Filter Null items in Stream

问题:

When using a Java Stream, sometimes null values can occur after mapping. Currently when these values need to be omitted, I use:

.stream()
.<other operations...>
.filter(element -> element != null)
.<other operations...>

For a more functional style a tiny helper method is quickly written:

public static <T> boolean nonNull(T entity) {
    return entity != null;
}

So that you can use a method reference instead:

.stream()
.<other operations...>
.filter(Elements::nonNull)
.<other operations...>

I could not find such a jdk method, even though I would suspect they have included one. Is there a different approach here? Or did they omit this for a reason?

回答1:

You can use Objects::nonNull from the Java8 SDK:

.stream()
.<other operations...>
.filter(Objects::nonNull)
.<other operations...>

回答2:

You can use the Objects::nonNull

Returns true if the provided reference is non-null otherwise returns false.

.stream()
.<other operations...>
.filter(Objects::nonNull)
.<other operations...>