Avoid NoSuchElementException with Stream

Question

I have the following Stream:

Stream<T> stream = stream();  T result = stream.filter(t -> {     double x = getX(t);     double y = getY(t);     return (x == tx && y == ty); }).findFirst().get();  return result; 

However, there is not always a result which gives me the following error:

NoSuchElementException: No value present

So how can I return a null if there is no value present?

Answer 1

You can use Optional.orElse, it's much simpler than checking isPresent:

T result = stream.filter(t -> {     double x = getX(t);     double y = getY(t);     return (x == tx && y == ty); }).findFirst().orElse(null);  return result; 

Answer 2

Stream#findFirst() returns an Optional which exists specifically so that you don't need to operate on null values.

A container object which may or may not contain a non-null value. If a value is present, isPresent() will return true and get() will return the value.

Otherwise, Optional#get() throws a NoSuchElementException.

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

An Optional will never expose its value if it is null.

If you really have to, just check isPresent() and return null yourself.

Stream<T> stream = stream();  Optional<T> result = stream.filter(t -> {     double x = getX(t);     double y = getY(t);     return (x == tx && y == ty); }).findFirst();  if (result.isPresent())      return result.get(); return null;