ExpandableListFragment 与 LoaderManager 兼容包

Question

我想让我的 ExpandableListActivity 与 Honeycomb 兼容。 我想知道为什么兼容包没有 ExpandableListFragment。

有没有办法让 ExpandableListView 与普通的 Fragment 类一起工作？ 如何使用 LoaderManager 加载游标？

Answer 1

我也有同样的问题。我没有找到解决方案，所以我决定自己基于 android.support.v4.app.ListFragment （兼容性 API）和 API 级别 8 的 android.app.ExpandableListActivity 的组合来实现 ExpandableListFragment，所以这应该兼容API级别< 11.

不过，我无法回答您关于 Cursors 和 LoaderManager 的问题。

关于我的 ExpandableListFragment 版本需要注意的一件事是，您必须自己从封装活动的 oncontentchanged() 方法定义中调用其方法 onContentChanged() ，否则不会有任何侦听器附加到列表项。

ExpandableListFragment 的源代码（在 android.support.v4.app 的本地包副本中，将其命名为您想要的名称）：

package android.support.v4.app;

import android.app.Fragment;
import android.os.Bundle;
import android.os.Handler;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnCreateContextMenuListener;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.FrameLayout;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class ExpandableListFragment extends Fragment
    implements OnCreateContextMenuListener,
    ExpandableListView.OnChildClickListener, ExpandableListView.OnGroupCollapseListener,
    ExpandableListView.OnGroupExpandListener
    {

    static final int INTERNAL_EMPTY_ID = 0x00ff0001;

    final private Handler mHandler = new Handler();

    final private Runnable mRequestFocus = new Runnable() {
        public void run() {
            mList.focusableViewAvailable(mList);
        }
    };

    final private AdapterView.OnItemClickListener mOnClickListener
            = new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
            onListItemClick((ListView)parent, v, position, id);
        }
    };

    ExpandableListAdapter mAdapter;
    ExpandableListView mList;
    View mEmptyView;
    TextView mStandardEmptyView;
    View mListContainer;
    boolean mSetEmptyText;
    boolean mListShown;
    boolean mFinishedStart = false;

    public ExpandableListFragment() {
    }

    /**
     * Provide default implementation to return a simple list view.  Subclasses
     * can override to replace with their own layout.  If doing so, the
     * returned view hierarchy <em>must</em> have a ListView whose id
     * is {@link android.R.id#list android.R.id.list} and can optionally
     * have a sibling view id {@link android.R.id#empty android.R.id.empty}
     * that is to be shown when the list is empty.
     *
     * <p>If you are overriding this method with your own custom content,
     * consider including the standard layout {@link android.R.layout#list_content}
     * in your layout file, so that you continue to retain all of the standard
     * behavior of ListFragment.  In particular, this is currently the only
     * way to have the built-in indeterminant progress state be shown.
     */
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        FrameLayout root = new FrameLayout(getActivity());

        TextView tv = new TextView(getActivity());
        tv.setId(INTERNAL_EMPTY_ID);
        tv.setGravity(Gravity.CENTER);
        root.addView(tv, new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));

        ListView lv = new ListView(getActivity());
        lv.setId(android.R.id.list);
        lv.setDrawSelectorOnTop(false);
        root.addView(lv, new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));

        ListView.LayoutParams lp = new ListView.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT);
        root.setLayoutParams(lp);

        return root;
    }

    /**
     * Attach to list view once Fragment is ready to run.
     */
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        ensureList();
    }

    /**
     * Detach from list view.
     */
    @Override
    public void onDestroyView() {
        mHandler.removeCallbacks(mRequestFocus);
        mList = null;
        super.onDestroyView();
    }

    /**
     * This method will be called when an item in the list is selected.
     * Subclasses should override. Subclasses can call
     * getListView().getItemAtPosition(position) if they need to access the
     * data associated with the selected item.
     *
     * @param l The ListView where the click happened
     * @param v The view that was clicked within the ListView
     * @param position The position of the view in the list
     * @param id The row id of the item that was clicked
     */
    public void onListItemClick(ListView l, View v, int position, long id) {
    }

