Android search with Fragments

Question

In short, you can't. There are a couple of reasons why creating a search interface within a Fragment is not possible.

1. When creating a searchable interface, you must specify a default "searchable activity" in your Android manifest. As I'm sure you know, a Fragment cannot exist without a parent Activity and thus, this separation is not possible.

2. If you already figured out #1 already, I assume you asked this question in hopes that there is some magical "hack" out there that can get the job done. However, the documentation states that,

   When the user executes a search in the search dialog or widget, the system starts your searchable activity and delivers it the search query in an Intent with the ACTION_SEARCH action. Your searchable activity retrieves the query from the intent's QUERY extra, then searches your data and presents the results.

   The underlying, internal system that is responsible for providing search results expects an Activity, not a Fragment; thus, implementing a search interface that is completely independent of an Activity is not possible, as it would require changes to the underlying system itself. Check out the source code for the SearchableInfo class if you don't believe me :).

That being said, it doesn't seem like it would be too difficult to achieve something similar to what you are describing. For instance, you might consider implementing your searchable-Activity so that it will accept the android.intent.action.SEARCH intent and (instead of immediately displaying the results in a ListView, for example) will pass the search query to your Fragments. For instance, consider the following searchable Activity:

public class SearchableActivity extends Activity {

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

        if (Intent.ACTION_SEARCH.equals(getIntent().getAction())) {
          String query = intent.getStringExtra(SearchManager.QUERY);
          doMySearch(query);
        }
    }

    /**
     * Performs a search and passes the results to the container
     * Activity that holds your Fragments.
     */
    public void doMySearch(String query) {
        // TODO: implement this
    }
}

When a search-request is made, the system will launch your searchable activity, perform the query, and will pass the results to some container Activity (based on your implementation of doMySearch). The container Activity will then pass these results to the contained searchable Fragment, in which the results will be displayed. The implementation requires a bit more work than what you were probably hoping for, but I'm sure there are ways that you can make it more modular, and it seems like this might be the best that you can do.

p.s. If you use this approach, you might have to pay special attention to which Activitys are added/removed to the backstack. See this post for some more information on how this might be done.

p.p.s. You might also forget about the standard search interface completely and just implement a simple search within a Fragment as described in Raghav's post below.

Here is the example to search something using fragments. Hope it helps and this is what you are looking for:

public class LoaderCursor extends Activity {

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

        FragmentManager fm = getFragmentManager();

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

    public static class CursorLoaderListFragment extends ListFragment
            implements OnQueryTextListener, LoaderManager.LoaderCallbacks<Cursor> {

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

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

        @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 phone numbers");

            // 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 SimpleCursorAdapter(getActivity(),
                    android.R.layout.simple_list_item_2, null,
                    new String[] { Contacts.DISPLAY_NAME, Contacts.CONTACT_STATUS },
                    new int[] { android.R.id.text1, android.R.id.text2 }, 0);
            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);
            SearchView sv = new SearchView(getActivity());
            sv.setOnQueryTextListener(this);
            item.setActionView(sv);
        }

        public boolean onQueryTextChange(String newText) {
            // Called when the action bar search text has changed.  Update
            // the search filter, and restart the loader to do a new query
            // with this filter.
            mCurFilter = !TextUtils.isEmpty(newText) ? newText : null;
            getLoaderManager().restartLoader(0, null, this);
            return true;
        }

        @Override public boolean onQueryTextSubmit(String query) {
            // Don't care about this.
            return true;
        }

        @Override public void onListItemClick(ListView l, View v, int position, long id) {
            // Insert desired behavior here.
            Log.i("FragmentComplexList", "Item clicked: " + id);
        }

        // These are the Contacts rows that we will retrieve.
        static final String[] CONTACTS_SUMMARY_PROJECTION = new String[] {
            Contacts._ID,
            Contacts.DISPLAY_NAME,
            Contacts.CONTACT_STATUS,
            Contacts.CONTACT_PRESENCE,
            Contacts.PHOTO_ID,
            Contacts.LOOKUP_KEY,
        };

        public Loader<Cursor> onCreateLoader(int id, Bundle args) {
            // This is called when a new Loader needs to be created.  This
            // sample only has one Loader, so we don't care about the ID.
            // First, pick the base URI to use depending on whether we are
            // currently filtering.
            Uri baseUri;
            if (mCurFilter != null) {
                baseUri = Uri.withAppendedPath(Contacts.CONTENT_FILTER_URI,
                        Uri.encode(mCurFilter));
            } else {
                baseUri = Contacts.CONTENT_URI;
            }

