在导航抽屉片段之间切换后，无法在片段内添加ListView项目

Question

编辑：我的滑动标签片段ATabs似乎有问题。 无需使用ATabs片段，而仅使用导航抽屉在片段A1和B之间切换，一切正常！ 可以添加ListItems。 编辑的MainActivity：

@Override
public void onNavigationDrawerItemSelected(int position) {
    mFragment = null;
    switch (position) {
        case 0:
            mFragment = A1.newInstance(position + 1, this);
            break;
        case 1:
            mFragment = B.newInstance(position + 1);
            break;
    }
    onSectionAttached(position);
    FragmentManager fragmentManager = getSupportFragmentManager();
    fragmentManager.beginTransaction()
            .replace(R.id.container, mFragment)
            .commit();

    mFragment = null;
}

但是，一旦我使用了ATabs片段（请参见下面的MainActivity）并将其切换回去， 就无法再添加ListItems了 。 尽管Logcat显示Log.v(LOG_TAG, "Added Item"); 每次按添加（+）。

我不知道是什么原因导致了问题。 如果ATabs需要是一个Activity而不是一个Fragment或我的PagerAdapter引起了问题。 在我的ATabs类中，尝试使用两个不同的PagerAdapters：

public static class MyAdapter extends FragmentStatePagerAdapter {
 ...
}

和

public static class MyAdapter extends FragmentPagerAdapter {
 ...
}

后者甚至导致整个片段无法正确显示，也无法在选项卡之间切换。

---

我有一个导航抽屉，其中显示两个不同的片段ATab和B。片段ATab包含两个滑动选项卡。 每个选项卡都包含另一个片段A1和A2。 到现在为止，A2和B只是带有简单TextView的空片段，所以基本上相同的A2 =B。片段A1带有一个ListView ，其中包含应用程序启动时预定义的EditText项。 用户可以通过为此特定片段（A1）按下“自定义”操作栏中的“添加”来添加其他EditText项目。

通常，片段A1应该具有与片段A2和B不同的操作栏项。这似乎已经起作用。 为此，我添加了set setHasOptionsMenu(true); 对于每个片段，请覆盖onCreateOptionsMenu方法（包括menu.clear()并从资源中设置所需的菜单。

这已经是我的第一个问题：是否有必要在所有将使用默认主活动操作栏的片段中执行此操作？

我的主要问题是向列表视图添加其他项：

当我在应用程序启动时显示的初始片段A1之间切换到片段A2并回到ATabs片段中的A1时，一切正常。 我可以添加其他项目，并且以前添加的项目仍然可见。 但是，一旦使用导航抽屉在片段B和片段A1之间切换，就无法再添加任何项目，也看不到以前添加的项目。 稍后，我将使用数据库来存储我的物品，但是仍然可以像以前一样添加其他物品。

以下是一些可以更好地说明我的问题的屏幕：

应用从A1片段开始，在A1和A2之间切换，可以通过+项目添加

使用导航抽屉在ATabs和B之间切换后，添加项（+）得到显示，但对片段A1没有影响。

这是保存导航抽屉的MainActivity：我不太确定片段之间的onNavigationDrawerItemSelected内部切换是否正确，或者每次切换时是否创建新的片段。 Android是删除前一个片段还是在多次切换后导致内存溢出？ 而我的“第一个” A1片段仍然“隐藏”在新创建的片段之后吗？ 我是Android的新手，我真的不明白为什么在导航抽屉片段之间切换后无法添加任何项目。

public class MainActivity extends ActionBarActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks, A1.OnFragmentInteractionListener, A2.OnFragmentInteractionListener, B.OnFragmentInteractionListener {

    private NavigationDrawerFragment mNavigationDrawerFragment;

    private CharSequence mTitle;

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

        mNavigationDrawerFragment = (NavigationDrawerFragment)
                getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
        mTitle = getTitle();

        // Set up the drawer.
        mNavigationDrawerFragment.setUp(
                R.id.navigation_drawer,
                (DrawerLayout) findViewById(R.id.drawer_layout));
    }

