How to fix run-time error: Could not find class 'winterwell.jtwitter.Twitter'

If you follow the Marakana Android Bootcamp Series 2012 Video Tutorials, you may get this run-time error when practice the sample application Yamba-1.

06-03 10:48:43.695: E/dalvikvm(274): Could not find class 'winterwell.jtwitter.Twitter', referenced from method com.marakana.yamba1.StatusActivity.onCreate
06-03 10:48:43.695: W/dalvikvm(274): VFY: unable to resolve new-instance 42 (Lwinterwell/jtwitter/Twitter;) in Lcom/marakana/yamba1/StatusActivity;
06-03 10:48:43.695: D/dalvikvm(274): VFY: replacing opcode 0x22 at 0x0045
06-03 10:48:43.695: D/dalvikvm(274): VFY: dead code 0x0047-0057 in Lcom/marakana/yamba1/StatusActivity;.onCreate (Landroid/os/Bundle;)V
06-03 10:48:43.955: D/dalvikvm(274): GC_EXTERNAL_ALLOC freed 794 objects / 58272 bytes in 127ms
06-03 10:48:44.184: D/AndroidRuntime(274): Shutting down VM
06-03 10:48:44.184: W/dalvikvm(274): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
06-03 10:48:44.194: E/AndroidRuntime(274): FATAL EXCEPTION: main
06-03 10:48:44.194: E/AndroidRuntime(274): java.lang.NoClassDefFoundError: winterwell.jtwitter.Twitter
06-03 10:48:44.194: E/AndroidRuntime(274):     at com.marakana.yamba1.StatusActivity.onCreate(StatusActivity.java:43)
06-03 10:48:44.194: E/AndroidRuntime(274):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
06-03 10:48:44.194: E/AndroidRuntime(274):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
06-03 10:48:44.194: E/AndroidRuntime(274):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
06-03 10:48:44.194: E/AndroidRuntime(274):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
06-03 10:48:44.194: E/AndroidRuntime(274):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
06-03 10:48:44.194: E/AndroidRuntime(274):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-03 10:48:44.194: E/AndroidRuntime(274):     at android.os.Looper.loop(Looper.java:123)
06-03 10:48:44.194: E/AndroidRuntime(274):     at android.app.ActivityThread.main(ActivityThread.java:4627)
06-03 10:48:44.194: E/AndroidRuntime(274):     at java.lang.reflect.Method.invokeNative(Native Method)
06-03 10:48:44.194: E/AndroidRuntime(274):     at java.lang.reflect.Method.invoke(Method.java:521)
06-03 10:48:44.194: E/AndroidRuntime(274):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
06-03 10:48:44.194: E/AndroidRuntime(274):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
06-03 10:48:44.194: E/AndroidRuntime(274):     at dalvik.system.NativeStart.main(Native Method)

Looked back into the Yamba-1 folder, jtwitter-yamba.jar was there.

Solution:
Make a new folder called libs under Yamba-1 and move this external libary inside sub-folder libs

Credit:
Sven Rau  http://marakana.com/forums/android/learning_android_book/689.html#p1790