            // Now create and return a CursorLoader that will take care of
            // creating a Cursor for the data being displayed.
            String select = "((" + Contacts.DISPLAY_NAME + " NOTNULL) AND ("
                    + Contacts.HAS_PHONE_NUMBER + "=1) AND ("
                    + Contacts.DISPLAY_NAME + " != '' ))";
            return new CursorLoader(getActivity(), baseUri,
                    CONTACTS_SUMMARY_PROJECTION, select, null,
                    Contacts.DISPLAY_NAME + " COLLATE LOCALIZED ASC");
        }

        public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
            // Swap the new cursor in.  (The framework will take care of closing the
            // old cursor once we return.)
            mAdapter.swapCursor(data);

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

        public void onLoaderReset(Loader<Cursor> loader) {
            // This is called when the last Cursor provided to onLoadFinished()
            // above is about to be closed.  We need to make sure we are no
            // longer using it.
            mAdapter.swapCursor(null);
        }
    }
}

It is quite possible to search in a fragment using the standard ActionBar SearchView ActionView API. This will work back to Android 2.1 (API level 7) too using AppCompat support classes v7.

In your fragment:

@Override
public void onCreateOptionsMenu (Menu menu, MenuInflater inflater){
    inflater.inflate(R.menu.search, menu);
    MenuItem item = menu.findItem(R.id.action_search);
    SearchView sv = new SearchView(((YourActivity) getActivity()).getSupportActionBar().getThemedContext());
    MenuItemCompat.setShowAsAction(item, MenuItemCompat.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW | MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
    MenuItemCompat.setActionView(item, sv);
    sv.setOnQueryTextListener(new OnQueryTextListener() {
        @Override
        public boolean onQueryTextSubmit(String query) {
            System.out.println("search query submit");
            return false;
        }

        @Override
        public boolean onQueryTextChange(String newText) {
            System.out.println("tap");
            return false;
        }
    });
}

In your menu XML

<item
    android:id="@+id/action_search"
    android:icon="@drawable/ic_action_search"
    android:title="Search Waste Items"
    android:showAsAction="ifRoom|collapseActionView"
    nz.govt.app:actionViewClass="android.support.v7.widget.SearchView"
    nz.govt.app:showAsAction="ifRoom|collapseActionView" />

Using AppCompat support classes v7. Just adding something to @David 's solution from @Rookie solution to get it work properly in a simple manner, here is my fragment code:

MyFragment:

public class MyFragment extends Fragment implements SearchView.OnQueryTextListener {

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        // What i have added is this
        setHasOptionsMenu(true);
    }

    @Override
    public void onCreateOptionsMenu (Menu menu, MenuInflater inflater) {

        //inflater.inflate(R.menu.main, menu); // removed to not double the menu items
        MenuItem item = menu.findItem(R.id.action_search);
        SearchView sv = new SearchView(((MainActivity) getActivity()).getSupportActionBar().getThemedContext());
        MenuItemCompat.setShowAsAction(item, MenuItemCompat.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW | MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
        MenuItemCompat.setActionView(item, sv);
        sv.setOnQueryTextListener(this);
        sv.setIconifiedByDefault(false);
        sv.setOnSearchClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Utils.LogDebug("Clicked: ");
            }
        });

        MenuItemCompat.setOnActionExpandListener(item, new MenuItemCompat.OnActionExpandListener() {
            @Override
            public boolean onMenuItemActionCollapse(MenuItem item) {
                // Do something when collapsed
                Utils.LogDebug("Closed: ");
                return true;  // Return true to collapse action view
            }

