title: java.lang.NoClassDefFoundError: Exception for Loading Tabs in an Activity
body: <p>I try to implement an activity that contains some tab views, but when I want to run the project, I got following Exception:</p>
  
  <pre><code> java.lang.NoClassDefFoundError: 
   com.example.activities.TabBarActivity$SectionsPagerAdapter
   E/AndroidRuntime(5072):    at
   com.example.activities.TabBarAcitivity.loadMainTabs(TabBarAcitivity.java:129)
   E/AndroidRuntime(5072):    at 
   com.example.activities.TabBarAcitivity.access$1(TabBarAcitivity.java:122)
   E/AndroidRuntime(5072):    at 
   com.example.activities.TabBarAcitivity$ServiceMessageHandler.handleMessage(TabBarAcitivity.java:370)
   E/AndroidRuntime(5072):    at
   android.os.Handler.dispatchMessage(Handler.java:102)
   E/AndroidRuntime(5072):    at android.os.Looper.loop(Looper.java:149)
   E/AndroidRuntime(5072):    at 
   android.app.ActivityThread.main(ActivityThread.java:5061)
   E/AndroidRuntime(5072):    at java.lang.reflect.Method.invokeNative(Native Method)
   E/AndroidRuntime(5072):    at java.lang.reflect.Method.invoke(Method.java:515)
   E/AndroidRuntime(5072):    at 
   com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:788)
   E/AndroidRuntime(5072):    at 
   com.android.internal.os.ZygoteInit.main(ZygoteInit.java:604)
   E/AndroidRuntime(5072):    at dalvik.system.NativeStart.main(Native Method)
  </code></pre>
  
  <p>I searched and googled about this exception a lot, but I could not find a useful and detailed solution for my problem. Most of the responses in case of fixing this issue was about Changing 'Order and Export' list ([project] Properties) and checking or unchecking them to solving this problem. Here is a capture of my project Properties:</p>
  
  <p><a href="https://i.stack.imgur.com/KuKyo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KuKyo.png" alt="enter image description here"></a></p>
  
  <p>Please guide me, that what can be the exact reason of this exception and also please help me to solve this problem.</p>