Android java.lang.NoClassDefFoundError

I have an Android project in eclipse IDE which was working. After some imports and tests, I get the error: java.lang.NoClassDefFoundError.

In my project I have two packages: the main one and the second one with some classes.

When I try to instantiate an object from the second package class in the main activity class, I am getting this error.

Here is the logcat:

FATAL EXCEPTION: main
java.lang.NoClassDefFoundError: com.neurospeech.wsclient.MDPIforEditorialBoard
at milos.mdpi.Journals.<init>(Journals.java:41)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1409)
at android.app.Instrumentation.newActivity(Instrumentation.java:1040)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1777)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1893)
at android.app.ActivityThread.access$1500(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1054)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:150)
at android.app.ActivityThread.main(ActivityThread.java:4389)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)
at dalvik.system.NativeStart.main(Native Method)

Found the solution to my problem:

The solution can be found here: http://android.foxykeep.com/dev/how-to-fix-the-classdefnotfounderror-with-adt-17

Did you recently updated your eclipse android plugin (adt r17)? Then the following link might help:

How to fix the classdefnotfounderror with adt-17

Update: One year has passed since the question arose. I will keep the link, because even in 2013 it seem to help some people to solve the problem. But please take care what you are doing, see Erics comment below. Current ADT-Version is 22, I recommend using the most current version.

Edit the build path in this order, this worked for me.

Make sure the /gen is before /src

I fixed the issue by just adding private libraries of the main project to export here:

Project Properties->Java Build Path->Order And Export

And make sure Android Private Libraries are checked.

Screenshot:

Make sure google-play-services_lib.jar and google-play-services.jar are checked. Clean the project and re-run and the classNotfound exception goes away.

Go to Order and export from project properties and make sure you're including the required jars in the export, this did it for me

I've run into this problem a few times opening old projects that include other Android libraries. What works for me is to:

move Android to the top in the Order and Export tab and deselecting it.

Yes, this really makes the difference. Maybe it's time for me to ditch ADT for Android Studio!

You can also get this error if you try to include a jar which was compiled with jdk 1.7 instead of 1.6.

In my case, I figured this out by trying to package my app with the Ant scripts provided by the SDK, instead of ADT, and I noticed these errors, which ADT did not show me:

  [dex] Pre-Dexing libjingle_peerconnection.jar -> libjingle_peerconnection-2f82c9bf868a6c58eaf2c3b2fe6a09f3.jar
   [dx]
   [dx] trouble processing:
   [dx] bad class file magic (cafebabe) or version (0033.0000)
   [dx] ...while parsing org/webrtc/StatsReport$Value.class
   [dx] ...while processing org/webrtc/StatsReport$Value.class

I recompiled my jar with jdk 1.6 and the error was fixed.

Try going to Project -> Properties -> Java Build Path -> Order & Export And Confirm Android Private Libraries are checked for your project and for all other library projects you are using in your Application.

After Checking Java Build Path, Then add lines of code in manifest file.

<meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />