Ich entwickle eine Android App. In dieser App gibt es eine Schaltfläche zum Aufrufen einer anderen Aktivität, die eine Liste der auf dem Telefon installierten Apps enthält. Wenn der Benutzer eine App auswählt, wird der Paketname gespeichert und der Benutzer kehrt zur vorherigen Aktivität zurück. Aber wie kann ich den Paketnamen bekommen?

public class LoaderCustomSupport extends SherlockFragmentActivity {

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

        FragmentManager fm = getSupportFragmentManager();

        // Create the list fragment and add it as our sole content.
        if (fm.findFragmentById(android.R.id.content) == null) {
            AppListFragment list = new AppListFragment();
            fm.beginTransaction().add(android.R.id.content, list).commit();
        }
    }

    /**
     * This class holds the per-item data in our Loader.
     */
    public static class AppEntry {
        public AppEntry(AppListLoader loader, ApplicationInfo info) {
            mLoader = loader;
            mInfo = info;
            mApkFile = new File(info.sourceDir);
        }

        public ApplicationInfo getApplicationInfo() {
            return mInfo;
        }

        public String getLabel() {
            return mLabel;
        }

        public Drawable getIcon() {
            if (mIcon == null) {
                if (mApkFile.exists()) {
                    mIcon = mInfo.loadIcon(mLoader.mPm);
                    return mIcon;
                } else {
                    mMounted = false;
                }
            } else if (!mMounted) {
                // If the app wasn't mounted but is now mounted, reload
                // its icon.
                if (mApkFile.exists()) {
                    mMounted = true;
                    mIcon = mInfo.loadIcon(mLoader.mPm);
                    return mIcon;
                }
            } else {
                return mIcon;
            }

            return mLoader.getContext().getResources().getDrawable(
                android.R.drawable.sym_def_app_icon);
        }

        @Override
        public String toString() {
            return mLabel;
        }

        void loadLabel(Context context) {
            if (mLabel == null || !mMounted) {
                if (!mApkFile.exists()) {
                    mMounted = false;
                    mLabel = mInfo.packageName;
                } else {
                    mMounted = true;
                    CharSequence label = mInfo.loadLabel(context.getPackageManager());
                    mLabel = label != null ? label.toString() : mInfo.packageName;
                }
            }
        }

        private final AppListLoader mLoader;
        private final ApplicationInfo mInfo;
        private final File mApkFile;
        private String mLabel;
        private Drawable mIcon;
        private boolean mMounted;
    }

    /**
     * Perform alphabetical comparison of application entry objects.
     */
    public static final Comparator<AppEntry> ALPHA_COMPARATOR = new Comparator<AppEntry>() {
        private final Collator sCollator = Collator.getInstance();

        @Override
        public int compare(AppEntry object1, AppEntry object2) {
            return sCollator.compare(object1.getLabel(), object2.getLabel());
        }
    };

    /**
     * Helper for determining if the configuration has changed in an interesting
     * way so we need to rebuild the app list.
     */
    public static class InterestingConfigChanges {
        final Configuration mLastConfiguration = new Configuration();
        int mLastDensity;

        boolean applyNewConfig(Resources res) {
            int configChanges = mLastConfiguration.updateFrom(res.getConfiguration());
            boolean densityChanged = mLastDensity != res.getDisplayMetrics().densityDpi;
            if (densityChanged || (configChanges&(ActivityInfo.CONFIG_LOCALE
                    |ActivityInfoCompat.CONFIG_UI_MODE|ActivityInfo.CONFIG_SCREEN_LAYOUT)) != 0) {
                mLastDensity = res.getDisplayMetrics().densityDpi;
                return true;
            }
            return false;
        }
    }

    /**
     * Helper class to look for interesting changes to the installed apps
     * so that the loader can be updated.
     */
    public static class PackageIntentReceiver extends BroadcastReceiver {
        final AppListLoader mLoader;

        public PackageIntentReceiver(AppListLoader loader) {
            mLoader = loader;
            IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);
            filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
            filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
            filter.addDataScheme("package");
            mLoader.getContext().registerReceiver(this, filter);
            // Register for events related to sdcard installation.
            IntentFilter sdFilter = new IntentFilter();
            sdFilter.addAction(IntentCompat.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE);
            sdFilter.addAction(IntentCompat.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE);
            mLoader.getContext().registerReceiver(this, sdFilter);
        }