    @Override
    public void onNavigationDrawerItemSelected(int position) {
        // update the main content by replacing fragments
        Fragment fragment = null;
        switch (position) {
            case 0:
                fragment = ATabs.newInstance(position + 1, this);
                break;
            case 1:
                fragment = B.newInstance(position + 1);
                break;
        }
        onSectionAttached(position);
        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction()
                .replace(R.id.container, fragment)
                .commit();

    }

    public void onSectionAttached(int number) {
        switch (number+1) {
            case 1:
                mTitle = getString(R.string.title_ATabs);
                break;
            case 2:
                mTitle = getString(R.string.title_B);
                break;
        }
    }

    public void restoreActionBar() {
        ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setTitle(mTitle);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (!mNavigationDrawerFragment.isDrawerOpen()) {
            // Only show items in the action bar relevant to this screen
            // if the drawer is not showing. Otherwise, let the drawer
            // decide what to show in the action bar.
            getMenuInflater().inflate(R.menu.main, menu);
            restoreActionBar();
            return true;
        }
        return super.onCreateOptionsMenu(menu);

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onFragmentInteraction(Uri uri) {

    }

}

使用滑动选项卡分割ATab：

public class ATabs extends Fragment {

    static final String LOG_TAG = "ATabs";
    private static final String ARG_PARAM1 = "param1";
    private static Context mContext;

    private SlidingTabLayout mSlidingTabLayout;

    private ViewPager mViewPager;


    public static ATabs newInstance(int sectionNumber, Context context) {
        ATabs fragment = new ATabs();
        mContext = context;
        Bundle args = new Bundle();
        args.putInt(ARG_PARAM1, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

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

        setHasOptionsMenu(true);
    }


    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        menu.clear();
        super.onCreateOptionsMenu(menu, inflater);
        inflater.inflate(R.menu.main, menu);
    }

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

    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        mViewPager = (ViewPager) view.findViewById(R.id.viewpager);
        mViewPager.setAdapter(new MyAdapter(getFragmentManager()));


        mSlidingTabLayout = (SlidingTabLayout) view.findViewById(R.id.sliding_tabs);
        mSlidingTabLayout.setViewPager(mViewPager);
    }



    public static class MyAdapter extends FragmentStatePagerAdapter {
        public MyAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public int getCount() {
            return 2;
        }

        @Override
        public Fragment getItem(int position) {
            Fragment fragment = null;
            switch (position) {
                case 0:
                    fragment = A1.newInstance(position, mContext);
                    break;
                case 1:
                    fragment = A2.newInstance(position);
                    break;
            }
            return fragment;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            CharSequence pageTitle = "NOT SET";
            switch (position) {
                case 0:
                    pageTitle = "A1 Tab";
                    break;
                case 1:
                    pageTitle = "A2 Tab";
                    break;
            }
            return pageTitle;
        }
    }
}

正如已经问到的：是否有必要调用setHasOptionsMenu(true)并在使用默认主活动操作栏的片段内覆盖onCreateOptionsMenu() ？

这是使用默认主活动操作栏的片段A2（与类B相同）：

public class A2 extends Fragment {
    private static final String ARG_PARAM1 = "param1";
    private String mParam1;

    private OnFragmentInteractionListener mListener;

    public static A2 newInstance(int sectionNumber) {
        A2 fragment = new A2();
        Bundle args = new Bundle();
        args.putInt(ARG_PARAM1, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public A2() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
        }

        setHasOptionsMenu(true);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        menu.clear();
        super.onCreateOptionsMenu(menu, inflater);
        inflater.inflate(R.menu.main, menu);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_a2, container, false);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        public void onFragmentInteraction(Uri uri);
    }