            @Override
            public boolean onMenuItemActionExpand(MenuItem item) {
                // Do something when expanded
                Utils.LogDebug("Openeed: ");
                return true;  // Return true to expand action view
            }
        });

        super.onCreateOptionsMenu(menu,inflater);
    }

    @Override
    public boolean onQueryTextSubmit(String query) {
        Utils.LogDebug("Submitted: "+query);
        return true;
    }

    @Override
    public boolean onQueryTextChange(String newText) {
        Utils.LogDebug("Changed: "+newText);
        return false;
    }
}

I added the onActivityCreated, cuz without calling setHasOptionsMenu(true); the system will not know that this fragment needs to interact with the menu.

then I removed the line inflater.inflate(R.menu.main, menu); because it doubled the menu items since Activity inflated a menu, then Fragment inflated another menu

Thanks to @David and @Rookie

When working with Fragments you still need to use an Activity to control and assign the Fragments. This Activity can have search functionality as before.

I've recently switched from a 'normal' Activity based app, to a Fragment based app and the search functionality worked just the same for me.

Have you tried working on it, and didn't succeed? If so give some more detail in your question.

EDIT:

If you want to have a fragment specific search, have all your Fragments extend an interface MyFragment with a startSearch method, and have your Activity's startSearch method call the current fragment's startSearch method.

I think I achieved it : you can actually use fragments and add a search icon to an action bar so that a search is possible inside the fragments. The trick is to use an action bar, an action view, a listener for it, a loader and an adapter of course.

This works pretty well although it completely bypasses the android platform search mechanism (but it could be completed with some work to find what @Alex Lockwood describes and pass the search to fragments). It would not react to an intent as expected in the case of an activity, but it works : users can search inside fragments.

Here is the code :

SearchInFragmentActivity

package com.sof.test.searchfragment;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.View;

import com.actionbarsherlock.app.ActionBar;
import com.actionbarsherlock.app.ActionBar.Tab;
import com.actionbarsherlock.app.ActionBar.TabListener;
import com.actionbarsherlock.app.SherlockFragmentActivity;
import com.sof.test.searchfragment.SearchFragment;
import com.sof.test.R;


public class SearchInFragmentActivity extends SherlockFragmentActivity implements TabListener {

    private SearchFragment tab1 = new SearchFragment();
    private SearchFragment tab2 = new SearchFragment();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView( R.layout.search_in_fragments );

        getSupportActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        createTab( R.string.tab1, R.drawable.ic_menu_search );
        createTab( R.string.tab2, R.drawable.ic_menu_search );
        getSupportActionBar().setSelectedNavigationItem( 0 );
        invalidateOptionsMenu();
    }

    private void createTab(int tabNameResId, int tabIconResId) {
        ActionBar.Tab tab = getSupportActionBar().newTab();
        tab.setText( tabNameResId );
        tab.setTabListener(this);
        getSupportActionBar().addTab(tab);
    }// met

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        if( ft == null ) {
            return;
        }//if
        View fragmentSlot = findViewById( R.id.fragment );
        Fragment newFragment = null;
        if( fragmentSlot != null ) {
            newFragment = (tab.getPosition() == 0) ? tab1 : tab2;
            ft.replace(R.id.fragment, newFragment );
            ft.setTransition( FragmentTransaction.TRANSIT_FRAGMENT_FADE);
        }//if
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    }

}//class

The fragment class SearchFragment (I use 2 instances inside the activity above).

package com.sof.test.searchfragment;


import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.LoaderManager.LoaderCallbacks;
import android.support.v4.content.AsyncTaskLoader;
import android.support.v4.content.Loader;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.SearchView;
import android.widget.TextView;

import com.sof.test.R;
import com.actionbarsherlock.app.SherlockListFragment;
import com.actionbarsherlock.view.Menu;
import com.actionbarsherlock.view.MenuInflater;

public class SearchFragment extends SherlockListFragment {

    private StringLoader loader = null;
    private StringAdapter adapter = null;
    private List<String> listData = new ArrayList<String>();
    private String query;


