Why does findFirst() throw a NullPointerException if the first element it finds is null?

Question

Why does this throw a java.lang.NullPointerException?

List strings = new ArrayList<>();
        strings.add(null);
        s         


        

Answer 1

The following code replaces findFirst() with limit(1) and replaces orElse() with reduce():

String firstString = strings.
   stream().
   limit(1).
   reduce("StringWhenListIsEmpty", (first, second) -> second);

limit() allows only 1 element to reach reduce. The BinaryOperator passed to reduce returns that 1 element or else "StringWhenListIsEmpty" if no elements reach the reduce.

The beauty of this solution is that Optional isn't allocated and the BinaryOperator lambda isn't going to allocate anything.