    /**
     * Provide the cursor for the list view.
     */
    public void setListAdapter(ExpandableListAdapter adapter) {
        boolean hadAdapter = mAdapter != null;
        mAdapter = adapter;
        if (mList != null) {
            mList.setAdapter(adapter);
            if (!mListShown && !hadAdapter) {
                // The list was hidden, and previously didn't have an
                // adapter.  It is now time to show it.
                setListShown(true, getView().getWindowToken() != null);
            }
        }
    }

    /**
     * Set the currently selected list item to the specified
     * position with the adapter's data
     *
     * @param position
     */
    public void setSelection(int position) {
        ensureList();
        mList.setSelection(position);
    }

    public long getSelectedPosition() {
        ensureList();
        return mList.getSelectedPosition();
    }

    public long getSelectedId() {
        ensureList();
        return mList.getSelectedId();
    }

    public ExpandableListView getExpandableListView() {
        ensureList();
        return mList;
    }

    /**
     * The default content for a ListFragment has a TextView that can
     * be shown when the list is empty.  If you would like to have it
     * shown, call this method to supply the text it should use.
     */
    public void setEmptyText(CharSequence text) {
        ensureList();
        if (mStandardEmptyView == null) {
            throw new IllegalStateException("Can't be used with a custom content view");
        }
        mStandardEmptyView.setText(text);
        if (!mSetEmptyText) {
            mList.setEmptyView(mStandardEmptyView);
            mSetEmptyText = true;
        }
    }

    /**
     * Control whether the list is being displayed.  You can make it not
     * displayed if you are waiting for the initial data to show in it.  During
     * this time an indeterminant progress indicator will be shown instead.
     *
     * <p>Applications do not normally need to use this themselves.  The default
     * behavior of ListFragment is to start with the list not being shown, only
     * showing it once an adapter is given with {@link #setListAdapter(ListAdapter)}.
     * If the list at that point had not been shown, when it does get shown
     * it will be do without the user ever seeing the hidden state.
     *
     * @param shown If true, the list view is shown; if false, the progress
     * indicator.  The initial value is true.
     */
    public void setListShown(boolean shown) {
        setListShown(shown, true);
    }

    /**
     * Like {@link #setListShown(boolean)}, but no animation is used when
     * transitioning from the previous state.
     */
    public void setListShownNoAnimation(boolean shown) {
        setListShown(shown, false);
    }

    /**
     * Control whether the list is being displayed.  You can make it not
     * displayed if you are waiting for the initial data to show in it.  During
     * this time an indeterminant progress indicator will be shown instead.
     *
     * @param shown If true, the list view is shown; if false, the progress
     * indicator.  The initial value is true.
     * @param animate If true, an animation will be used to transition to the
     * new state.
     */
    private void setListShown(boolean shown, boolean animate) {
        ensureList();
        if (mListShown == shown) {
            return;
        }
        mListShown = shown;
        if (shown) {
            if (animate) {
                mListContainer.startAnimation(AnimationUtils.loadAnimation(
                        getActivity(), android.R.anim.fade_in));
            }
            mListContainer.setVisibility(View.VISIBLE);
        } else {
            if (animate) {
                mListContainer.startAnimation(AnimationUtils.loadAnimation(
                        getActivity(), android.R.anim.fade_out));
            }
            mListContainer.setVisibility(View.GONE);
        }
    }

    /**
     * Get the ListAdapter associated with this activity's ListView.
     */
    public ExpandableListAdapter getExpandableListAdapter() {
        return mAdapter;
    }

    private void ensureList() {
        if (mList != null) {
            return;
        }
        View root = getView();
        if (root == null) {
            throw new IllegalStateException("Content view not yet created");
        }
        if (root instanceof ExpandableListView) {
            mList = (ExpandableListView)root;
        } else {
            mStandardEmptyView = (TextView)root.findViewById(INTERNAL_EMPTY_ID);
            if (mStandardEmptyView == null) {
                mEmptyView = root.findViewById(android.R.id.empty);
            }
            mListContainer = null; //root.findViewById(com.android.internal.R.id.listContainer);
            View rawListView = root.findViewById(android.R.id.list);
            if (!(rawListView instanceof ExpandableListView)) {
                if (rawListView == null) {
                    throw new RuntimeException(
                            "Your content must have a ExpandableListView whose id attribute is " +
                            "'android.R.id.list'");
                }
                throw new RuntimeException(
                        "Content has view with id attribute 'android.R.id.list' "
                        + "that is not a ExpandableListView class");
            }
            mList = (ExpandableListView)rawListView;
            if (mEmptyView != null) {
                mList.setEmptyView(mEmptyView);
            }
        }
        mListShown = true;
        mList.setOnItemClickListener(mOnClickListener);
        if (mAdapter != null) {
            setListAdapter(mAdapter);
        } else {
            // We are starting without an adapter, so assume we won't
            // have our data right away and start with the progress indicator.
            setListShown(false, false);
        }
        mHandler.post(mRequestFocus);
    }

