- java.lang.Object
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- java.util.OptionalLong
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public final class OptionalLong extends Object
A container object which may or may not contain alongvalue. If a value is present,isPresent()returnstrue. If no value is present, the object is considered empty andisPresent()returnsfalse.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 ofOptionalLongmay have unpredictable results and should be avoided.- API Note:
OptionalLongis primarily intended for use as a method return type where there is a clear need to represent "no result." A variable whose type isOptionalLongshould never itself benull; it should always point to anOptionalLonginstance.- Since:
- 1.8
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static OptionalLongempty()Returns an emptyOptionalLonginstance.booleanequals(Object obj)Indicates whether some other object is "equal to" thisOptionalLong.longgetAsLong()If a value is present, returns the value, otherwise throwsNoSuchElementException.inthashCode()Returns the hash code of the value, if present, otherwise0(zero) if no value is present.voidifPresent(LongConsumer action)If a value is present, performs the given action with the value, otherwise does nothing.voidifPresentOrElse(LongConsumer action, Runnable emptyAction)If a value is present, performs the given action with the value, otherwise performs the given empty-based action.booleanisEmpty()If a value is not present, returnstrue, otherwisefalse.booleanisPresent()If a value is present, returnstrue, otherwisefalse.static OptionalLongof(long value)Returns anOptionalLongdescribing the given value.longorElse(long other)If a value is present, returns the value, otherwise returnsother.longorElseGet(LongSupplier supplier)If a value is present, returns the value, otherwise returns the result produced by the supplying function.longorElseThrow()If a value is present, returns the value, otherwise throwsNoSuchElementException.<X extends Throwable>
longorElseThrow(Supplier<? extends X> exceptionSupplier)If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function.LongStreamstream()If a value is present, returns a sequentialLongStreamcontaining only that value, otherwise returns an emptyLongStream.StringtoString()Returns a non-empty string representation of thisOptionalLongsuitable for debugging.
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Method Detail
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empty
public static OptionalLong empty()
Returns an emptyOptionalLonginstance. No value is present for thisOptionalLong.- API Note:
- Though it may be tempting to do so, avoid testing if an object is empty
by comparing with
==against instances returned byOptionalLong.empty(). There is no guarantee that it is a singleton. Instead, useisPresent(). - Returns:
- an empty
OptionalLong.
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of
public static OptionalLong of(long value)
Returns anOptionalLongdescribing the given value.- Parameters:
value- the value to describe- Returns:
- an
OptionalLongwith the value present
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getAsLong
public long getAsLong()
If a value is present, returns the value, otherwise throwsNoSuchElementException.- API Note:
- The preferred alternative to this method is
orElseThrow(). - Returns:
- the value described by this
OptionalLong - Throws:
NoSuchElementException- if no value is present
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isPresent
public boolean isPresent()
If a value is present, returnstrue, otherwisefalse.- Returns:
trueif a value is present, otherwisefalse
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isEmpty
public boolean isEmpty()
If a value is not present, returnstrue, otherwisefalse.- Returns:
trueif a value is not present, otherwisefalse- Since:
- 11
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ifPresent
public void ifPresent(LongConsumer 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 isnull
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ifPresentOrElse
public 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.- Parameters:
action- the action to be performed, if a value is presentemptyAction- the empty-based action to be performed, if no value is present- Throws:
NullPointerException- if a value is present and the given action isnull, or no value is present and the given empty-based action isnull.- Since:
- 9
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stream
public LongStream stream()
If a value is present, returns a sequentialLongStreamcontaining only that value, otherwise returns an emptyLongStream.- API Note:
- This method can be used to transform a
Streamof optional longs to anLongStreamof present longs:Stream<OptionalLong> os = .. LongStream s = os.flatMapToLong(OptionalLong::stream) - Returns:
- the optional value as an
LongStream - Since:
- 9
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orElse
public long orElse(long other)
If a value is present, returns the value, otherwise returnsother.- Parameters:
other- the value to be returned, if no value is present- Returns:
- the value, if present, otherwise
other
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orElseGet
public long orElseGet(LongSupplier 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 isnull
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orElseThrow
public long orElseThrow()
If a value is present, returns the value, otherwise throwsNoSuchElementException.- Returns:
- the value described by this
OptionalLong - Throws:
NoSuchElementException- if no value is present- Since:
- 10
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orElseThrow
public <X extends Throwable> long 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 presentNullPointerException- if no value is present and the exception supplying function isnullX extends Throwable
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equals
public boolean equals(Object obj)
Indicates whether some other object is "equal to" thisOptionalLong. The other object is considered equal if:- it is also an
OptionalLongand; - both instances have no value present or;
- the present values are "equal to" each other via
==.
- Overrides:
equalsin classObject- Parameters:
obj- an object to be tested for equality- Returns:
trueif the other object is "equal to" this object otherwisefalse- See Also:
Object.hashCode(),HashMap
- it is also an
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hashCode
public int hashCode()
Returns the hash code of the value, if present, otherwise0(zero) if no value is present.- Overrides:
hashCodein classObject- Returns:
- hash code value of the present value or
0if no value is present - See Also:
Object.equals(java.lang.Object),System.identityHashCode(java.lang.Object)
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toString
public String toString()
Returns a non-empty string representation of thisOptionalLongsuitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.
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