Bucket Sort (java)

=============My BucketSort. Example===================

 

import java.util.HashMap;
import java.util.LinkedList;
import java.util.ListIterator;

public class BucketSort {

    private HashMap<Integer, LinkedList> hMap;
    /*
      input: unSorted Array, #bucket(number of Bucket)
      process: bucket sorting Using #bucket
      return: sorted Array.
     */
    public Integer[] bucketSort(Integer data[], int numBucket){
        Integer[] ret = new Integer[data.length];
        hMap = new HashMap<Integer, LinkedList>();

        for (int i: data) {
            Integer key = numBucket * (i / numBucket);   //분모가 maxInt 가 맞을듯.(16.6)
                              ==> 그냥 i%numBucket가 맞을 듯한데.. 좀더 보자.(2017.10)

            LinkedList<Integer> prevList;


            //make new List and add to HashMap.. when there's no data
            if ( (prevList = hMap.get(key)) == null ) {
                LinkedList<Integer> list = new LinkedList<Integer>();
                list.add(i);
                hMap.put(key,list);
            }else{                         //prevList traverse and add i to apporate position
                ListIterator<Integer> it = prevList.listIterator();

                boolean added = false;   //added flag prevents Concurrent Modify Error.
                while (it.hasNext()) {      //at least 1 element. SO always on this loop.
                    if (it.next() > i ) {   //Add to Proper position
                        prevList.add(it.previousIndex(),i);
                        added = true;
                        break;
                    }
                }
                if (!added)
                    prevList.add(i);         //Add to End

            }//else
        } //for


        //to array.
        int k=0;
        for (int j=0; j< numBucket; j++){
            Integer key = numBucket*j;
            LinkedList<Integer> list = hMap.get(key);

            if (list!=null) {
                ListIterator<Integer> it = list.listIterator();

                while (it.hasNext())
                    ret[k++] = it.next();
            }
        }

        return ret;
    }

    /////////MAIN /////////////////
    public static Integer datas[]={77, 11, 22, 55, 44, 33, 99, 88, 21, 23, 37, 41, 81, 91, 74, 19, 30, 40  };

    public static void main(String args[]){

        BucketSort b = new BucketSort();
        Integer[] data = b.bucketSort(datas, 10);

        for ( int i : data)
            System.out.print(i+",");
    }
}