Value (Javaslang 2.0.0 API)

Type Parameters:

T - The type of the wrapped value.

All Superinterfaces:

Iterable<T>

All Known Subinterfaces:

Either<L,R>, Future<T>, IndexedSeq<T>, Iterator<T>, LinearSeq<T>, List<T>, Map<K,V>, Option<T>, Seq<T>, Set<T>, SortedMap<K,V>, SortedSet<T>, Stream<T>, Traversable<T>, Tree<T>, Try<T>, Validation<E,T>

All Known Implementing Classes:

AbstractIterator, Array, CharSeq, Either.Left, Either.LeftProjection, Either.Right, Either.RightProjection, HashMap, HashSet, Lazy, LinkedHashMap, LinkedHashSet, List.Cons, List.Nil, Option.None, Option.Some, Queue, Stream.Cons, Stream.Empty, Tree.Empty, Tree.Node, TreeMap, TreeSet, Try.Failure, Try.Success, Validation.Invalid, Validation.Valid, Vector
```
public interface Value<T>
extends Iterable<T>
```
Functional programming is all about values and transformation of values using functions. The Value type reflects the values in a functional setting. It can be seen as the result of a partial function application. Hence the result may be undefined. If a value is undefined, we say it is empty.
How the empty state is interpreted depends on the context, i.e. it may be undefined, failed, no elements, etc.
Basic operations:
Equality checks:
- corresponds(Iterable, BiPredicate)
- eq(Object)
Iterable extensions:
Side-effects:
Type conversion:
Please note: flatMap signatures are manifold and have to be declared by subclasses of Value.
Since:

2.0.0

Author:

Daniel Dietrich

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`default boolean`	`contains(T element)` Shortcut for `exists(e -> Objects.equals(e, element))`, tests if the given `element` is contained.
`default <U> boolean`	`corresponds(Iterable<U> that, BiPredicate<? super T,? super U> predicate)` Tests whether every element of this iterable relates to the corresponding element of another iterable by satisfying a test predicate.
`default boolean`	`eq(Object o)` A smoothing replacement for `equals`.
`boolean`	`equals(Object o)` Clarifies that values have a proper equals() method implemented.
`default boolean`	`exists(Predicate<? super T> predicate)` Checks, if an element exists such that the predicate holds.
`default boolean`	`forAll(Predicate<? super T> predicate)` Checks, if the given predicate holds for all elements.
`default void`	`forEach(Consumer<? super T> action)` Performs an action on each element.
`T`	`get()` Gets the underlying value or throws if no value is present.
`default Option<T>`	`getOption()` Gets the underlying value as Option.
`default T`	`getOrElse(Supplier<? extends T> supplier)` Returns the underlying value if present, otherwise `other`.
`default T`	`getOrElse(T other)` Returns the underlying value if present, otherwise `other`.
`default <X extends Throwable> T`	`getOrElseThrow(Supplier<X> supplier)` Returns the underlying value if present, otherwise throws `supplier.get()`.
`default T`	`getOrElseTry(Try.CheckedSupplier<? extends T> supplier)` Returns the underlying value if present, otherwise returns the result of `Try.of(supplier).get()`.
`int`	`hashCode()` Clarifies that values have a proper hashCode() method implemented.
`boolean`	`isEmpty()` Checks, this `Value` is empty, i.e.
`boolean`	`isSingleValued()` States whether this is a single-valued type.
`Iterator<T>`	`iterator()` Returns a rich `javaslang.collection.Iterator`.
`<U> Value<U>`	`map(Function<? super T,? extends U> mapper)` Maps the underlying value to a different component type.
`static <T> Value<T>`	`narrow(Value<? extends T> value)` Narrows a widened `Value<? extends T>` to `Value<T>` by performing a type safe-cast.
`default void`	`out(PrintStream out)` Sends the string representations of this to the `PrintStream`.
`default void`	`out(PrintWriter writer)` Sends the string representations of this to the `PrintWriter`.
`Value<T>`	`peek(Consumer<? super T> action)` Performs the given `action` on the first element if this is an eager implementation.
`default void`	`stderr()` Sends the string representations of this to the standard error stream System.err.
`default void`	`stdout()` Sends the string representations of this to the standard output stream System.out.
`String`	`stringPrefix()` Returns the name of this Value type, which is used by toString().
`default Array<T>`	`toArray()` Converts this to a `Array`.
`default CharSeq`	`toCharSeq()` Converts this to a `CharSeq`.
`default Object[]`	`toJavaArray()` Converts this to an untyped Java array.
`default T[]`	`toJavaArray(Class<T> componentType)` Converts this to a typed Java array.
`default <C extends Collection<T>> C`	`toJavaCollection(Supplier<C> factory)` Converts this to a specific `Collection`.
`default List<T>`	`toJavaList()` Converts this to an `List`.
`default <LIST extends List<T>> LIST`	`toJavaList(Supplier<LIST> factory)` Converts this to a specific `List`.
`default <K,V> Map<K,V>`	`toJavaMap(Function<? super T,? extends Tuple2<? extends K,? extends V>> f)` Converts this to a `Map`.
`default <K,V,MAP extends Map<K,V>> MAP`	`toJavaMap(Supplier<MAP> factory, Function<? super T,? extends Tuple2<? extends K,? extends V>> f)` Converts this to a specific `Map`.
`default Optional<T>`	`toJavaOptional()` Converts this to an `Optional`.
`default Set<T>`	`toJavaSet()` Converts this to a `Set`.
`default <SET extends Set<T>> SET`	`toJavaSet(Supplier<SET> factory)` Converts this to a specific `Set`.
`default Stream<T>`	`toJavaStream()` Converts this to a `Stream`.
`default <R> Either<T,R>`	`toLeft(R right)` Converts this to a `Either`.
`default <R> Either<T,R>`	`toLeft(Supplier<? extends R> right)` Converts this to a `Either`.
`default List<T>`	`toList()` Converts this to a `List`.
`default <K,V> Map<K,V>`	`toMap(Function<? super T,? extends Tuple2<? extends K,? extends V>> f)` Converts this to a `Map`.
`default Option<T>`	`toOption()` Converts this to an `Option`.
`default Queue<T>`	`toQueue()` Converts this to a `Queue`.
`default <L> Either<L,T>`	`toRight(L left)` Converts this to a `Either`.
`default <L> Either<L,T>`	`toRight(Supplier<? extends L> left)` Converts this to a `Either`.
`default Set<T>`	`toSet()` Converts this to a `Set`.
`default Stack<T>`	`toStack()` Converts this to a `Stack`.
`default Stream<T>`	`toStream()` Converts this to a `Stream`.
`String`	`toString()` Clarifies that values have a proper toString() method implemented.
`default Tree<T>`	`toTree()` Converts this to a `Tree`.
`default Try<T>`	`toTry()` Converts this to a `Try`.
`default Try<T>`	`toTry(Supplier<? extends Throwable> ifEmpty)` Converts this to a `Try`.
`default Vector<T>`	`toVector()` Converts this to a `Vector`.

