Question

I’m trying to run the Playn html web application samples in Eclipse. I’ve followed the steps here:

http://code.google.com/p/playn/wiki/GettingStarted#Running_via_Eclipse

I’m running Eclipse 3.7 on Ubuntu 11.10. I installed the plugins and I was able to run the Java version successfully.

However, when I run GWT Compile by right-clicking the html listing in the Package Explorer, I get the following error:

An internal error occurred during: “playn-showcase-html – GWT Compile”.
java.lang.NullPointerException

This occurs with the other samples too. When I get to the GWT Compile dialogue box, a message at top says “The project has errors.”

When I start Eclipse, I get the following message in the console:

GWT SDK not installed.

However, the SDK is installed. I double-checked by redoing the steps here:

http://code.google.com/intl/da-DK/eclipse/docs/install-eclipse-3.7.html

And I get the following message:

“Google Web Toolkit SDK 2.4.0” will be ignored because it is already installed.

Answer 1

By reinstalling the GWT plugin and then editing the configuration settings in Eclipse, I was able to solve this problem. The general problem seems to be one of wiring the correct paths together. I’m not sure what exactly resolved it as I did a bit of fiddling but this is how I think I did it:

1. Clicked Preferences > Google > Web Toolkit
2. Added path: ..com.google.gwt.eclipse.sdkbundle_2.4.0.v201201120043-rel-r37/gwt-2.4.0/ and hit OK
3. Right-clicked playn-showcase-html in Package Explorer
4. Selected Build Path > Configure Build Path…
5. Selected Google > Web Tool Kit from list in left panel
6. In GWT SDK box, clicked Use specific SDK, selected only option there, and hit OK

I was able to compile and generate a web server link.

I then loaded the link in Chrome. If you get a message saying the module needs to be recompiled, go back to Eclipse and recompile the HTML dir (right-click on the HTML directory > Google > GWT compile.) Then reload (F5) page in Chrome.