Comment utiliser FragmentPagerAdapter pour avoir des onglets avec un contenu différent?

Question

Je veux avoir différents onglets, sur lesquels vous pouvez glisser comme sur le marché Android. Chaque onglet doit utiliser un fragment et une méthode pour cela.

Voici ma classe FragmentPagerAdapter:

public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);  
    }

    @Override
    public Fragment getItem(int position) {
        Fragment fragment =null;
        switch (position) {
            case 0:
                fragment = new ConnectionFragment();
                break;
            case 1:
                fragment = new DataFragment();
                break;              
            case 2:
                fragment = new GraphFragment();
                break;          }
        return fragment;    
    }
    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }
}

Et j'ai trois classes pour chaque type/onglet de fragment:

public static class ConnectionFragment extends Fragment {
    public static final String ARG_SECTION_NUMBER = "section_number";
    public String stringConnectionStatus = "Offline";
    public String stringWiflyIp = "0.0.0.0";

    public ConnectionFragment() {}

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View connectionView = inflater.inflate(R.layout.fragment_connection,
                container, false);
        TextView statusView = (TextView) connectionView.findViewById(R.id.status_label);
        statusView.setText("Connection status: " + stringConnectionStatus);
        TextView ipView = (TextView) connectionView.findViewById(R.id.ip_label);
        ipView.setText("WiFly IP: " + stringWiflyIp);
        /**TextView sectionBarView = (TextView) connectionView
                .findViewById(R.id.section_label);
        sectionBarView.setText("pups");"*/

        return connectionView;
    }
}

public static class DataFragment extends Fragment {

    public DataFragment() {}

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View dataView = inflater.inflate(R.layout.fragment_data,
                container, false);
        TextView sectionBarView = (TextView) dataView
                .findViewById(R.id.section_label);
        sectionBarView.setText("pups2");
        return dataView;
    }
}

public static class GraphFragment extends Fragment {

    public GraphFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_graph,
                container, false);
        TextView sectionBarView = (TextView) rootView
                .findViewById(R.id.section_label);
        sectionBarView.setText("pups3");
        return rootView;
    }
}

Chaque fragment devrait être personnalisable, c’est pourquoi j’ai trois classes. 

Néanmoins, l'application se bloque dans la méthode getItem. Des idées? Merci!

Edit: L'intégralité de MainActivity.Java:

import ...
public class MainActivity extends FragmentActivity {

    /**
     * The {@link Android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. 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}.
     */
    SectionsPagerAdapter mSectionsPagerAdapter;
    public List<String> fragments = new Vector<String>();

    /**
     * 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 app.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.pager); //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;
    }

    /**
     * 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);
            fragments.add(ConnectionFragment.class.getName());
            fragments.add(DataFragment.class.getName());
            fragments.add(GraphFragment.class.getName());
            //fragmentsA = "fragments";

        }

        @Override
        public Fragment getItem(int position) {
            // getItem is called to instantiate the fragment for the given page.
            // Return a DummySectionFragment (defined as a static inner class
            // below) with the page number as its lone argument.
            /*Fragment fragment =null;
            switch (position) {
                case 0:
                    fragment = new ConnectionFragment();
                    break;
                case 1:
                    fragment = new DataFragment();
                    break;              
                case 2:
                    fragment = new GraphFragment();
                    break;          }
            return fragment;*/
            return Fragment.instantiate(getBaseContext(), fragments.get(position));

        }
        @Override
        public int getCount() {
            // Show 3 total pages.
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            Locale l = Locale.getDefault();
            switch (position) {
            case 0:
                return getString(R.string.title_section1).toUpperCase(l);
            case 1:
                return getString(R.string.title_section2).toUpperCase(l);
            case 2:
                return getString(R.string.title_section3).toUpperCase(l);
            }
            return null;
        }
    }