Methods inherited from interface java.lang.Iterable
spliterator

- Method Detail
  - narrow
```
static <T> Value<T> narrow(Value<? extends T> value)
```
    Narrows a widened Value<? extends T> to Value<T> by performing a type safe-cast. This is eligible because immutable/read-only collections are covariant.
    
    Type Parameters:
    
    T - Component type of the Value.
    
    Parameters:
    
    value - A Value.
    
    Returns:
    
    the given value instance as narrowed type Value<T>.
  - contains
```
default boolean contains(T element)
```
    Shortcut for exists(e -> Objects.equals(e, element)), tests if the given element is contained.
    
    Parameters:
    
    element - An Object of type A, may be null.
    
    Returns:
    
    true, if element is contained, false otherwise.
  - corresponds
```
default <U> boolean corresponds(Iterable<U> that,
                                BiPredicate<? super T,? super U> predicate)
```
    Tests whether every element of this iterable relates to the corresponding element of another iterable by satisfying a test predicate.
    
    Type Parameters:
    
    U - Component type of that iterable
    
    Parameters:
    
    that - the other iterable
    
    predicate - the test predicate, which relates elements from both iterables
    
    Returns:
    
    true if both iterables have the same length and predicate(x, y) is true for all corresponding elements x of this iterable and y of that, otherwise false.
  - eq
```
default boolean eq(Object o)
```
    A smoothing replacement for equals. It is similar to Scala's == but better in the way that it is not limited to collection types, e.g. Some(1) eq List(1), None eq Failure(x) etc.
    In a nutshell: eq checks congruence of structures and equality of contained values.
    Example:
```
 // ((1, 2), ((3))) => structure: (()(())) values: 1, 2, 3
 final Value<?> i1 = List.of(List.of(1, 2), Arrays.asList(List.of(3)));
 final Value<?> i2 = Queue.of(Stream.of(1, 2), List.of(Lazy.of(() -> 3)));
 assertThat(i1.eq(i2)).isTrue();
 
```
    Semantics:
```
 o == this             : true
 o instanceof Value    : iterable elements are eq, non-iterable elements equals, for all (o1, o2) in (this, o)
 o instanceof Iterable : this eq Iterator.of((Iterable<?>) o);
 otherwise             : false
 
```
    Parameters:
    
    o - An object
    
    Returns:
    
    true, if this equals o according to the rules defined above, otherwise false.
  - exists
```
default boolean exists(Predicate<? super T> predicate)
```
    Checks, if an element exists such that the predicate holds.
    
