如何使用异常使用流构建器

问题描述

我制作了一个使用文本框txtdescription查看文件文本数据的应用程序
和button display_message并在按钮事件上编写了以下代码

I made an application to view the text data of a file using one textbox txtdescription
and button display_message and wrote following code on button event

try
{
TextReader tr = new StreamReader("asd.txt");
try
{ txtdescription.Text = tr.ReadToEnd(); }
catch (Exception ex)
{ MessageBox.Show(ex.Message); }
finally
{ tr.Close(); }
}
catch (Exception ex)
{ MessageBox.Show(ex.Message); }

应用程序正在运行

Application is running

catch (Exception ex)
{ MessageBox.Show(ex.Message); 

当我将定义不存在的文件时，就会发生此捕获

但是我没有理解fllowin try catch try
的概念

this catch will occur when i "ll define that file which do not exist

but i am not getting the concept of fllowin try catch try

txtdescription.Text = tr.ReadToEnd(); }
catch (Exception ex)
{ MessageBox.Show(ex.Message); }
finally
{ tr.Close(); }

什么时候会发生这种捕获????

Thanx ion advance

when will this catch occur???

Thanx ion advance

推荐答案

try
{
   TextReader tr = new StreamReader("asd.txt");
   txtdescription.Text = tr.ReadToEnd();
}
catch (ConcreteException ex)
{
   MessageBox.Show(ex.Message);
}
catch (Exception ex)
{
   MessageBox.Show(ex.Message);
}
finally
{
   tr.Close();
}

但是，如果您确实想在代码中获取异常，则可以在

But if you really want to get exception in your code, you can write

tr.Close()

 before 

;

或者，您可以阅读有关 TextReader ReadToEnd方法 [ ^ ]并考虑大小写可以引发此异常.

Or you can read about TextReader ReadToEnd method[^] and think of case, when this exceptions can be raised.

class Test
{
    public static void Main()
    {
        try
        {
            // Create an instance of StreamReader to read from a file.
            // The using statement also closes the StreamReader.
            using (StreamReader sr = new StreamReader("TestFile.txt"))
            {
                string line;
                // Read and display lines from the file until the end of
                // the file is reached.
                while ((line = sr.ReadLine()) != null)
                {
                    Console.WriteLine(line);
                }
            }
        }
        catch (Exception e)
        {
            // Let the user know what went wrong.
            Console.WriteLine("The file could not be read:");
            Console.WriteLine(e.Message);
        }
    }
}

祝你好运！

Good luck!

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