## Why is this an issue?

There are two types of stream operations: intermediate operations, which return another stream, and terminal operations, which return something other than a stream. Intermediate operations are lazy, meaning they aren’t actually executed until and unless a terminal stream operation is performed on their results. Consequently, if the result of an intermediate stream operation is not fed to a terminal operation, it serves no purpose, which is almost certainly an error.

### Noncompliant code example

    widgets.stream().filter(b -> b.getColor() == RED); // Noncompliant

### Compliant solution

    int sum = widgets.stream()
                          .filter(b -> b.getColor() == RED)
                          .mapToInt(b -> b.getWeight())
                          .sum();
    Stream<Widget> pipeline = widgets.stream()
                                     .filter(b -> b.getColor() == GREEN)
                                     .mapToInt(b -> b.getWeight());
    sum = pipeline.sum();

## Resources

- Stream Operations