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();
