public static Object getFieldValue(Object obj, String fieldName) {
        try {
            Field field = obj.getClass().getDeclaredField(fieldName);
            field.setAccessible(true);
            return field.get(obj);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
@Test
    void testGetFieldValue() {
        Object elementData = ReflectUtils.getFieldValue(listStr, "elementData");
        assertTrue(elementData instanceof Object[]);
        assertEquals(2, ((Object[]) elementData).length);
    }