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I'm running windows 7 and juno. Jdk 1.7, gwt 2.4, app engine 1.7.

I did the stockwatcher tutorial here and everything worked great. I then deployed it to app engine. Everything still worked great!

However, I then did the RPC part of the tutorial here. When I ran locally, I got a java.lang.VerifyError that I fixed by following this thread (putting -XX:-UseSplitVerifier in default VM arguments). It then worked locally and I deployed to app engine.

In app engine, I get a java.lang.UpsupportedClassVersionError. I found two threads that seem to have the same problem, here and here. I'm using a fresh install of windows 7 and the only jdk I downloaded was 1.7. Looking through eclipse, I see jre7, jdk 1.7, and app engine 1.7.

I read somewhere that app engine doesn't work with 1.7. However the app engine sdk version on the downloads page is 1.7 (I think that might be super recent) but I don't really know if those things are related. I went ahead and downloaded java 6 and app engine sdk 1.6.6, added jre6 to the installed jres, set the compiler compliance level to 1.6, changed it in my project too for good measure, and changed the default app engine sdk to 1.6.6.

Now I'm getting the error, "Java compiler level does not match the version of the installed java project facet." I googled the problem and everyone says to right click the project and change the facet, but I can't seem to find that option. I also have no idea if I'm going about this the right way. I'd much rather use the most recent versions of everything if possible. I also don't understand why app engine worked the first time with no RPC, but broke with the RPC.

Any help would be greatly appreciated!!! THANK YOU!!!

Community
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Adam
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4 Answers4

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GAE does not currently support java 1.7, only 1.5 and 1.6 are supported. See the java docs for more information.

The relevant paragraph is the following:

App Engine runs Java applications using the Java 6 virtual machine (JVM). The App Engine SDK supports Java 5 and later, and the Java 6 JVM can use classes compiled with any version of the Java compiler up to Java 6.

The version of the GAE sdk you downloaded (1.7) isn't related in any way with the java version.

Sebastian Kreft
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GAE is a sandbox environment. Currently it supports only Java 6. But to solve your problem, if you can downgrade your compile version to Java 6, you should be able to take advantage of GAE. But if you want a standalone server environment without any restrictions, check other cloud platforms like heroku or cloudbee

sathish_at_madison
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Possibilities are

  • you don't have right JDK or
  • GAE you using that does not support 1.7

Open below file under .settings (use Navigator window) and change java project facet to 1.6 org.eclipse.wst.common.project.facet.core.xml

After change you must close and restart the eclipse.

karthikr
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Mahesh
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Currently ,... java 7 already supported

Warning: In a future release, support for Java 6 will be removed, so it is a good idea to start migrating to Java 7 now. If you've been using Java 6 and are interested in learning about possible issues migrating to Java 7, this white paper may be helpful.

from : https://developers.google.com/appengine/docs/java/overview

SMJ
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