OptionalDouble (Java Platform SE 8 )

java.lang.Object
- java.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() will return true and getAsDouble() will return the value.
Additional methods that depend on the presence or absence of a contained value are provided, such as orElse() (return a default value if value not present) and ifPresent() (execute a block of code if the 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.

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 in this `OptionalDouble`, returns the value, otherwise throws `NoSuchElementException`.
`int`	`hashCode()` Returns the hash code value of the present value, if any, or 0 (zero) if no value is present.
`void`	`ifPresent(DoubleConsumer consumer)` Have the specified consumer accept the value if a value is present, otherwise do nothing.
`boolean`	`isPresent()` Return `true` if there is a value present, otherwise `false`.
`static OptionalDouble`	`of(double value)` Return an `OptionalDouble` with the specified value present.
`double`	`orElse(double other)` Return the value if present, otherwise return `other`.
`double`	`orElseGet(DoubleSupplier other)` Return the value if present, otherwise invoke `other` and return the result of that invocation.
`<X extends Throwable> double`	`orElseThrow(Supplier<X> exceptionSupplier)` Return the contained value, if present, otherwise throw an exception to be created by the provided supplier.
`String`	`toString()` Returns a string representation of the object.

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 Option.empty(). There is no guarantee that it is a singleton. Instead, use isPresent().
    
    Returns:
    
    an empty OptionalDouble.
  - of
```
public static OptionalDouble of(double value)
```
    Return an OptionalDouble with the specified value present.
    
    Parameters:
    
    value - the value to be present
    
    Returns:
    
    an OptionalDouble with the value present
  - getAsDouble
```
public double getAsDouble()
```
    If a value is present in this OptionalDouble, returns the value, otherwise throws NoSuchElementException.
    
    Returns:
    
    the value held by this OptionalDouble
    
    Throws:
    
    NoSuchElementException - if there is no value present
    
    See Also:
    
    isPresent()
  - isPresent
```
public boolean isPresent()
```
    Return true if there is a value present, otherwise false.
    
    Returns:
    
    true if there is a value present, otherwise false
  - ifPresent
```
public void ifPresent(DoubleConsumer consumer)
```
    Have the specified consumer accept the value if a value is present, otherwise do nothing.
    
    Parameters:
    
    consumer - block to be executed if a value is present
    
    Throws:
    
    NullPointerException - if value is present and consumer is null
  - orElse
```
public double orElse(double other)
```
    Return the value if present, otherwise return other.
    
    Parameters:
    
    other - the value to be returned if there is no value present
    
    Returns:
    
    the value, if present, otherwise other
  - orElseGet
```
public double orElseGet(DoubleSupplier other)
```
    Return the value if present, otherwise invoke other and return the result of that invocation.
    
    Parameters:
    
    other - a DoubleSupplier whose result is returned if no value is present
    
    Returns:
    
    the value if present otherwise the result of other.getAsDouble()
    
    Throws:
    
    NullPointerException - if value is not present and other is null
  - orElseThrow
```
public <X extends Throwable> double orElseThrow(Supplier<X> exceptionSupplier)
                                         throws X
```
    Return the contained value, if present, otherwise throw an exception to be created by the provided supplier.
    
    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 supplier which will return the exception to be thrown
    
    Returns:
    
    the present value
    
    Throws:
    
    X - if there is no value present
    
    NullPointerException - if no value is present and exceptionSupplier 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:
    
    {code true} if the other object is "equal to" this object otherwise false
    
    See Also:
    
    Object.hashCode(), HashMap
  - hashCode
```
public int hashCode()
```
    Returns the hash code value of the present value, if any, or 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
    
    See Also:
    
    Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)
  - toString
```
public String toString()
```
    Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.
    The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:
    getClass().getName() + '@' + Integer.toHexString(hashCode())
    Returns a non-empty string representation of this object suitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.
    Overrides:
    
    toString in class Object
    
    Implementation Requirements:
    
    If a value is present the result must include its string representation in the result. Empty and present instances must be unambiguously differentiable.
    
    Returns:
    
    the string representation of this instance

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Class OptionalDouble

Method Summary

Methods inherited from class java.lang.Object

Method Detail

empty

of

getAsDouble

isPresent

ifPresent

orElse

orElseGet

orElseThrow

equals

hashCode

toString