Else method for ifPresent Stream [duplicate]

Question

I want to know how to do some behavior if some value is not present after filter a stream.

Let's suppose that code:

foo.stream().filter(p -> p.someField == someValue).findFirst().ifPresent(p -> {p.someField = anotherValue; someBoolean = true;}); 

How I put some kind of Else after ifPresent in case of value is not present?

There are some orElse methods on Stream that I can call after findFirst, but I can't see a way to do that with those orElse

Answer 1

findFirst returns an Optional describing the first element of this stream, or an empty Optional if the stream is empty.

If you want to apply a function when Optional is not empty you should use map. orElseGet can call another lambda if Optional is empty E.g.

foo.stream()
   .filter(p -> p.someField == someValue)
   .findFirst().map(p -> {
       p.someField = anotherValue;
       someBoolean = true;
       return p;
   }).orElseGet(() -> {
       P p = new P();
       p.someField = evenAnotherValue;
       someBoolean = false;
       return p;
   });