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new 02a95c9fda Operator docs: add description and example for
StreamConverters.javaCollector (#2992)
02a95c9fda is described below
commit 02a95c9fda3ffdeb3f5e0e13e4582ec94b989f95
Author: wolf8334 <[email protected]>
AuthorDate: Mon May 25 20:42:41 2026 +0800
Operator docs: add description and example for
StreamConverters.javaCollector (#2992)
* Operator docs: add description and example for
StreamConverters.javaCollector
Motivation:
The javaCollector operator doc page had a TODO placeholder instead of
documentation.
Modification:
- Replace TODO with a Description section explaining how javaCollector
works
- Add references to javaCollectorParallelUnordered and Sink.collect
- Add Scala and Java code examples using Collectors.toList
Result:
The StreamConverters.javaCollector operator docs are now complete.
Tests:
sbt "docs/Test/compile" -- passed
References:
Refs https://github.com/akka/akka-core/issues/25468
* docs: remove Java version reference in javaCollector example
Signed-off-by: 钱多多 <[email protected]>
* docs: add license header to JavaCollectorDocExamples
Signed-off-by: 钱多多 <[email protected]>
* docs: add license header to JavaCollectorDocExamples
Signed-off-by: 钱多多 <[email protected]>
* docs: add license header to JavaCollectorDocExamples
Signed-off-by: 钱多多 <[email protected]>
---------
Signed-off-by: 钱多多 <[email protected]>
---
.../operators/StreamConverters/javaCollector.md | 25 +++++++++++--
.../stream/operators/JavaCollectorDocExamples.java | 41 ++++++++++++++++++++++
.../stream/operators/JavaCollectorDocExample.scala | 36 +++++++++++++++++++
3 files changed, 100 insertions(+), 2 deletions(-)
diff --git
a/docs/src/main/paradox/stream/operators/StreamConverters/javaCollector.md
b/docs/src/main/paradox/stream/operators/StreamConverters/javaCollector.md
index c4ac8615e7..d125e8c7bf 100644
--- a/docs/src/main/paradox/stream/operators/StreamConverters/javaCollector.md
+++ b/docs/src/main/paradox/stream/operators/StreamConverters/javaCollector.md
@@ -1,6 +1,6 @@
# StreamConverters.javaCollector
-Create a sink which materializes into a @scala[`Future`]
@java[`CompletionStage`] which will be completed with a result of the Java 8
`Collector` transformation and reduction operations.
+Create a sink which materializes into a @scala[`Future`]
@java[`CompletionStage`] which will be completed with a result of the Java
`Collector` transformation and reduction operations.
@ref[Additional Sink and Source
converters](../index.md#additional-sink-and-source-converters)
@@ -11,4 +11,25 @@ Create a sink which materializes into a @scala[`Future`]
@java[`CompletionStage`
## Description
-TODO: We would welcome help on contributing descriptions and examples, see:
https://github.com/akka/akka/issues/25646
+`javaCollector` creates a @apidoc[Sink] that accepts a Java 8
@javadoc[java.util.stream.Collector](java.util.stream.Collector)
+factory. The `Collector` accumulates incoming elements into a mutable
container as downstream demand is
+triggered, and after the stream completes, an optional finisher transforms the
accumulated result. The sink
+materializes into a @scala[`Future`]@java[`CompletionStage`] holding the final
result. All processing
+happens sequentially on the stream's materialized execution context.
+
+Since each materialization of the sink must start with a fresh accumulator,
the factory is invoked once per
+materialization. Use
@ref:[javaCollectorParallelUnordered](javaCollectorParallelUnordered.md) if
parallel
+collection is needed.
+
+@ref:[`Sink.collect`](../Sink/collect.md) provides a simpler API for common
collection scenarios.
+
+## Example
+
+In this example, `StreamConverters.javaCollector` uses ``Collectors.toList``
to gather stream elements
+into a ``List``.
+
+Scala
+: @@snip
[JavaCollectorDocExample.scala](/docs/src/test/scala/docs/stream/operators/JavaCollectorDocExample.scala)
{ #javaCollector }
+
+Java
+: @@snip
[JavaCollectorDocExamples.java](/docs/src/test/java/jdocs/stream/operators/JavaCollectorDocExamples.java)
{ #javaCollector }
diff --git
a/docs/src/test/java/jdocs/stream/operators/JavaCollectorDocExamples.java
b/docs/src/test/java/jdocs/stream/operators/JavaCollectorDocExamples.java
new file mode 100644
index 0000000000..34087a9f8b
--- /dev/null
+++ b/docs/src/test/java/jdocs/stream/operators/JavaCollectorDocExamples.java
@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package jdocs.stream.operators;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CompletionStage;
+import java.util.stream.Collectors;
+import org.apache.pekko.NotUsed;
+import org.apache.pekko.actor.ActorSystem;
+import org.apache.pekko.stream.javadsl.Source;
+import org.apache.pekko.stream.javadsl.StreamConverters;
+
+public class JavaCollectorDocExamples {
+
+ static void example() {
+ ActorSystem system = null;
+
+ // #javaCollector
+ Source<String, NotUsed> source = Source.from(Arrays.asList("Apache",
"Pekko", "Streams"));
+
+ CompletionStage<List<String>> result =
+ source.runWith(StreamConverters.javaCollector(Collectors::toList),
system);
+ // #javaCollector
+ }
+}
diff --git
a/docs/src/test/scala/docs/stream/operators/JavaCollectorDocExample.scala
b/docs/src/test/scala/docs/stream/operators/JavaCollectorDocExample.scala
new file mode 100644
index 0000000000..29bfcd1b4c
--- /dev/null
+++ b/docs/src/test/scala/docs/stream/operators/JavaCollectorDocExample.scala
@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package docs.stream.operators
+
+import java.util.stream.Collectors
+
+import org.apache.pekko.NotUsed
+import org.apache.pekko.stream.scaladsl.Sink
+import org.apache.pekko.stream.scaladsl.Source
+import org.apache.pekko.stream.scaladsl.StreamConverters
+
+object JavaCollectorDocExample {
+
+ // #javaCollector
+ val source: Source[String, NotUsed] =
+ Source(List("Apache", "Pekko", "Streams"))
+
+ val sink: Sink[String, _] =
+ StreamConverters.javaCollector(() => Collectors.toList[String]())
+ // #javaCollector
+}
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