    Parameters:
    
    predicate - A Predicate
    
    Returns:
    
    true, if predicate holds for one or more elements, false otherwise
    
    Throws:
    
    NullPointerException - if predicate is null
  - forAll
```
default boolean forAll(Predicate<? super T> predicate)
```
    Checks, if the given predicate holds for all elements.
    
    Parameters:
    
    predicate - A Predicate
    
    Returns:
    
    true, if the predicate holds for all elements, false otherwise
    
    Throws:
    
    NullPointerException - if predicate is null
  - forEach
```
default void forEach(Consumer<? super T> action)
```
    Performs an action on each element.
    
    Specified by:
    
    forEach in interface Iterable<T>
    
    Parameters:
    
    action - A Consumer
    
    Throws:
    
    NullPointerException - if action is null
  - get
```
T get()
```
    Gets the underlying value or throws if no value is present.
    
    Returns:
    
    the underlying value
    
    Throws:
    
    NoSuchElementException - if no value is defined
  - getOption
```
default Option<T> getOption()
```
    Gets the underlying value as Option.
    
    Returns:
    
    Some(value) if a value is present, None otherwise
  - getOrElse
```
default T getOrElse(T other)
```
    Returns the underlying value if present, otherwise other.
    
    Parameters:
    
    other - An alternative value.
    
    Returns:
    
    A value of type T
  - getOrElse
```
default T getOrElse(Supplier<? extends T> supplier)
```
    Returns the underlying value if present, otherwise other.
    
    Parameters:
    
    supplier - An alternative value supplier.
    
    Returns:
    
    A value of type T
    
    Throws:
    
    NullPointerException - if supplier is null
  - getOrElseThrow
```
default <X extends Throwable> T getOrElseThrow(Supplier<X> supplier)
                                        throws X extends Throwable
```
    Returns the underlying value if present, otherwise throws supplier.get().
    
    Type Parameters:
    
    X - a Throwable type
    
    Parameters:
    
    supplier - An exception supplier.
    
    Returns:
    
    A value of type T.
    
    Throws:
    
    NullPointerException - if supplier is null
    
    X - if no value is present
    
    X extends Throwable
  - getOrElseTry
```
default T getOrElseTry(Try.CheckedSupplier<? extends T> supplier)
```
    Returns the underlying value if present, otherwise returns the result of Try.of(supplier).get().
    
    Parameters:
    
    supplier - An alternative value supplier.
    
    Returns:
    
    A value of type T.
    
    Throws:
    
    NullPointerException - if supplier is null
    
    Try.NonFatalException - containing the original exception if this Value was empty and the Try failed.
  - isEmpty
```
boolean isEmpty()
```
    Checks, this Value is empty, i.e. if the underlying value is absent.
    
    Returns:
    
    false, if no underlying value is present, true otherwise.
  - isSingleValued
```
boolean isSingleValued()
```
    States whether this is a single-valued type.
    
    Returns:
    
    true if this is single-valued, false otherwise.
  - map
```
<U> Value<U> map(Function<? super T,? extends U> mapper)
```
    Maps the underlying value to a different component type.
    
    Type Parameters:
    
    U - The new component type
    
    Parameters:
    
    mapper - A mapper
    
    Returns:
    
    A new value
  - peek
```
Value<T> peek(Consumer<? super T> action)
```
    Performs the given action on the first element if this is an eager implementation. Performs the given action on all elements (the first immediately, successive deferred), if this is a lazy implementation.
    
    Parameters:
    
    action - The action that will be performed on the element(s).
    
    Returns:
    
    this instance
  - stringPrefix
```
String stringPrefix()
```
    Returns the name of this Value type, which is used by toString().
    
    Returns:
    
    This type name.
  - out
```
default void out(PrintStream out)
```
    Sends the string representations of this to the PrintStream. If this value consists of multiple elements, each element is displayed in a new line.
    
    Parameters:
    
    out - The PrintStream to write to
    
    Throws:
    
    IllegalStateException - if PrintStream.checkError() is true after writing to stream.
  - out
```
default void out(PrintWriter writer)
```
    Sends the string representations of this to the PrintWriter. If this value consists of multiple elements, each element is displayed in a new line.
    
