Google App Engine - recompile GWT module

Question

I've created Google App Engine project in Java using Eclipse following the book Beginning Java Google App Engine

Before I bought this book I had created projects with unchecked option 'Use Google Web Toolkit' but for this project I checked it (following the book)

Eclipse generated several files for me and I run my applications, copy link to Web Browser (http://localhost:8888) and it gives me an error:

GWT module name_of_my_project may need to be (re)complied

I work on Ubuntu 10.04 (I was testing my application using Firefox and Chromium) and I was trying run my application on Windows XP (using the same Web Browsers) with the same effect (just one difference - Google Chrome made me install Web Toolkit...so I did it but it still gives the same error)

Thanks in advance :)

Answer 1

Thanks for your comments and suggestions. I re-installed Eclipse on Ubuntu and I installed plugin one more time and it works :)

So, be careful which version of Eclipse you use - Eclipse 3.4 has problem with GWT.

Answer 2

I get the same error message at unexpected times using development on IntelliJ with Chrome. The message still appears when I stop and start development mode. The problem is fixed after I delete the compiled files (class files, js files) in the out folder. On eclipse, you can try deleting files and folders generated in the war folder (delete the folder that has the project name, if it exists, and the classes folder under /war/WEB-INF/classes). Hope this helps.

Answer 3

Check in your "Java Build Path" if you have the correct Default output folder (something like /target/project-name/WEB-INF/classes).

In Eclipse, do a "Clean Build".

Click on the google blue button in the Eclipse menu and select "GWT Compile Project..."

Make sure the GWT plugin is compiling your project by checking the compiler output. The GWT compiler outputs lots of things, for example you will always see something like "Compiling 6 permutations.... Compiling permutation 0..."

If you still have problems, try this page on setting up Eclipse with GWT: http://code.google.com/webtoolkit/usingeclipse.html