise return an Optional.empty.
    
    Parameters:
    
    predicate - to apply to the right value, if present
    
    Returns:
    
    an Optional describing filtered right value, if a right value is present and the right value matches the given predicate, otherwise an empty Optional
    
    Throws:
    
    NullPointerException - if the predicate is null throw a NullPointerException
  - getLeft
```
public E getLeft()
```
    Gets the left value.
    
    Returns:
    
    left left value
    
    Throws:
    
    NoSuchElementException - a NoSuchElementException is thrown when left is not present
  - getRight
```
public T getRight()
```
    Gets the right value.
    
    Returns:
    
    right right value
    
    Throws:
    
    NoSuchElementException - a NoSuchElementException is thrown when right is not present
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - ifLeftNotPresent
```
public E ifLeftNotPresent(E other)
```
    Returns provided other value if left is not present.
    
    Parameters:
    
    other - value to return if left is not present
    
    Returns:
    
    left if left is present else other
  - ifLeftNotPresentGet
```
public E ifLeftNotPresentGet(Supplier<? extends E> other)
```
    Returns value provided by a Provider if left is not present.
    
    Parameters:
    
    other - provider to provide a value to return if left is not present
    
    Returns:
    
    left if left is present else other
    
    Throws:
    
    NullPointerException - throws a NullPointerException if other is null
  - ifLeftNotPresentThrow
```
public <X extends Throwable> E ifLeftNotPresentThrow(Supplier<? extends X> other)
                                              throws X extends Throwable
```
    Throw a Throwable of type X provided by a Provider if {code left} is not present.
    
    Type Parameters:
    
    X - type of the Throwable to throw
    
    Parameters:
    
    other - provider to provide exception to throw if {code left} is not present
    
    Returns:
    
    left if left is present
    
    Throws:
    
    X - Throwable that will be thrown if {code left} is not present
    
    NullPointerException - throws a NullPointerException if other is null
    
    X extends Throwable
  - ifLeftPresent
```
public void ifLeftPresent(Consumer<? super E> consumer)
```
    If {code left} has a value apply the Consumer to the {code left} value.
    
    Parameters:
    
    consumer - left to apply if left is present
    
    Throws:
    
    NullPointerException - throws a NullPointerException if consumer is null
  - ifRightNotPresent
```
public T ifRightNotPresent(T other)
```
    Returns provided other value if right is not present.
    
    Parameters:
    
    other - value to return if right is not present
    
    Returns:
    
    left if right is present else other
  - ifRightNotPresentGet
```
public T ifRightNotPresentGet(Supplier<? extends T> other)
```
    Returns value provided by a Provider if right is not present.
    
    Parameters:
    
    other - provider to provide a value to return if right is not present
    
    Returns:
    
    right if right is present else other
    
    Throws:
    
    NullPointerException - throws a NullPointerException if other is null
  - ifRightNotPresentThrow
```
public <X extends Throwable> T ifRightNotPresentThrow(Supplier<? extends X> other)
                                               throws X extends Throwable
```
    Throw a Throwable of type X provided by a Provider if {code right} is not present.
    
    Type Parameters:
    
    X - type of the Throwable to throw
    
    Parameters:
    
    other - provider to provide exception to throw if {code right} is not present
    
    Returns:
    
    right if right is present
    
    Throws:
    
    X - Throwable that will be thrown if {code right} is not present
    
    NullPointerException - throws a NullPointerException if other is null
    
    X extends Throwable
  - ifRightPresent
```
public void ifRightPresent(Consumer<? super T> consumer)
```
    If {code right} has a value apply the Consumer to the {code right} value.
    
    Parameters:
    
    consumer - left to apply if right is present
    
    Throws:
    
    NullPointerException - throws a NullPointerException if consumer is null
  - isEmpty
```
public boolean isEmpty()
```
    True if neither left or right are present.
    
    Returns:
    
    true if neither left or right are present
  - isLeftPresent
```
public boolean isLeftPresent()
```
    True if the left value is present.
    
    Returns:
    
    true if the left value is present
  - isRightPresent
```
public boolean isRightPresent()
```
    True if the right value is present.
    
    Returns:
    
    true if the right value is present
  - mapLeft
```
public <U> Optional<? extends U> mapLeft(Function<? super E,? extends U> mapper)
```
    If a left value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result.
    
    Type Parameters:
    
    U - the type of the result of the mapping function
    
    Parameters:
    
    mapper - a mapping function to apply to the left value, if present left value of this Either, if a left value is present, otherwise an empty Optional
    
    Returns:
    
    an Optional describing mapped left value, if a left value is present, otherwise an empty Optional
    
    Throws:
    
    NullPointerException - a NullPointerException if mapper is null
  - mapRight
```
public <U> Optional<? extends U> mapRight(Function<? super T,? extends U> mapper)
```
    If a right value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result.
    
    Type Parameters:
    
    U - the type of the result of the mapping function
    
    Parameters:
    
    mapper - a mapping function to apply to the right value, if present right value of this Either, if a right value is present, otherwise an empty Optional
    
    Returns:
    
    an Optional describing mapped right value, if a right value is present, otherwise an empty Optional
    
    Throws:
    
    NullPointerException - a NullPointerException if mapper is null
  - swap
```
public Either<T,E> swap()
```
    Gets a new Either with left and right swapped.
    
    Returns:
    
    Swapped Either
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class Either<E,T>

Method Summary

Methods inherited from class java.lang.Object

Method Detail

empty

ofLeft

ofNullableLeft

ofNullableRight

ofRight

equals

filterLeft

filterRight

getLeft

getRight

hashCode

ifLeftNotPresent

ifLeftNotPresentGet

ifLeftNotPresentThrow

ifLeftPresent

ifRightNotPresent

ifRightNotPresentGet

ifRightNotPresentThrow

ifRightPresent

isEmpty

isLeftPresent

isRightPresent

mapLeft

mapRight

swap

toString