com.shinobicontrols.messageme.ConversationListFragment.java Source code

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Here is the source code for com.shinobicontrols.messageme.ConversationListFragment.java

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/*
Copyright 2014 Scott Logic Ltd
    
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at
    
    http://www.apache.org/licenses/LICENSE-2.0
    
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

package com.shinobicontrols.messageme;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import com.shinobicontrols.messageme.models.Conversation;
import com.shinobicontrols.messageme.models.DataProvider;

import java.util.Observable;
import java.util.Observer;

/**
 * A list fragment representing a list of Conversations. 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 ConversationDetailFragment}.
 * <p>
 * Activities containing this fragment MUST implement the {@link Callbacks}
 * interface.
 */
public class ConversationListFragment extends ListFragment implements Observer {

    /**
     * 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;

    /**
     * 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 ConversationListFragment() {
    }

    private ArrayAdapter<Conversation> conversationArrayAdapter;

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

        conversationArrayAdapter = new ArrayAdapter<Conversation>(getActivity(),
                android.R.layout.simple_list_item_activated_1, android.R.id.text1,
                DataProvider.getInstance().getConversations());
        setListAdapter(conversationArrayAdapter);

        // Listen for changes in the data provider
        DataProvider.getInstance().addObserver(this);

    }

    @Override
    public void onDestroy() {
        // Remove ourself as an observer on the data provider
        DataProvider.getInstance().deleteObserver(this);

        super.onDestroy();
    }

    @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.
        mCallbacks.onItemSelected(DataProvider.getInstance().getConversations().get(position).getSender());
    }

    @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;
    }

    /**
     * Implement observer interface
     * @param observable
     * @param data
     */
    @Override
    public void update(Observable observable, Object data) {
        // If the data adapter has changed then we need to reload the list dataadapter
        conversationArrayAdapter.notifyDataSetChanged();
    }

}