NoClassDefFoundError for code in an Java library on Android

Question

I am experiencing an error quite often among my users  The app crashes during startup  When the MainActivity is supposed to be loaded the VM apparently cannot find the class  I cannot figure out why  The architecture of the app is that there is a common project that both my free and pro version are using  Don t know if it is relevant  See the stack trace below  Any thoughts   java lang NoClassDefFoundError  com android common MainActivity at com mycompany myapp Splash onCreate Splash java 23  at android app Instrumentation callActivityOnCreate Instrumentation java 1047  at android app ActivityThread performLaunchActivity ActivityThread java 1615  at android app ActivityThread handleLaunchActivity ActivityThread java 1667  at android app ActivityThread access 1500 ActivityThread java 117  at android app ActivityThread H handleMessage ActivityThread java 935  at android os Handler dispatchMessage Handler java 99  at android os Looper loop Looper java 130  at android app ActivityThread main ActivityThread java 3687  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 842  at com android internal os ZygoteInit main ZygoteInit java 600  at dalvik system NativeStart main Native Method  Caused by  java lang ClassNotFoundException  com android common MainActivity in loader     dalvik system PathClassLoader  system framework com google android maps jar  data app com android pro-1 apk    Edit  Thanks for the comment below  Richard  Now I have changed com android Splash to something else  It wasn t the real classname anyway  My bad

User · Answer

For me this problem was related to the API that I was using not being deployed. For example, I used a ZSDK_API.jar as a reference.

To fix the issue I had to right click on the project and select properties. From JAVA BUILD PATH, I had to add the API that was not being deployed. This was weird as the app was throwing MainActivity class not found and in reality the error was caused by the DiscoveryHandler class not being found.

Hopes this helps someone.

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Try go to   Right click project Java build path Source right side -  Add folder button selected libs folder and OK   I hope it helps

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The NoClassDefFoundError description is  from the SO tag      The Java Error thrown if the Java Virtual Machine or a ClassLoader   instance tries to load in the definition of a class  as part of a   normal method call or as part of creating a new instance using the new   expression  and no definition of the class could be found   The   searched-for class definition existed when the currently executing   class was compiled  but the definition can no longer be found    Or better      NoClassDefFoundError in Java comes when Java Virtual Machine is not   able to find a particular class at runtime which was available during   compile time    from this page  Check it  there are some ways to solve the error  I hope it helps

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If none of the above works  like it happened to me   and you re using as a library another project in Eclipse   Do so  Right click project -  Properties -  Android -  Library -  Add  That did it for me  Adding a project as a library  Project Properties

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Solutions    List item Check Exports Order Enable Multi Dex Check api level of views in layout  I faced same problem with searchView  I have check api level while adding searchview but added implements SearchView OnQueryTextListener to class file

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Just in case it helps someone  I faced the same issue  My jar file was under the libs directory and the jar was added to the build path  Still it was throwing that exception   I just cleaned the project and it worked for me   Eclipse -  Project -  Clean -  Select the project and clean

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I fixed this issue by adding library project path in project propertied manually   some how eclipse did not added this entry automaticvally along with  add project   so the point where app was trying to refer any componenrt inside lib project it was crashing    you also can try the same thing   app dependecy in projec properties like     android library reference 1      android-sdks extras google google play services libproject google-play-services lib   and run

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For me  the issue was that the referenced library was built using java 7  I solved this by rebuilding using the 1 6 JDK

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I met NoClassDefFoundError for a class that exists in my project  not a library class   The class exists but i got NoClassDefFoundError  In my case  the problem was multidex support  The problem and solution is here  Android Multidex and support libraries  You get this error for Android versions lower than 5 0

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I m currently using SDK 20 0 3 and none of the previous solutions worked for me    I was able to get things to work by   Right clicking the Android project Then selecting Build Path -  Link Source to bring up the Link Source dialog  Then I specified the  src  folder of the Java project and gave it a name other than the default of  src   e g   src2    You can now right-click -  delete the new  src2  folder    This brought this created Java class files that were compiled for the Dalvik VM instead of the Java VM when the Android project was built  This allowed the Java class files in the Android Library jar file to go thru dexing when the Android project  apk was created  Now when the app was run the Java project classes were found instead of a Java lang NoClassDefFoundError being thrown   If you want to use a jar file instead of linking the source  then you will need to create a Library Android project   An Android Project with  is library  checked in Properties -  Android   You will then need to either link the source of the Java Project to the Android Library project as described above or copy the source files from the  src  folder of the Java Project to the  src  folder of the Android Library project  Build the Android Library project  Then you will be able copy the Android Project jar file that was created into the  libs  folder of the Android folder because the class files in it were compiled for the Davlik VM instead of the Java VM when the Android project was built  This allows the Java class files in the Android Library jar file to go thru dexing when the Android project  apk is created  Now when the app is run the Java project classes will be found instead of a Java lang NoClassDefFoundError being thrown