    @Override
    public void onGroupExpand(int arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onGroupCollapse(int arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public boolean onChildClick(ExpandableListView arg0, View arg1, int arg2,
            int arg3, long arg4) {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
    }

    public void onContentChanged() {
        View emptyView = getView().findViewById(android.R.id.empty);
        mList = (ExpandableListView)getView().findViewById(android.R.id.list);
        if (mList == null) {
            throw new RuntimeException(
                    "Your content must have a ExpandableListView whose id attribute is " +
                    "'android.R.id.list'");
        }
        if (emptyView != null) {
            mList.setEmptyView(emptyView);
        }
        mList.setOnChildClickListener(this);
        mList.setOnGroupExpandListener(this);
        mList.setOnGroupCollapseListener(this);

        if (mFinishedStart) {
            setListAdapter(mAdapter);
        }
        mFinishedStart = true;
    }
}

Answer 2

不确定是否有人可以从 arne.jans 的帖子中获取代码，但我不能，因为 mListContainer 始终为空。每次我们调用 setListShown 方法时，ensureList() 实际上都会被调用。

因此，我使用了与 arne.jans 相同的想法，结合了 ListFragment 和 ExpandableListActivity 中的代码（从 http://grepcode.com/ 下载）。我终于让它发挥作用，并认为这对其他人可能有帮助。下面是代码：

package mypackage.util;

import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnCreateContextMenuListener;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.ListAdapter;
import android.widget.ProgressBar;
import android.widget.TextView;

public class ExpandableListFragment extends Fragment
    implements OnCreateContextMenuListener,
    ExpandableListView.OnChildClickListener, ExpandableListView.OnGroupCollapseListener,
    ExpandableListView.OnGroupExpandListener
    {

    static final int INTERNAL_EMPTY_ID = 0x00ff0001;
    static final int INTERNAL_PROGRESS_CONTAINER_ID = 0x00ff0002;
    static final int INTERNAL_LIST_CONTAINER_ID = 0x00ff0003;

    final private Handler mHandler = new Handler();

    final private Runnable mRequestFocus = new Runnable() {
        public void run() {
            mExpandableList.focusableViewAvailable(mExpandableList);
        }
    };

    final private AdapterView.OnItemClickListener mOnClickListener
            = new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
            onListItemClick((ExpandableListView)parent, v, position, id);
        }
    };

    ExpandableListAdapter mAdapter;
    ExpandableListView mExpandableList;
    boolean mFinishedStart = false;
    View mEmptyView;
    TextView mStandardEmptyView;
    View mProgressContainer;
    View mExpandableListContainer;
    CharSequence mEmptyText;
    boolean mExpandableListShown;

    public ExpandableListFragment() {
    }

    /**
     * Provide default implementation to return a simple list view.  Subclasses
     * can override to replace with their own layout.  If doing so, the
     * returned view hierarchy <em>must</em> have a ListView whose id
     * is {@link android.R.id#list android.R.id.list} and can optionally
     * have a sibling view id {@link android.R.id#empty android.R.id.empty}
     * that is to be shown when the list is empty.
     * 
     * <p>If you are overriding this method with your own custom content,
     * consider including the standard layout {@link android.R.layout#list_content}
     * in your layout file, so that you continue to retain all of the standard
     * behavior of ListFragment.  In particular, this is currently the only
     * way to have the built-in indeterminant progress state be shown.
     */
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        final Context context = getActivity();

        FrameLayout root = new FrameLayout(context);

        // ------------------------------------------------------------------

        LinearLayout pframe = new LinearLayout(context);
        pframe.setId(INTERNAL_PROGRESS_CONTAINER_ID);
        pframe.setOrientation(LinearLayout.VERTICAL);
        pframe.setVisibility(View.GONE);
        pframe.setGravity(Gravity.CENTER);

