OptionalDouble (net.sourceforge.streamsupport:streamsupport 1.6.2 API)

java.lang.Object
- java8.util.OptionalDouble

```
public final class OptionalDouble
extends Object
```
A container object which may or may not contain a double value. If a value is present, isPresent() returns true. If no value is present, the object is considered empty and isPresent() returns false.
Additional methods that depend on the presence or absence of a contained value are provided, such as orElse() (returns a default value if no value is present) and ifPresent() (performs an action if a value is present).
This is a value-based class; use of identity-sensitive operations (including reference equality (==), identity hash code, or synchronization) on instances of OptionalDouble may have unpredictable results and should be avoided.
API Note:
OptionalDouble is primarily intended for use as a method return type where there is a clear need to represent "no result". A variable whose type is OptionalDouble should never itself be null; it should always point to an OptionalDouble instance.

Since:

1.8

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`static OptionalDouble`	`empty()` Returns an empty `OptionalDouble` instance.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this `OptionalDouble`.
`double`	`getAsDouble()` If a value is present, returns the value, otherwise throws `NoSuchElementException`.
`int`	`hashCode()` Returns the hash code of the value, if present, otherwise `0` (zero) if no value is present.
`void`	`ifPresent(DoubleConsumer action)` If a value is present, performs the given action with the value, otherwise does nothing.
`void`	`ifPresentOrElse(DoubleConsumer action, Runnable emptyAction)` If a value is present, performs the given action with the value, otherwise performs the given empty-based action.
`boolean`	`isPresent()` If a value is present, returns `true`, otherwise `false`.
`static OptionalDouble`	`of(double value)` Returns an `OptionalDouble` describing the given value.
`double`	`orElse(double other)` If a value is present, returns the value, otherwise returns `other`.
`double`	`orElseGet(DoubleSupplier supplier)` If a value is present, returns the value, otherwise returns the result produced by the supplying function.
`double`	`orElseThrow()` If a value is present, returns the value, otherwise throws `NoSuchElementException`.
`<X extends Throwable> double`	`orElseThrow(Supplier<? extends X> exceptionSupplier)` If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function.
`DoubleStream`	`stream()` If a value is present, returns a sequential `DoubleStream` containing only that value, otherwise returns an empty `DoubleStream`.
`String`	`toString()` Returns a non-empty string representation of this `OptionalDouble` suitable for debugging.

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

- Method Detail
  - empty
```
public static OptionalDouble empty()
```
    Returns an empty OptionalDouble instance. No value is present for this OptionalDouble.
    API Note:
    Though it may be tempting to do so, avoid testing if an object is empty by comparing with == against instances returned by OptionalDouble.empty(). There is no guarantee that it is a singleton. Instead, use isPresent().
    
    Returns:
    
    an empty OptionalDouble.
  - of
```
public static OptionalDouble of(double value)
```
    Returns an OptionalDouble describing the given value.
    
    Parameters:
    
    value - the value to describe
    
    Returns:
    
    an OptionalDouble with the value present
  - getAsDouble
```
public double getAsDouble()
```
    If a value is present, returns the value, otherwise throws NoSuchElementException.
    API Note:
    The preferred alternative to this method is orElseThrow().
    
    Returns:
    
    the value described by this OptionalDouble
    
    Throws:
    
    NoSuchElementException - if no value is present
  - isPresent
```
public boolean isPresent()
```
    If a value is present, returns true, otherwise false.
    
    Returns:
    
    true if a value is present, otherwise false
  - ifPresent
```
public void ifPresent(DoubleConsumer action)
```
    If a value is present, performs the given action with the value, otherwise does nothing.
    
    Parameters:
    
    action - the action to be performed if a value is present
    
    Throws:
    
    NullPointerException - if value is present and the given action is null
  - ifPresentOrElse
```
public void ifPresentOrElse(DoubleConsumer action,
                            Runnable emptyAction)
```
    If a value is present, performs the given action with the value, otherwise performs the given empty-based action.
    
    Parameters:
    
    action - the action to be performed, if a value is present
    
    emptyAction - the empty-based action to be performed, if no value is present
    
    Throws:
    
    NullPointerException - if a value is present and the given action is null, or no value is present and the given empty-based action is null.
    
    Since:
    
    9
  - stream
```
public DoubleStream stream()
```
    If a value is present, returns a sequential DoubleStream containing only that value, otherwise returns an empty DoubleStream.
    API Note:
    This method can be used to transform a Stream of optional doubles to a DoubleStream of present doubles:
```
     Stream<OptionalDouble> os = ..
     DoubleStream s = os.flatMapToDouble(OptionalDouble::stream)
 
```
    Returns:
    
    the optional value as a DoubleStream
    
    Since:
    
    9
  - orElse
```
public double orElse(double other)
```
    If a value is present, returns the value, otherwise returns other.
    
    Parameters:
    
    other - the value to be returned, if no value is present
    
    Returns:
    
    the value, if present, otherwise other
  - orElseGet
```
public double orElseGet(DoubleSupplier supplier)
```
    If a value is present, returns the value, otherwise returns the result produced by the supplying function.
    
    Parameters:
    
    supplier - the supplying function that produces a value to be returned
    
    Returns:
    
    the value, if present, otherwise the result produced by the supplying function
    
    Throws:
    
    NullPointerException - if no value is present and the supplying function is null
  - orElseThrow
```
public double orElseThrow()
```
    If a value is present, returns the value, otherwise throws NoSuchElementException.
    
    Returns:
    
    the value described by this OptionalDouble
    
    Throws:
    
    NoSuchElementException - if no value is present
    
    Since:
    
    10
  - orElseThrow
```
public <X extends Throwable> double orElseThrow(Supplier<? extends X> exceptionSupplier)
                                         throws X extends Throwable
```
    If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function.
    API Note:
    A method reference to the exception constructor with an empty argument list can be used as the supplier. For example, IllegalStateException::new
    
    Type Parameters:
    
    X - Type of the exception to be thrown
    
    Parameters:
    
    exceptionSupplier - the supplying function that produces an exception to be thrown
    
    Returns:
    
    the value, if present
    
    Throws:
    
    X - if no value is present
    
    NullPointerException - if no value is present and the exception supplying function is null
    
    X extends Throwable
  - equals
```
public boolean equals(Object obj)
```
    Indicates whether some other object is "equal to" this OptionalDouble. The other object is considered equal if:
    - it is also an OptionalDouble and;
    - both instances have no value present or;
    - the present values are "equal to" each other via Double.compare() == 0.
    Overrides:
    
    equals in class Object
    
    Parameters:
    
    obj - an object to be tested for equality
    
    Returns:
    
    true if the other object is "equal to" this object otherwise false
  - hashCode
```
public int hashCode()
```
    Returns the hash code of the value, if present, otherwise 0 (zero) if no value is present.
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    
    hash code value of the present value or 0 if no value is present
  - toString
```
public String toString()
```
    Returns a non-empty string representation of this OptionalDouble suitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.
    Implementation Requirements:
    If a value is present the result must include its string representation in the result. Empty and present OptionalDoubles must be unambiguously differentiable.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    the string representation of this instance

Class OptionalDouble

Method Summary

Methods inherited from class java.lang.Object

Method Detail

empty

of

getAsDouble

isPresent

ifPresent

ifPresentOrElse

stream

orElse

orElseGet

orElseThrow

orElseThrow

equals

hashCode

toString