Vermeidung der manuellen Behandlung von Konfigurationsänderungen

Dieses Projekt ist eine Erweiterung der Master / Detail-Flow-Vorlage, die in Android Studio verfügbar ist. Der Unterschied besteht darin, dass diese Anwendung eine einzelne Aktivität und einen ViewPager verwendet, der drei Fragmente verwaltet. Das dritte Fragment ist das Master- (Listen-) Fragment, das eine anklickbare RecycleView enthält. Wenn Sie auf ein Listenelement klicken, wird das Fragment durch das untergeordnete Fragment (Detailfragment) ersetzt.

Während das Projekt funktioniert, möchte ich die Verwendung von @ vermeideandroid:configChanges= "orientation|keyboardHidden|screenSize" im Manifest. Wie soll ich das machen?

Wenn das Attribut entfernt wird, wird mListener in ItemListFragment beim Drehen zusammen mit ItemFragmentList zerstört, jedoch nie neu erstellt, wenn ItemListFragment neu erstellt wird. Dies hat zur Folge, dass beim Klicken auf ein Listenelement im Hochformat nichts passiert.

Meine ursprüngliche Lösung bestand darin, die Behandlung von Konfigurationsänderungen manuell zu überschreiben, was bedeutete, dass ItemListFragment beim Drehen des Bildschirms nicht zerstört wurde.onConfigurationChanged() undpopulateViewForOrientation() wurden hinzugefügt, um das Layout wieder aufzublasen. Sicherlich gibt es eine bessere Lösung, als die Konfigurationsbehandlung manuell zu überschreiben.

Project verfügbar unter:https: //github.com/lukeallison/ViewPagerMasterDetai, Video:http: //tinypic.com/r/1zltyeq/

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: Mit Attribut hinzugefügt zu 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: Ohne Attribut

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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