代码中的空引用异常。 [英] Null reference exception in code.
问题描述
这是源代码。 Github Link [ ^ ]
Here is the source code. Github Link[^]
An unhandled exception of type 'System.NullReferenceException' occurred in Analysis (PCA).exe
Additional information: Object reference not set to an instance of an object.
这发生在MainForm.cs文件中，用于
This occurred in the file MainForm.cs for
distributionView.DataSource= pca.Components;
如何解决这个问题？
我尝试了什么：
我尝试过使用new运算符，但这并没有解决问题。
使用调试器，发现distributionView为null并生成此异常。但新的运营商不会解决我的问题。因为如果我使用new，某些图形将不起作用。
它声明为
How do I solve this?
What I have tried:
I've tried using the new operator but that doesnt solve the problem.
Used the Debugger and found the distributionView is null and generating this exception. But the new operator will not solve my problem. Since some of the graphs will not work if I use new.
Its declared as
private Accord.Controls.ComponentView distributionView
推荐答案
当你不理解你的代码在做什么或为什么它做它的作用时，答案是调试器。
使用调试器查看代码正在执行的操作。只需设置断点并查看代码执行情况，调试器允许您逐行执行第1行并在执行时检查变量，这是一个令人难以置信的学习工具。
调试器 - 维基百科，免费的百科全书 [ ^ ]
掌握Visual Studio 2010中的调试 - 初学者指南 [ ^ ]
使用Visual Studio 2010进行基本调试 - YouTube [ ^ ]
调试器在这里向您展示您的代码正在做什么以及您的任务是与它应该做的比较。
调试器中没有魔法，它没有发现错误，它只是帮助你。当代码没有达到预期效果时，你就接近了一个错误。
When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute, it is an incredible learning tool.
Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
Basic Debugging with Visual Studio 2010 - YouTube[^]
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.
调试器表明distributionView为null。我现在如何解决这个问题？它声明为私有Accord.Controls.ComponentView distributionView
The debugger showed that distributionView is null. How do i solve this now? Its declared as private Accord.Controls.ComponentView distributionView
现在在前一行放置一个BreakPoint，你可以在其中设置distributionView的值，它可能就是失败的地方。
Now put a BreakPoint in previous line where you set the value of distributionView, it is probably where is the fail.
这篇关于代码中的空引用异常。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IT屋！
