how to combine 3 pair RDDs

I have a sort of complex requirement

1) 1) for Pinterest

twitter handle , pinterest_post , pinterest_likes.

  handle                  "what"       , 7



JavaPairRDD<String ,Pinterest>  PintRDD

2) for Instagram

Twitter handle , instargam_post , instagram_likes 

 handle                "hello"              , 10 
 handle2               "hi"                 ,20


JavaPairRDD<String ,Pinterest>  instRDD

3) for ontologies

twitter handle , categories , sub_categories 

handle        ,  Products ,    MakeUp 
handle        ,  Products,     MakeUp
handle2        , Services ,     Face

JavaPairRDD<String ,ontologies1> ontologiesPair

Final output should be

for a key if the values are found , that should be printed from the corresponding object , otherwise blank values should be printed.

EDIT - As per the code from Umberto

public class Combine3PairRDD {



public static void main(String[] args) {

    CommonUtils generateSparkContext = new CommonUtils();
    JavaSparkContext sc = generateSparkContext.createSparkContext();

   JavaPairRDD<String, Pinterest> pintRDD = sc
           .parallelizePairs(Arrays.asList(new Tuple2<String, Pinterest>("handle", new Pinterest("what", 7))));

   JavaPairRDD<String, Instagram> instRDD = sc
           .parallelizePairs(Arrays.asList(new Tuple2<String, Instagram>("handle", new Instagram("hello", 10)),
                   new Tuple2<String, Instagram>("handle2", new Instagram("Hi", 20))));

   JavaPairRDD<String, Ontologies> ontologiesPair = sc.parallelizePairs(
     Arrays.asList(new Tuple2<String, Ontologies>("handle", new Ontologies("marketing", "MakeUp")),
                   new Tuple2<String, Ontologies>("handle2", new Ontologies("Service", "Face")),
                   new Tuple2<String, Ontologies>("handle", new Ontologies("products", "MakeUp"))));



   JavaPairRDD<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>> grouped = ontologiesPair
           .cogroup(instRDD, pintRDD);

   System.out.println("size of cogreop"+grouped.count());

   grouped.foreach(new functionn());



   JavaPairRDD<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>> groupedWithDuplicated = grouped
           .flatMapToPair(new PairFlatMapFunction<Tuple2<String,Tuple3<Iterable<Ontologies>,Iterable<Instagram>,Iterable<Pinterest>>>,String,Tuple3<Iterable<Ontologies>,Iterable<Instagram>,Iterable<Pinterest>>>() {

               private static final long serialVersionUID = 853578182309543660L;

               @Override
               public Iterable<Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>>> call(
                       Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>> entry)
                               throws Exception {
                   List<Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>>> withDuplicate = new ArrayList<Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>>>();

                   String key = entry._1();  


                   List<Ontologies>listOntologies = Lists.newArrayList(entry._2()._1());

                   List<Instagram>listInstagram = Lists.newArrayList(entry._2()._2());
                   List<Pinterest>listPinterest = Lists.newArrayList(entry._2()._3());

                   Set<Ontologies> setOntologies = new HashSet<Ontologies>(listOntologies);

                   Set<Instagram> setInstagram = new HashSet<Instagram>(listInstagram);
                   Set<Pinterest> setPinterest = new HashSet<Pinterest>(listPinterest);  




                   if(setOntologies.size() < listOntologies.size()){
                       /* There are duplicates */
                       withDuplicate
                       .add(new Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>>(
                               key, new Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>(
                                       entry._2()._1(), entry._2()._2(), entry._2()._3())));
                   }

                   if(setInstagram.size() < listInstagram.size()){
                       /* There are duplicates */
                       withDuplicate
                       .add(new Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>>(
                               key, new Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>(
                                       entry._2()._1(), entry._2()._2(), entry._2()._3())));
                   }

                   if(setPinterest.size() < listPinterest.size()){
                       /* There are duplicates */
                       withDuplicate
                       .add(new Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>>(
                               key, new Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>(
                                       entry._2()._1(), entry._2()._2(), entry._2()._3())));
                   }

                       withDuplicate
                               .add(new Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>>(
                                       key, new Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>(
                                               entry._2()._1(), entry._2()._2(), entry._2()._3())));

                   return withDuplicate;
               }

           });



