Optional (Groovy JDK enhancements)

Methods Summary

Methods
Return type	Name and parameters
`boolean`	`asBoolean()` Coerce an `Optional` instance to a `boolean` value.
`Optional`	`collect(Closure transform)` If the optional contains a value, returns an optional containing the transformed value obtained using the `transform` closure or otherwise an empty optional.
`Optional`	`filter(Class type)` Tests given value against specified type and changes generics of result.
`OptionalDouble`	`mapToDouble(ToDoubleFunction mapper)` If a value is present in the `OptionalDouble`, returns an `OptionalDouble` consisting of the result of applying the given function to the value or else empty.
`OptionalInt`	`mapToInt(ToIntFunction mapper)` If a value is present in the `OptionalInt`, returns an `OptionalInt` consisting of the result of applying the given function to the value or else empty.
`OptionalLong`	`mapToLong(ToLongFunction mapper)` If a value is present in the `OptionalLong`, returns an `OptionalLong` consisting of the result of applying the given function to the value or else empty.
`Optional`	`orOptional(Supplier supplier)` Provide similar functionality to JDK9 `or` on JDK8.
`Stream`	`stream()` If a value is present in the Optional, returns a Stream with the value as its source or else an empty stream.

Methods inherited from class java.lang.Object

addShutdownHook, any, any, asBoolean, asType, collect, collect, collect, dump, each, eachMatch, eachMatch, eachWithIndex, every, every, find, find, findAll, findAll, findIndexOf, findIndexOf, findIndexValues, findIndexValues, findLastIndexOf, findLastIndexOf, findResult, findResult, getAt, getMetaClass, getMetaPropertyValues, getProperties, grep, grep, hasProperty, identity, inject, inject, inspect, invokeMethod, is, isCase, iterator, metaClass, print, print, printf, printf, println, println, println, putAt, respondsTo, respondsTo, setMetaClass, split, sprintf, sprintf, stream, tap, toString, use, use, use, with, with, withCloseable, withStream, withTraits

- Methods Detail
  - public boolean asBoolean()
    
    Coerce an Optional instance to a boolean value.
```
assert !Optional.empty().asBoolean()
assert Optional.of(1234).asBoolean()
```
    Returns:
    
    true if a value is present, otherwise false
    
    Since:
    
    2.5.0
  - public Optional collect(Closure transform)
    
    If the optional contains a value, returns an optional containing the transformed value obtained using the transform closure or otherwise an empty optional.
```
assert Optional.of("foobar").collect{ it.size() }.get() == 6
assert !Optional.empty().collect{ it.size() }.isPresent()
```
    Parameters:
    
    transform - the closure used to transform the optional value if present
    
    Returns:
    
    an Optional containing the transformed value or empty if the optional is empty or the transform returns null
    
    Since:
    
    3.0.0
  - public Optional filter(Class type)
    
    Tests given value against specified type and changes generics of result. This is equivalent to: self.filter(it -> it instanceof Type).map(it -> (Type) it)
```
assert !Optional.empty().filter(Number).isPresent()
assert !Optional.of('x').filter(Number).isPresent()
assert Optional.of(1234).filter(Number).isPresent()
assert Optional.of(1234).filter(Number).get().equals(1234)
```
    Parameters:
    
    Since:
    
    3.0.0
  - public OptionalDouble mapToDouble(ToDoubleFunction mapper)
    
    If a value is present in the OptionalDouble, returns an OptionalDouble consisting of the result of applying the given function to the value or else empty.
```
assert !Optional.empty().mapToDouble(x -> Math.PI).isPresent()
assert  Optional.of('x').mapToDouble(x -> Math.PI).getAsDouble() == Math.PI
```
    Parameters:
    
    Since:
    
    3.0.0
  - public OptionalInt mapToInt(ToIntFunction mapper)
    
    If a value is present in the OptionalInt, returns an OptionalInt consisting of the result of applying the given function to the value or else empty.
```
assert !Optional.empty().mapToInt(x -> 42).isPresent()
assert  Optional.of('x').mapToInt(x -> 42).getAsInt() == 42
```
    Parameters:
    
    Since:
    
    3.0.0
  - public OptionalLong mapToLong(ToLongFunction mapper)
    
    If a value is present in the OptionalLong, returns an OptionalLong consisting of the result of applying the given function to the value or else empty.
```
assert !Optional.empty().mapToLong(x -> 42L).isPresent()
assert  Optional.of('x').mapToLong(x -> 42L).getAsLong() == 42L
```
    Parameters:
    
    Since:
    
    3.0.0
  - public Optional orOptional(Supplier supplier)
    
    Provide similar functionality to JDK9 or on JDK8.
    
    Parameters:
    
    Since:
    
    3.0.6
  - public Stream stream()
    
    If a value is present in the Optional, returns a Stream with the value as its source or else an empty stream.
    
    Since:
    
    3.0.0

Class Optional

Methods Summary

Methods inherited from class java.lang.Object

Methods Detail

public boolean asBoolean()

public Optional collect(Closure transform)

public Optional filter(Class type)

public OptionalDouble mapToDouble(ToDoubleFunction mapper)

public OptionalInt mapToInt(ToIntFunction mapper)

public OptionalLong mapToLong(ToLongFunction mapper)

public Optional orOptional(Supplier supplier)

public Stream stream()