ExpandableListFragment with LoaderManager for Compatibility Package

Question

I want to make my ExpandableListActivity compatible with Honeycomb. I am wondering why there is no ExpandableListFragment for the Compatibility Package.

Is there a way to make ExpandableListView work with the normal Fragment class? How do I load the Cursors with the LoaderManager?

Answer 1

I had the same problem. I didnt find a solution for this, so I decided to implement the ExpandableListFragment myself based on a combination of the android.support.v4.app.ListFragment (Compatibility API) and the android.app.ExpandableListActivity from API level 8, so this should be compatible with API level < 11.

I dont have an answer to your question about Cursors and LoaderManagers, though.

One thing to note about my version of the ExpandableListFragment, you have to call its method onContentChanged() yourself from the oncontentchanged()-method-definition of your encapsulating activity, or else there wont be any listener attached to the listitems.

The sourcecode for ExpandableListFragment (in a local package-copy of android.support.v4.app, name it what you want):

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;
    }
}