error "object reference not set to instance of an object" while performing search on a array list

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i am performing a search on a array type.. the code is:

XML

public List<Employee_Ranking> EmployeeRankingSearchList(string employeeName)
   {
       Employee_Ranking[] employeeRanking;
       List<Employee_Ranking> employeeRankingSearchResult = null; ;
       Employee_Ranking_Binding employeeRanking_Serv = new Employee_Ranking_Binding();
       employeeRanking_Serv.Credentials = new NetworkCredential(G_UserName, G_PassWord, G_Domain);
       employeeRanking = employeeRanking_Serv.ReadMultiple(null, null, 0);
       employeeRankingSearchResult= employeeRanking.Where(x => x.Full_Name.Contains(employeeName)).ToList();

return employeeRankingSearchResult;
}

here Employee_Ranking is a type defined in webservices that contains attributes like no, fullname, age and so on.. employeeRanking in employeeRanking = employeeRanking_Serv.ReadMultiple(null, null, 0); returns all the records and i wanted to perform search on this array.. when i searched by employeeRankingSearchResult= employeeRanking.Where(x => x.Full_Name.Contains(employeeName)).ToList();it shows error i.e. object reference not set to instance of an object.. this might be showing because in debuggin mode, full_name value is null.. i have no idea of why full_name is shown null... any help???

Posted 11-Mar-14 14:24pm

Codes DeCodes

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Sergey Alexandrovich Kryukov 11-Mar-14 21:55pm

In what line?
—SA

2 solutions

Solution 2

Solution 1 is a very good suggestion, but you cannot be 100% sure that this is a final solution. Actually, you cannot ask for help every time you face with similar problem. You really, really need to learn how to deal with such basic problems by yourself.

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: 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

Posted 11-Mar-14 15:57pm

Sergey Alexandrovich Kryukov

Comments

Codes DeCodes 13-Mar-14 6:13am

the error i types here was detected by using debugger.. any way thanks for the suggestions...

Sergey Alexandrovich Kryukov 13-Mar-14 8:52am

You are welcome... and..?
—SA

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Matt T Heffron · Accepted Answer · 2014-03-11T15:31:00

Solution 1

I suppose your ReadMultiple() method is suspect, or the data has some records where that value is read as null.
A simple way to filter that is to modify the Where():

C#

employeeRankingSearchResult= employeeRanking.Where(x => !string.IsNullOrEmpty(x.Full_Name) && x.Full_Name.Contains(employeeName)).ToList();

Posted 11-Mar-14 15:31pm

Matt T Heffron

Comments

Sergey Alexandrovich Kryukov 11-Mar-14 21:58pm

Good suggestion, my 5.
I credited it in my answer. At the same time, OP needs to learn how to deal with such basic problems.
—SA

Codes DeCodes 13-Mar-14 6:10am

u were right matt and sa..null was not handled.. thanks..