错误“对象引用未设置为对象的实例”。 [英] Error "Object reference not set to an instance of an object."

问题描述

有人帮我解决了这个错误，它说对象引用未设置为对象的实例。这段代码Page.Header.Controls.Add（javascriptRef）;的行是红色的。



下面我发布了所有代码...



LiteralControl javascriptRef = new LiteralControl（"< script type =''text / javascript''src =''〜/ Dodatoci za Master / scripts / colorBoxWidth.js' '>< / script>"）;

Page.Header.Controls.Add（javascriptRef）;

解决方案

部分引用类型实例为null，而您假设它不为null。这种情况不是在您显示的代码中创建的。当您尝试取消引用此类null成员/变量时抛出异常。



您没有显示带有对象引用未设置为实例的消息的异常的位置一个物体被抛出。



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/变量通过使用和它的实例（非静态）成员解除引用，这要求此成员/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：确保将成员/变量正确初始化为非空引用，或者将其检查为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。但是如果下一条记录功能的条件对象引用没有设置为对象的实例 [ ^ ]。



祝你好运，

-SA

Some one to help me with this error it says "Object reference not set to an instance of an object." and the line with this code "Page.Header.Controls.Add(javascriptRef); " is red.

Down below i post you all code...

LiteralControl javascriptRef = new LiteralControl("<script type=''text/javascript'' src=''~/Dodatoci za Master/scripts/colorBoxWidth.js''></script>");
Page.Header.Controls.Add(javascriptRef);

解决方案

Some of the reference-type instances is null while you assume it is not null. This situation is created not in the code you show. The exception is thrown when you try to dereference such null member/variable.

You 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 dereferenced 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: wither 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"[^].

Good luck,

—SA

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