    Parameters:
    
    writer - The PrintWriter to write to
    
    Throws:
    
    IllegalStateException - if PrintWriter.checkError() is true after writing to writer.
  - stderr
```
default void stderr()
```
    Sends the string representations of this to the standard error stream System.err. If this value consists of multiple elements, each element is displayed in a new line.
    
    Throws:
    
    IllegalStateException - if PrintStream.checkError() is true after writing to stderr.
  - stdout
```
default void stdout()
```
    Sends the string representations of this to the standard output stream System.out. If this value consists of multiple elements, each element is displayed in a new line.
    
    Throws:
    
    IllegalStateException - if PrintStream.checkError() is true after writing to stdout.
  - iterator
```
Iterator<T> iterator()
```
    Returns a rich javaslang.collection.Iterator.
    
    Specified by:
    
    iterator in interface Iterable<T>
    
    Returns:
    
    A new Iterator
  - toArray
```
default Array<T> toArray()
```
    Converts this to a Array.
    
    Returns:
    
    A new Array.
  - toCharSeq
```
default CharSeq toCharSeq()
```
    Converts this to a CharSeq.
    
    Returns:
    
    A new CharSeq.
  - toJavaCollection
```
default <C extends Collection<T>> C toJavaCollection(Supplier<C> factory)
```
    Converts this to a specific Collection.
    
    Type Parameters:
    
    C - a sub-type of java.util.Collection
    
    Parameters:
    
    factory - A java.util.Collection factory
    
    Returns:
    
    a new java.util.Collection of type C
  - toJavaArray
```
default Object[] toJavaArray()
```
    Converts this to an untyped Java array.
    
    Returns:
    
    A new Java array.
  - toJavaArray
```
default T[] toJavaArray(Class<T> componentType)
```
    Converts this to a typed Java array.
    
    Parameters:
    
    componentType - Component type of the array
    
    Returns:
    
    A new Java array.
    
    Throws:
    
    NullPointerException - if componentType is null
  - toJavaList
```
default List<T> toJavaList()
```
    Converts this to an List.
    
    Returns:
    
    A new ArrayList.
  - toJavaList
```
default <LIST extends List<T>> LIST toJavaList(Supplier<LIST> factory)
```
    Converts this to a specific List.
    
    Type Parameters:
    
    LIST - a sub-type of java.util.List
    
    Parameters:
    
    factory - A java.util.List factory
    
    Returns:
    
    a new java.util.List of type LIST
  - toJavaMap
```
default <K,V> Map<K,V> toJavaMap(Function<? super T,? extends Tuple2<? extends K,? extends V>> f)
```
    Converts this to a Map.
    
    Type Parameters:
    
    K - The key type
    
    V - The value type
    
    Parameters:
    
    f - A function that maps an element to a key/value pair represented by Tuple2
    
    Returns:
    
    A new HashMap.
  - toJavaMap
```
default <K,V,MAP extends Map<K,V>> MAP toJavaMap(Supplier<MAP> factory,
                                                 Function<? super T,? extends Tuple2<? extends K,? extends V>> f)
```
    Converts this to a specific Map.
    
    Type Parameters:
    
    K - The key type
    
    V - The value type
    
    MAP - a sub-type of java.util.Map
    
    Parameters:
    
    factory - A java.util.Map factory
    
    f - A function that maps an element to a key/value pair represented by Tuple2
    
    Returns:
    
    a new java.util.Map of type MAP
  - toJavaOptional
```
default Optional<T> toJavaOptional()
```
    Converts this to an Optional.
    
    Returns:
    
    A new Optional.
  - toJavaSet
```
default Set<T> toJavaSet()
```
    Converts this to a Set.
    
    Returns:
    
    A new HashSet.
  - toJavaSet
```
default <SET extends Set<T>> SET toJavaSet(Supplier<SET> factory)
```
    Converts this to a specific Set.
    
    Type Parameters:
    
    SET - a sub-type of java.util.Set
    
    Parameters:
    
    factory - A java.util.Set factory
    
    Returns:
    
    a new java.util.Set of type SET
  - toJavaStream
```
default Stream<T> toJavaStream()
```
    Converts this to a Stream.
    
    Returns:
    
    A new Stream.
  - toLeft
```
default <R> Either<T,R> toLeft(Supplier<? extends R> right)
```
    Converts this to a Either.
    
    Type Parameters:
    
    R - right type
    
    Parameters:
    
    right - A supplier of a right value
    
    Returns:
    
    A new Either.Right containing the result of right if this is empty, otherwise a new Either.Left containing this value.
    
