MapElements (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

com.google.cloud.dataflow.sdk.transforms

Class MapElements<InputT,OutputT>

    • Method Detail

      • via

        public static <InputT,OutputT> MapElements.MissingOutputTypeDescriptor<InputT,OutputT> via(SerializableFunction<InputT,OutputT> fn)
        For a SerializableFunction<InputT, OutputT> fn and output type descriptor, returns a PTransform that takes an input PCollection<InputT> and returns a PCollection<OutputT> containing fn.apply(v) for every element v in the input.

        Example of use in Java 8:

        
         PCollection<Integer> wordLengths = words.apply(
             MapElements.via((String word) -> word.length())
                 .withOutputType(new TypeDescriptor<Integer>() {});
         

        In Java 7, the overload via(SimpleFunction) is more concise as the output type descriptor need not be provided.

      • via

        public static <InputT,OutputT> MapElements<InputT,OutputT> via(SimpleFunction<InputT,OutputT> fn)
        For a SimpleFunction<InputT, OutputT> fn, returns a PTransform that takes an input PCollection<InputT> and returns a PCollection<OutputT> containing fn.apply(v) for every element v in the input.

        This overload is intended primarily for use in Java 7. In Java 8, the overload via(SerializableFunction) supports use of lambda for greater concision.

        Example of use in Java 7:

        
         PCollection<String> words = ...;
         PCollection<Integer> wordsPerLine = words.apply(MapElements.via(
             new SimpleFunction<String, Integer>() {
               public Integer apply(String word) {
                 return word.length();
               }
             }));
         
      • populateDisplayData

        public void populateDisplayData(DisplayData.Builder builder)
        Description copied from class: PTransform
        Register display data for the given transform or component.

        populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

        By default, does not register any display data. Implementors may override this method to provide their own display data.

        Specified by:
        populateDisplayData in interface HasDisplayData
        Overrides:
        populateDisplayData in class PTransform<PCollection<InputT>,PCollection<OutputT>>
        Parameters:
        builder - The builder to populate with display data.
        See Also:
        HasDisplayData


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