jhnmora000 commented on a change in pull request #11333:
URL: https://github.com/apache/beam/pull/11333#discussion_r418279156
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Sample.java
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@@ -246,6 +254,36 @@ private SampleAnyCombineFn(long limit) {
}
}
+ /** A {@link CombineFn} that combines into a single element. */
+ private static class AnyValueCombineFn<T> extends CombineFn<T, List<T>, T> {
+ private SampleAnyCombineFn internal;
+
+ private AnyValueCombineFn() {
+ internal = new SampleAnyCombineFn<>(1);
+ }
+
+ @Override
+ public List<T> createAccumulator() {
+ return internal.createAccumulator();
+ }
+
+ @Override
+ public List<T> addInput(List<T> accumulator, T input) {
+ return internal.addInput(accumulator, input);
+ }
+
+ @Override
+ public List<T> mergeAccumulators(Iterable<List<T>> accumulators) {
+ return internal.mergeAccumulators(accumulators);
+ }
+
+ @Override
+ public T extractOutput(List<T> accumulator) {
+ Iterator<T> it = internal.extractOutput(accumulator).iterator();
+ return it.hasNext() ? it.next() : null;
Review comment:
Yes, I was aware of that. I thought that I could have used java
Optional<T> or similar, but I was not sure it would be compliant with other
components. Are there other functions that return optional or nullable objects
in the Java SDK?, I could give them a look.
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