ParseWithRx.java

import rx.Observable;

import java.util.ArrayList;
import java.util.Collection;

import static java.util.Arrays.asList;

public class ParseWithRx {
    public static void main(String[] args) {
        String[][] sourceData = {
                {"Master1", "Master2", "Master3"},
                {"A1", "B1", "C1", "D1"},
                {"A2", "B2", "C2", "D2"},
        };

        Observable.from(asList(sourceData)).publish(rows -> {
          Observable<String[]> master = rows.take(1);
          Observable<String[]> detail = rows.skip(1);

          return detail
                  .map(row -> new Detail(row[0], row[1], row[2], row[3]))
                  .collect(() -> new ArrayList<Detail>(), (acc, row) -> { acc.add(row); })
                  .zipWith(master, (details, row) -> new MasterDetail(row[0], row[1], row[2], details));
        }).subscribe(System.out::println);
        /* Output: 
          MasterDetail{
          master1='Master1', 
          master2='Master2', 
          master3='Master3', 
          details=[
            Detail{a='A1', b='B1', c='C1', d='D1'}, 
            Detail{a='A2', b='B2', c='C2', d='D2'}
          ]}
        */
    }

    private static class MasterDetail {
        private String master1;
        private String master2;
        private String master3;
        private Collection<Detail> details;

        public MasterDetail(String master1, String master2, String master3, Collection<Detail> details) {
            this.master1 = master1;
            this.master2 = master2;
            this.master3 = master3;
            this.details = details;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            MasterDetail that = (MasterDetail) o;

            if (master1 != null ? !master1.equals(that.master1) : that.master1 != null) return false;
            if (master2 != null ? !master2.equals(that.master2) : that.master2 != null) return false;
            if (master3 != null ? !master3.equals(that.master3) : that.master3 != null) return false;
            return details != null ? details.equals(that.details) : that.details == null;

        }

        @Override
        public int hashCode() {
            int result = master1 != null ? master1.hashCode() : 0;
            result = 31 * result + (master2 != null ? master2.hashCode() : 0);
            result = 31 * result + (master3 != null ? master3.hashCode() : 0);
            result = 31 * result + (details != null ? details.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return "MasterDetail{" +
                    "master1='" + master1 + '\'' +
                    ", master2='" + master2 + '\'' +
                    ", master3='" + master3 + '\'' +
                    ", details=" + details +
                    '}';
        }
    }

    private static class Detail {
        private String a;
        private String b;
        private String c;
        private String d;

        public Detail(String a, String b, String c, String d) {
            this.a = a;
            this.b = b;
            this.c = c;
            this.d = d;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Detail detail = (Detail) o;

            if (a != null ? !a.equals(detail.a) : detail.a != null) return false;
            if (b != null ? !b.equals(detail.b) : detail.b != null) return false;
            if (c != null ? !c.equals(detail.c) : detail.c != null) return false;
            return d != null ? d.equals(detail.d) : detail.d == null;

        }

        @Override
        public int hashCode() {
            int result = a != null ? a.hashCode() : 0;
            result = 31 * result + (b != null ? b.hashCode() : 0);
            result = 31 * result + (c != null ? c.hashCode() : 0);
            result = 31 * result + (d != null ? d.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return "Detail{" +
                    "a='" + a + '\'' +
                    ", b='" + b + '\'' +
                    ", c='" + c + '\'' +
                    ", d='" + d + '\'' +
                    '}';
        }
    }
}