        ProgressBar progress = new ProgressBar(context, null,
                android.R.attr.progressBarStyleLarge);
        pframe.addView(progress, new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));

        root.addView(pframe, new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));

        // ------------------------------------------------------------------

        FrameLayout lframe = new FrameLayout(context);
        lframe.setId(INTERNAL_LIST_CONTAINER_ID);

        TextView tv = new TextView(getActivity());
        tv.setId(INTERNAL_EMPTY_ID);
        tv.setGravity(Gravity.CENTER);
        lframe.addView(tv, new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));

        ExpandableListView lv = new ExpandableListView(getActivity());
        lv.setId(android.R.id.list);
        lv.setDrawSelectorOnTop(false);
        lframe.addView(lv, new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));

        root.addView(lframe, new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));

        // ------------------------------------------------------------------

        root.setLayoutParams(new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));

        return root;
    }

    /**
     * Attach to list view once the view hierarchy has been created.
     */
    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        ensureList();
    }

    /**
     * Detach from list view.
     */
    @Override
    public void onDestroyView() {
        mHandler.removeCallbacks(mRequestFocus);
        mExpandableList = null;
        mExpandableListShown = false;
        mEmptyView = mProgressContainer = mExpandableListContainer = null;
        mStandardEmptyView = null;
        super.onDestroyView();
    }

    /**
     * This method will be called when an item in the list is selected.
     * Subclasses should override. Subclasses can call
     * getListView().getItemAtPosition(position) if they need to access the
     * data associated with the selected item.
     *
     * @param l The ListView where the click happened
     * @param v The view that was clicked within the ListView
     * @param position The position of the view in the list
     * @param id The row id of the item that was clicked
     */
    public void onListItemClick(ExpandableListView l, View v, int position, long id) {
    }

    /**
     * Provide the cursor for the list view.
     */
    public void setListAdapter(ExpandableListAdapter adapter) {
        boolean hadAdapter = mAdapter != null;
        mAdapter = adapter;
        if (mExpandableList != null) {
            mExpandableList.setAdapter(adapter);
            if (!mExpandableListShown && !hadAdapter) {
                // The list was hidden, and previously didn't have an
                // adapter.  It is now time to show it.
                setListShown(true, getView().getWindowToken() != null);
            }
        }
    }

    /**
     * Set the currently selected list item to the specified
     * position with the adapter's data
     *
     * @param position
     */
    public void setSelection(int position) {
        ensureList();
        mExpandableList.setSelection(position);
    }

    /**
     * Get the position of the currently selected list item.
     */
    public int getSelectedItemPosition() {
        ensureList();
        return mExpandableList.getSelectedItemPosition();
    }

    /**
     * Get the cursor row ID of the currently selected list item.
     */
    public long getSelectedItemId() {
        ensureList();
        return mExpandableList.getSelectedItemId();
    }

    /**
     * Get the activity's list view widget.
     */
    public ExpandableListView getListView() {
        ensureList();
        return mExpandableList;
    }

    /**
     * The default content for a ListFragment has a TextView that can
     * be shown when the list is empty.  If you would like to have it
     * shown, call this method to supply the text it should use.
     */
    public void setEmptyText(CharSequence text) {
        ensureList();
        if (mStandardEmptyView == null) {
            throw new IllegalStateException("Can't be used with a custom content view");
        }
        mStandardEmptyView.setText(text);
        if (mEmptyText == null) {
            mExpandableList.setEmptyView(mStandardEmptyView);
        }
        mEmptyText = text;
    }

    /**
     * Control whether the list is being displayed.  You can make it not
     * displayed if you are waiting for the initial data to show in it.  During
     * this time an indeterminant progress indicator will be shown instead.
     * 
     * <p>Applications do not normally need to use this themselves.  The default
     * behavior of ListFragment is to start with the list not being shown, only
     * showing it once an adapter is given with {@link #setListAdapter(ListAdapter)}.
     * If the list at that point had not been shown, when it does get shown
     * it will be do without the user ever seeing the hidden state.
     * 
     * @param shown If true, the list view is shown; if false, the progress
     * indicator.  The initial value is true.
     */
    public void setListShown(boolean shown) {
        setListShown(shown, true);
    }

