Example of how to use FieldExtractor with DelimitedRecordMarshaller #EasyBatch

Launcher.java

package org.easybatch.tutorials.fieldext;

import org.easybatch.core.job.Job;
import org.easybatch.core.job.JobBuilder;
import org.easybatch.core.job.JobExecutor;
import org.easybatch.core.reader.IterableRecordReader;
import org.easybatch.core.writer.StandardOutputRecordWriter;
import org.easybatch.flatfile.DelimitedRecordMarshaller;
import org.easybatch.tutorials.common.Tweet;

import java.util.Arrays;
import java.util.List;

public class Launcher {

    public static void main(String[] args) throws Exception {

        Tweet t1 = new Tweet(1, "foo", "hello");
        Tweet t2 = new Tweet(2, "bar", "hi");
        List<Tweet> tweets = Arrays.asList(t1, t2);

        Job job = new JobBuilder()
                .reader(new IterableRecordReader(tweets))
                .marshaller(new DelimitedRecordMarshaller<>(new TweetFieldExtractor(), "|", "'"))
                .writer(new StandardOutputRecordWriter())
                .build();

        JobExecutor jobExecutor = new JobExecutor();
        jobExecutor.execute(job);
        jobExecutor.shutdown();
        
        // This prints:
        // 'hello'|'foo'
        // 'hi'|'bar'

    }
}

Tweet.java

public class Tweet {

    private int id;
    private String user;
    private String message;

    public Tweet() {
    }

    public Tweet(int id, String user, String message) {
        this.id = id;
        this.user = user;
        this.message = message;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUser() {
        return user;
    }

    public void setUser(String user) {
        this.user = user;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

}

TweetFieldExtractor.java

import org.easybatch.core.field.FieldExtractor;
import org.easybatch.tutorials.common.Tweet;

import java.util.ArrayList;
import java.util.List;

public class TweetFieldExtractor implements FieldExtractor<Tweet> {

    // in this example we select only "user" and "message" fields (filter id field) and marshal them in this order: message,id
    @Override
    public Iterable<Object> extractFields(Tweet tweet) throws Exception {
        List<Object> fields = new ArrayList<>();
        fields.add(tweet.getMessage());
        fields.add(tweet.getUser());
        return fields;
    }

}