如何解决这个“未设置为对象实例的对象引用”

本文介绍了如何解决这个“未设置为对象实例的对象引用”的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！For r As Integer = 0 To DataGridView1.Columns.Count - 1 For i As Integer = 0 To DataGridView1.Rows.Count - 1 con.Open() accountno = DataGridView1.Rows(i).Cells(0).Value.ToString accountno = DataGridView1.Columns(r).ToString area = DataGridView1.Rows(i).Cells(1).Value.ToString area = DataGridView1.Columns(r).ToString accountname = DataGridView1.Rows(i).Cells(2).Value.ToString accountname = DataGridView1.Columns(r).ToString address = DataGridView1.Rows(i).Cells(3).Value.ToString address = DataGridView1.Columns(r).ToString yr = DataGridView1.Rows(i).Cells(4).Value.ToString yr = DataGridView1.Columns(r).ToString fname = DataGridView1.Rows(i).Cells(5).Value.ToString fname = DataGridView1.Columns(r).ToString mname = DataGridView1.Rows(i).Cells(6).Value.ToString mname = DataGridView1.Columns(r).ToString lname = DataGridView1.Rows(i).Cells(7).Value.ToString lname = DataGridView1.Columns(r).ToString sqlComm.Connection = con 我尝试了什么： 如何解决这个问题未将对象引用设置为对象的实例What I have tried:how to solve this "Object reference not set to an instance of an object"推荐答案您没有显示带有Object refere消息的异常nce未设置为对象的实例被抛出。 不用担心。这是检测和修复的最简单的案例之一。它只是意味着某些引用类型的某个成员/变量通过使用及其实例（非静态）成员进行解引用，这需要此成员/变量为非null，但实际上它似乎为null。只需在调试器下执行它，它将停止抛出异常的执行。在该行上设置一个断点，重新启动应用程序并再次到达这一点。评估下一行中涉及的所有引用，并查看哪一个为null，而不需要为null。解决这个问题之后，修复代码：要么确保将成员/变量正确初始化为非空引用，要么将其检查为null，如果为null，则执行其他操作。 另请参阅：想要在按钮点击时显示下一条记录。但是如果下一个记录功能的条件对象引用未设置为对象的实例则会出错。 有时候，你不能这样做在调试器下，由一个或另一个原因。一个非常讨厌的情况是，只有在调试信息不​​可用时构建软件时才会出现问题。在这种情况下，你必须使用更难的方式。首先，你需要确保你永远不会通过静默处理异常来阻止异常的传播（这是开发人员对自己的犯罪，但很常见）。您需要在每个线程的最顶层堆栈帧上捕获绝对所有异常。如果处理类型 System.Exception 的异常，则可以执行此操作。在处理程序中，您需要记录所有异常信息，尤其是 System.Exception.StackTrace ： http://msdn.microsoft.com/en-us/library/system.exception.aspx ， http://msdn.microsoft.com/en-us/library/ system.exception.stacktrace.aspx 。 堆栈跟踪只是一个字符串，显示从throw语句到处理程序的异常传播的完整路径。通过阅读，您总能找到目的。对于日志记录，使用类 System.Diagnostics.EventLog ： http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx 。 祝你好运， -SAYou did not show where the exception with the message "Object reference not set to an instance of an object" is thrown.Not to worry. This is one of the very easiest cases to detect and fix. It simply means that some member/variable of some reference type is dereferences by using and of its instance (non-static) members, which requires this member/variable to be non-null, but in fact it appears to be null. Simply execute it under debugger, it will stop the execution where the exception is thrown. Put a break point on that line, restart the application and come to this point again. Evaluate all references involved in next line and see which one is null while it needs to be not null. After you figure this out, fix the code: either make sure the member/variable is properly initialized to a non-null reference, or check it for null and, in case of null, do something else.Please see also: want to display next record on button click. but got an error in if condition of next record function "object reference not set to an instance of an object".Sometimes, you cannot do it under debugger, by one or another reason. One really nasty case is when the problem is only manifested if software is built when debug information is not available. In this case, you have to use the harder way. First, you need to make sure that you never block propagation of exceptions by handling them silently (this is a crime of developers against themselves, yet very usual). The you need to catch absolutely all exceptions on the very top stack frame of each thread. You can do it if you handle the exceptions of the type System.Exception. In the handler, you need to log all the exception information, especially the System.Exception.StackTrace:http://msdn.microsoft.com/en-us/library/system.exception.aspx,http://msdn.microsoft.com/en-us/library/system.exception.stacktrace.aspx.The stack trace is just a string showing the full path of exception propagation from the throw statement to the handler. By reading it, you can always find ends. For logging, it's the best (in most cases) to use the class System.Diagnostics.EventLog:http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx.Good luck,—SA你不要告诉你这个异常发生在哪一行并且它不明显，所以我无法确定它。 一般来说，这意味着你没有初始化变量应该引用一个对象，例如：You don't tell on which line this exception occurs and it's not obvious, so I can't pinpoint it.In general, it means that you didn't initialize a variable that is supposed to reference an object, e.g.:Dim s As StringConsole.WriteLine(s.Length) ' <--- 在标记的行上，您将获得相同的异常。因为s虽然已声明，但未初始化。它就像没有连接到门上的门把手:) 显示代码中的可能候选人 con 和 sqlComm 。 在调试器中运行代码并查看由异常精确定位的代码行。然后将鼠标悬停在该行上的变量上，以找到工具提示中显示为 Nothing 的变量。然后做点什么。On the marked line you would get the same exception. Because s, though declared, is not initialized. It's like a door handle not attached to a door :)Likely candidates from the shown code are con and sqlComm.Run your code in the debugger and look at the code line that gets pinpointed by the exception. Then hover your mouse over the variable(s) on that line to find which one shows up as Nothing in the tooltip. Then do something about that. 这篇关于如何解决这个“未设置为对象实例的对象引用”的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！