        @Override
        public void onReceive(Context context, Intent intent) {
            // Tell the loader about the change.
            mLoader.onContentChanged();
        }
    }

    /**
     * A custom Loader that loads all of the installed applications.
     */
    public static class AppListLoader extends AsyncTaskLoader<List<AppEntry>> {
        final InterestingConfigChanges mLastConfig = new InterestingConfigChanges();
        final PackageManager mPm;

        List<AppEntry> mApps;
        PackageIntentReceiver mPackageObserver;

        public AppListLoader(Context context) {
            super(context);

            // Retrieve the package manager for later use; note we don't
            // use 'context' directly but instead the save global application
            // context returned by getContext().
            mPm = getContext().getPackageManager();
        }

        /**
         * This is where the bulk of our work is done.  This function is
         * called in a background thread and should generate a new set of
         * data to be published by the loader.
         */
        @Override
        public List<AppEntry> loadInBackground() {
            // Retrieve all known applications.
            List<ApplicationInfo> apps = mPm.getInstalledApplications(
                PackageManager.GET_UNINSTALLED_PACKAGES |
                PackageManager.GET_DISABLED_COMPONENTS);
            if (apps == null) {
                apps = new ArrayList<ApplicationInfo>();
            }

            final Context context = getContext();

            // Create corresponding array of entries and load their labels.
            List<AppEntry> entries = new ArrayList<AppEntry>(apps.size());
            for (int i=0; i<apps.size(); i++) {
                AppEntry entry = new AppEntry(this, apps.get(i));
                entry.loadLabel(context);
                entries.add(entry);
            }

            // Sort the list.
            Collections.sort(entries, ALPHA_COMPARATOR);

            // Done!
            return entries;
        }

        /**
         * Called when there is new data to deliver to the client.  The
         * super class will take care of delivering it; the implementation
         * here just adds a little more logic.
         */
        @Override
        public void deliverResult(List<AppEntry> apps) {
            if (isReset()) {
                // An async query came in while the loader is stopped.  We
                // don't need the result.
                if (apps != null) {
                    onReleaseResources(apps);
                }
            }
            List<AppEntry> oldApps = apps;
            mApps = apps;

            if (isStarted()) {
                // If the Loader is currently started, we can immediately
                // deliver its results.
                super.deliverResult(apps);
            }

            // At this point we can release the resources associated with
            // 'oldApps' if needed; now that the new result is delivered we
            // know that it is no longer in use.
            if (oldApps != null) {
                onReleaseResources(oldApps);
            }
        }

        /**
         * Handles a request to start the Loader.
         */
        @Override
        protected void onStartLoading() {
            if (mApps != null) {
                // If we currently have a result available, deliver it
                // immediately.
                deliverResult(mApps);
            }

            // Start watching for changes in the app data.
            if (mPackageObserver == null) {
                mPackageObserver = new PackageIntentReceiver(this);
            }

            // Has something interesting in the configuration changed since we
            // last built the app list?
            boolean configChange = mLastConfig.applyNewConfig(getContext().getResources());

            if (takeContentChanged() || mApps == null || configChange) {
                // If the data has changed since the last time it was loaded
                // or is not currently available, start a load.
                forceLoad();
            }
       }

        /**
         * Handles a request to stop the Loader.
         */
        @Override
        protected void onStopLoading() {
            // Attempt to cancel the current load task if possible.
            cancelLoad();
        }

        /**
         * Handles a request to cancel a load.
         */
        @Override
        public void onCanceled(List<AppEntry> apps) {
            super.onCanceled(apps);

            // At this point we can release the resources associated with 'apps'
            // if needed.
            onReleaseResources(apps);
        }

        /**
         * Handles a request to completely reset the Loader.
         */
        @Override
        protected void onReset() {
            super.onReset();

            // Ensure the loader is stopped
            onStopLoading();

