Class Optional<T>

If a value is present, and the value matches the given predicate, returns an Optional describing the value, otherwise returns an empty Optional.

If a value is present, returns the result of applying the given Optional-bearing mapping function to the value, otherwise returns an empty Optional.

Essentially, use [[map]] if you're returning an Object and flatMap if you're returning an Optional.

If a value is present, returns the value, otherwise throws NoSuchElementException.

If a value is present, performs the given action with the value, otherwise does nothing.

If a value is present, performs the given action with the value, otherwise performs the given empty-based action.

If a value is not present, returns true, otherwise false.

If a value is present, returns true, otherwise false.

If a value is present, returns an Optional describing (as if by [[Optional.ofNullable]]) the result of applying the given mapping function to the value, otherwise returns an empty Optional.

If you're familiar with JavaScript, you know that Array.prototype.map() works like a factory. You supply it with an input set, it applies the same process to each item, then it outputs them as an array. Optional.map() is the same concept, except instead of taking and returning arrays, it takes and returns single items.

If a value is present, returns an Optional describing the value, otherwise returns an Optional produced by the supplying function.

If a value is present, returns the value, otherwise returns other.

If a value is present, returns the value, otherwise returns the result produced by the supplying function.

If a value is present, returns the value, otherwise throws NoSuchElementException.

If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function.

If a value is present, returns a sequential Stream containing only that value, otherwise returns an empty Stream.

Returns an empty Optional instance.

Returns an Optional describing the given non-null value.

Returns an Optional describing the given value, if non-null, otherwise returns an empty Optional.