java.lang.IllegalArgumentException

[amarkirt saroay]

java.lang.IllegalArgumentException is thrown If the Path of the request.getrequestDispatcher("testabc.jsp") does not start with a "/" character .

Should not it throw IllegalStatexception?

[Mateus Lucio]

IllegalArgumentException makes sense for me ... you see, getRequestDispatcher method takes a String argument that must start with a slash "/", so any String that doesn't start with a slash is an illegal argument.

Remember that this rule only applies when you get the RequestDispatcher from the ServletContext, in your example you got it from the HttpServletRequest so a String that doesn't start with a slash is a perfectly valid argument.

[Bindu Lakhanpal]

I know its an old thread.
But my question is related to same thing somehow.
Even i got IllegalArgumentException in folllowing code:

RequestDispatcher reqDispatch = getServletContext().getRequestDispatcher("Login.jsp");   

But i could not find it in API.
In API it is written :

getRequestDispatcher
public RequestDispatcher getRequestDispatcher(java.lang.String path)Returns a RequestDispatcher object that acts as a wrapper for the resource located at the given path. A RequestDispatcher object can be used to forward a request to the resource or to include the resource in a response. The resource can be dynamic or static.
The pathname must begin with a "/" and is interpreted as relative to the current context root. Use getContext to obtain a RequestDispatcher for resources in foreign contexts. This method returns null if the ServletContext cannot return a RequestDispatcher.

Parameters:
path - a String specifying the pathname to the resource
Returns:
a RequestDispatcher object that acts as a wrapper for the resource at the specified path, or null if the ServletContext cannot return a RequestDispatcher

Where is it written that IllegalArgumentException will be thrown?

[Pete Pommelich]

Hi,

it depends if you get the RequestDisptacher from the ServletRequest or from the SverletContext. If you use the ServletContext, e.g.

RequestDispatcher view = getServletContext().getRequestDispatcher("/index.jsp");

the String has to start with a slash.

The pathname must begin with a "/" and is interpreted as relative to the current context root. Use getContext to obtain a RequestDispatcher for resources in foreign contexts. This method returns null if the ServletContext cannot return a RequestDispatcher.

If you use the request the String might start with a slash, but it doesn't have to (depending on the current dir etc.):

RequestDispatcher view = request.getRequestDispatcher("index.jsp");

The pathname specified may be relative, although it cannot extend outside the current servlet context. If the path begins with a "/" it is interpreted as relative to the current context root. This method returns null if the servlet container cannot return a RequestDispatcher.

[Bindu Lakhanpal]

Hi Pete,
Thanks for your reply.I agree that we must use a "/" in case we are using ServletContext to get a requestDispatcher.
But i was not clear about what would happen if we try to use it like

 RequestDispatcher reqDispatch = getServletContext().getRequestDispatcher("Login.jsp"); 

So i tested it and got IllegalArgumentException.
But all that is written in api is

This method returns null if the ServletContext cannot return a RequestDispatcher.

There is no mention of IllegalArgumentException there.
Now i see many disparities in spec and containers.Thats why i asked this question here.
But anyway, i think the right answer is that it will throw IllegalArgumentException.