Apache Beam ValueProvider usage sample from GCP document (https://cloud.google.com/dataflow/docs/guides/templates/creating-templates?hl=ja)

SumInteger.java

package dummy;

import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.io.TextIO;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.options.ValueProvider;
import org.apache.beam.sdk.transforms.Create;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.MapElements;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.values.TypeDescriptors;

/**
 * Usage: ./gradlew run --args="--runner=DirectRunner --int=10"
 *
 * This program requires that this class is specified main class via
 * `application` plugin setting of gradle.build
 */
public class SumInteger {

	public interface SumIntOptions extends PipelineOptions {

		ValueProvider<Integer> getInt();
		void setInt(ValueProvider<Integer> value);
	}

	static class MySumFn extends DoFn<Integer, Integer> {
		ValueProvider<Integer> mySumInteger;

		MySumFn(ValueProvider<Integer> sumInt) {
			this.mySumInteger = sumInt;
		}

		@ProcessElement
		public void processElement(ProcessContext c) {
			c.output(c.element() + mySumInteger.get());
		}
	}

	public static void main(String... args) {
		SumIntOptions options = PipelineOptionsFactory.fromArgs(args).withValidation().as(SumIntOptions.class);

		Pipeline p = Pipeline.create(options);

		p.apply(Create.of(1,2,3))
				.apply(ParDo.of(new MySumFn(options.getInt())))
				.apply("ToString", MapElements.into(TypeDescriptors.strings()).via(x -> x.toString()))
				.apply("OutputNums", TextIO.write().to("numvalues"));

		p.run();
	}
}