Java apache tomcat is not detecting the jsp file even when it exists.

I'd recommending seeing if you can deploy a WAR file successfully in Tomcat without using Eclipse.

Right now it sounds like you don't understand Java web apps or Tomcat very well.

When you throw Eclipse on top of it there's too much ignorance to make progress.

So remove one of the things you don't understand. See if you can make the WAR file, deploy it manually, and see your JSP in the browser by hand. Once that works, you have a baseline for comparing how Eclipse needs to do things.

Eclipse wont always deploy dynamically aka hot deploy and you need to make it re-deploy. So sure shot way of checking is to actually going into the war file, or the root directory and checking if the jsp exists. Also you have to provided much information as to what kind of a web application it is, for me to understand the problem better. For example, in struts a wrong entry in struts-config.xml will result in 404 even if the intended jsp is present.