4 1 C:\Users\32184\Desktop\444\lll.c [Error] expected identifier or '(' before '{' token

这个错误通常是由于代码中缺少标识符或括号导致的。请检查您的代码，确保所有的标识符和括号都正确地匹配和使用。此外，您还可以尝试将代码分解为更小的部分，并逐步添加代码以确定哪个部分导致了错误。\n\```++\// 以下是一个示例代码，其中包含了一个类似的错误\#inclu <stdi.h>\n\i mai() {\ i x = 10;\ if (x > 5) {\ printf(\x is greater th 5\\\");\ }\ els {\ printf(\x is less th or equ 5\\\");\ }\ // 缺少一个右括号\ if (x < 20 {\ printf(\x is less th 20\\\");\ }\ els {\ printf(\x is greater th or equ 20\\\");\ }\ retur ;\}\```\n\

相关问题

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: Cannot invoke "java.sql.Connection.prepareStatement(String)" because "conn" is null at lll.dao.TypeDao.selectTypes(TypeDao.java:28) at lll.tt$2.actionPerformed(tt.java:94) at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1972) at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2313) at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405) at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262) at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:279) at java.desktop/java.awt.Component.processMouseEvent(Component.java:6626) at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3389) at java.desktop/java.awt.Component.processEvent(Component.java:6391) at java.desktop/java.awt.Container.processEvent(Container.java:2266) at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5001) at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324) at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833) at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4948) at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4575) at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4516) at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2310) at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2780) at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833) at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:716) at java.base/java.security.AccessController.doPrivileged(AccessController.java:399) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:97) at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:746) at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:744) at java.base/java.security.AccessController.doPrivileged(AccessController.java:399) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:743) at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203) at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124) at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113) at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109) at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

这是一个 Java 代码中的异常信息，错误类型是 NullPointerException，意思是空指针异常。错误出现在 lll.dao.TypeDao 类的 selectTypes 方法中第 28 行，因为 conn 对象为空，导致无法执行 prepareStatement 方法，从而抛出了空指针异常。建议检查代码中的 conn 对象是否正确初始化，或者在使用 conn 对象前进行判空操作。

Caused by: java.lang.NullPointerException at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1439) at java.text.DateFormat.parse(DateFormat.java:364) at cn.lll.javaweb.servlet.StudentServlet.addStudent(StudentServlet.java:59)解释一下

这是一个 Java 异常，具体是空指针异常（NullPointerException）。在这个异常的堆栈跟踪信息中，可以看到在 cn.lll.javaweb.servlet.StudentServlet.addStudent 方法的第 59 行出现了问题。根据堆栈跟踪信息，问题出现在 SimpleDateFormat.parse 方法上，这个方法是用于解析日期时间字符串的。可能的原因是在解析日期时间字符串时，传入了一个 null 值或者格式不正确的字符串导致的。需要检查代码中传入的日期时间字符串是否正确，并确保传入的参数不为空。