Evitando Manipular Manualmente Alterações na Configuração

Este projeto é uma extensão do modelo de fluxo Mestre / Detalhe que pode ser encontrado no Android Studio. A diferença é que esse aplicativo usa uma única atividade e um ViewPager que gerencia três fragmentos. O terceiro fragmento é o fragmento principal (lista), que contém um RecycleView clicável. Quando um item da lista é clicado, ele alterna o fragmento com o fragmento filho (detalhe).

Enquanto o projeto funciona, eu gostaria de evitar o usoandroid:configChanges= "orientation|keyboardHidden|screenSize" no manifesto. Como devo fazer isso?

Se o atributo for removido, o mListener no ItemListFragment será destruído junto com o ItemFragmentList ao girar, mas nunca será recriado quando o ItemListFragment for recriado. Isso resulta em nada acontecendo ao clicar em um item da lista no modo retrato.

Minha solução inicial foi substituir manualmente a manipulação de alterações na configuração, o que significou que ItemListFragment não foi destruído ao girar a tela.onConfigurationChanged() epopulateViewForOrientation() foram adicionados para inflar novamente o layout. Certamente, existe uma solução melhor do que substituir manualmente o manuseio da configuração.

Projeto disponível em:https://github.com/lukeallison/ViewPagerMasterDetail, Vídeo:http://tinypic.com/r/1zltyeq/9

BaseFragment.java

public class BaseFragment extends Fragment {

    public Bridge mBridget;

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        mBridget = (MainActivity) getActivity();
    }
}

Interface: Bridge.java

public interface Bridge {
    abstract void onBack();
}

ItemListFragment.java

public class ItemListFragment extends BaseFragment{

    private boolean mTwoPane = false;
    private PageFragmentListener mListener;

    public static ItemListFragment newInstance(PageFragmentListener listener) {
        ItemListFragment fragment = new ItemListFragment();
        fragment.mListener = listener;
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_item_list, container, false);
        initLayout(root);
        return root;
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);

        LayoutInflater inflater = LayoutInflater.from(getActivity());
        populateViewForOrientation(inflater, (ViewGroup) getView());
    }

    private void populateViewForOrientation(LayoutInflater inflater, ViewGroup viewGroup) {
        viewGroup.removeAllViewsInLayout();
        View subview = inflater.inflate(R.layout.fragment_item_list, viewGroup);

        initLayout(subview);
    }

    public void initLayout(View root) {
        View recyclerView = root.findViewById(R.id.item_list);

        mTwoPane = false;
        if (root.findViewById(R.id.item_detail_container) != null) {        // R.layout.list_item is located "layout", "layout-land"..
            mTwoPane = true;            // currently loaded "layout-land/list_item".  landscape mode
        }

        Toolbar toolbar = (Toolbar) root.findViewById(R.id.toolbar);
        ((AppCompatActivity)getActivity()).setSupportActionBar(toolbar);
        toolbar.setTitle("List");
        assert recyclerView != null;
        setupRecyclerView((RecyclerView) recyclerView);
    }

    private void setupRecyclerView(RecyclerView recyclerView) {
        recyclerView.setAdapter(new SimpleItemRecyclerViewAdapter(DummyContent.ITEMS));
    }

    public class SimpleItemRecyclerViewAdapter
            extends RecyclerView.Adapter<SimpleItemRecyclerViewAdapter.ViewHolder> {

        private final List<DummyContent.DummyItem> mValues;

        public SimpleItemRecyclerViewAdapter(List<DummyContent.DummyItem> items) {
            mValues = items;
        }

        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.item_list_content, parent, false);
            return new ViewHolder(view);
        }

        @Override
        public void onBindViewHolder(final ViewHolder holder, int position) {
            holder.mItem = mValues.get(position);
            holder.mIdView.setText(mValues.get(position).id);
            holder.mContentView.setText(mValues.get(position).content);

            // One row of List.  define click event
            holder.mView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (mTwoPane) {     // landscape mode
                        Bundle arguments = new Bundle();
                        arguments.putString(Constants.ARG_ITEM_ID, holder.mItem.id);
                        ItemTwoDetailFragment fragment = ItemTwoDetailFragment.newInstance();
                        fragment.setArguments(arguments);

                        // show detail fragment to right side of screen
                        getActivity().getSupportFragmentManager().beginTransaction()
                                .replace(R.id.item_detail_container, fragment)
                                .commit();
                    } else {    // portrait mode
                        if (mListener!=null)
                            mListener.onSwitchToNextFragment(holder.mItem.id);      // switch detail fragment
                    }
                }
            });
        }

        @Override
        public int getItemCount() {
            return mValues.size();
        }

        public class ViewHolder extends RecyclerView.ViewHolder {
            public final View mView;
            public final TextView mIdView;
            public final TextView mContentView;
            public DummyContent.DummyItem mItem;

            public ViewHolder(View view) {
                super(view);
                mView = view;
                mIdView = (TextView) view.findViewById(R.id.id);
                mContentView = (TextView) view.findViewById(R.id.content);
            }

