Suppose I have an array or a list of status, and want to filter a list for elements whose status matches any of the given. So I go on creating a predicate. I started by initializing it with the comparison to the first, then adding more conditions with or
, which resulted in the minimal predicate but was a lot of code:
Predicate<Rec> predicate = null;
for (SendStatus status : statuss) {
Predicate<Rec> innerPred = nr -> nr.getStatus() == status;
if (predicate == null)
predicate = innerPred;
else
predicate = predicate.or(innerpred);
}
More elegantly, I came up with the following code:
Predicate<Rec> predicate = nr -> false;
for (SendStatus status : statuss) {
predicate = predicate.or(nr -> nr.getStatus() == status);
}
This looks nicer, but has a useless predicate at the beginning of the chain. Apache Collections had an AnyPredicate
that could be composed of any number of predicates, and I'm basically looking for a replacement.
Is this superfluous predicate acceptable? Is there an even more elegant way to write this?
How about this, assuming statuss
is a Collection<SendStatus>
:
Predicate<Rec> predicate = nr -> statuss.stream().anyMatch(status -> nr.getStatus() == status);
Or this, if statuss
is a SendStatus[]
:
Predicate<Rec> predicate = nr -> Arrays.stream(statuss).anyMatch(status -> nr.getStatus() == status);
Or do as suggested by @Jerry06 in a comment , which is faster if statuss
is a Set<SendStatus>
, and simpler than streaming collection solution above:
Predicate<Rec> predicate = nr -> statuss.contains(nr.getStatus());
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