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Java Standard Edition (SE)

OptionalLong


compact1, compact2, compact3
java.util

Class 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() will return true and getAsLong() 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 OptionalLong 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 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 in this OptionalLong, 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(LongConsumer 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 OptionalLong of(long value)
      Return an OptionalLong with the specified value present.
      long orElse(long other)
      Return the value if present, otherwise return other.
      long orElseGet(LongSupplier other)
      Return the value if present, otherwise invoke other and return the result of that invocation.
      <X extends Throwable>
      long
      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.
    • Method Detail

      • 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 == against instances returned by Option.empty(). There is no guarantee that it is a singleton. Instead, use isPresent().
        Returns:
        an empty OptionalLong.
      • of

        public static OptionalLong of(long value)
        Return an OptionalLong with the specified value present.
        Parameters:
        value - the value to be present
        Returns:
        an OptionalLong with the value present
      • getAsLong

        public long getAsLong()
        If a value is present in this OptionalLong, returns the value, otherwise throws NoSuchElementException.
        Returns:
        the value held by this OptionalLong
        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(LongConsumer 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 long orElse(long 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 long orElseGet(LongSupplier other)
        Return the value if present, otherwise invoke other and return the result of that invocation.
        Parameters:
        other - a LongSupplier whose result is returned if no value is present
        Returns:
        the value if present otherwise the result of other.getAsLong()
        Throws:
        NullPointerException - if value is not present and other is null
      • orElseThrow

        public <X extends Throwable> long orElseThrow(Supplier<X> exceptionSupplier)
                                               throws X extends Throwable
        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 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:
        {code true} if the other object is "equal to" this object otherwise false
        See Also:
        Object.hashCode(), HashMap
      • 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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