}

片段A1使用其自己的a1操作栏菜单：附加添加项。

public class A1 extends Fragment {
    private static final String ARG_PARAM1 = "param1";
    private final String LOG_TAG = A1.class.getSimpleName();
    private ArrayAdapter<String> mForecastAdapter;
    private static Context mContext = null;

    private ListView myList;
    private MyAdapter myAdapter;
    private String mParam1;
    private OnFragmentInteractionListener mListener;

    public static A1 newInstance(int sectionNumber, Context context) {
        A1 fragment = new A1();
        mContext = context;
        Bundle args = new Bundle();
        args.putInt(ARG_PARAM1, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public A1() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
        }

        setHasOptionsMenu(true);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);
        menu.clear();
        inflater.inflate(R.menu.a1, menu);
    }

    public ArrayList myItems = new ArrayList();

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // handle item selection
        switch (item.getItemId()) {
            case R.id.action_add_item:
                ListItem listItem = new ListItem();
                listItem.caption = "Added Item";
                myItems.add(listItem);
                Log.v(LOG_TAG, "Added Item");
                myAdapter.notifyDataSetChanged();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    public class MyAdapter extends BaseAdapter {
        private LayoutInflater mInflater;


        public MyAdapter() {
            mInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

            for (int i = 0; i < 3; i++) {
                ListItem listItem = new ListItem();
                listItem.caption = "Caption" + i;
                myItems.add(listItem);
            }

            notifyDataSetChanged();
        }

        public int getCount() {
            return myItems.size();
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder;
            if (convertView == null) {
                holder = new ViewHolder();
                convertView = mInflater.inflate(R.layout.list_item_a1, null);
                holder.caption = (EditText) convertView
                        .findViewById(R.id.list_item_a1_edit_text);
                convertView.setTag(holder);
            } else {
                holder = (ViewHolder) convertView.getTag();
            }
            //Fill EditText with the value you have in data source
            ListItem item = (ListItem) myItems.get(position);
            holder.caption.setText(item.caption);
            holder.caption.setId(position);

            //we need to update adapter once we finish with editing
            holder.caption.setOnFocusChangeListener(new View.OnFocusChangeListener() {
                public void onFocusChange(View v, boolean hasFocus) {
                    if (!hasFocus){
                        final int position = v.getId();
                        final EditText Caption = (EditText) v;
                        ListItem item = (ListItem) myItems.get(position);
                        item.caption = Caption.getText().toString();
                    }
                }
            });

            return convertView;
        }
    }

    class ViewHolder {
        EditText caption;
    }

    class ListItem {
        String caption;
    }

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

        View rootView = inflater.inflate(R.layout.fragment_a1, container, false);

        // Get a reference to the ListView, and attach this adapter to it.
        myList = (ListView) rootView.findViewById(R.id.listview_a1);
        myList.setItemsCanFocus(true);
        myAdapter = new MyAdapter();
        myList.setAdapter(myAdapter);

        return rootView;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener {
        public void onFragmentInteraction(Uri uri);
    }
}

最后是操作栏菜单：main：

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools" tools:context=".MainActivity">

    <item
        android:id="@+id/action_example"
        android:title="@string/action_example"
        app:showAsAction="never" />

    <item
        android:id="@+id/action_settings"
        android:title="@string/action_settings"
        android:orderInCategory="100"
        app:showAsAction="never" />


    <item
        android:id="@+id/action_help"
        android:title="@string/action_help"
        android:orderInCategory="100"
        app:showAsAction="never" />

</menu>

A1：

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools" tools:context=".MainActivity">

    <item
        android:id="@+id/action_add_item"
        android:title="@string/action_add_item"
        android:icon="@drawable/ic_action_new"
        app:showAsAction="always" />

    <item
        android:id="@+id/action_example"
        android:title="@string/action_example"
        app:showAsAction="never" />

    <item
        android:id="@+id/action_settings"
        android:title="@string/action_settings"
        android:orderInCategory="100"
        app:showAsAction="never" />

    <item
        android:id="@+id/action_help"
        android:title="@string/action_help"
        android:orderInCategory="100"
        app:showAsAction="never" />

</menu>

请让我知道是否需要其他代码来解决我的问题。

Answer 1

感谢@Luksprog，主要问题是通过在ATabs中使用getChildFragmentManager()而不是FragmentManager()解决的。