java - ¿Cómo uso FragmentPagerAdapter para tener pestañas con contenido diferente?

android android-fragments

Question

Quiero tener diferentes pestañas, donde puedes deslizarte como en el mercado de Android. Cada pestaña debe usar un fragmento y usar un método para ello.

Esta es mi clase 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;
}
}

Y tengo tres clases para cada tipo de fragmento / pestaña:

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;
}
}

Cada fragmento debe ser personalizable, por eso tengo tres clases.

Sin embargo, la aplicación se bloquea en el método getItem. ¿Algunas ideas? ¡Gracias!

Editar: El MainActivity.java completo:

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

Crea el adaptador:

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;
}
}

Cada fragmento pertenece a diferentes clases.

Así que tienes que definir una lista de fragmentos (estos van a la FragmentActivity principal):

static MyPagerAdapter adapter;

y rellenarlo con los fragmentos:

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

Luego tienes que agregar los fragmentos al adaptador de esta manera:

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

El MyPagerAdaper revisará todos los fragmentos contenidos en la lista de fragments y luego creará una instancia de cada uno de ellos.

Answer 2

En su método GetItem FragmentPagerAdapter #, no cree el objeto de los Fragmentos. Debes devolver el Fragmento de la siguiente manera:

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

Esto significa que el método se verá así:

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

Vea este ejemplo:

 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;
}
}