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Posted to issues@flink.apache.org by "Moshe Sayag (JIRA)" <ji...@apache.org> on 2017/04/30 08:56:04 UTC
[jira] [Created] (FLINK-6423) JoinFunction can not be replaced with
lambda
Moshe Sayag created FLINK-6423:
----------------------------------
Summary: JoinFunction can not be replaced with lambda
Key: FLINK-6423
URL: https://issues.apache.org/jira/browse/FLINK-6423
Project: Flink
Issue Type: Bug
Components: DataStream API
Affects Versions: 1.2.0
Reporter: Moshe Sayag
Priority: Minor
JoinedStreams.WithWindow.apply(...) can get a JoinFunction as a parameter, but not an equivalent lambda.
Consider the following code, runWithFunction completes successfully, while runWithLambda throws "java.lang.ArrayIndexOutOfBoundsException: -1"
As this might look like a very minor issue, the exception is not clear and might cause a developer to spend precious time while looking for the cause
public void runWithFunction() throws Exception {
StreamExecutionEnvironment env = LocalStreamEnvironment.getExecutionEnvironment();
env.setStreamTimeCharacteristic(TimeCharacteristic.ProcessingTime);
DataStream<String> stream1 = env.fromElements("a", "b", "c");
DataStream<String> stream2 = env.fromElements("A", "B", "C");
DataStream<String> joined = stream1.join(stream2)
.where(String::toLowerCase).equalTo(String::toLowerCase)
.window(ProcessingTimeSessionWindows.withGap(Time.minutes(1)))
.apply(new JoinFunction<String, String, String>() {
@Override
public String join(String s1, String s2) {
return s1 + "_" + s2;
}
});
joined.print();
env.execute();
}
public void runWithLambda() throws Exception {
StreamExecutionEnvironment env = LocalStreamEnvironment.getExecutionEnvironment();
env.setStreamTimeCharacteristic(TimeCharacteristic.ProcessingTime);
DataStream<String> stream1 = env.fromElements("a", "b", "c");
DataStream<String> stream2 = env.fromElements("A", "B", "C");
DataStream<String> joined = stream1.join(stream2)
.where(String::toLowerCase).equalTo(String::toLowerCase)
.window(ProcessingTimeSessionWindows.withGap(Time.minutes(1)))
.apply((JoinFunction<String, String, String>) (s1, s2) -> s1 + "_" + s2);
joined.print();
env.execute();
}
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