Remove Optional Empty/Null values from list

In this Article , we’ll Discuss, How we can Convert Stream of Optional elements to a Stream of present value elements.

Java 8 has added Optional type to avoid null pointer exception.

lets say we have List<Optional<String>> and for further processing we want List<Strings>.
In This case we need to remove the null and empty elements from stream and convert it into a Stream of present value elements.

Convert Stream of Optional elements to a Stream of present value elements

//Input List 
List<Optional<String>> list = new ArrayList<>();
list.add(Optional.empty());
list.add(Optional.of("Str1"));
list.add(Optional.of("Str2"));
list.add(Optional.empty());
list.add(Optional.ofNullable(null));
//Using Filter
List<String> listWithoutNull = list.stream()
                                   .filter(Optional::isPresent)
                                   .map(obj ->obj.get())
                                   .collect(Collectors.toList());

//Using removeIf (if that list supports removal )
                        list.removeIf(iteam->!iteam.isPresent());                                  

Java 9

In java 9 We can easily convert Stream of optionals to a stream of present values.
Using newly addded Optional::stream API

java 9

List<String> listWithoutNull = list.stream()
                                  .flatMap(Optional::stream)
                                 .collect(Collectors.toList());