            // At this point we can release the resources associated with 'apps'
            // if needed.
            if (mApps != null) {
                onReleaseResources(mApps);
                mApps = null;
            }

            // Stop monitoring for changes.
            if (mPackageObserver != null) {
                getContext().unregisterReceiver(mPackageObserver);
                mPackageObserver = null;
            }
        }

        /**
         * Helper function to take care of releasing resources associated
         * with an actively loaded data set.
         */
        protected void onReleaseResources(List<AppEntry> apps) {
            // For a simple List<> there is nothing to do.  For something
            // like a Cursor, we would close it here.
        }
    }

    public static class AppListAdapter extends ArrayAdapter<AppEntry> {
        private final LayoutInflater mInflater;

        public AppListAdapter(Context context) {
            super(context, android.R.layout.simple_list_item_2);
            mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }

        public void setData(List<AppEntry> data) {
            clear();
            if (data != null) {
                for (AppEntry appEntry : data) {
                    add(appEntry);
                }
            }
        }

        /**
         * Populate new items in the list.
         */
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View view;

            if (convertView == null) {
                view = mInflater.inflate(R.layout.list_item_icon_text, parent, false);
            } else {
                view = convertView;
            }

            AppEntry item = getItem(position);
            ((ImageView)view.findViewById(R.id.icon)).setImageDrawable(item.getIcon());
            ((TextView)view.findViewById(R.id.text)).setText(item.getLabel());

            return view;
        }
    }

    public static class AppListFragment extends SherlockListFragment
            implements LoaderManager.LoaderCallbacks<List<AppEntry>> {

        // This is the Adapter being used to display the list's data.
        AppListAdapter mAdapter;

        // If non-null, this is the current filter the user has provided.
        String mCurFilter;

        OnQueryTextListenerCompat mOnQueryTextListenerCompat;

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

            // Give some text to display if there is no data.  In a real
            // application this would come from a resource.
            setEmptyText("No applications");

            // We have a menu item to show in action bar.
            setHasOptionsMenu(true);

            // Create an empty adapter we will use to display the loaded data.
            mAdapter = new AppListAdapter(getActivity());
            setListAdapter(mAdapter);

            // Start out with a progress indicator.
            setListShown(false);

            // Prepare the loader.  Either re-connect with an existing one,
            // or start a new one.
            getLoaderManager().initLoader(0, null, this);
        }

        @Override
        public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
            // Place an action bar item for searching.
            MenuItem item = menu.add("Search");
            item.setIcon(android.R.drawable.ic_menu_search);
            item.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
            View searchView = SearchViewCompat.newSearchView(getActivity());
            if (searchView != null) {
                SearchViewCompat.setOnQueryTextListener(searchView,
                        new OnQueryTextListenerCompat() {
                    @Override
                    public boolean onQueryTextChange(String newText) {
                        // Called when the action bar search text has changed.  Since this
                        // is a simple array adapter, we can just have it do the filtering.
                        mCurFilter = !TextUtils.isEmpty(newText) ? newText : null;
                        mAdapter.getFilter().filter(mCurFilter);
                        return true;
                    }
                });
                item.setActionView(searchView);
            }
        }

        @Override
        public void onListItemClick(ListView l, View v, int position, long id) {
            // Insert desired behavior here.
            Log.i("LoaderCustom", "Item clicked: " + id);
           //Here i want to know the package name of the selected app item in the list
        }

        @Override
        public Loader<List<AppEntry>> onCreateLoader(int id, Bundle args) {
            // This is called when a new Loader needs to be created.  This
            // sample only has one Loader with no arguments, so it is simple.
            return new AppListLoader(getActivity());
        }

        @Override
        public void onLoadFinished(Loader<List<AppEntry>> loader, List<AppEntry> data) {
            // Set the new data in the adapter.
            mAdapter.setData(data);

            // The list should now be shown.
            if (isResumed()) {
                setListShown(true);
            } else {
                setListShownNoAnimation(true);
            }
        }

        @Override
        public void onLoaderReset(Loader<List<AppEntry>> loader) {
            // Clear the data in the adapter.
            mAdapter.setData(null);
        }
    }
}