title: how to open fragment from navigation drawer list
body: <p>I have a problem with opening fragment activities, I'm new on programming android devices but I think it is very interesting and i would like to make some applications for myself.<br>
  I have a sample with sliding menu, everything it is working, so i have three list item (home, settings, about) I would like to open an activity when I press on one of them this is my mainActivity, it would be great if somebody should tell me how should I complete this code to be able to open other activities.
  thank you in advance.</p>
  
  <p>My MainActivity is:</p>
  
  <pre><code>public class MainActivity extends BaseActivity {
      FragmentStackManager fm, sliding_menu;
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          setUpView();
          menuToggeleSetUp(savedInstanceState);
      }
       void setUpView() {
          fm = new FragmentStackManager(this);
          sliding_menu = new FragmentStackManager(this);
          drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
          fm.addFragment(new MainFragment(), R.id.main_frame, false, FragmentTransaction.TRANSIT_NONE, false);
          sliding_menu.addFragment(new SlidingMenuFragment(), R.id.slide_fragment, false, FragmentTransaction.TRANSIT_NONE, false);
      }
      void menuToggeleSetUp(Bundle savedInstanceState) {
          mDrawerToggle = new ActionBarDrawerToggle(this, drawer,
                  R.drawable.ic_drawer, // nav menu toggle icon
                  R.string.app_name
          ) {
              public void onDrawerClosed(View view) {
                  getSupportActionBar().setTitle(mTitle);
                                 invalidateOptionsMenu();
              }
              public void onDrawerOpened(View drawerView) {
                  getSupportActionBar().setTitle(mDrawerTitle);
                                  invalidateOptionsMenu();
              }
          };
          drawer.setDrawerListener(mDrawerToggle);
  
          if (savedInstanceState == null) {
                    }
      }
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
            getMenuInflater().inflate(R.menu.main, menu);
          return true;
      }
      @Override
      protected void onPostCreate(Bundle savedInstanceState) {
          super.onPostCreate(savedInstanceState);
                 mDrawerToggle.syncState();
      }
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          int id = item.getItemId();
          if (mDrawerToggle.onOptionsItemSelected(item)) {
                       return true;
          }
          if (id == R.id.action_settings) {
              System.out.println("CLEAR SETTINGS STARTED");
              return true;
          }
          return super.onOptionsItemSelected(item);
      }
  
  
      @Override
      public void onConfigurationChanged(Configuration newConfig) {
          super.onConfigurationChanged(newConfig);
                  mDrawerToggle.onConfigurationChanged(newConfig);
      }
  }
  </code></pre>
  
  <hr>
  
  <p>thank you for your help 
  bu i would like to keep this one because the hamburger animation so i found something that i completed my code but is got an error on logcat
  if somebody should help me it would be great 
  so what i did is this:</p>
  
  <pre><code>mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
   private class DrawerItemClickListener implements ListView.OnItemClickListener {
      @Override
      public void onItemClick(AdapterView parent, View view, int position, long id) {
        updateDisplay(position);
      }
  }
   private void updateDisplay(int position) {
      Fragment fragment = null;
      switch (position) {
          case 0:
              System.out.println("ACTIVITY ONE");
              //fragment = new Home_Fragment();
              break;
          case 1:
              //fragment = new Settings_Fragment();
              System.out.println("ACTIVITY TWO");
             // startActivity(new Intent(this, Preferences.class));
  
                  break;
              //case 2:
              //  fragment = new TB_Fragment();
              //break;
          default:
              break;
      }
  if (fragment != null) {
          android.app.FragmentManager fragmentManager = getFragmentManager();
          fragmentManager.beginTransaction().replace(R.id.frame_container, fragment).commit();
  
          // update selected item and title, then close the drawer
          //setTitle(menutitles[position]);
          drawer.closeDrawer(mDrawerList);
      } else {
          // error in creating fragment
          Log.e("MainActivity", "Error in creating fragment");
      }
  </code></pre>
  
  <p>an my logcat is</p>
  
  <blockquote>
    <p>java.lang.RuntimeException: Unable to start activity ComponentInfo{com.intelligent_screen/com.intelligent.screen.View.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener(android.widget.AdapterView$OnItemClickListener)' on a null object reference</p>
  </blockquote>