title: Android ViewPager set different action bar contents & navigation
body: <p>With ViewPager, I have 2 fragments: the 'main' and the 'second'.<br />
  1) I want to set different action bar titles for the two fragments.<br />
  2) I want to set different action bar items for the two fragments.<br />
  3) When I am in 'second', I want to perform an 'up navigation' to the 'main'.<br />
  <hr />
  My MainActivity.java :</p>
  
  <pre><code>public class MainActivity extends ActionBarActivity {
  
      /**
       * The {@link android.support.v4.view.PagerAdapter} that will provide
       * fragments for each of the sections. We use a {@link 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}.
       */
      SectionsPagerAdapter mSectionsPagerAdapter;
  
      /**
       * The {@link ViewPager} that will host the section contents.
       */
      ViewPager mViewPager;
  
      @Override
      protected 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 activity.
          mSectionsPagerAdapter = new SectionsPagerAdapter(
                  getSupportFragmentManager());
  
          // Set up the ViewPager with the sections adapter.
          mViewPager = (ViewPager) findViewById(R.id.pager);
          mViewPager.setAdapter(mSectionsPagerAdapter);
  
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
  
          // Inflate the menu; this adds items to the action bar if it is present.
          getMenuInflater().inflate(R.menu.main, menu);
          return true;
      }
  
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          // Handle action bar item clicks here. The action bar will
          // automatically handle clicks on the Home/Up button, so long
          // as you specify a parent activity in AndroidManifest.xml.
          int id = item.getItemId();
          if (id == R.id.action_settings) {
              return true;
          }
          return super.onOptionsItemSelected(item);
      }
  
      /**
       * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
       * one of the sections/tabs/pages.
       */
      public class SectionsPagerAdapter extends FragmentPagerAdapter {
  
          public SectionsPagerAdapter(FragmentManager fm) {
              super(fm);
          }
  
          @Override
          public Fragment getItem(int position) {
              // getItem is called to instantiate the fragment for the given page.
              // Return a PlaceholderFragment (defined as a static inner class
              // below).
              switch (position) {
              case 0:
                  return new FragmentMain();
              case 1:
                  return new FragmentSettings();
              }
              return null;
          }
  
          @Override
          public int getCount() {
              // Show 2 total pages.
              return 2;
          }
      }
  }
  </code></pre>