Java 8 Stream String Null Or Empty Filter

In java 11 there is a new method Predicate::not.

So you can filter out empty string :

list.stream()
  .filter(Objects::nonNull)
  .filter(Predicate.not(String::isEmpty))

You can create your own Strings class with your own predicate:

public class Strings {
  public static boolean isNotNullOrEmpty (String str) {
    return str != null && !str.isEmpty();
  }
}

Then in your code:

.filter(Strings::isNotNullOrEmpty)

But as @fge mentionned, you can't use that on a Map.Entry<?,?>...

If you prefer to use commons-lang3, StringUtils has

These methods can be used in filters as method references:

this.stringList.stream().filter(StringUtils::isNotBlank);

or as lambdas:

this.stringList.stream().filter(s -> StringUtils.isNotBlank(s));

You can write your own predicate:

final Predicate<Map.Entry<?, String>> valueNotNullOrEmpty
    = e -> e.getValue() != null && !e.getValue().isEmpty();

Then just use valueNotNullOrEmpty as your filter argument.

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