title: How to change the fragments or pages in view pager while changing the pages
body: <p>I am working on an app which has 3 pages in a ViewPager. But I am not able to change the fragment while swiping the pages. Please can any one help me understand how to do it....</p>
  
  <pre><code>public class HomePage extends FragmentActivity {
  
      ViewPager viewPager;
      PagerTabStrip pagerTabStrip;
      PagerAdapter adapter;
      TextView pageTag;
  
      FragmentManager fragmentManager;
      FragmentTransaction fragmentTransaction;
  
      /*
       * ActionBar Fragment Class
       */
  
      ActionBar actionBar;
  
      Fragment fragment;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          // TODO Auto-generated method stub
          super.onCreate(savedInstanceState);
          setContentView(R.layout.homepage);
  
          /*
           * Setting adapter for viewPager
           */
          viewPager = (ViewPager) findViewById(R.id.pager);
          adapter = new TabView(getSupportFragmentManager());
          viewPager.setAdapter(adapter);
  
          /*
           * Setting coustom Animation for ViewPager
           */
  
          viewPager.setPageTransformer(true, new CoustomPageTransform());
  
          /*
           * All properties for pagerTabStrip //
           */
          pagerTabStrip = (PagerTabStrip) findViewById(R.id.tabstrip);
          pagerTabStrip.setDrawFullUnderline(true);
          pagerTabStrip.setTabIndicatorColor(Color.parseColor("#33B5E5"));
          pagerTabStrip.setTextSpacing(80);
          pagerTabStrip.setTextColor(Color.parseColor("#666666"));
  
          /*
           * Setting Up ActionBar Fragment
           */
  
          if (savedInstanceState != null) {
  
              actionBar = new ActionBar();
              fragmentManager = getSupportFragmentManager();
              fragmentTransaction = fragmentManager.beginTransaction();
              fragmentTransaction.add(R.id.fragment_container, actionBar)
                      .commit();
  
          }
  
      }
  
      public class TabView extends FragmentStatePagerAdapter {
  
          public TabView(FragmentManager fm) {
              super(fm);
              // TODO Auto-generated constructor stub
          }
  
          @Override
          public Fragment getItem(int position) {
              // TODO Auto-generated method stub
              return null;
          }
  
          @Override
          public int getCount() {
              // TODO Auto-generated method stub
              return 3;
          }
  
          @Override
          public CharSequence getPageTitle(int position) {
  
              switch (position) {
              case 0:
  
                  return "TASKS";
  
              case 1:
                  return "WORKBOOK";
  
              case 2:
                  return "ITINERARY";
              default:
                  break;
              }
              return null;
          }
  
      }
  
      public class CoustomPageTransform implements ViewPager.PageTransformer {
  
          float MIN_SCALE = 0.85f;
          float MIN_ALPHA = 0.5f;
  
          @Override
          public void transformPage(View view, float position) {
  
              int pageHeight = view.getHeight();
              int pageWidth = view.getWidth();
  
              if (position &lt; -1) {
                  view.setAlpha(0);
              } else if (position &lt;= 1) {
                  float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
                  float vertMargin = pageHeight * (1 - scaleFactor) / 2;
                  float horMargin = pageWidth * (1 - scaleFactor) / 2;
  
                  if (position &lt; 0) {
  
                      view.setTranslationX(horMargin - vertMargin / 2);
  
                  } else {
  
                      view.setTranslationX(-horMargin + vertMargin / 2);
  
                  }
  
                  view.setScaleX(scaleFactor);
                  view.setScaleY(scaleFactor);
  
                  view.setAlpha(MIN_ALPHA + scaleFactor - MIN_SCALE
                          / (1 - MIN_SCALE) * (1 - MIN_ALPHA));
              } else {
                  view.setAlpha(0);
              }
  
          }
      }
  
  }
  </code></pre>