Try-catch-finally: How should I use the reverse?

Today, a netizen asked me a question.
She said that she had a page where she saved data to the database. If the data was not saved successfully, no error was reported. She did not know what the problem was.
I asked her if she had any exception information during the operation. She said no. I immediately felt a serious challenge from her which was a bit unreasonable.

Ask her to askCodeI was speechless. The Code is as follows:

  1   Public     Partial     Class  _ Default: system. Web. UI. Page
  2   {
  3    Private     String  Strcon  =  Configurationmanager. connectionstrings [  "  Constr  "  ]. Tostring ();
  4   
  5     Protected     Void Page_load (  Object  Sender, eventargs e ){}
  6   
  7     Protected     Void  Login_click (  Object  Sender, eventargs E)
  8   {
  9  Oledbconnection con  =     New  Oledbconnection (strcon );
  10     String  SQL  =     "  Insert into text (uname, unickname) values (@ uname, @ unickname)  "  ;
  11  Oledbcommand cmd  =     New  Oledbcommand (SQL, con );
  12     Try  
  13   {
  14   Cmd. Parameters. addwithvalue (  "  @ Uname  " ,  This  . Tbuname. Text );
  15   Cmd. Parameters. addwithvalue (  "  @ Unickname  "  ,  This  . Tbunickname. Text );
  16   Con. open ();
  17     Int I  =  Cmd. executenonquery ();
  18     If  (I  >     0  )
  19   {
  20   Response. Write (  "  Registered successfully "  );
  21   }
  22     Else  
  23   {
  24   Response. Write (  "  Registration failed  "  );
  25  }
  26   }
  27     Catch  (Exception ex)
  28   {}
  29     Finally  
  30   {
  31  Con. Close ();
  32   }
  33   }
  34   }
  35     

From the code above, it is not difficult to see why she did not save successfully or report an error.
She used a try {} catch () {} finally {} statement group to capture exceptions in database operations. However, after the capture, no processing was done and the process was completed. If the file is not saved successfully, an exception will be thrown theoretically. However, if the exception is caught, no corresponding processing is performed. Of course, the error message cannot be displayed.

 

As we all know, try {} catch () {} finally {} is an exception handling mechanism, which provides a custom mechanism for handling errors, separate the error identification code from the error handling code. We can use it to process applications.ProgramCan be predicted.
When we use it, it indicates that we must take the initiative to handle exceptions for the specified code segment. That is to say, the catch statement will capture the specified type of errors in the try statement block, then, use the catch statement block to perform corresponding processing operations.
If the catch code block does not contain any processing statement, it means we have to discard the exception, that is, ignore the exception.

 

Here I want to say that exception handling is a technology that must be used selectively and never be abused.
Exception Handling is performed to enhance Application robustness, rather than exception handling is required in every code segment that may generate exceptions. In particular, use empty catch statement blocks with caution. unless you really want to discard this exception information, you do not even want to record the logs.

 

Here, I suggest that beginners do not add the exception capture function when debugging this program. After writing the code, select the statement segment that determines the exception information to handle the exception.

 

Be cautious with the inexplicable exception capture code.