How can you implement multi-selection and Contextual ActionMode in ActionBarSherlock?

Question

How should I implement multi selection on AdapterView with ActionBarSherlock, because it does not provide MultiChoiceModeListener?

This is what it looks like

How can you do this?

Answer 1

So here's what I did.

Edit: Over a year passed since I found out the previous answer had alot of useless code (woops) and the CAB thing can be achieved with much less effort and a cleaner code, so I took some time and updated it

The LibraryFragment ListView should be defined with choice mode "none"

<ListView
    android:id="@android:id/list"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:choiceMode="none"/>

The list item should have an ?attr/activatedBackgroundIndicator foreground in order to automatically draw highlighted semitransparent overlay on list.setItemChecked(pos, true)

list_item_library.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:foreground="?attr/activatedBackgroundIndicator"
    android:paddingBottom="5dp"
    android:paddingTop="5dp" >

....

The ListFragment

import android.support.v4.app.DialogFragment;
import com.actionbarsherlock.app.SherlockListFragment;
import com.actionbarsherlock.view.ActionMode;
import com.actionbarsherlock.view.Menu;

public final class LibraryFragment
        extends SherlockListFragment
{

    private MyListAdapter adapter;
    private ListView list;

    // if ActoinMode is null - assume we are in normal mode
    private ActionMode actionMode;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState)
    {
        View v = inflater.inflate(R.layout.fragment_library, null);
        this.list = (ListView) v.findViewById(android.R.id.list);
        this.initListView();
        return v;
    }

    @Override
    public void onPause()
    {
        super.onPause();
        if (this.actionMode != null) {
            this.actionMode.finish();
        }
    }

    @Override
    public void onResume() {
        super.onResume();
        updateData();
    }

    // update ListView
    protected void updateData()
    {
        if (adapter == null) {
            return;
        }
        adapter.clear();
        // my kinda stuff :)
        File[] items = scan();
        if (items != null) {
            adapter.updateData(items);
            if (actionMode != null) {
                actionMode.invalidate();
            }
        }
        // if empty - finish action mode.
        if (actionMode != null && (files == null || files.length == 0)) {
            actionMode.finish();
        }
    }

    private void initListView()
    {
        this.adapter = new MyAdapter(getActivity());
        this.list.setAdapter(adapter);
        this.list.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener()
        {

            @Override
            public boolean onItemLongClick(AdapterView<?> arg0,
                    View arg1, int arg2, long arg3)
            {
                if (actionMode != null) {
                    // if already in action mode - do nothing
                    return false;
                }
                // set checked selected item and enter multi selection mode
                list.setChoiceMode(AbsListView.CHOICE_MODE_MULTIPLE);
                list.setItemChecked(arg2, true);

                getSherlockActivity().startActionMode(
                        new ActionModeCallback());
                return true;
            }
        });
        this.list.setOnItemClickListener(new AdapterView.OnItemClickListener()
        {
            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                    long arg3)
            {
                if (actionMode != null) {
                    // the items are auomatically "checked" becaise we've set AbsListView.CHOICE_MODE_MULTIPLE before
                    // starting action mode, so the only thing we have to care about is invalidating the actionmode
                    actionMode.invalidate(); //invalidate title and menus.
                } else {
                    // do whatever you should on item click
                }
            }
        });
    }


    // all our ActionMode stuff here :)
    private final class ActionModeCallback
            implements ActionMode.Callback
    {

        // " selected" string resource to update ActionBar text
        private String selected = getActivity().getString(
                R.string.library_selected);

        @Override
        public boolean onCreateActionMode(ActionMode mode, Menu menu)
        {
            actionMode = mode;
            return true;
        }

        @Override
        public boolean onPrepareActionMode(ActionMode mode, Menu menu)
        {
            // remove previous items
            menu.clear();
            final int checked = list.getCheckedItemCount();
            // update title with number of checked items
            mode.setTitle(checked + this.selected);
            switch (checked) {
            case 0:
                // if nothing checked - exit action mode
                mode.finish();
                return true;
            case 1:
                // all items - rename + delete
                getSherlockActivity().getSupportMenuInflater().inflate(
                        R.menu.library_context, menu);
                return true;
            default:
                getSherlockActivity().getSupportMenuInflater().inflate(
                        R.menu.library_context, menu);
                // remove rename option - because we have more than one selected
                menu.removeItem(R.id.library_context_rename);
                return true;
            }
        }

        @Override
        public boolean onActionItemClicked(ActionMode mode,
                com.actionbarsherlock.view.MenuItem item)
        {
            SparseBooleanArray checked;
            switch (item.getItemId()) {
            case R.id.library_context_rename:
                // the rename action is present only when only one item is selected. 
                // so when the first checked item found, show the dialog and break
                checked = list.getCheckedItemPositions();
                for (int i = 0; i < checked.size(); i++) {
                    final int index = checked.keyAt(i);
                    if (checked.get(index)) {
                        final DialogFragment d = RenameDialog.instantiate(adapter.getItem(index).getFile(), LibraryFragment.this);
                        d.show(getActivity().getSupportFragmentManager(), "dialog");
                        break;
                    }
                }
                return true;

            case R.id.library_context_delete:
                // delete every checked item
                checked = list.getCheckedItemPositions();
                for (int i = 0; i < checked.size(); i++) {
                    final int index = checked.keyAt(i);
                    if (checked.get(index)) {
                        adapter.getItem(index).getFile().delete();
                    }
                }
                updateData();
                return true;
            default:
                return false;
            }
        }

        @Override
        public void onDestroyActionMode(ActionMode mode)
        {
            list.clearChoices();

            //workaround for some items not being unchecked.
            //see http://stackoverflow.com/a/10542628/1366471
            for (int i = 0; i < list.getChildCount(); i++) {
                (list.getChildAt(i).getBackground()).setState(new int[] { 0 });
            }

            list.setChoiceMode(AbsListView.CHOICE_MODE_NONE);
            actionMode = null;
        }

    }