zeppelin/docs/interpreter/java.md

layout	title	description	group
page	Java interpreter in Apache Zeppelin	Run Java code and any distributed java computation engine by importing the dependencies in the interpreter configuration.	interpreter

{% include JB/setup %}

Java interpreter for Apache Zeppelin

How to use

Basically, you can write normal java code. You should write the main method inside a class because the interpreter invoke this main to execute the code. Unlike Zeppelin normal pattern, each paragraph is considered as a separate job, there isn't any relation to any other paragraph.

TODO: UPDATE EXAMPLE BELOW WITH A JAVA ONE... TRY IT IN THE INTERPRETER FIRST The following is a demonstration of a word count example with data represented in array of strings But it can read data from files by replacing Create.of(SENTENCES).withCoder(StringUtf8Coder.of()) with TextIO.Read.from("path/to/filename.txt")

%java

// most used imports
import org.apache.beam.sdk.coders.StringUtf8Coder;
import org.apache.beam.sdk.transforms.Create;
import java.io.Serializable;
import java.util.Arrays;
import java.util.List;
import java.util.ArrayList;
import org.apache.beam.runners.direct.*;
import org.apache.beam.sdk.runners.*;
import org.apache.beam.sdk.options.*;
import org.apache.beam.runners.flink.*;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.io.TextIO;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.transforms.Count;
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.transforms.SimpleFunction;
import org.apache.beam.sdk.values.KV;
import org.apache.beam.sdk.options.PipelineOptions;

public class MinimalWordCount {
  static List<String> s = new ArrayList<>();
  
  static final String[] SENTENCES_ARRAY = new String[] {
    "Hadoop is the Elephant King!",
    "A yellow and elegant thing.",
    "He never forgets",
    "Useful data, or lets",
    "An extraneous element cling!",
    "A wonderful king is Hadoop.",
    "The elephant plays well with Sqoop.",
    "But what helps him to thrive",
    "Are Impala, and Hive,",
    "And HDFS in the group.",
    "Hadoop is an elegant fellow.",
    "An elephant gentle and mellow.",
    "He never gets mad,",
    "Or does anything bad,",
    "Because, at his core, he is yellow",
	};  
  static final List<String> SENTENCES = Arrays.asList(SENTENCES_ARRAY);
  public static void main(String[] args) {
    PipelineOptions options = PipelineOptionsFactory.create().as(PipelineOptions.class);
    options.setRunner(FlinkRunner.class);
    Pipeline p = Pipeline.create(options);
    p.apply(Create.of(SENTENCES).withCoder(StringUtf8Coder.of()))
         .apply("ExtractWords", ParDo.of(new DoFn<String, String>() {
           @ProcessElement
           public void processElement(ProcessContext c) {
             for (String word : c.element().split("[^a-zA-Z']+")) {
               if (!word.isEmpty()) {
                 c.output(word);
               }
             }
           }
         }))
        .apply(Count.<String> perElement())
        .apply("FormatResults", ParDo.of(new DoFn<KV<String, Long>, String>() {
          @ProcessElement
          public void processElement(DoFn<KV<String, Long>, String>.ProcessContext arg0)
            throws Exception {
            s.add("\n" + arg0.element().getKey() + "\t" + arg0.element().getValue());
          	}
        }));
    p.run();
    System.out.println("%table word\tcount");
    for (int i = 0; i < s.size(); i++) {
      System.out.print(s.get(i));
    }

  }
}