ItemListFragment.java

package com.yokmama.learn10.chapter04.lesson18;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

import com.yokmama.learn10.chapter04.lesson18.demo.DemoContent;

/**
 * A list fragment representing a list of Items. 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 com.yokmama.learn10.chapter04.lesson18.demo.DemoCreator}.
 * <p/>
 * Activities containing this fragment MUST implement the {@link com.yokmama.learn10.chapter04.lesson18.ItemListFragment.Callbacks}
 * interface.
 */
public class ItemListFragment extends ListFragment {

    /**
     * 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 = sDemoCallbacks;

    /**
     * The current activated item position. Only used on tablets.
     */
    private int mActivatedPosition = ListView.INVALID_POSITION;

    /**
     * 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(DemoContent.DemoItem demoItem);
    }

    /**
     * A Demo implementation of the {@link com.yokmama.learn10.chapter04.lesson18.ItemListFragment.Callbacks} interface that does
     * nothing. Used only when this fragment is not attached to an activity.
     */
    private static Callbacks sDemoCallbacks = new Callbacks() {
        @Override
        public void onItemSelected(DemoContent.DemoItem demoItem) {
        }
    };

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

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

        // TODO: replace with a real list adapter.
        setListAdapter(new MyArrayAdapter(getActivity()));
    }

    @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 demo implementation.
        mCallbacks = sDemoCallbacks;
    }

    @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.
        mCallbacks.onItemSelected(DemoContent.ITEMS.get(position));
    }

    @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;
    }

    private class MyArrayAdapter extends ArrayAdapter<DemoContent.DemoItem>{
        LayoutInflater mLayoutInflater;

        public MyArrayAdapter(Context context) {
            super(context, R.layout.menu_list_item,
                    R.id.text1,
                    DemoContent.ITEMS);
            mLayoutInflater = LayoutInflater.from(context);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if(convertView == null){
                convertView = mLayoutInflater.inflate(R.layout.menu_list_item, parent, false);
            }
            TextView text1 = (TextView)convertView.findViewById(R.id.text1);
            TextView text2 = (TextView)convertView.findViewById(R.id.text2);
            DemoContent.DemoItem item = getItem(position);
            text1.setText(item.getContent());
            text2.setText(item.getDescription());

            return convertView;
        }
    }
}