Java+spark problems encountered in implementing Flatmaptopair lambda functions and their solutions

Today, using Java+spark to implement Flatmaptopair's lambda function, the code is as follows:

javapairrdd<string, string> Extractsessionsrdd = Time2sessionsrdd.flatmaptopair (tuple->{    List  New arraylist<>();     // ...     return  extractsessionids;});

Result Error:

No instance (s) of type variable (s) k2,v2 so, list<tuple2<string,string>> conforms to ITERATOR<TUPLE2&L T String,string>>

The reason for surfing the internet is because the Spark 2.0 above requires returning an instance of iterator.

So the code below (red) is changed, and the error disappears.

javapairrdd<string, string> Extractsessionsrdd = Time2sessionsrdd.flatmaptopair (tuple->{    List< tuple2<string, string>> extractsessionids = new arraylist<>();    // ...    return extractsessionids. iterator ();});  

Record, Memo.

Reference: http://blog.csdn.net/t1dmzks/article/details/70234272

Java+spark problems encountered in implementing Flatmaptopair lambda functions and their solutions