Hi,
I think you can use State to achieve your goal:
https://ci.apache.org/projects/flink/flink-docs-release-1.3/dev/stream/state.html
Best,
Kurt
On Thu, Jul 13, 2017 at 1:14 PM, ZalaCheung <gzzhangdesh...@corp.netease.com
> wrote:
> Hi all,
>
> I am stuck with a problem. I have a stream, I want keyby it and then do a
> map function on it. But for each map operator, I want to maintain a
> variable for it. Is that possible? I tried a naive version on local
> IntelliJ IDE and it works. But I got nullpointerException while trying to
> run it on a cluster.
>
> Here is the pseudo code for my naive version, wish it will help you guys
> understand my question.
>
> public class anomalydetection{
> private static List<TimeSeries> queue;
> public static void main(String[] args)throws Exception{
> initialize();
> getStreamExecutionEnvironment();
> DataStream input = ...
> stream.keyby("some key").map(
> MapFunction(){
> if(queue.size() < some_num){
> queue.add()
> //do something
> }
> else{
> //dosomething
> }
> }
> )
>
> public void initialize(){
> queue = new ArrayList<>();
> }}
>
>
> when I try to get the size of the arraylist, I get a
> *NullPointerException*. Beside that, I want to *maintain a list for each
> map operator after I group the stream by some key*.
>
>
> Is that possible to do what I want in Flink?
>
> Desheng Zhang
>
> E-mail: gzzhangdesh...@corp.netease.com;
>
>