   List<Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>>> mapResult2 = groupedWithDuplicated
           .collect();
   for (Tuple2<String, Tuple3<Iterable<Ontologies>, Iterable<Instagram>, Iterable<Pinterest>>> entry : mapResult2) {
       Ontologies ontologies = new Ontologies("", "");
       Pinterest pinterest = new Pinterest("", -1);
       Instagram instagram = new Instagram("", -1);



       if (entry._2()._1().iterator().hasNext()) {
           ontologies = entry._2()._1().iterator().next();
       }

       if (entry._2()._2().iterator().hasNext()) {
           instagram = entry._2()._2().iterator().next();
       }

       if (entry._2()._3().iterator().hasNext()) {
           pinterest = entry._2()._3().iterator().next();
       }



       System.out.println(entry._1() + " " + pinterest.getPinterest_post() + " " + " " + pinterest.getPinterest_likes() + " "
               + instagram.getInstagram_post() + " " + instagram.getInstagram_likes() + " " + ontologies.getCategories() + " "
               + ontologies.getSub_categories());



   }
}
}


The three wrappers are as follows 



 public class Pinterest implements Serializable{

private static final long serialVersionUID = 1226764093455880169L;
 public String twitterHandle;
 public String pinterest_post ;
 public int pinterest_likes;

Pinterest(String pinterest_post,int pinterest_likes){

    this.pinterest_post=pinterest_post;
    this.pinterest_likes=pinterest_likes;
  } 
public int hashCode(){
        return (int)
                pinterest_post.hashCode() *
                pinterest_likes;
      }

 public boolean equals(Object o) {
       if(o == null)                return false;
       Pinterest other = (Pinterest) o;
        if(this.twitterHandle != other.twitterHandle)      return false;
        if(! this.pinterest_post.equals(other.pinterest_post)) return false;
        if(this.pinterest_likes != other.pinterest_likes)   return false;

        return true;
  }

}



  public class Ontologies implements Serializable{

    private static final long serialVersionUID = 1996294848173720136L;
    public String twitterHandle;
    public String categories  ;
    public String sub_categories ;

    Ontologies(String categories,String sub_categories){

        this.categories=categories;
        this.sub_categories=sub_categories;
   }
     public int hashCode(){
        return (int)

                categories.hashCode() *
                sub_categories.hashCode();
      }

     public boolean equals(Object o) {
       if(o == null)                return false;
            Ontologies other = (Ontologies) o;
        if(this.twitterHandle != other.twitterHandle)      return false;
        if(! this.categories.equals(other.categories)) return false;
        if(! this.sub_categories.equals(other.sub_categories))   return false;

        return true;
  }

}

 public class Instagram implements Serializable {

    private static final long serialVersionUID = 7351892713578143761L;
    public String twitterHandle;
    public String instagram_post ;
    public int instagram_likes;

    Instagram(String instagram_post,int instagram_likes){

        this.instagram_post=instagram_post;
        this.instagram_likes=instagram_likes;
    }
 public int hashCode(){
        return (int)
                instagram_post.hashCode() *
                instagram_likes;
      }
 public boolean equals(Object o) {
       if(o == null)                return false;
       Instagram other = (Instagram) o;
        if(this.twitterHandle != other.twitterHandle)      return false;
        if(! this.instagram_post.equals(other.instagram_post)) return false;
        if(this.instagram_likes != other.instagram_likes)   return false;

        return true;
  }


}

The above code works all fine when the values of constructor as in the code

new Tuple2<String, Ontologies>("handle", new Ontologies("Products", "MakeUp")),
new Tuple2<String, Ontologies>("handle2", new Ontologies("Service", "Face")),
new Tuple2<String, Ontologies>("handle", new Ontologies("Products", "MakeUp")))

It works fine and prints

handle what  7 hello 10 Products MakeUp
handle what  7 hello 10 Products MakeUp
handle2   -1 Hi 20 Service Face

But when I change the constructors

 new Tuple2<String, Ontologies>("handle", new Ontologies("Marketing", "MakeUp"))
 new Tuple2<String, Ontologies>("handle2", new Ontologies("Service", "Face")),
new Tuple2<String, Ontologies>("handle", new Ontologies("Products", "MakeUp")))
new Tuple2<String, Ontologies>("handle", new Ontologies("Products", "MakeUp")))

I want both the rows to be printed for the key's ie handle and handle2 ie

handle what  7 hello 10 Marketing MakeUp
handle what  7 hello 10 Products MakeUp
handle what  7 hello 10 Products MakeUp
handle2   -1 Hi 20 Service Face

, how do I achieve it

You can use cogroup method :

https://spark.apache.org/docs/1.6.2/api/java/org/apache/spark/rdd/PairRDDFunctions.html#cogroup(org.apache.spark.rdd.RDD)