[jira] [Created] (FLINK-3881) Error in Java 8 Documentation Sample

["Mans Singh (JIRA)" <ji...@apache.org>]

Mans Singh created FLINK-3881:
---------------------------------

             Summary: Error in Java 8 Documentation Sample
                 Key: FLINK-3881
                 URL: https://issues.apache.org/jira/browse/FLINK-3881
             Project: Flink
          Issue Type: Bug
          Components: Documentation
    Affects Versions: 1.0.3
         Environment: All
            Reporter: Mans Singh
            Priority: Minor


The java8 documentation (https://ci.apache.org/projects/flink/flink-docs-master/apis/java8.html) has samples (one of them) included below:

DataSet<String> input = env.fromElements(1, 2, 3);

// collector type must be declared
input.flatMap((Integer number, Collector<String> out) -> {
    for(int i = 0; i < number; i++) {
        out.collect("a");
    }
})
// returns "a", "a", "aa", "a", "aa" , "aaa"
.print();

I tried the sample and I think there are two issues with it (unless I have missed anything):
1. The DataSet should be DataSet<Integer> and not DataSet<String>
2. It should have a StringBuffer that appends "a" in the for loop and output (out.collect(buffer.toString()) it rather than just out.collect("a");.  Currently, this produces only "a" each time rather than   "a", "a", "aa", "a", "aa" , "aaa" as shown the comments.



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