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• May 25, 2012
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• Richard

  Richard B.

  Software Engineering Consultant

  If you are using eclipse:
  - Right click the project
  - Click on Properties
  - Click on Java Build Path
  - Select the Libraries tab
  - Click Add External Jars
  - Find and select each .jar file
  - Click OK when done adding JARs

• Preference 1. Java > Build Path > User Libraries 1. Click "New" and give a name in "User Library Name" field and click OK. 1. Select Library Name and click on "Add JARs" button. 5. Select JARs required to be used in your Android project and click OK." height="60" width="60">

  Chrysa

  Chrysa P.

  Software Engineer at Intracom Telecom

  In addition, to avoid adb message "Unable to execute dex: Java heap space" , i recommend you to create a User Library and add jars to it :
  
  1. Windows > Preference
  2. Java > Build Path > User Libraries
  3. Click "New" and give a name in "User Library Name" field and click OK.
  4. Select Library Name and click on "Add JARs" button.
  5. Select JARs required to be used in your Android project and click OK.

• Java Build Path > Libraries and remove all jar files except Android 2.2/4.0 and Android Dependacies." height="60" width="60">

  Stephen

  Stephen M.

  Web Designer & Android App Developer

  Since ADT 17 the process has changed. You need to copy the jar files into the 'libs' folder. Then go into your project Properties > Java Build Path > Libraries and remove all jar files except Android 2.2/4.0 and Android Dependacies.

• Nikhil

  Nikhil S.

  Teamcenter professional working with Siemens PLM Japan. at Geometric Ltd.

  Thank you all for your support.
  
  Actually I am able to add the jars successfully from eclipse, as mensioned by Chryssa Papadaki. Also implemented them in my code. At the time of compile i found no errors, means my jars are there.
  
  But at run time I am getting the exception(class not found.) I am using Android 2.3.3

• Prakash

  Prakash N.

  Android Developer at Jawbone

  You need to export them in "order and export" tab in Java Build Path.

• "Configure Build Path" and then select "Source" > "Add Folder". Here tick the "libs" folder, then select "OK". Then, run the program you wont get class not found exception." height="60" width="60">

  Arshad

  Arshad P.

  Android Developer at Konstant Infosolutions Pvt. Ltd.

  For removing run time exception(class not found) :-
  
  First copy all the jar files into the '"libs'" folder. Then go to "Java Build Path" > "Configure Build Path" and then select "Source" > "Add Folder". Here tick the "libs" folder, then select "OK".
  
  Then, run the program you wont get class not found exception.

• Prakash

  Prakash N.

  Android Developer at Jawbone

  The OP is talking about adding external jars, i.e. no copying is involved.

• configure build path----> libraries-----> if you see the added library then go to order and export. there you should select the added external library as well and close it. now again under the project click clean. now exit the eclipse. again restart eclipse and run the project. let me know if you have a problem." height="60" width="60">

  Hari

  Hari K.

  Android developer at Mode fin server pvt ltd

  just check the manifest file.... if everything is fine go to the eclipse. under the project click clean. now exit the eclipse. again restart and run it. again if you have a problem, Right click on whatever you are doing project, go to the build path---->configure build path----> libraries-----> if you see the added library then go to order and export. there you should select the added external library as well and close it. now again under the project click clean. now exit the eclipse. again restart eclipse and run the project. let me know if you have a problem.

• Nikhil

  Nikhil S.

  Teamcenter professional working with Siemens PLM Japan. at Geometric Ltd.

  Thank you Prashant Hari.
  it really worked ..
  
  
  But actually my external jar was using IOException from "java.io"
  And now i got stuck for this class .
  Do we need to handle the IOException class differently? Cause this package is a part of jre. As my external jar is using this package/class I can not avoid its use / can not use some Android ioexception classes.. if any.
  
  Please help.
  thanking in advance.

• Hari

  Hari K.

  Android developer at Mode fin server pvt ltd

  no need to handle io exception class seperately...... you can write throws exception where it the ignores that exception

• Library -> Add JAR should allow you to pick the one out of your project. IIRC, this works with Eclipse. If you decide someday to dump Eclipse, just having your JAR in libs/ is enough -- the command-line build tools will pick it up automatically. UPDATE: If you have the R17 or newer version of the ADT Eclipse plugin, now you only need to add a libs/ directory and put your JAR in there. It will automatically be added to your build path, much like with command-line builds." height="60" width="60">

  pavan

  pavan R.

  student at RJS polytechnic at RJS POLYTECHNIC

  Put the JAR in your project's libs/ directory. Then Build Path -> Library -> Add JAR should allow you to pick the one out of your project. IIRC, this works with Eclipse.
  
  If you decide someday to dump Eclipse, just having your JAR in libs/ is enough -- the command-line build tools will pick it up automatically.
  
  UPDATE: If you have the R17 or newer version of the ADT Eclipse plugin, now you only need to add a libs/ directory and put your JAR in there. It will automatically be added to your build path, much like with command-line builds.

• Tomasz

  Tomasz C.

  Software engineer at DC S.A.

  How do you run your app? Is this some android virtual device?

• properties-->java Build Path -->Libraries -->Add external Jars .it must be work..." height="60" width="60">

  Thusitha

  Thusitha W.

  Software Engineer at Ascensor Partners(pvt)Ltd.

  if You are using eclipse please follow like this..Right click your project folder -->properties-->java Build Path -->Libraries -->Add external Jars .it must be work...

• John

  John O.

  Applications Designer at Riverside County Office of Education

  http://stackoverflow.com/questions/2247998/noclassdeffounderror-eclipse-and-android/9916751#9916751
  
  The real problem here is that ADT isn't packaging the JAR files / libraries into the .apk, so while the application builds properly, the NoClassDefFoundError occurs when you're trying to run on the actual device.
  
  Putting your .jar files in the /libs directory is one way to ensure that your .JAR's get included in the final .apk.

• Dandre

  Dandre A.

  Android Developer for KeepandShare.com

  You can manage project dependencies with a build tool like Maven or Ant.

• Dandre

  Dandre A.

  Android Developer for KeepandShare.com

  If proguard is making the apk it is sometimes necessary to tell it to not skip certain classes in the config file, because from its view the class is not used, when classes are used dynamically at runtime.

• Java Build Path > Order and Exportâ€Â�, and check all the references you want exported."" height="60" width="60">

  pasquale

  pasquale O.

  Product manager presso DotAndMedia S.r.l.

  Hi All,
  a good explanation/solution of this problem in this post: http://android.foxykeep.com/dev/how-to-fix-the-classdefnotfounderror-with-adt-17
  
  "If you have references to jars that are not in the ‘libs’ folder, for example if you use ‘classpath variable’, you can resolve the NoClassDefFoundError issue with the new ADT 17 by exporting the references.
  
  To export the references: simply go to “Properties > Java Build Path > Order and Export�, and check all the references you want exported."

• Richard

  Richard B.

  Software Engineering Consultant

  @pasquale, you are correct. I ran into this exact problem recently. I also discoverd that the order of export is important (though I can't imagine why). The external jars need to be at the top of the list.

• Nikhil

  Nikhil S.

  Teamcenter professional working with Siemens PLM Japan. at Geometric Ltd.

  Thank you all of you.
  
  Copying in to "libs" folder solved my problem.
  thank you all of you once again.