Check ArrayList content with Java stream

Question

Consider following ArrayList:

[0] => Person
[1] => User
[2] => Dummy

How can one with Java streams check if this arraylist contains any other objects than Person or User ?

So that I can make an if statement to return null if it contains only Person and User, or return the arraylist itself if it contains any other objects besides Person or User like so:

if( /*arrayList contains only Person and User*/ ) {
  return null;
}
else {
  //arrayList contains other objects besides Person and User
  return arrayList;
}

Answer 1

Assuming Person and User are types, rather than specific objects, you can do something like this.

return list.stream()
           .filter(o -> !(o instanceof Person) && !(o instanceof User))
           .findAny()
           .isPresent() ? list : null;

Answer 2

Alternative to Paul's answer (with the if-else in your question)

if (arrayList.stream().allMatch(o -> o instanceof Person || o instanceof User)) {
    return null;
} else {
    return arrayList;
}