I have a Tomcat server installed on Eclipse Luna IDE... and I'm developing a Java Enterprise Edition project.

The problem is when I start working a simple `"Hello world example"` with servlets in a dynamic web application and then run it on the server, I get the output and then when I change the code and save and then run again, it's always the last execution result. even if I define a new server and I run the application on the result won't change and the output stays the same. I tried basically everything, spent hours, and then it started giving me 404 HTTP error, `"the requested resource is not available"`. Nothing seems to be working. Any ideas guys?