Multiple statements can be created and used on the same connection, but only one resultset at once can be created and used on the same statement. If you create/open another one by the same statement, then any previously opened resultset will be implicitly closed, leading to "ResultSet closed" exceptions on any attempt to access it.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…