    Throws:
    
    NullPointerException - if right is null
  - toLeft
```
default <R> Either<T,R> toLeft(R right)
```
    Converts this to a Either.
    
    Type Parameters:
    
    R - right type
    
    Parameters:
    
    right - An instance of a right value
    
    Returns:
    
    A new Either.Right containing the value of right if this is empty, otherwise a new Either.Left containing this value.
    
    Throws:
    
    NullPointerException - if right is null
  - toList
```
default List<T> toList()
```
    Converts this to a List.
    
    Returns:
    
    A new List.
  - toMap
```
default <K,V> Map<K,V> toMap(Function<? super T,? extends Tuple2<? extends K,? extends V>> f)
```
    Converts this to a Map.
    
    Type Parameters:
    
    K - The key type
    
    V - The value type
    
    Parameters:
    
    f - A function that maps an element to a key/value pair represented by Tuple2
    
    Returns:
    
    A new HashMap.
  - toOption
```
default Option<T> toOption()
```
    Converts this to an Option.
    
    Returns:
    
    A new Option.
  - toQueue
```
default Queue<T> toQueue()
```
    Converts this to a Queue.
    
    Returns:
    
    A new Queue.
  - toRight
```
default <L> Either<L,T> toRight(Supplier<? extends L> left)
```
    Converts this to a Either.
    
    Type Parameters:
    
    L - left type
    
    Parameters:
    
    left - A supplier of a left value
    
    Returns:
    
    A new Either.Left containing the result of left if this is empty, otherwise a new Either.Right containing this value.
    
    Throws:
    
    NullPointerException - if left is null
  - toRight
```
default <L> Either<L,T> toRight(L left)
```
    Converts this to a Either.
    
    Type Parameters:
    
    L - left type
    
    Parameters:
    
    left - An instance of a left value
    
    Returns:
    
    A new Either.Left containing the value of left if this is empty, otherwise a new Either.Right containing this value.
    
    Throws:
    
    NullPointerException - if left is null
  - toSet
```
default Set<T> toSet()
```
    Converts this to a Set.
    
    Returns:
    
    A new HashSet.
  - toStack
```
default Stack<T> toStack()
```
    Converts this to a Stack.
    
    Returns:
    
    A new List, which is a Stack.
  - toStream
```
default Stream<T> toStream()
```
    Converts this to a Stream.
    
    Returns:
    
    A new Stream.
  - toTry
```
default Try<T> toTry()
```
    Converts this to a Try.
    If this value is undefined, i.e. empty, then a new Failure(NoSuchElementException) is returned, otherwise a new Success(value) is returned.
    
    Returns:
    
    A new Try.
  - toTry
```
default Try<T> toTry(Supplier<? extends Throwable> ifEmpty)
```
    Converts this to a Try.
    If this value is undefined, i.e. empty, then a new Failure(ifEmpty.get()) is returned, otherwise a new Success(value) is returned.
    
    Parameters:
    
    ifEmpty - an exception supplier
    
    Returns:
    
    A new Try.
  - toTree
```
default Tree<T> toTree()
```
    Converts this to a Tree.
    
    Returns:
    
    A new Tree.
  - toVector
```
default Vector<T> toVector()
```
    Converts this to a Vector.
    
    Returns:
    
    A new Vector.
  - equals
```
boolean equals(Object o)
```
    Clarifies that values have a proper equals() method implemented.
    See Object.equals(Object).
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    
    o - An object
    
    Returns:
    
    true, if this equals o, false otherwise
  - hashCode
```
int hashCode()
```
    Clarifies that values have a proper hashCode() method implemented.
    See Object.hashCode().
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    
    The hashcode of this object
  - toString
```
String toString()
```
    Clarifies that values have a proper toString() method implemented.
    See Object.toString().
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    A String representation of this object

Interface Value<T>

Method Summary

Methods inherited from interface java.lang.Iterable

Method Detail

narrow

contains

corresponds

eq

exists

forAll

forEach

get

getOption

getOrElse

getOrElse

getOrElseThrow

getOrElseTry

isEmpty

isSingleValued

map

peek

stringPrefix

out

out

stderr

stdout

iterator

toArray

toCharSeq

toJavaCollection

toJavaArray

toJavaArray

toJavaList

toJavaList

toJavaMap

toJavaMap

toJavaOptional

toJavaSet

toJavaSet

toJavaStream

toLeft

toLeft

toList

toMap

toOption

toQueue

toRight

toRight

toSet

toStack

toStream

toTry

toTry

toTree

toVector

equals

hashCode

toString