    /**
     * Like {@link #setListShown(boolean)}, but no animation is used when
     * transitioning from the previous state.
     */
    public void setListShownNoAnimation(boolean shown) {
        setListShown(shown, false);
    }

    /**
     * Control whether the list is being displayed.  You can make it not
     * displayed if you are waiting for the initial data to show in it.  During
     * this time an indeterminant progress indicator will be shown instead.
     * 
     * @param shown If true, the list view is shown; if false, the progress
     * indicator.  The initial value is true.
     * @param animate If true, an animation will be used to transition to the
     * new state.
     */
    private void setListShown(boolean shown, boolean animate) {
        ensureList();
        if (mProgressContainer == null) {
            throw new IllegalStateException("Can't be used with a custom content view");
        }
        if (mExpandableListShown == shown) {
            return;
        }
        mExpandableListShown = shown;
        if (shown) {
            if (animate) {
                mProgressContainer.startAnimation(AnimationUtils.loadAnimation(
                        getActivity(), android.R.anim.fade_out));
                mExpandableListContainer.startAnimation(AnimationUtils.loadAnimation(
                        getActivity(), android.R.anim.fade_in));
            } else {
                mProgressContainer.clearAnimation();
                mExpandableListContainer.clearAnimation();
            }
            mProgressContainer.setVisibility(View.GONE);
            mExpandableListContainer.setVisibility(View.VISIBLE);
        } else {
            if (animate) {
                mProgressContainer.startAnimation(AnimationUtils.loadAnimation(
                        getActivity(), android.R.anim.fade_in));
                mExpandableListContainer.startAnimation(AnimationUtils.loadAnimation(
                        getActivity(), android.R.anim.fade_out));
            } else {
                mProgressContainer.clearAnimation();
                mExpandableListContainer.clearAnimation();
            }
            mProgressContainer.setVisibility(View.VISIBLE);
            mExpandableListContainer.setVisibility(View.GONE);
        }
    }

    /**
     * Get the ListAdapter associated with this activity's ListView.
     */
    public ExpandableListAdapter getListAdapter() {
        return mAdapter;
    }

    private void ensureList() {
        if (mExpandableList != null) {
            return;
        }
        View root = getView();
        if (root == null) {
            throw new IllegalStateException("Content view not yet created");
        }
        if (root instanceof ExpandableListView) {
            mExpandableList = (ExpandableListView)root;
        } else {
            mStandardEmptyView = (TextView)root.findViewById(INTERNAL_EMPTY_ID);
            if (mStandardEmptyView == null) {
                mEmptyView = root.findViewById(android.R.id.empty);
            } else {
                mStandardEmptyView.setVisibility(View.GONE);
            }
            mProgressContainer = root.findViewById(INTERNAL_PROGRESS_CONTAINER_ID);
            mExpandableListContainer = root.findViewById(INTERNAL_LIST_CONTAINER_ID);
            View rawExpandableListView = root.findViewById(android.R.id.list);
            if (!(rawExpandableListView instanceof ExpandableListView)) {
                if (rawExpandableListView == null) {
                    throw new RuntimeException(
                            "Your content must have a ListView whose id attribute is " +
                            "'android.R.id.list'");
                }
                throw new RuntimeException(
                        "Content has view with id attribute 'android.R.id.list' "
                        + "that is not a ListView class");
            }
            mExpandableList = (ExpandableListView)rawExpandableListView;
            if (mEmptyView != null) {
                mExpandableList.setEmptyView(mEmptyView);
            } else if (mEmptyText != null) {
                mStandardEmptyView.setText(mEmptyText);
                mExpandableList.setEmptyView(mStandardEmptyView);
            }
        }
        mExpandableListShown = true;
        mExpandableList.setOnItemClickListener(mOnClickListener);
        if (mAdapter != null) {
            ExpandableListAdapter adapter = mAdapter;
            mAdapter = null;
            setListAdapter(adapter);
        } else {
            // We are starting without an adapter, so assume we won't
            // have our data right away and start with the progress indicator.
            if (mProgressContainer != null) {
                setListShown(false, false);
            }
        }
        mHandler.post(mRequestFocus);
    }

    /**
     * Override this to populate the context menu when an item is long pressed. menuInfo
     * will contain an {@link android.widget.ExpandableListView.ExpandableListContextMenuInfo}
     * whose packedPosition is a packed position
     * that should be used with {@link ExpandableListView#getPackedPositionType(long)} and
     * the other similar methods.
     * <p>
     * {@inheritDoc}
     */
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
    }

