Android Open Source - EasyVote Question List Fragment

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License

The source code is released under:

Apache License

Java Source Code

package com.llanox.mobile.easyvote;
//  w  w w  .  j  av a2  s  .  c  om
import java.util.List;

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

import com.backendless.Backendless;
import com.backendless.BackendlessCollection;
import com.backendless.async.callback.AsyncCallback;
import com.backendless.exceptions.BackendlessFault;
import com.llanox.mobile.easyvote.model.Question;

/**
 * A list fragment representing a list of Questions. 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 QuestionDetailFragment}.
 * <p>
 * Activities containing this fragment MUST implement the {@link Callbacks}
 * interface.
 */
public class QuestionListFragment 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 = mCallBack;

  /**
   * The current activated item position. Only used on tablets.
   */
  private int mActivatedPosition = ListView.INVALID_POSITION;
  
  
  private List<Question> questions;

  /**
   * 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 mCallBack = 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 QuestionListFragment() {
  }

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
//    QuestionData data = (QuestionData) DataLayerManager.getInstance(getActivity()).getDataSession(QuestionData.class);
//      questions = data.findAll();
//      
//    setListAdapter(new ArrayAdapter<Question>(getActivity(),android.R.layout.simple_list_item_activated_1,android.R.id.text1, questions));
//    
    updateAsync();
  }
  
  
  
  private void updateAsync() {
    
    Backendless.Persistence.of( Question.class).find( new AsyncCallback<BackendlessCollection<Question>>(){
       @Override
       public void handleResponse( BackendlessCollection<Question> data )
       {
            questions = data.getData();      
          setListAdapter(new ArrayAdapter<Question>(getActivity(),android.R.layout.simple_list_item_activated_1,android.R.id.text1, questions));
       }
       @Override
       public void handleFault( BackendlessFault fault )
       {
         Toast.makeText(getActivity(),R.string.toast_err_retrieving_data, Toast.LENGTH_LONG).show();
       }
    });
    
  }
  

  @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 = mCallBack;
  }

  @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(questions.get(position).getObjectId()+"");
  }

  @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;
  }
}

Java Source Code List

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