好，我按照顶楼的语句执行，运行没有问题，实现完毕后会报出
java.sql.SQLException: ResultSet is closed

at sun.jdbc.odbc.JdbcOdbcResultSet.checkOpen(JdbcOdbcResultSet.java:6650)

at sun.jdbc.odbc.JdbcOdbcResultSet.next(JdbcOdbcResultSet.java:1251)

at exam2.BuyFrame.btnOk_actionPerformed(BuyFrame.java:107)

at exam2.BuyFrame_btnOk_actionAdapter.actionPerformed(BuyFrame.java:159)

at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1786)

at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1839)

at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)

at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)

at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:245)

at java.awt.Component.processMouseEvent(Component.java:5100)

at java.awt.Component.processEvent(Component.java:4897)

at java.awt.Container.processEvent(Container.java:1569)

at java.awt.Component.dispatchEventImpl(Component.java:3615)

at java.awt.Container.dispatchEventImpl(Container.java:1627)

at java.awt.Component.dispatchEvent(Component.java:3477)

at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3483)

at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3198)

at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3128)

at java.awt.Container.dispatchEventImpl(Container.java:1613)

at java.awt.Window.dispatchEventImpl(Window.java:1606)

at java.awt.Component.dispatchEvent(Component.java:3477)

at java.awt.EventQueue.dispatchEvent(EventQueue.java:456)

at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)

at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)

当我把3个关闭写在finally后，也就是
catch (Exception ee) {
ee.printStackTrace();
}finally{
if (rs!= null) rs.close();
if (sm!= null) sm.close();
if (con!= null) con.close();
}
我加了以下语句，改了一下，但是报了新的错误，运行都通不过
"BuyFrame.java": variable rs might not have been initialized at line 147, column 17
"BuyFrame.java": variable rs might not have been initialized at line 148, column 17
"BuyFrame.java": variable rs might not have been initialized at line 149, column 17
"BuyFrame.java": unreported exception java.sql.SQLException; must be caught or declared to be thrown at line 147, column 36
"BuyFrame.java": unreported exception java.sql.SQLException; must be caught or declared to be thrown at line 148, column 36
"BuyFrame.java": unreported exception java.sql.SQLException; must be caught or declared to be thrown at line 149, column 36

也就是这3句话报错

麻烦大家帮我看看，谢谢拉

你应该重新生成一个Statement去执行新的语句

而不是用那个已经执行过的statement

sm.execute("update TrainTicket set seatNum="+result+" where TrainNo='"+No+"'");

这个sm已经被用过了，你应该重新生成过一个

哦

这样啊

LZ在去试试