I need to calculate the ratio of two parts of the big List, wherein the first part contains the second:
Stream<Element> part1 = list.stream().filter(x -> x.getN1() < x.getN2);
int result = part1.filter(y -> y.isRight()).count() / part1.count();
But this code throws the Exception: java.lang.IllegalStateException: stream has already been operated upon or closed
Can I write a code without creating the same part1 stream in result?
You can only reuse a collection as it has memoriation of results.
List<Element> part1 = list.stream().filter(x -> x.getN1() < x.getN2).collect(toList());
double result = (double) part1.stream().filter(y -> y.isRight()).count() / part1.size();
A Stream is a builder for some code which is optimised at run time. It's execution isn't as dynamic as it appears.
Streams are not supposed to be reused, or if you want something seemed to it, you can use suppliers as mentioned here : Copy a stream to avoid "stream has already been operated upon or closed" (java 8)
