Null array to empty list

Question

Arrays.asList(E[] e) returns a view of the array as a List, but when array is null it throws a NullPointerException.

Arrays.asList(null); //NullPointerException.

Actually I'm doing

 List list = possibleNullArray != null ? Arrays.asList(possibleNullArray) : Collections.EMPTY_LIST;

However, creating a Utility class in my project only for this purpose is a thing that I prefer not to do. Is there some utility Class, or library like Apache Commons or Guava to convert null arrays to empty List? (i.e. a null-safe converter between arrays and Collections).

How would you solve this problem?

Answer 1

You can use Java 8 Optional:

String[] arr = null;
List<String> list = Arrays.asList(Optional.ofNullable(arr).orElse(new String[0]));

Answer 2

You can use Java 8 Optionaland Stream

Optional.ofNullable(possibleNullArray)
        .map(Arrays::stream)
        .orElseGet(Stream::empty)
        .collect(Collectors.toList())

Answer 3

I'm not aware of any util method in Apache Commons / Guava that would create an empty List instance out of null.

The best thing you can probably do is to initialize the possibly null array beforehand, e.g. with ArrayUtils.nullToEmpty(). Get rid of the null as soon as you can.

SomeObject[] array = ArrayUtils.nullToEmpty(possiblyNullArray);