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = super.onCreateView(inflater, container, savedInstanceState);
        createListData();

        loader = new StringLoader( getActivity(), this );
        adapter = new StringAdapter(listData);
        setListAdapter(adapter);

        getLoaderManager().initLoader(0, null,  new LoaderCallBacks() );
        loader.forceLoad();
        setHasOptionsMenu( true );
        return view;
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater ) {
        super.onCreateOptionsMenu(menu, inflater);
        inflater.inflate( R.menu.menu_search, menu);
        System.out.println( "inflating menu");

        final SearchView searchView = (SearchView) menu.findItem(R.id.menu_search).getActionView();
        final SearchView.OnQueryTextListener queryTextListener = new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextChange(String newText) {
                showFilteredItems( newText );
                return true;
            }

            @Override
            public boolean onQueryTextSubmit(String query) {
                return true;
            }
        };

        searchView.setOnQueryTextListener(queryTextListener);

        return;
    }//met

    private void showFilteredItems( String query ) {
        this.query = query;
        loader.onContentChanged();
    }

    private void createListData() {
        for( int i = 0; i < 100 ; i ++ ) {
          listData.add( "String "+ i ); 
        }
    }

    public List<String> getData() {
        List<String> listFilteredData = new ArrayList<String>();
        for( String string : listData ) {
            if( query == null || string.contains( query ) ) {
                listFilteredData.add( string );
            }
        }
        return listFilteredData;
    }//met

    private class LoaderCallBacks implements LoaderCallbacks< List<String>> {
        @Override
        public void onLoadFinished(Loader<List<String>> loader,
                List<String> listData) {
            adapter.setListData( listData );
        }// met

        @Override
        public void onLoaderReset(Loader<List<String>> listData) {
            adapter.setListData( new ArrayList<String>() );
        }// met

        @Override
        public Loader<List<String>> onCreateLoader(int arg0,
                Bundle arg1) {
            return loader;
        }// met
    }//class

    private class StringAdapter extends ArrayAdapter< String > {

        private List<String> listDataToDisplay = new ArrayList<String>();
        private LayoutInflater mInflater;

        public StringAdapter( List<String> listData ) {
            super( getActivity(), android.R.layout.simple_list_item_1, android.R.id.text1, listData );
            listDataToDisplay = listData;
            mInflater = (LayoutInflater)getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }//cons

        private void setListData( List<String> newListData ) {
            this.listDataToDisplay.clear();
            this.listDataToDisplay.addAll( newListData );
            notifyDataSetChanged();
        }//met

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

            if (convertView == null) {
                view = mInflater.inflate(android.R.layout.simple_list_item_1, parent, false);
            } else {
                view = convertView;
            }

            ((TextView)view.findViewById( android.R.id.text1)).setText( listDataToDisplay.get( position ) );

            return view;
        }
    }//inner class
}//class

class StringLoader extends AsyncTaskLoader<List<String>> {

    SearchFragment fragment = null;

    public StringLoader(Context context, SearchFragment fragment) {
        super(context);
        this.fragment = fragment;
    }// cons

    @Override
    public List<String> loadInBackground() {
        return fragment.getData();
    }// met
}// class

The xml file for the menu of the search fragments res/menu/menu_search.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:baselineAligned="false"
    android:orientation="horizontal" >
    <FrameLayout
        android:id="@+id/fragment"
        android:layout_width="0px"
        android:layout_height="match_parent"
        android:layout_weight="1" />
</LinearLayout>

And the xml layout file res/layout/search_in_fragments.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:baselineAligned="false"
    android:orientation="horizontal" >
    <FrameLayout
        android:id="@+id/fragment"
        android:layout_width="0px"
        android:layout_height="match_parent"
        android:layout_weight="1" />
</LinearLayout>

Use the ActionBar and SearchView. You will be able to handle searches without any connection to Activity. Just set an OnQueryTextListener to the SearchView.

MenuItem item = menu.add("Search");
SearchView sv = new SearchView(getActionBar().getThemedContext());
item.setActionView(sv);
item.setIcon(R.drawable.ic_search);
item.setShowAsAction(MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW
        | MenuItem.SHOW_AS_ACTION_IF_ROOM);
sv.setOnQueryTextListener(new OnQueryTextListener() {
    @Override
    public boolean onQueryTextSubmit(String query) {
        //...
        return false;
    }
    @Override
    public boolean onQueryTextChange(String newText) {
        //...
        return false;
    }
});

See this post for more details on custom search.