stream has already been operated upon or closed, even after using suplier

Question

I have below code, but gettting error:

Stream<BigDecimal> method(Stream<BigDecimal> in) {
    if (in == null)
        return Stream.empty();

    Supplier<Stream<BigDecimal>> supplier = () -> in;
    
    Stream<BigDecimal> s1 = supplier.get().filter(e -> e != null);
    long count = s1.count();
    

    double average = supplier.get().mapToDouble(BigDecimal::doubleValue).average().orElse(Double.NaN);
    
    return supplier.get();
}

Error says:

Exception in thread "main" java.lang.IllegalStateException: stream has already been operated upon or closed
    at java.util.stream.AbstractPipeline.<init>(AbstractPipeline.java:203)
    at java.util.stream.DoublePipeline.<init>(DoublePipeline.java:90)
    at java.util.stream.DoublePipeline$StatelessOp.<init>(DoublePipeline.java:597)
    at java.util.stream.ReferencePipeline$6.<init>(ReferencePipeline.java:238)
    at java.util.stream.ReferencePipeline.mapToDouble(ReferencePipeline.java:237)

How to fix this issue, I already tried using supplier.get method, but still getting errors.

`.count()` is a terminal operation, see https://stackoverflow.com/q/43653761/6245535 and https://stackoverflow.com/q/38044849/6245535 for more info. — Loris Securo, Jul 21 '20 at 16:52

score 0 · Answer 1 · answered Jul 21 '20 at 16:57

0

You're not really using the Supplier here. If you want this to work, the argument to method must itself be a Supplier<Stream<BigDecimal>>. () -> in doesn't actually do what you need the supplier to do, which is to generate an entirely new stream.

answered Jul 21 '20 at 16:57

Louis Wasserman

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Then how to perform multiple operations with my stream? – learner Jul 21 '20 at 16:58
The rest of it is fine. You just have to accept a `Supplier>` instead of a `Stream`. – Louis Wasserman Jul 21 '20 at 16:59
I cannot change my method signature of my program, it is fixed in my case. – learner Jul 21 '20 at 16:59
Then the only option you have is to collect the stream to a list or array and then to operate over that list or array. – Louis Wasserman Jul 21 '20 at 17:00

stream has already been operated upon or closed, even after using suplier

1 Answers1