    /**
     * A dummy fragment representing a section of the app, but that simply
     * displays dummy text.
     */
    public static class ConnectionFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        public static final String ARG_SECTION_NUMBER = "section_number";
        public String stringConnectionStatus = "Offline";
        public String stringWiflyIp = "0.0.0.0";

        public ConnectionFragment() {}

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View connectionView = inflater.inflate(R.layout.fragment_connection,container, false);
            TextView statusView = (TextView) connectionView.findViewById(R.id.status_label);
            statusView.setText("Connection status: " + stringConnectionStatus);
            TextView ipView = (TextView) connectionView.findViewById(R.id.ip_label);
            ipView.setText("WiFly IP: " + stringWiflyIp);
            /**TextView sectionBarView = (TextView) connectionView
                    .findViewById(R.id.section_label);
            sectionBarView.setText("pups");"*/

            return connectionView;
        }
    }
    public static class DataFragment extends Fragment {

        public DataFragment() {}

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View dataView = inflater.inflate(R.layout.fragment_data,
                    container, false);
            //TextView sectionBarView = (TextView) dataView.findViewById(R.id.section_label);
            //sectionBarView.setText("pups2");
            return dataView;
        }
    }
    public static class GraphFragment extends Fragment {

        public GraphFragment() {}

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_graph,
                    container, false);
            //TextView sectionBarView = (TextView) rootView.findViewById(R.id.section_label);
            //sectionBarView.setText("pups3");
            return rootView;
        }
    }
}

Answer 1

Créez l'adaptateur:

class MyPagerAdapter extends FragmentPagerAdapter {
        public List<String> fragmentsA; 

        public MyPagerAdapter(FragmentManager fm) {
            super(fm);
            fragmentsA = fragments;
        }

        @Override
        public Fragment getItem(int position) {
            //return MyFragment.newInstance();
            return Fragment.instantiate(context, fragmentsA.get(position));

        }

        @Override
        public CharSequence getPageTitle(int position) {
            //return CONTENT[position % CONTENT.length].toUpperCase();
            return mEntries.get(position % CONTENT.length).toUpperCase();
        }

        @Override
        public int getCount() {
           // return CONTENT.length;
            return mEntries.size();
        }

        @Override
        public int getItemPosition(Object object) {
            return POSITION_NONE;
        }
    }

Chaque fragment appartient à différentes classes.

Vous devez donc définir une liste de fragments (ceux-ci vont à la FragmentActivity principale):

static MyPagerAdapter adapter;

et remplissez-le avec les fragments:

fragments.add(ConnectionFragment.class.getName());
fragments.add(DataFragment.class.getName());
fragments.add(Tab3.class.getName());
//..etc

Ensuite, vous devez ajouter les fragments à l'adaptateur comme ceci:

 pager = (ViewPager)findViewById(R.id.viewpager);
 adapter = new MyPagerAdapter(getSupportFragmentManager());
 pager.setAdapter(adapter);

MyPagerAdaper parcourt tous les fragments contenus dans la liste fragments, puis instancie chacun d'eux.

Answer 2

Dans votre méthode FragmentPagerAdapter # getItem, ne créez pas d'objet des fragments. Vous devez retourner le fragment de la manière suivante - 

return Fragment.instantiate(context, ConnectionFragment.class.getName());

Cela signifie que la méthode ressemblera à ceci - 

public class SectionsPagerAdapter extends FragmentPagerAdapter {

  public SectionsPagerAdapter(FragmentManager fm) {
    super(fm);  
  }

  @Override
  public Fragment getItem(int position) {
    Fragment fragment =null;
    switch (position) {
        case 0:
            fragment = Fragment.instantiate(context, ConnectionFragment.class.getName());
            break;
        case 1:
            fragment = Fragment.instantiate(context, DataFragment.class.getName());
            break;              
        case 2:
            fragment = Fragment.instantiate(context, GraphFragment.class.getName());
            break;          }
    return fragment;    
  }

  @Override
  public int getCount() {
    // Show 3 total pages.
    return 3;
  }
}

Answer 3

Voir cet exemple:

 public static class MyPagerAdapter extends FragmentPagerAdapter {
    private static int NUM_ITEMS = 3;

    public MyPagerAdapter(FragmentManager fragmentManager) {
        super(fragmentManager);
    }

    // Returns total number of pages
    @Override
    public int getCount() {
        return NUM_ITEMS;
    }

    // Returns the fragment to display for that page
    @Override
    public Fragment getItem(int position) {
        switch (position) {
        case 0: // Fragment # 0 - This will show FirstFragment
            return FirstFragment.newInstance(0, "Page # 1");
        case 1: // Fragment # 0 - This will show FirstFragment different title
            return FirstFragment.newInstance(1, "Page # 2");
        case 2: // Fragment # 1 - This will show SecondFragment
            return SecondFragment.newInstance(2, "Page # 3");
        default:
            return null;
        }
    }

    // Returns the page title for the top indicator
    @Override
    public CharSequence getPageTitle(int position) {
        return "Page " + position;
    }        
}