            @Override
            public String toString() {
                return super.toString() + " '" + mContentView.getText() + "'";
            }
        }
    }

}

ItemOneDetailFragment.java

/**
 * A fragment representing a single Item detail screen.
 * on handsets.
 */
public class ItemOneDetailFragment extends BaseFragment {

    private DummyContent.DummyItem mItem;

    /*
    Listener for switch fragment
     */
    private PageFragmentListener mListener;

    public static ItemOneDetailFragment newInstance(PageFragmentListener listener) {
        ItemOneDetailFragment fragment = new ItemOneDetailFragment();
        fragment.mListener = listener;
        return fragment;
    }

    public ItemOneDetailFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (getArguments().containsKey(Constants.ARG_ITEM_ID)) {
            mItem = DummyContent.ITEM_MAP.get(getArguments().getString(Constants.ARG_ITEM_ID)); // Get selected Item ID to show details
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_item_one_detail, container, false);

        // Show the dummy content as text in a TextView.
        if (mItem != null) {

            Toolbar toolbar = (Toolbar) rootView.findViewById(R.id.detail_toolbar);
            toolbar.setTitle(mItem.content);
            toolbar.setNavigationIcon(R.drawable.ic_ab_back_material);
            toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    mBridget.onBack();
                }
            });

            ((TextView) rootView.findViewById(R.id.item_detail)).setText(mItem.details);    // show details
        }

        return rootView;
    }

}

ItemTwoDetailFragment.java

// for landscape orientation
public class ItemTwoDetailFragment extends BaseFragment {

    private DummyContent.DummyItem mItem;


    public static ItemTwoDetailFragment newInstance() {
        return new ItemTwoDetailFragment();
    }

    public ItemTwoDetailFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (getArguments().containsKey(Constants.ARG_ITEM_ID)) {
            mItem = DummyContent.ITEM_MAP.get(getArguments().getString(Constants.ARG_ITEM_ID));     // Get selected item to show details
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_item_two_detail, container, false);

        // Show the dummy content as text in a TextView.
        if (mItem != null) {
            ((TextView) rootView.findViewById(R.id.item_detail)).setText(mItem.details);        // show details
        }
        return rootView;
    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity implements Bridge{

    private ViewPager viewPager = null;
    private MyAdapter mAdapter;
    PageChangeListener mListener = new PageChangeListener();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        viewPager = (ViewPager) findViewById(R.id.pager);
        viewPager.setOnPageChangeListener(mListener);       // Page Change Listener

        mAdapter = new MyAdapter(getSupportFragmentManager());
        viewPager.setAdapter(mAdapter);

        // Show the Up button in the action bar.
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.setDisplayHomeAsUpEnabled(true);
        }
    }

    @Override
    public void onBackPressed() {
        if (mListener.getCurrentPage()==2 && mAdapter.mFragment instanceof ItemOneDetailFragment) {     // current page is Tab-3, current fragment is detail fragment
            mAdapter.mListener.onSwitchToNextFragment("0");     // show List fragment
            return;     // prevent to finish app.
        }

        super.onBackPressed();
    }

    // Do the same thing as the back button - go back to ItemListFragment
    // Only when in ItemOneDetailFragment
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == android.R.id.home) {
            if (mListener.getCurrentPage() == 2 && mAdapter.mFragment instanceof ItemOneDetailFragment) {     // current page is Tab-3, current fragment is detail fragment
                mAdapter.mListener.onSwitchToNextFragment("0");     // show List fragment
//                return;     // prevent to finish app.
            }
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onBack() {
        onBackPressed();
    }
}

class PageChangeListener extends ViewPager.SimpleOnPageChangeListener {
    private int currentPage;

    @Override
    public void onPageSelected(int position) {
        currentPage = position;     // current selected page
    }

    public final int getCurrentPage() {
        return currentPage;
    }
}

/**
 * Fragment Page Adapter
 */
class MyAdapter extends FragmentPagerAdapter{

    private final FragmentManager mFragmentManager;
    public BaseFragment mFragment;

    /**
     *  PageFragmentListener for switching fragment.
     */
    public PageFragmentListener mListener = new PageFragmentListener() {
        @Override
        public void onSwitchToNextFragment(final String id) {
            mFragmentManager.beginTransaction().remove(mFragment).commit();
            if (mFragment instanceof ItemListFragment){     // current fragment is List Fragment
                Bundle arguments = new Bundle();
                arguments.putString(Constants.ARG_ITEM_ID, id);     // selected item id
                mFragment = ItemOneDetailFragment.newInstance(mListener);       // switch detail fragment
                mFragment.setArguments(arguments);
            }else{      // DetailFragment
                mFragment = ItemListFragment.newInstance(mListener);    // => switch list fragment
            }

            notifyDataSetChanged();     // notify changes
        }
    };

    public MyAdapter(FragmentManager fm) {
        super(fm);
        mFragmentManager = fm;
    }

