title: How to update ListView after onResume from other activity?
body: <p>Im trying to create an application that enable user to create event, then invite participant. So when user go to "add participant" page, after entering all information, im trying to direct back to the "participant list" page by using onResume(), but how to update the listview? i tried to use notifyDataSetChanged() but not working. </p>
  
  <p>Here is the code for participant list:</p>
  
  <pre><code>public class EventPage extends ListActivity implements OnClickListener {
  Intent intent;
  TextView friendId;
  EventController controller = new EventController(this);
  TabHost th;
  Button addparticipant;
  String eventId;
  ListView lv;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      // TODO Auto-generated method stub
      super.onCreate(savedInstanceState);
      setContentView(R.layout.eventpage);
      addparticipant = (Button) findViewById(R.id.addpart);
      addparticipant.setOnClickListener(this);
      // create tabs
      th = (TabHost) findViewById(R.id.tabhost);
  
      th.setup();
      TabSpec specs = th.newTabSpec("tag1"); // setting up a tabspec in
                                              // tabhost(th) call it tag1
      specs.setContent(R.id.tab1);// set content of "tab1" xml
      specs.setIndicator("Participants");
      th.addTab(specs);
      specs = th.newTabSpec("tag2"); // setting up a tabspec in tabhost(th)
                                      // call it tag1
      specs.setContent(R.id.tab2);// set content of "tab1" xml
      specs.setIndicator("Total Expenses");
      th.addTab(specs);
      specs = th.newTabSpec("tag3"); // setting up a tabspec in tabhost(th)
      HashMap&lt;String, String&gt; queryValues = new HashMap&lt;String, String&gt;();
      Intent objIntent = getIntent();
      eventId = objIntent.getStringExtra("eventId");
      queryValues.put("eventId", eventId);
      ArrayList&lt;HashMap&lt;String, String&gt;&gt; friendList = controller
              .getAllFriends(queryValues);
      if (friendList.size() != 0) {
          lv = getListView();
          lv.setOnItemClickListener(new OnItemClickListener() {
              @Override
              public void onItemClick(AdapterView&lt;?&gt; parent, View view,
                      int position, long id) {
                  friendId = (TextView) view.findViewById(R.id.friendId);
                  String valFriendId = friendId.getText().toString();
                  Intent objIndent = new Intent(getApplicationContext(),
                          EventPage.class);
                  objIndent.putExtra("friendId", valFriendId);
                  startActivity(objIndent);
              }
          });
          SimpleAdapter adapter = new SimpleAdapter(EventPage.this,
                  friendList, R.layout.view_friend_entry, new String[] {
                          "friendId", "friendName" }, new int[] {
                          R.id.friendId, R.id.friendName });
          adapter.notifyDataSetChanged();
          setListAdapter(adapter);
          registerForContextMenu(lv);
      }
  }
  
  @Override
  public void onClick(View v) {
      // TODO Auto-generated method stub
      Intent objIntent = new Intent(getApplicationContext(),
              AddParticipant.class);
      objIntent.putExtra("eventId", eventId);
      startActivity(objIntent);
  }
  
  @Override
  public void onCreateContextMenu(ContextMenu menu, View v,
          ContextMenuInfo menuInfo) {
      String[] menuItems = getResources().getStringArray(R.array.menu);
      for (int i = 0; i &lt; menuItems.length; i++) {
          menu.add(Menu.NONE, i, i, menuItems[i]);
      }
  }
  
  @Override
  public boolean onContextItemSelected(MenuItem item) {
      int menuItemIndex = item.getItemId();
      switch (menuItemIndex) {
      case 0:
          friendId = (TextView) findViewById(R.id.friendId);
          String valFriendId = friendId.getText().toString();
          Intent objIndent = new Intent(getApplicationContext(),
                  EditParticipant.class);
          objIndent.putExtra("friendId", valFriendId);
          startActivity(objIndent);
          break;
      case 1:
          friendId = (TextView) findViewById(R.id.friendId);
          String valFriendId2 = friendId.getText().toString();
          controller.deleteFriend(valFriendId2);
          onResume();
      }
  
      return true;
  }
  </code></pre>
  
  <p>This is the code for add participant which involved onResume() :</p>
  
  <pre><code>public class AddParticipant extends Activity implements OnClickListener{
  
  EditText friendName;
  EditText friendNumber;
  EditText friendEmail;
  EventController controller = new EventController(this);
  Button btnadd;
  
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.addparticipant);
      friendName = (EditText) findViewById(R.id.friendName);
      friendNumber = (EditText) findViewById(R.id.friendNumber);
      friendEmail = (EditText) findViewById(R.id.friendEmail);
      btnadd = (Button)findViewById(R.id.saveButton);
      btnadd.setOnClickListener(this);
  }
  
  @Override
  public void onClick(View v) {
      // TODO Auto-generated method stub
      HashMap&lt;String, String&gt; queryValues = new HashMap&lt;String, String&gt;();
      Intent objIntent = getIntent();
      String eventId = objIntent.getStringExtra("eventId");
      queryValues.put("eventId", eventId);
      queryValues.put("friendName", friendName.getText().toString());
      queryValues.put("friendNumber", friendNumber.getText().toString());
      queryValues.put("friendEmail", friendEmail.getText().toString());
      controller.insertFriend(queryValues);
      this.callHomeActivity(v);
      finish();
  }
  
  public void callHomeActivity(View view) {
      super.onResume();
  }
  </code></pre>