OptionalLong (Java SE 10 & JDK 10 ) (original) (raw)

java.lang.Object
- java.util.OptionalLong

public final class OptionalLong
extends Object
A container object which may or may not contain a long value. If a value is present, isPresent() returns true. If no value is present, the object is considered empty andisPresent() 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) andifPresent() (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 ofOptionalLong may have unpredictable results and should be avoided.
API Note:
OptionalLong is primarily intended for use as a method return type where there is a clear need to represent "no result." A variable whose type isOptionalLong should never itself be null; it should always point to an OptionalLong instance.
Since:
1.8

Method Summary

All Methods Static Methods Instance Methods Concrete Methods

Modifier and Type	Method	Description
static OptionalLong	empty()	Returns an empty OptionalLong instance.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" thisOptionalLong.
long	getAsLong()	If a value is present, returns the value, otherwise throwsNoSuchElementException.
int	hashCode()	Returns the hash code of the value, if present, otherwise 0 (zero) if no value is present.
void	ifPresent(LongConsumer action)	If a value is present, performs the given action with the value, otherwise does nothing.
void	ifPresentOrElse(LongConsumer 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 OptionalLong	of(long value)	Returns an OptionalLong describing the given value.
long	orElse(long other)	If a value is present, returns the value, otherwise returnsother.
long	orElseGet(LongSupplier supplier)	If a value is present, returns the value, otherwise returns the result produced by the supplying function.
long	orElseThrow()	If a value is present, returns the value, otherwise throwsNoSuchElementException.
<X extends Throwable>long	orElseThrow(Supplier<? extends X> exceptionSupplier)	If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function.
LongStream	stream()	If a value is present, returns a sequential LongStream containing only that value, otherwise returns an empty LongStream.
String	toString()	Returns a non-empty string representation of this OptionalLong suitable for debugging.

   * ### Methods declared in class java.lang.[Object](../../java/lang/Object.html "class in java.lang")  
   `[clone](../../java/lang/Object.html#clone%28%29), [finalize](../../java/lang/Object.html#finalize%28%29), [getClass](../../java/lang/Object.html#getClass%28%29), [notify](../../java/lang/Object.html#notify%28%29), [notifyAll](../../java/lang/Object.html#notifyAll%28%29), [wait](../../java/lang/Object.html#wait%28%29), [wait](../../java/lang/Object.html#wait%28long%29), [wait](../../java/lang/Object.html#wait%28long,int%29)`

