Google App Engine - java.lang.NoClassDefFoundError: com.google.appengine.api.datastore.DatastoreServiceFactory

Question

I have an app that is successfully uploading content to a server on Google´s App Engine. What I wanna do now, is retrieve that content using a DataStore constructed like this:

 DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();

Whenever I call that line, I get the following error:

09-05 11:21:37.922: E/AndroidRuntime(27138): FATAL EXCEPTION: AsyncTask #2
Caused by: java.lang.NoClassDefFoundError: 
com.google.appengine.api.datastore.DatastoreServiceFactory

I´m unsure at the moment if the problem lies on the application itself, or on the AppEngine. I have already tried to add some suggested JARs to my buildpath, for example appengine-agent.jar and appengineagentimpl.jar without success.

I would deeply appreciate any inputs on this. Thanks!

Are you using eclipse or Android Studio?

hoomi
– hoomi

2014-09-05 14:42:03 +00:00
Commented Sep 5, 2014 at 14:42 — hoomi
– hoomi, Commented Sep 5, 2014 at 14:42

Andrei Volgin · Accepted Answer · 2014-09-05 15:13:01Z

2

Note that DatastoreServiceFactory is only available on the server-side. If that's the case, then you need to add required jars to your war/WEB-INF/lib/ folder. It's not enough to have them on your buildpath.

If you use Eclipse, click on the Problems tab. You may see a warning saying that this jar is not available on a server. Right click on this warning, select QuickFix, select "Copy..." option. Or copy this jar to this directory manually.

answered Sep 5, 2014 at 15:13

Andrei Volgin

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6 Comments

TGCBraun Over a year ago

Hey, thank you for your response. I don't see that warning and here are the JARs I have on my war/WEB-INF/lib folder: appengine-agent, appengine-impl, appengine-api-1.0-sdk-1.9.10, appengine-api-labs, appengine-api-stubs, appengine-api, appengine-datastore-filter, appengine-endpoinds-deps, appengine-endpoints, appengine-jsr107cache-1.9.10, appengine-remote, asm-4.0, datanucleus-api-jdo-3.1.3, datanucleus-api-jpa-3.1.3, datanucleus-appengine-2.1.2, datanucleus-core-3.1.3, gcm-server, geronimo-jpa, jod-api, json_simple, jsr17cache, jta-1.1. Pretty extensive list. Do you see any missing?

TGCBraun Over a year ago

I just added ALL the jar files inside Google's AppEngine SDK to the war/WEB-INF/lib folder, redeployed to App Engine and I got the same error. Really frustrating.

Andrei Volgin Over a year ago

Are you sure you have no references to this class in your client (Android) code?

TGCBraun Over a year ago

Well the code that I posted in the OP ( DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();) is actually called in an AsyncTask to retrieve the entites from the server. Is this a problem?

Andrei Volgin Over a year ago

App Engine SDK can only be used on the server-side. There should be no references to SDK classes in the client code. Look at using endpoints in Android: developers.google.com/appengine/docs/java/endpoints/…

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