Syntax error insert in Apache Beam code

Question

I am writing Apache beam code for testing. Please refer the code below. I created sample SimpleFunction and apply code and trying to compile.

    public static void main(String[] args) throws IOException {
        System.out.println("Test Log");

        PipelineOptions options = PipelineOptionsFactory.create();
        //options.setRunner(SparkRunner.class);
        options.setRunner(SparkRunner.class);

        Pipeline p = Pipeline.create(options);

        p.apply(FileIO.match().filepattern("hdfs://path/to/*.gz"))
            // withCompression can be omitted - by default compression is detected from the filename.
            .apply(FileIO.readMatches())
            .apply(MapElements
                // uses imports from TypeDescriptors
                .via(
                    new SimpleFunction <ReadableFile, KV<String,String>>() {

                        private static final long serialVersionUID = -7867677L;

                        @SuppressWarnings("unused")
                        public KV<String,String> createKV(ReadableFile f) {
                            String temp = null;
                            try{
                            temp = f.readFullyAsUTF8String();
                            }catch(IOException e){

                            }
                            return KV.of(f.getMetadata().resourceId().toString(), temp);
                        }

                        @Override
                        public String apply(ReadableFile element, KV<String, String> input) {
                            StringBuilder str = new StringBuilder();
                            return str.toString();
                        }
                    }

            ))
            .apply(FileIO.write());
        p.run();
    }

but compiler is throwing syntax error at public String apply(ReadableFile

I tried but not successful to fix this, Could someone guide me?

Answer 1

SimpleFunction<InputT, OutputT> takes a value of InputT and returns the value of OutputT . The signature of apply in this case is OutputT apply(InputT input); , see here .

In your case for your types the SimpleFunction will have to look like this:

new SimpleFunction <ReadableFile, KV<String,String>>() {
   ...
   @Override
   public KV<String,String> apply(ReadableFile input) {
      ...
   }
}

For example see how it is used here .

In your case you need more logic around readMatches() , see here for example how it is applied to parse Avros, and this is the implementation details of the PTransform from that code.