Quck Sort (using Java Generic)

Quick Sort using java Generic.

==>   <T extends Comparable> working. <T implements Comparable> not working.

 (Java Generic을 이용해서 Quick Sort를 구현하여보았는데..

            ==>  <T extends Comparable> 이건 동작하는데 <T implements Comparable>은 동작하지 않음)

public class QSortGen<T extends Comparable> {  


    void swap(T data[], int i, int j){
        T tmp = data[i];
        data[i]=data[j];
        data[j]=tmp;
    }

    public void qSort( T[] data, int st, int end){
        if (st == end || end < 0) return;

        T pivot=data[end];  //Pivot is End (temporary)

        int j=end-1;
        int i=0;
        while (i<j) {
            while ( i<j && data[i].compareTo(pivot) < 0 ) i++;
            while ( j>i && data[j].compareTo(pivot) > 0) j--;
            if (i < j)
                swap(data, i, j);
        };

        System.out.println( "new Pivot:" +i + ","+j);

        //IF pivot Largest ?
        if ( j == end-1 && data[j].compareTo(pivot) < 0 )  // (j == end-1) =>sometimes wrong. when only 3 data.
            qSort(data, 0, end-1);

        //General pivot
        else {
            swap(data, i ,end);  //i is real Pivot
            qSort(data, 0,   i-1); //left divide and conquer:recursive
            qSort(data, j+1, end); //right divide and comquer:recursive
        }
    }

    /////////MAIN /////////////////
    public static String datas[]={"adf", "kk", "bb", "aa", "dd", "cc", "ff" };

    public static void main(String args[]){
        QSortGen<String> q = new QSortGen<String>();
        q.qSort(datas, 0, datas.length-1);

        for( String a : datas)
            System.out.println(a);
    }
}