Hi, Yeah, using instanceof or isAssignableFrom are much better approaches for this.
You cannot simply trim the [L from an array class name and get a valid class name: that's not guaranteed by the JLS and it's cruising for a bruising, as you've already found out. Yoav Shapira http://www.yoavshapira.com >-----Original Message----- >From: Dov Rosenberg [mailto:[EMAIL PROTECTED] >Sent: Friday, October 22, 2004 9:52 AM >To: Tomcat Users List >Subject: Re: Taglib loading classes of web application > >Instead of checking the type of class by doing getClass().getName() I would >recommend using > >If (myclass instanceof com.name.webapp.entities.MetaDataEntity){ >... >} else { >... >} > >This is better because you can check the presence of a class at compile >time >instead of runtime when you do things like Class.forName(className) > > >-- >Dov Rosenberg >Conviveon Corporation >http://www.conviveon.com > > >On 10/21/04 7:49 PM, "Michael Wille" <[EMAIL PROTECTED]> wrote: > >> Hello all, >> >> I have a strange question. I need to load a class that is inside a >packkage >> of a web application from within a taglib that the web application is >using >> within its context. >> >> Let me try and explain this: >> >> I have a bunch of entities in the package: com.name.webapp.entities. In >this >> package, there are two base classes: Entity and MetaDataEntity. There >are >> quite a few entity classes that are derived from these two clases. >> >> I've setup a taglib to take an array of either Entity or MetaDataEntity >from >> the request's attribute map and loop through the array do some >processing. >> The problem I have is that different processing needs to be done if the >array >> is of a type derived from Entity or derived from MetaDataEntity. To do >this, >> I get the first element in the array and get that object's superclass. >> >> So the code I have in the taglib to discover the super class is: >> >> Object entities[] = (Object []) >pageContext.getRequest().getAttribute("list"); >> Object entity = entities[0]; >> className = entity.getClass().getSuperclass().getName(); >> if(className.startsWith("com.name.webapp.entities.Entity")) >> // do one thing... >> else if(className.startsWith("com.name.webapp.entities.MetaDataEntity")) >> // do another... >> else >> // throw exception. >> >> (realizing that this will only work with direct descendants of the 2 base >> classes) >> >> Which works fine if the array is not empty. However, when >entities.length == >> 0, I have to use a different method: >> >> Object entities[] = (Object []) >pageContext.getRequest().getAttribute("list"); >> // class name from the array is [Lcom.name.webapp.entities.entityname, >get rid >> of the [L... >> className = entities.getClass().getName().substring(2); >> className = Class.forName(className).getSuperclass().getName(); >> >> However, I get a ClassNotFoundException. I believe that is because the >taglib >> is using a different class loader than my webapp, which makes sense. But >is >> there any other way (short of creating my own class loader for the webapp >and >> accessing that loader from the taglib) to do this? I'd rather avoid a >custom >> classloader at all costs. >> >> Thanks for any advice. >> >> -Mike >> >> > > > >--------------------------------------------------------------------- >To unsubscribe, e-mail: [EMAIL PROTECTED] >For additional commands, e-mail: [EMAIL PROTECTED] This e-mail, including any attachments, is a confidential business communication, and may contain information that is confidential, proprietary and/or privileged. This e-mail is intended only for the individual(s) to whom it is addressed, and may not be saved, copied, printed, disclosed or used by anyone else. If you are not the(an) intended recipient, please immediately delete this e-mail from your computer system and notify the sender. Thank you. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