    @Override
    public Fragment getItem(int position) {
        if (position == 0)      // Tab-1
            return FragmentA.newInstance();

        if (position == 1)      // Tab-2
            return FragmentB.newInstance();

        if (position == 2) {    // Tab-3
            if (mFragment==null)    // first time => create list fragment
                mFragment = ItemListFragment.newInstance(mListener);

            return mFragment;
        }

        return null;
    }


    @Override
    public CharSequence getPageTitle(int position) {
        if (position == 0) {    // Tab-1
            return "Tab 1";
        }
        if (position == 1) {    // Tab-2
            return "Tab 2";
        }
    if (position == 2) {        //Tab-3
            return "Tab 3";
        }
        return null;
    }

    @Override
    public int getCount() {     // Count of Tabs
        return 3;
    }

    @Override
    public int getItemPosition(Object object) {
        Log.i("Adapter", "ItemPosition>>>" + object.toString());
        if (object instanceof ItemListFragment && mFragment instanceof ItemOneDetailFragment) {     //  fragment changed
            return POSITION_NONE;
        }

        if (object instanceof ItemOneDetailFragment && mFragment instanceof ItemListFragment) {     // fragment changed
            return POSITION_NONE;
        }

        return POSITION_UNCHANGED;
    }
}

Interface: PageFragmentListener.java

public interface PageFragmentListener {
    void onSwitchToNextFragment(String id);
}

Log: com o atributo adicionado ao Manifest.xml

First instantiation 
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: newInstance
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreate()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreateView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: initLayout
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: setupRecyclerView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onBindViewHolder

ClickItem
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onClick(): single pane
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: removed fragment
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: is instance of List Fragment
03-16 .../com.allison.viewpagermasterdetail D/ItemOneDetailFragment: newInstance
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>FragmentB{41dd3810 #1 id=0x7f0c0069 android:switcher:2131492969:1}
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>ItemListFragment{41df1528 #2 id=0x7f0c0069 android:switcher:2131492969:2}
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onStop()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroyView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroy()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()

Back
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: removed fragment
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: is instance of Detail Fragment
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: newInstance
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>FragmentB{41dd3810 #1 id=0x7f0c0069 android:switcher:2131492969:1}
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>ItemOneDetailFragment{41e896a8 #2 id=0x7f0c0069 android:switcher:2131492969:2}
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreate()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreateView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: initLayout
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: setupRecyclerView()

Rotate
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onConfigurationChanged
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: populateViewForOrientation
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: initLayout
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: setupRecyclerView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onBindViewHolder

ClickItemLand
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onClick(): mTwoPane

Rotate
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onConfigurationChanged
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: populateViewForOrientation
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: initLayout
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: setupRecyclerView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onBindViewHolder

ClickIemPortrait
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onClick(): single pane
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: removed fragment
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: is instance of List Fragment
03-16 .../com.allison.viewpagermasterdetail D/ItemOneDetailFragment: newInstance
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>FragmentB{41dd3810 #1 id=0x7f0c0069 android:switcher:2131492969:1}
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>ItemListFragment{41ea8b68 #2 id=0x7f0c0069 android:switcher:2131492969:2}
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onStop()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroyView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroy()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()

Log: sem atributo

First instantiation 
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: newInstance
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreate()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreateView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: initLayout
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: setupRecyclerView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onBindViewHolder

ClickItem
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onClick(): single pane
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: removed fragment
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: is instance of List Fragment
03-16 .../com.allison.viewpagermasterdetail D/ItemOneDetailFragment: newInstance
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>FragmentB{41dd4758 #1 id=0x7f0c0069 android:switcher:2131492969:1}
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>ItemListFragment{41ded998 #2 id=0x7f0c0069 android:switcher:2131492969:2}
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onStop()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroyView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroy()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()

Back
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: removed fragment
03-16 .../com.allison.viewpagermasterdetail D/MyAdapter: is instance of Detail Fragment
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: newInstance
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>FragmentB{41dd56b8 #1 id=0x7f0c0069 android:switcher:2131492969:1}
03-16 .../com.allison.viewpagermasterdetail I/Adapter: ItemPosition>>>ItemOneDetailFragment{41e830b8 #2 id=0x7f0c0069 android:switcher:2131492969:2}
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreate()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreateView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: initLayout
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: setupRecyclerView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onBindViewHolder

Rotate
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onSaveInstanceState()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onStop()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroyView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroy()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreate()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreateView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: initLayout
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: setupRecyclerView()

ClickItemLand
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onClick(): mTwoPane

Rotate
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onSaveInstanceState()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onStop()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroyView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onDestroy()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onPause()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreate()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onCreateView()
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: initLayout
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: setupRecyclerView()
03-16 .../com.allison.viewpagermasterdetail E/ViewRootImpl: sendUserActionEvent() mView == null
03-16 .../com.allison.viewpagermasterdetail D/ItemListFragment: onBindViewHolder

ClickIemPortrait
// nothing happens

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