Class OptionalLong

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 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; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail.

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 is OptionalLong should never itself be null; it should always point to an OptionalLong instance.
Since:
1.8

  • Method Summary

    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" this OptionalLong.
    long
    getAsLong()
    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(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
    isEmpty()
    If a value is not present, returns true, otherwise false.
    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 returns other.
    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 throws NoSuchElementException.
    <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 Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait
    Modifier and Type
    Method
    Description
    protected Object
    clone()
    Creates and returns a copy of this object.
    protected void
    finalize()
    Deprecated, for removal: This API element is subject to removal in a future version.
    Finalization is deprecated and subject to removal in a future release.
    final Class<?>
    getClass()
    Returns the runtime class of this Object.
    final void
    notify()
    Wakes up a single thread that is waiting on this object's monitor.
    final void
    notifyAll()
    Wakes up all threads that are waiting on this object's monitor.
    final void
    wait()
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
    final void
    wait(long timeoutMillis)
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
    final void
    wait(long timeoutMillis, int nanos)
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

  • Method Details

    • empty

      public static OptionalLong 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 == or != against instances returned by OptionalLong.empty(). There is no guarantee that it is a singleton. Instead, use isEmpty() or isPresent().
      Returns:
      an empty OptionalLong.

    • of

      public static OptionalLong 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().
      Returns:
      the value described by this OptionalLong
      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

    • isEmpty

      public boolean isEmpty()
      If a value is not present, returns true, otherwise false.
      Returns:
      true if a value is not present, otherwise false
      Since:
      11

    • 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 is null

    • 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 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 LongStream stream()
      If a value is present, returns a sequential LongStream 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 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 long orElseThrow()
      If a value is present, returns the value, otherwise throws NoSuchElementException.
      Returns:
      the value described by this OptionalLong
      Throws:
      NoSuchElementException - if no value is present
      Since:
      10

    • orElseThrow

      public <X extends Throwable> long orElseThrow(Supplier<? extends X> exceptionSupplier) throws X
      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

    • equals

      public boolean equals(Object 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 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
      See Also:

    • 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
      See Also:

    • toString

      public String 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 in class Object
      Implementation Requirements:
      If a value is present the result must include its string representation in the result. Empty and present OptionalLongs must be unambiguously differentiable.
      Returns:
      the string representation of this instance