如何从主Activity中刷新片段中的ListView？

Question

I have a MainActivity which contains a tab bar with two fragments: MainFragment and WishlistFragment . They both extend as ListFragment .

When someone touches a menu item from the Option menu, I want the ListView within the Fragment that is showing to refresh its list using its custom adapter called LazyAdapter adapter .

So in here is where I want the refresh to go in my MainActivity code:

public boolean onOptionsItemSelected(MenuItem item) {   
     switch (item.getItemId()) {
        case R.id.menu_edit:

               // find out which fragment is showing here
               // refresh the fragment's listview here
               // adapter.notifyDataSetChanged();

               return true;
        }
}

How can I do this? I am not sure how to call forward into the fragment and how to determine which fragment is showing.

Here is how I have my tabs set up in MainActivity :

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    actionBar.addTab(actionBar.newTab().setText("Main").setTabListener(this));
    actionBar.addTab(actionBar.newTab().setText("Wishlist").setTabListener(this));
}

public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    // When the given tab is selected, show the tab contents in the container
    ListFragment newfragment = null;

    switch (tab.getPosition() + 1)
    {
    case 1:
        newfragment = new MainFragment();
        break;

    case 2:
        newfragment = new WishlistFragment();           
        break;
    }

    getSupportFragmentManager().beginTransaction()
            .replace(R.id.container, newfragment)
            .commit();
}

Answer 1

How can I do this?

Step #1: Fix your implementation of onTabSelected() . You do not want to be creating a new fragment each time the user chooses a tab. Instead, you want to have two fragments, held onto by the activity in data members, and use those in the replace() transaction.

Step #2: When needed, call getSelectedNavigationIndex() on the ActionBar , use that to choose which of the two fragments you need (obtained from the data members mentioned in Step #1 above), and call some method on the fragment to do what you want.