Android Open Source - Android-HCI Item List Fragment

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License

The source code is released under:

MIT License

Java Source Code

package ar.edu.itba;
/*w w  w  . j ava  2  s.c  o m*/
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 ar.edu.itba.dummy.DummyContent;

/**
 * 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 ItemDetailFragment}.
 * <p>
 * Activities containing this fragment MUST implement the {@link 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 = 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 ItemListFragment() {
  }

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

    // TODO: replace with a real list adapter.
    setListAdapter(new ArrayAdapter<DummyContent.DummyItem>(getActivity(),
        android.R.layout.simple_list_item_activated_1,
        android.R.id.text1, DummyContent.ITEMS));
  }

  @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(DummyContent.ITEMS.get(position).id);
  }

  @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;
  }
}

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