public String getString(int col) {
        return resultRows.get(rowIdx).get(col);
    }
@Test(expected = IndexOutOfBoundsException.class)
    public void testOutOfBound() {
        List<List<String>> rows = Lists.newArrayList();

        rows.add(Lists.newArrayList("col1-0", "col2-0"));
        rows.add(Lists.newArrayList("123", "456"));
        ShowResultSet resultSet = new ShowResultSet(metaData, rows);
        resultSet.getString(0);
        Assert.fail("No exception throws.");
    }