User · Answer

jars used to be in the lib  folder  now they re in libs  If you use lib  you can move your jars from lib to libs  and remove the dependencies from project properties java build path because Android will now find them automatically

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Some time java lang NoClassDefFoundError  error appear when use ART instead of Dalvik runtime  To change runtime just go to Developer Option -  Select Runtime -  Dalvik

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Activity again added to manifest I tried in my manifest then app worked     lt activity         android name  com xxx xxx MainActivity

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On Android Studio   1  Add multiDexEnabled   true in your default Config  2  Add compile com android support multidex 1 0 0 in your dependencies  3  Application class extend MultiDexApplication instead of just Application

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Other idea  For example  you have class derived from  android support v4 app Fragment    However you made a mistake and inherited it from  android app Fragment   Then you will have this error on the Android 2 devices

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I encountered this NoClassDefFoundError when I used java nio charset StandardCharsets    The reason is that StandardCharsets has not existed until JRE 1 7  If I make the java compile version set to 1 7  Eclipse complained that  Android requires compiler compliance level 5 0 or 6 0   So  I fixed it by right-click the project name- Android Tools- Fix Project Properties  It is compiled with JRE1 6   However  because StandardCharsets has not existed until 1 7  It reported NoClassDefFoundError when I ran it   I has not come to realize this until after trying a lot of other methods including reinstalling JDK  The real reason is clearly told by the meaning of NoClassDefFoundError  The class cannot be found at run time although it passed compilation    General conclusion is that as long as Android does not work with JRE 1 7  if you use any new feature provided since 1 7  you will encounter this error   My solution is that I copied those source code into my code

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I had the same issue  I did the following to fix the problem    Go to  Properties  of the project  Select  Java Build Path  Select  Order and Export  Tab You should see the selected project s  src  and  gen  paths and dependencies here  The order how they listed were first  src  and then  gen  path I switch them  so that  gen  folder is build before the  src    gen - automated code in project  from dependencies and references  src - source code in project  There was no need to restart the Eclipse  It just started working    Honestly I have never tried  Android Tools   Fix Project Properties   sometimes it might be doing the same thing  I do not know  I just did above after seen the error message  thinking something is wrong with the build paths     Edit    Later on it was not sufficient  I was getting the error again  Then I   checked  all the dependencies listed in that view  Now it works again  So far so good  I will keep this updated if it fails again    FYI  in my last attempt  I tried  Android Tools   Fix Project Properties   but it didn t work out for me

User · Answer

I have just figured out something with this error   Just make sure that the library jar file contains the compiled R class under android support v7 appcompat package and copy all the res in the v7 appcompat support  project  in your ANDROID SDK HOME extras android support v7 appcompat folder   I use Netbeans with the Android plugin and this solved my issue

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Try going to Project -  Properties -  Java Build Path -  Order  amp  Export and ensure Android Private Libraries are checked for your project and for all other library projects you are using  i got the solution by following below link NoClassDefFoundError Android Project

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In my case  I was trying to add a normal java class  from a normal java project  compiled with jre 1 7 to an android app project compiled with jre 1 7   The solution was to recompile that normal java class with jre 1 6 and add references to the android app project  compiled with jre 1 6 also  as usual  in tab order and export be sure to check the class  project  etc    The same process  when using an android library to reference external normal java classes   Don t know what s wrong with jre 1 7  when compiling normal java classes from a normal java project and try to reference them in android app or android library projects   If you don t use normal java classes  from a normal java project  you don t need to downgrade to jre 1 6

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I tried all of the above said solutions but did not worked out for me  Here is what i did to get it done project-  config build path-  order and export-  move dependent project on top

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I am guessing that you don t specify javac s target when creating the common library  so javac automatically uses the latest available target  which is likely 1 7  Java7  or 1 8  Java8    It has already been stated that     Android requires compiler compliance level 5 0 or 6 0   dx of Android s build tools  lt  19 0 0 isn t able to convert Java7  or higher  bytecode to Dalvik bytecode   So either use a build tools version    19 0 0 or  use javac with -target 6  by modifying for example your ant build xml like this    lt javac srcdir  src   destdir  build   target  6    gt

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This error is also generated when you make an app that uses the Google API  such as Maps  but run it on a device that targets the Android API

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1 In Manifest file mention your activity name and action for it and   also category    2 In your Activity mention your starting contentview   and mention your view id s in the activity

[android] NoClassDefFoundError for code in an Java library on Android

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