BierListFragment.java

package be.swimberghe.niels.bieren;

import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.ListFragment;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.View;
import android.widget.ListView;

import java.util.ArrayList;

import be.swimberghe.niels.bieren.data.BeerContract;
import be.swimberghe.niels.bieren.data.BeerDbHelper;
import be.swimberghe.niels.bieren.model.Beer;

/**
 * A list fragment representing a list of Bieren. This fragment
 * also supports tablet devices by allowing list items to be given an
 * 'activated' state upon selection. This helps indicate which item is
 * currently being viewed in a {@link BierDetailFragment}.
 * <p>
 * Activities containing this fragment MUST implement the {@link Callbacks}
 * interface.
 */
public class BierListFragment extends ListFragment implements LoaderManager.LoaderCallbacks<Cursor> {

    /**
     * The serialization (saved instance state) Bundle key representing the
     * activated item position. Only used on tablets.
     */
    private static final String STATE_ACTIVATED_POSITION = "activated_position";

    /**
     * The fragment's current callback object, which is notified of list item
     * clicks.
     */
    private Callbacks mCallbacks = sDummyCallbacks;

    /**
     * The current activated item position. Only used on tablets.
     */
    private int mActivatedPosition = ListView.INVALID_POSITION;
    private SimpleCursorAdapter mAdapter;
    private ArrayList<Beer> mBeers;
    private ArrayList<String> mBrewers;

    @Override
    public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
        return new CursorLoader( getActivity(),null, new String[]{BeerContract.BrewerEntry._ID,BeerContract.BrewerEntry.COLUMN_NAME}, null, null, null )
        {
            @Override
            public Cursor loadInBackground()
            {
                // You better know how to get your database.
                SQLiteDatabase DB = new BeerDbHelper(getActivity()).getReadableDatabase();
                // You can use any query that returns a cursor.
                return DB.query(BeerContract.BrewerEntry.TABLE_NAME, getProjection(), getSelection(), getSelectionArgs(), null, null, getSortOrder(), null );
            }
        };
    }

    @Override
    public void onLoadFinished(Loader<Cursor> arrayListLoader, Cursor cursor) {
        mAdapter.swapCursor(cursor);
        mAdapter.notifyDataSetChanged();
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        mAdapter.swapCursor(null);
        mAdapter.notifyDataSetChanged();
    }


    /**
     * A callback interface that all activities containing this fragment must
     * implement. This mechanism allows activities to be notified of item
     * selections.
     */
    public interface Callbacks {
        /**
         * Callback for when an item has been selected.
         */
        public void onItemSelected(String id);
    }

    /**
     * A dummy implementation of the {@link Callbacks} interface that does
     * nothing. Used only when this fragment is not attached to an activity.
     */
    private static Callbacks sDummyCallbacks = new Callbacks() {
        @Override
        public void onItemSelected(String id) {
        }
    };

    /**
     * Mandatory empty constructor for the fragment manager to instantiate the
     * fragment (e.g. upon screen orientation changes).
     */
    public BierListFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        String[] colums = {BeerContract.BrewerEntry.COLUMN_NAME};
        int[] ids = {android.R.id.text1};
        // TODO: replace with a real list adapter.
        mBeers= new ArrayList<Beer>();
        mBrewers = new ArrayList<String>();
        mAdapter = new SimpleCursorAdapter(getActivity(),android.R.layout.simple_list_item_1,null,
                colums,
                ids,0);
        setListAdapter(mAdapter);
        getLoaderManager().initLoader(0,null,this);
    }

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

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        // Restore the previously serialized activated item position.
        if (savedInstanceState != null
                && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
            setActivatedPosition(savedInstanceState.getInt(STATE_ACTIVATED_POSITION));
        }
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        // Activities containing this fragment must implement its callbacks.
        if (!(activity instanceof Callbacks)) {
            throw new IllegalStateException("Activity must implement fragment's callbacks.");
        }

        mCallbacks = (Callbacks) activity;
    }

    @Override
    public void onDetach() {
        super.onDetach();

        // Reset the active callbacks interface to the dummy implementation.
        mCallbacks = sDummyCallbacks;
    }

    @Override
    public void onListItemClick(ListView listView, View view, int position, long id) {
        super.onListItemClick(listView, view, position, id);

        // Notify the active callbacks interface (the activity, if the
        // fragment is attached to one) that an item has been selected.
        Cursor cursor =(Cursor) mAdapter.getItem(position);
        String brewerName = cursor.getString(cursor.getColumnIndex(BeerContract.BrewerEntry.COLUMN_NAME));
        mCallbacks.onItemSelected(brewerName);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (mActivatedPosition != ListView.INVALID_POSITION) {
            // Serialize and persist the activated item position.
            outState.putInt(STATE_ACTIVATED_POSITION, mActivatedPosition);
        }
    }

    /**
     * Turns on activate-on-click mode. When this mode is on, list items will be
     * given the 'activated' state when touched.
     */
    public void setActivateOnItemClick(boolean activateOnItemClick) {
        // When setting CHOICE_MODE_SINGLE, ListView will automatically
        // give items the 'activated' state when touched.
        getListView().setChoiceMode(activateOnItemClick
                ? ListView.CHOICE_MODE_SINGLE
                : ListView.CHOICE_MODE_NONE);
    }

    private void setActivatedPosition(int position) {
        if (position == ListView.INVALID_POSITION) {
            getListView().setItemChecked(mActivatedPosition, false);
        } else {
            getListView().setItemChecked(position, true);
        }

        mActivatedPosition = position;
    }
}