eclipse with GWT

when i am going to create web applic开发者_JAVA百科ation and writing package name for example com.example.helloworld it writes following errors

The selected App Engine SDK is not valid: SDK directory 'C:\Users\David\AppData\Local\Temp\Rar$EX00.443\eclipse\plugins

what it means?

Do you have AppEngine in your eclipse plugin folder? While creating a project in eclipse, it will show you a dialog box, where you can select a App Engine for GWT if you need for your project. Or You can configure from dialog box [Configure Sdks... link]. You need to specify a correct SDK directory like: plugins\com.google.appengine.eclipse.sdkbundle_1.2.0.v200904062254\appengine-java-sdk-1.2.0.

It looks like you haven't installed Eclipse properly --- it looks like you're trying to run it from WinRAR?

eclipse.org doesn't provide a proper installer, and it's not obvious how to do it; you need to unpack the zipfile into a directory somewhere. There's some reasonable instructions here:

http://ist.berkeley.edu/as-ag/tools/howto/install-eclipse-win.html