Get Distinct values from column

`i want distinct value.This Method gives me same value again and again. Any suggestions ? people

ArrayList<String> getNumberFromNote(String note) {
    Cursor cursor;
    mDbHelper = mSqliteHelper.getReadableDatabase();
    String whereClause =  SqliteHelpers.NUMBER_COLUMN +" = ?";
    String[] whereArgs = new String[] {note};
    cursor = mDbHelper.query(SqliteHelpers.TABLE_NAME, null, whereClause, whereArgs,
            null, null, null);
    ArrayList<String> arrayList = new ArrayList<>();
    while (cursor.moveToNext()) {
        String itemname = cursor.getString(cursor.getColumnIndex(
                SqliteHelpers.NUMBER_COLUMN));
        if (itemname != null) {
            arrayList.add(itemname);
            System.out.println(itemname);
        }
    }
    return arrayList;

}