title: class not found exception android for fragment activity
body: <p>I am working on fragment activity to work on gingerbread OS. when I am trying to run the application on gingerbread emulator the application is getting forced close due to <code>ClassNotFound</code> error. I am providing my main fragment activity code below</p>
  
  <p>A peace of help would be appreciable.</p>
  
  <pre><code>  package com.example.android.effectivenavigation;
  import android.annotation.SuppressLint;
  import android.annotation.TargetApi;
  import android.app.ActionBar;
  import android.app.FragmentTransaction;
  import android.os.Build;
  import android.os.Bundle;
  import android.support.v4.app.Fragment;
  import android.support.v4.app.FragmentActivity;
  import android.support.v4.app.FragmentManager;
  import android.support.v4.app.FragmentPagerAdapter;
  import android.support.v4.view.ViewPager;
  import android.view.LayoutInflater;
  import android.view.View;
  import android.view.ViewGroup;
  import android.widget.ArrayAdapter;
  import android.widget.ListView;
  import android.widget.TextView;
  
  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
  @SuppressLint("NewApi")
  public class MainActivity extends FragmentActivity implements ActionBar.TabListener {
  
  /**
   * The {@link android.support.v4.view.PagerAdapter} that will provide fragments for each of the
   * three primary sections of the app. We use a {@link android.support.v4.app.FragmentPagerAdapter}
   * derivative, which will keep every loaded fragment in memory. If this becomes too memory
   * intensive, it may be best to switch to a {@link android.support.v4.app.FragmentStatePagerAdapter}.
   */
  AppSectionsPagerAdapter mAppSectionsPagerAdapter;
  
  /**
   * The {@link ViewPager} that will display the three primary sections of the app, one at a
   * time.
   */
  ViewPager mViewPager;
  
  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
  @SuppressLint("NewApi")
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      // Create the adapter that will return a fragment for each of the three primary sections
      // of the app.
      mAppSectionsPagerAdapter = new AppSectionsPagerAdapter(getSupportFragmentManager());
  
      // Set up the action bar.
      final ActionBar actionBar = getActionBar();
  
      // Specify that the Home/Up button should not be enabled, since there is no hierarchical
      // parent.
      actionBar.setHomeButtonEnabled(false);
  
      // Specify that we will be displaying tabs in the action bar.
      actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
  
      // Set up the ViewPager, attaching the adapter and setting up a listener for when the
      // user swipes between sections.
      mViewPager = (ViewPager) findViewById(R.id.pager);
      mViewPager.setAdapter(mAppSectionsPagerAdapter);
      mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
          @SuppressLint("NewApi")
          @Override
          public void onPageSelected(int position) {
              // When swiping between different app sections, select the corresponding tab.
              // We can also use ActionBar.Tab#select() to do this if we have a reference to the
              // Tab.
              actionBar.setSelectedNavigationItem(position);
          }
      });
  
      // For each of the sections in the app, add a tab to the action bar.
      for (int i = 0; i &lt; mAppSectionsPagerAdapter.getCount(); i++) {
          // Create a tab with text corresponding to the page title defined by the adapter.
          // Also specify this Activity object, which implements the TabListener interface, as the
          // listener for when this tab is selected.
          actionBar.addTab(
                  actionBar.newTab()
                          .setText(mAppSectionsPagerAdapter.getPageTitle(i))
                          .setTabListener(this));
      }
  }
  
  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
  @Override
  public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
  }
  
  @Override
  public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
      // When the given tab is selected, switch to the corresponding page in the ViewPager.
      mViewPager.setCurrentItem(tab.getPosition());
  }
  
  @Override
  public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
  }
  
  /**
   * A {@link FragmentPagerAdapter} that returns a fragment corresponding to one of the primary
   * sections of the app.
   */
  public static class AppSectionsPagerAdapter extends FragmentPagerAdapter {
  
      public AppSectionsPagerAdapter(FragmentManager fm) {
          super(fm);
      }
  
      @Override
      public Fragment getItem(int i) {
          switch (i) {
              case 0:
                  // The first section of the app is the most interesting -- it offers
                  // a launchpad into the other demonstrations in this example application.
                  return new LaunchpadSectionFragment();
  
              default:
                  // The other sections of the app are dummy placeholders.
                  Fragment fragment = new DummySectionFragment();
                  Bundle args = new Bundle();
                  args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, i + 1);
                  fragment.setArguments(args);
                  return fragment;
          }
      }
  
      @Override
      public int getCount() {
          return 3;
      }
  
      @Override
      public CharSequence getPageTitle(int position) {
          return "Section " + (position + 1);
      }
  }
  