Method Detail

 * #### empty  
 public static [OptionalLong](../../java/util/OptionalLong.html "class in java.util") empty()  
 Returns an empty `OptionalLong` instance. No value is present for this `OptionalLong`.  
 API Note:  
 Though it may be tempting to do so, avoid testing if an object is empty by comparing with `==` against instances returned by`OptionalLong.empty()`. There is no guarantee that it is a singleton. Instead, use [isPresent()](../../java/util/OptionalLong.html#isPresent%28%29).  
 Returns:  
 an empty `OptionalLong`.  
 * #### of  
 public static [OptionalLong](../../java/util/OptionalLong.html "class in java.util") of(long value)  
 Returns an `OptionalLong` describing the given value.  
 Parameters:  
 `value` \- the value to describe  
 Returns:  
 an `OptionalLong` with the value present  
 * #### getAsLong  
 public long getAsLong()  
 If a value is present, returns the value, otherwise throws`NoSuchElementException`.  
 API Note:  
 The preferred alternative to this method is [orElseThrow()](../../java/util/OptionalLong.html#orElseThrow%28%29).  
 Returns:  
 the value described by this `OptionalLong`  
 Throws:  
 `[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util")` \- 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([LongConsumer](../../java/util/function/LongConsumer.html "interface in java.util.function") 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](../../java/lang/NullPointerException.html "class in java.lang")` \- if value is present and the given action is`null`  
 * #### ifPresentOrElse  
 public void ifPresentOrElse([LongConsumer](../../java/util/function/LongConsumer.html "interface in java.util.function") action,  
                             [Runnable](../../java/lang/Runnable.html "interface in java.lang") 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](../../java/lang/NullPointerException.html "class in java.lang")` \- 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 [LongStream](../../java/util/stream/LongStream.html "interface in java.util.stream") stream()  
 If a value is present, returns a sequential [LongStream](../../java/util/stream/LongStream.html "interface in java.util.stream") containing only that value, otherwise returns an empty `LongStream`.  
 API Note:  
 This method can be used to transform a `Stream` of optional longs to an `LongStream` of present longs:  
 ```  
      Stream<OptionalLong> os = ..  
      LongStream s = os.flatMapToLong(OptionalLong::stream)  
        
 ```  
 Returns:  
 the optional value as an `LongStream`  
 Since:  
 9  
 * #### orElse  
 public long orElse(long 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 long orElseGet([LongSupplier](../../java/util/function/LongSupplier.html "interface in java.util.function") 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](../../java/lang/NullPointerException.html "class in java.lang")` \- if no value is present and the supplying function is `null`  
 * #### orElseThrow  
 public long orElseThrow()  
 If a value is present, returns the value, otherwise throws`NoSuchElementException`.  
 Returns:  
 the value described by this `OptionalLong`  
 Throws:  
 `[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util")` \- if no value is present  
 Since:  
 10  
 * #### orElseThrow  
 public <X extends [Throwable](../../java/lang/Throwable.html "class in java.lang")> long orElseThrow([Supplier](../../java/util/function/Supplier.html "interface in java.util.function")<? extends X> exceptionSupplier)  
                                        throws X extends [Throwable](../../java/lang/Throwable.html "class in java.lang")  
 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](../../java/lang/NullPointerException.html "class in java.lang")` \- if no value is present and the exception supplying function is `null`  
 `X extends [Throwable](../../java/lang/Throwable.html "class in java.lang")`  
 * #### equals  
 public boolean equals([Object](../../java/lang/Object.html "class in java.lang") obj)  
 Indicates whether some other object is "equal to" this`OptionalLong`. The other object is considered equal if:  
          * it is also an `OptionalLong` and;  
          * both instances have no value present or;  
          * the present values are "equal to" each other via `==`.  
 Overrides:  
 `[equals](../../java/lang/Object.html#equals%28java.lang.Object%29)` in class `[Object](../../java/lang/Object.html "class in java.lang")`  
 Parameters:  
 `obj` \- an object to be tested for equality  
 Returns:  
 `true` if the other object is "equal to" this object otherwise `false`  
 See Also:  
 [Object.hashCode()](../../java/lang/Object.html#hashCode%28%29), [HashMap](../../java/util/HashMap.html "class in java.util")  
 * #### hashCode  
 public int hashCode()  
 Returns the hash code of the value, if present, otherwise `0` (zero) if no value is present.  
 Overrides:  
 `[hashCode](../../java/lang/Object.html#hashCode%28%29)` in class `[Object](../../java/lang/Object.html "class in java.lang")`  
 Returns:  
 hash code value of the present value or `0` if no value is present  
 See Also:  
 [Object.equals(java.lang.Object)](../../java/lang/Object.html#equals%28java.lang.Object%29), [System.identityHashCode(java.lang.Object)](../../java/lang/System.html#identityHashCode%28java.lang.Object%29)  
 * #### toString  
 public [String](../../java/lang/String.html "class in java.lang") toString()  
 Returns a non-empty string representation of this `OptionalLong` suitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.  
 Overrides:  
 `[toString](../../java/lang/Object.html#toString%28%29)` in class `[Object](../../java/lang/Object.html "class in java.lang")`  
 Implementation Requirements:  
 If a value is present the result must include its string representation in the result. Empty and present `OptionalLong`s must be unambiguously differentiable.  
 Returns:  
 the string representation of this instance

Report a bug or suggest an enhancement
For further API reference and developer documentation see the Java SE Documentation, which contains more detailed, developer-targeted descriptions with conceptual overviews, definitions of terms, workarounds, and working code examples.
Java is a trademark or registered trademark of Oracle and/or its affiliates in the US and other countries.
Copyright © 1993, 2018, Oracle and/or its affiliates, 500 Oracle Parkway, Redwood Shores, CA 94065 USA.
All rights reserved. Use is subject to license terms and the documentation redistribution policy.

OptionalLong (Java SE 10 & JDK 10 ) (original) (raw)

Method Summary

Method Detail