Calling Adapter From Fragments In ViewPager

I have Fragment which have a searchview and viewpager . My viewpager has 3 fragments and each fragment calling adapter . Now to implement searchview , i need to call adapter of vis

Solution 1:

With help of uploaded code I can tell that

make method in your fragments named search and call adapter filter method

public void search(String text)
{
adapter.filter(text)
}

you can check instance of fragment and call search method of fragment after this line

 Fragment fragment = adapter.getFragment(viewPager.getCurrentItem());

Solution 2:

I think the best design for this is to use the Activity as the central "hub" for events that need to go the fragments.

So this is how I would do this:

• First start with a listener interface. This can be declared as an inner interface of the Activity:

  static interface QueryListener {
  
      void onQueryChange(String query);
  }
  

• Activity gets properties for holding listeners and methods for adding and removing listeners (declared synchronized to prevent those pesky ConcurrentModificationExceptions:

  private List<QueryListener> mQueryListeners = new ArrayList<>();
  
  public synchronized void addQueryListener(@NonNull QueryListener listener) {
  
     // check if the listener was already added
     // you could also use a Set instead of a List for this
     if (mQueryListeners.contains(listener)) return;   
  
     mQueryListeners.add(listener);
  }
  
  public synchronized void removeQueryListener(@NonNull QueryListener listener) {
      mQueryListeners.remove(listener);
  }
  

• Activity also gets a method that can be called by the fragment with the SearchView:

  public synchronized void changeQuery(String query) {
  
          for (QueryListener listener : mQueryListeners) {
              listener.onQueryChange(query);
          }
  }
  

• Now your fragments with the adapters need to implement QueryListener and register/unregister themselves:

  Add this line somewhere in onCreate():

          ((YourActivity) getActivity()).addQueryListener(this);
  

  Unregister in onDestroy():

      @Override
      public void onDestroy() {
          ((YourActivity) getActivity()).removeQueryListener(this);
          super.onDestroy();
      }
  

  add the QueryListener method implementation:

  @Override
  public void onQueryChange(String query) {
  
      // if (isVisible()) {      if desired
      mAdapter.filter(query);
  }
  

  Note: You don't have to have the fragment implement QueryListener; you can use an anonymous class. But you'll have to hold the reference to it so you can call removeQueryListener() with it later.

• Now just hook up the SearchView:

  @Override
  public boolean onQueryTextChange(String query) {
  
      ((YourActivity) getActivity()).changeQuery(query);
  }
  

Another pattern I've used is to create a dedicated class for registering/notifying listeners. I create a single instance of this class and have a method on the Activity to access it:

        QueryHandler handler = ((YourActivity) getActivity()).getQueryHandler();
        // QueryHandler has all the listener properties and methods shown for the Activity

        ...

        handler.changeQuery(query);

Alternatively, you can also use one of the many open-source event bus packages like Otto to pass events amongst your fragments.