  /**
   * A fragment that launches other parts of the demo application.
   */
  public static class LaunchpadSectionFragment extends Fragment {
      ArrayAdapter&lt;String&gt; adapter;
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
              Bundle savedInstanceState) {
          View rootView = inflater.inflate(R.layout.fragment_section_launchpad, container, false);
          ListView listView = (ListView)rootView.findViewById(R.id.listview);
          String[] values = new String[] {"Akshay Borgave","Pramod Mahake","Vishal Lokhande","Vivek Chaudhari","Rahul Borole","Neha Gadekar"};
  
  
        adapter = new ArrayAdapter&lt;String&gt;(getActivity(),android.R.layout.simple_list_item_2, android.R.id.text1, values);
  
  
          listView.setAdapter(adapter);
          // Demonstration of a collection-browsing activity.
          /*rootView.findViewById(R.id.demo_collection_button)
                  .setOnClickListener(new View.OnClickListener() {
                      @Override
                      public void onClick(View view) {
                          Intent intent = new Intent(getActivity(), CollectionDemoActivity.class);
                          startActivity(intent);
                      }
                  });*/
  
          // Demonstration of navigating to external activities.
         /* rootView.findViewById(R.id.demo_external_activity)
                  .setOnClickListener(new View.OnClickListener() {
                      @Override
                      public void onClick(View view) {
                          // Create an intent that asks the user to pick a photo, but using
                          // FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET, ensures that relaunching
                          // the application from the device home screen does not return
                          // to the external activity.
                          Intent externalActivityIntent = new Intent(Intent.ACTION_PICK);
                          externalActivityIntent.setType("image/*");
                          externalActivityIntent.addFlags(
                                  Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
                          startActivity(externalActivityIntent);
                      }
                  });*/
  
          return rootView;
      }
  }
  
  /**
   * A dummy fragment representing a section of the app, but that simply displays dummy text.
   */
  public static class DummySectionFragment extends Fragment {
  
      public static final String ARG_SECTION_NUMBER = "section_number";
  
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
              Bundle savedInstanceState) {
          View rootView = inflater.inflate(R.layout.fragment_section_dummy, container, false);
          Bundle args = getArguments();
          ((TextView) rootView.findViewById(android.R.id.text1)).setText(
                  getString(R.string.dummy_section_text, args.getInt(ARG_SECTION_NUMBER)));
          return rootView;
      }
  }
  }
  </code></pre>
  
  <p>And the Manifest look  like this</p>
  
  <pre><code>&lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.example.android.effectivenavigation"
  android:versionCode="1"
  android:versionName="1.0" &gt;
  
  &lt;uses-sdk android:minSdkVersion="9" 
      android:targetSdkVersion="10"/&gt;
  
  &lt;application
      android:icon="@drawable/ic_launcher"
      android:label="@string/app_name"
      android:theme="@android:style/Theme.WithActionBar" &gt;
      &lt;activity
          android:name=".MainActivity"
          android:label="@string/app_name" &gt;
          &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
  
              &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
          &lt;/intent-filter&gt;
      &lt;/activity&gt;
      &lt;activity
          android:name=".CollectionDemoActivity"
          android:label="@string/demo_collection" /&gt;
  &lt;/application&gt;
  </code></pre>
  
  <p></p>
  
  <p>logcat is</p>
  
  <pre><code>06-12 16:37:17.099: E/AndroidRuntime(378): FATAL EXCEPTION: main
  06-12 16:37:17.099: E/AndroidRuntime(378): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.android.effectivenavigation/com.example.android.effectivenavigation.MainActivity}: java.lang.ClassNotFoundException: com.example.android.effectivenavigation.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.android.effectivenavigation-1.apk]
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1569)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.app.ActivityThread.access$1500(ActivityThread.java:117)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.os.Handler.dispatchMessage(Handler.java:99)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.os.Looper.loop(Looper.java:123)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.app.ActivityThread.main(ActivityThread.java:3683)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at java.lang.reflect.Method.invokeNative(Native Method)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at java.lang.reflect.Method.invoke(Method.java:507)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at dalvik.system.NativeStart.main(Native Method)
  06-12 16:37:17.099: E/AndroidRuntime(378): Caused by: java.lang.ClassNotFoundException: com.example.android.effectivenavigation.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.android.effectivenavigation-1.apk]
  06-12 16:37:17.099: E/AndroidRuntime(378):  at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:240)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at java.lang.ClassLoader.loadClass(ClassLoader.java:551)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at  java.lang.ClassLoader.loadClass(ClassLoader.java:511)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
  06-12 16:37:17.099: E/AndroidRuntime(378):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1561)
  06-12 16:37:17.099: E/AndroidRuntime(378):  ... 11 more
  </code></pre>
  
  <p>The Xml layout file for the fragment activity is as follows</p>
  
  <pre><code>&lt;android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/pager"
  android:layout_width="match_parent"
  android:layout_height="match_parent" /&gt;
  </code></pre>
  
  <p>thanks in advance again</p>