In Java 8, is there a way to apply the filter on a stream based on a condition,
example
I have this stream
if (isAccessDisplayEnabled) {
src = (List < Source > ) sourceMeta.getAllSources.parallelStream()
.filter(k - > isAccessDisplayEnabled((Source) k))
.filter(k - > containsAll((Source) k, substrings, searchString))
.collect(Collectors.toList());
} else {
src = (List < Source > ) sourceMeta.getAllSources.parallelStream()
.filter(k - > containsAll((Source) k, substrings, searchString))
.collect(Collectors.toList());
}
I am adding the filter
.filter(k - > isAccessDisplayEnabled((Source) k)))
on the stream based on the if-else condition. Is there a way to avoid that if-else, since if there are more filters coming up,then it will be hard to maintain.
Please let me know
One way to do it is
Stream<Source> stream = sourceMeta.getAllSources.parallelStream().map(x -> (Source)x);
if(isAccessDisplayEnabled) stream = stream.filter(s -> isAccessDisplayEnabled(s));
src = stream.filter(s - > containsAll(s, substrings, searchString))
.collect(Collectors.toList());
another
src = sourceMeta.getAllSources.parallelStream().map(x -> (Source)x)
.filter(isAccessDisplayEnabled? s - > isAccessDisplayEnabled(s): s -> true)
.filter(s - > containsAll(s, substrings, searchString))
.collect(Collectors.toList());
In either case, note how performing one type cast at the beginning simplifies the entire stream pipline.
Both solutions avoid re-evaluating isAccessDisplayEnabled
for every stream element, however, the second relies on the JVM’s capability of inlining s -> true
when this code turns out to be performance critical.