eclipse/tomcat: deploy doesn't work any more (ClassNotFoundException)

Question

I'm running Eclipse Helios Service Release 1, with Tomcat 7.0.12 in Linux Ubuntu Natty Narwhal.

I've been happily hot re-deploying my webapp until it stopped working for apparently no reason. The following exception is displayed:

SEVERE: Allocate exception for servlet Index
java.lang.ClassNotFoundException: obliquid.servlet.Index
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1676)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1521)

• In Servers tab I've "Tomcat v7.0 Server at localhost [Started,Synchronized]
• My project appears as a child of Tomcat v7.0 Server
• In Properties, Java Build Path, Source I've Project/src Source folder
• In Properties, Web Deployment Assembly, I've the following mappings: /WebContent -> /, /src -> /WEB-INF/classes, /test -> /build/classes
• My src directory contains a Servlet in obliquid/servlet/Index.java
• I tried already to click on Clean Module Work Directory... and Publish
• I tried to stop and start the Server from within Eclipse Servers tab

What else should I check? Thank you.

UPDATE Despite now I'm working with the new project, I came back to check the old one, and mysteriously now it's working. I think I won't be able to find what has happened.

However today with the new project, I had 404 errors with no apparent reason and I found out that right clicking on the Tomcat server and selecting "Clean..." can be useful. Maybe it could have helped.

Selecting "Clean..." says: "Clean will discard all publish state and republish from scratch. Are you sure you want to clean all published resources?". Selecting yes, I solved the problem

UPDATE 2 It happened again on the new project. 404 errors, this time they don't go away.

Stop -> Clean... -> Start (404)
Stop -> Clean Tomcat Work Directory... -> Start (404)
Stop -> Clean Tomcat Work Directory... -> Clean... -> Start (404)
Stop -> Remove on the application ->  Clean... -> Run As -> Run on Server -> (404)  
Exit Eclipse, Start Eclipse
Start the server -> (404)

UPDATE 3 It turned out that this time I just didn't notice an exception caused by a listener-class during startup. After solving the problem, it worked. Guess I should stop working at 3 AM.

Answer 1

While on Tomcat 6 and Eclipse Ganymede I found out the following chain to work like charm:

1 stop server

2 project -> clean

3 project build (I had automatic build disabled)

4 delete server

5 delete Servers folder

6 restart Eclipse

7 create new server, add project and start :)

takes some time but worked like charm. My problem was a irritating Listener start problem, but this seems to be something similar: a property at tomcat. Btw: nowadays I am also a big Glassfish fan.