title: Android Studio: Unable to instantiate activity ComponentInfo..ClassNotFoundException
body: <p>I used Android Studio 1.2 to create a new project then run it, but it couldn't work.The errors is below:</p>
  
  <pre><code>com.example.android.lifecycle E/AndroidRuntime﹕ FATAL EXCEPTION: main
  Process: com.example.android.lifecycle, PID: 8674
  java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.android.lifecycle/com.example.android.lifecycle.ActivityA}: java.lang.ClassNotFoundException: Didn't find class "com.example.android.lifecycle.ActivityA" on path: DexPathList[[zip file "/data/app/com.example.android.lifecycle-2/base.apk"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2236)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
      at android.app.ActivityThread.access$800(ActivityThread.java:151)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
      at android.os.Handler.dispatchMessage(Handler.java:102)
      at android.os.Looper.loop(Looper.java:135)
      at android.app.ActivityThread.main(ActivityThread.java:5257)
      at java.lang.reflect.Method.invoke(Native Method)
      at java.lang.reflect.Method.invoke(Method.java:372)
  
  Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack available
  </code></pre>