    /**
     * Override this for receiving callbacks when a child has been clicked.
     * <p>
     * {@inheritDoc}
     */
    public boolean onChildClick(ExpandableListView parent, View v, int groupPosition,
            int childPosition, long id) {
        return false;
    }

    /**
     * Override this for receiving callbacks when a group has been collapsed.
     */
    public void onGroupCollapse(int groupPosition) {
    }

    /**
     * Override this for receiving callbacks when a group has been expanded.
     */
    public void onGroupExpand(int groupPosition) {
    }

//    /**
//     * Ensures the expandable list view has been created before Activity restores all
//     * of the view states.
//     * 
//     *@see Activity#onRestoreInstanceState(Bundle)
//     */
//    @Override
//    protected void onRestoreInstanceState(Bundle state) {
//        ensureList();
//        super.onRestoreInstanceState(state);
//    }

    /**
     * Updates the screen state (current list and other views) when the
     * content changes.
     * 
     * @see Activity#onContentChanged()
     */

    public void onContentChanged() {
//        super.onContentChanged();
        View emptyView = getView().findViewById(android.R.id.empty);
        mExpandableList = (ExpandableListView)getView().findViewById(android.R.id.list);
        if (mExpandableList == null) {
            throw new RuntimeException(
                    "Your content must have a ExpandableListView whose id attribute is " +
                    "'android.R.id.list'");
        }
        if (emptyView != null) {
            mExpandableList.setEmptyView(emptyView);
        }
        mExpandableList.setOnChildClickListener(this);
        mExpandableList.setOnGroupExpandListener(this);
        mExpandableList.setOnGroupCollapseListener(this);

        if (mFinishedStart) {
            setListAdapter(mAdapter);
        }
        mFinishedStart = true;
    }

    /**
     * Get the activity's expandable list view widget.  This can be used to get the selection,
     * set the selection, and many other useful functions.
     * 
     * @see ExpandableListView
     */
    public ExpandableListView getExpandableListView() {
        ensureList();
        return mExpandableList;
    }

    /**
     * Get the ExpandableListAdapter associated with this activity's
     * ExpandableListView.
     */
    public ExpandableListAdapter getExpandableListAdapter() {
        return mAdapter;
    }

    /**
     * Gets the ID of the currently selected group or child.
     * 
     * @return The ID of the currently selected group or child.
     */
    public long getSelectedId() {
        return mExpandableList.getSelectedId();
    }

    /**
     * Gets the position (in packed position representation) of the currently
     * selected group or child. Use
     * {@link ExpandableListView#getPackedPositionType},
     * {@link ExpandableListView#getPackedPositionGroup}, and
     * {@link ExpandableListView#getPackedPositionChild} to unpack the returned
     * packed position.
     * 
     * @return A packed position representation containing the currently
     *         selected group or child's position and type.
     */
    public long getSelectedPosition() {
        return mExpandableList.getSelectedPosition();
    }

    /**
     * Sets the selection to the specified child. If the child is in a collapsed
     * group, the group will only be expanded and child subsequently selected if
     * shouldExpandGroup is set to true, otherwise the method will return false.
     * 
     * @param groupPosition The position of the group that contains the child.
     * @param childPosition The position of the child within the group.
     * @param shouldExpandGroup Whether the child's group should be expanded if
     *            it is collapsed.
     * @return Whether the selection was successfully set on the child.
     */
    public boolean setSelectedChild(int groupPosition, int childPosition, boolean shouldExpandGroup) {
        return mExpandableList.setSelectedChild(groupPosition, childPosition, shouldExpandGroup);
    }

    /**
     * Sets the selection to the specified group.
     * @param groupPosition The position of the group that should be selected.
     */
    public void setSelectedGroup(int groupPosition) {
        mExpandableList.setSelectedGroup(groupPosition);
    }
}

希望它有时能拯救你。

Answer 3

我想要尽可能少的改变；当已经使用 ExpandableListActivity 时，无需使用上面的片段实现，只需将 ExpandableListActivity 的代码复制到自己的应用程序中，更改内部 R.* 资源引用以使用对应的公共命名空间，并将类更改为从 FragmentActivity 继承。