Throw Exception gets unhandled error

I am creating a multi-layered application using dlls' and want to throw any exception that occurs (and also create my own exceptions to throw) back to the originating code. When I try this though I get an error that the exception is unhandled. I am trying to handle it by just throwing it. This occurs at the first throw which is in class a catch clause. The following dll deals with database access.

The code snippet is :

class a{

public object ExecuteScalar(QueryBuilder QB){

object res = "";

try{

string sql = BuildSQL(QB);

// connect to the database and run the query

SqlCommand cmd = new SqlCommand(sql, DBConnections.SQLConn);

DBConnections.SQLConn.Open();

res = cmd.ExecuteScalar();

DBConnections.SQLConn.Close();

} catch{

// system error

if (DBConnections.SQLConn.State != System.Data.ConnectionState.Closed)

DBConnections.SQLConn.Close();

throw; }

return res;}

class b{

public object GetObject(string UDOName){

try{

a mine = new a();

res = mine.ExecuteScalar(QB).ToString();

} catch {

throw;

}}

class c{

private void btnGetObj_Click(object sender, EventArgs e)

{

try{

b udo = new b;

string res = udo.GetObject("testing").ToString();

txtGetObj.Text = res;

} catch {

// handle the error here

}

Any ideas on why this happens I am using VS2005, .Net 2.0.

Thanks in advance

karen

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Throw Exception gets unhandled error

abhishek_6023
Make you own class like DBConnectionClosedException, Inherit it from Exception class, Add your fields and properties and throw your own Exception to catch it from calling code.
So user can know What exception was throun and why it was thrown (Which wil be know by Custom Exception's Properties)
Best Regards,
Jeff Williams
Thanks!

I was trying to do that but needed to make sure to close the connection to the database if there was an exception. I had put a Try/catch to close the DB but that was not allowing the exception to go back. Finally figured out I could use a try/catch/finally, using the finally to close the database and removing the catch.

Karen
Reino
I was thinking that the catch block was required with any try... also thought that you could use the 'throw' keyword to send a system exception back. If I understand you only use the throw command to throw a new user generated exception

Such as --- throw new ArgumentException(“Exception”);

Is it possible in .Net 1.1 to use the throw keyword to throw a system exception

I have seen several examples such as

try {//something} catch(DivideByZeroException e) { throw; }

But that does not work int .Net 2.0.

Karen

Matthew_Hlavacek

RizwanSharp wrote:
Make you own class like DBConnectionClosedException, Inherit it from Exception class, Add your fields and properties and throw your own Exception to catch it from calling code.
So user can know What exception was throun and why it was thrown (Which wil be know by Custom Exception's Properties)
Best Regards,

Is there a way to send back the pure system exception

Roger Lipscombe

Your question was something different so I did not know what were you actually wanting.

finally is the block which always executes if exception occurs or not so u can close connection in finally and you dont need to use catch at all, Just exception be thrown and caught in calling code.

Best Regards,
PedroCGD
2 Solutions for this:
1. Create your Excetion class and put it in Innner exception.
2. Dont Catch exception in this code and it'll automatically be thrown to the calling code.
Now think what is better for you.

Best Regards,
Throw Exception gets unhandled error

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