java.lang.NullPointerException 是Java 中一个常见的运行时异常,当程序试图在需要对象实例的地方使用 null 引用时,就会抛出这个异常。简单来说,就是程序在尝试访问或操作一个为 null 的对象引用时发生了错误。 可能导致 java.lang.NullPointerException 的常见原因 对象未初始化:在引用对象之前,没有为其分配内存。
Stacktrace:] with root causejava.lang.NullPointerExceptionat org.apache.jsp.update1_jsp._jspService(update1_jsp.java:110)at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)...
因为你session里的值取不到，所以赋给list的值为null，相当于 ArrayList list = null;这也就是出错的原因，空指针。解决方案：检查后台java代码，看是否将"allInfo"正确加入到session中。先判断list.size()>0&& list !=null 在执行循环。
解决方法如下：在 action.UsersAction.login(UsersAction.java:59)找到UserAction的第59行，空指针就在那里 ，然后找到int i = ud.checkLogin(username, password);在这句前，加上System.out.println("username: " + username);System.out.println("password: " + password);还可以单步调试看错误 ...
I still see the same exception. I can reproduce it by switching between the map and other tabs quickly. Thanks for your efforts though. (really appreciated) However, I fix this, by switching to to an IndexedStack, which will make the map view persistent. With the IndexedStack I do not se...
Could #TempTable within SP cause lock on tempdb? Could not complete cursor operation because the table schema changed after the cursor was declared Could not continue scan with NOLOCK due to data movement -error Could not convert the data value due to reasons other than sign mismatch or overfl...
Using runtime checking to find memory access errors is not unlike using a compiler to find syntax errors in your program. In both cases, a list of errors is produced, with each error message giving the cause of the error and the location in the program where the error occurred. In both...
Fatal Exception: android.runtime.JavaProxyThrowable: [System.ArgumentNullException]: ArgumentNull_Generic Arg_ParamName_Name, services at Microsoft.Maui.MauiContext..ctor() at Microsoft.Maui.MauiContext..ctor() at Microsoft.Maui.Controls.Compatibility.Hosting.AppHostBuilderExtensions+<>c.<OnConfigureLif...
[Request processing failed; nested exception isjava.lang.NullPointerException]withrootcausee 1.controller层没有加@ResponseBody 2.Service层实现类未添加注解@Autowired 记录一下,也希望对你有帮助。 严重: Servlet.service() for servlet [springMVC] in context with path [] threw exception [Request proce ...
Surfingkeys on the Mac App Storefor Safari, works for both macOS and iOS, except that for iOS an external keyboard is required to be connected with your device. There is one exception of thespecial feature designed for iOS device--Search selected with. ...