This is the cumulative form of mapPartitions and mapToPair. Like mapPartitions, it runs map transformations on every partition of the RDD, and instead of JavaRDD<T>, this transformation returns JaPairRDD <K,V>.

In the following example, will convert JavaPairRDD of <String, Integer> type using mapPartitionsToPair:

Java 7:

JavaPairRDD<String, Integer> pairRDD = intRDD.mapPartitionsToPair(new PairFlatMapFunction<Iterator<Integer>, String,Integer>() { 
@Override
  public Iterator<Tuple2<String, Integer>> call(Iterator<Integer> t) throws Exception {
   List<Tuple2<String,Integer>> list =new ArrayList<>();
  while(t.hasNext()) {
    int element=t.next();
    list.add(element%2==0?new Tuple2<String, Integer>("even",element): new 
    Tuple2<String, Integer>("odd",element)); 
  }
  return list.iterator();
}});

Java 8:

JavaPairRDD<String, Integer> pairRDD = intRDD.mapPartitionsToPair(t -> {
  List<Tuple2<String,Integer>> list =new ArrayList<>();
  while(t.hasNext()){
    int element=t.next();
    list.add(element%2==0?new Tuple2<String, Integer>("even",element):
    new Tuple2<String, Integer>("odd",element));
  }
  return list.iterator();});

Like mapPartitions and mapPartitionsWithIndex, mapPartitionsToPair also provides an overoaded method that helps user to specify value for preservePartioning.