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From "Huang Wei (JIRA)" <j...@apache.org>
Subject [jira] [Created] (FLINK-2495) Add a null point check in API DataStream.union
Date Fri, 07 Aug 2015 07:34:46 GMT
Huang Wei created FLINK-2495:

             Summary: Add a null point check in API DataStream.union
                 Key: FLINK-2495
                 URL: https://issues.apache.org/jira/browse/FLINK-2495
             Project: Flink
          Issue Type: Bug
          Components: Streaming
    Affects Versions: 0.10
            Reporter: Huang Wei
             Fix For: 0.10

The API(public DataStream<OUT> union(DataStream<OUT>... streams)) is a  external
interface for user.
The parameter "streams" maybe null and it will throw NullPointerException error.

This test below can be intuitive to explain this problem:

package org.apache.flink.streaming.api;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.source.RichParallelSourceFunction;
import org.junit.Test;

 * Created by HuangWHWHW on 2015/8/7.
public class test {

	public static class sourceFunction extends RichParallelSourceFunction<String> {

		public sourceFunction() {

		public void run(SourceContext<String> sourceContext) throws Exception {

		public void cancel() {


	public void testUnion(){
		StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
		DataStream<String> source = env.addSource(new sourceFunction());
		DataStream<String> temp1 = null;
		DataStream<String> temp2 = source.map(new MapFunction<String, String>() {
			public String map(String value) throws Exception {
				if (value == "a") {
					return "This is for test temp2.";
				return null;
		DataStream<String> sink = temp2.union(temp1);
		try {
		}catch (Exception e){


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