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Android

Posted by Kevin Haube
Kevin Haube
12,265 Points

RecyclerView Navigation Drawer -- swap Fragments?

I'm new to RecyclerViews (as most devs are) and my understanding is that to handle onClick events for a case such as a nav drawer, you need to handle it in the Adapter class, as well as the Activity your're swapping fragments in. So here's my code:

DrawerAdapter

public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        int holderId;

        TextView rowText;
        ImageView rowIcon;
        ImageView profileImage;
        TextView nameLabel;
        TextView emailLabel;
        private int mClickedItem;
        private Fragment mFragment;
        private static Fragment fragment;

        public ViewHolder(View itemView, int viewType) {
            super(itemView);

            if(viewType == TYPE_ITEM) {
                rowText = (TextView) itemView.findViewById(R.id.rowText);
                rowIcon = (ImageView) itemView.findViewById(R.id.rowIcon);
                holderId = 1;
            } else if (viewType == TYPE_HEADER) {
                nameLabel = (TextView) itemView.findViewById(R.id.name);
                emailLabel = (TextView) itemView.findViewById(R.id.email);
                profileImage = (ImageView) itemView.findViewById(R.id.circleView);
                holderId = 0;
            }
        }

        @Override
        public void onClick(View v) {
            int position = getAdapterPosition();
            Fragment fragment = new CrumbsFragment();
            switch (position) {
                case 0:
                    fragment = new CrumbsFragment();
                    Log.d("KMH", "Working case 0");
                    break;
                case 1:
                    fragment = new CrumbsFragment();
                    Log.d("KMH", "Working case 1");
                    break;
                case 2:
                    fragment = new CrumbsFragment();
                    Log.d("KMH", "Working case 2");
                    break;
            }

            setFragment(fragment);
        }

        public void setFragment(Fragment fragment) {
            mFragment = fragment;
        }

        public static Fragment getFragment() {
            return fragment;
        }
    }

So, in this calss, I'm handling the event by getting the position, applying it to the switch to get the correct fragment, and then setting the fragment member variable for public access with the getters and setters.

MainActivity

mDrawerRecyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
            @Override
            public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
                View child = rv.findChildViewUnder(e.getX(),e.getY());

                if(child!=null && mGestureDetector.onTouchEvent(e)){

                    Fragment fragment = DrawerAdapter.ViewHolder.getFragment();

                        // Insert the fragment by replacing any existing fragment
                        FragmentManager fragmentManager = getFragmentManager();
                        fragmentManager.beginTransaction()
                                .replace(R.id.container, fragment)
                                .commit();

                        // Highlight the selected item, update the title, and close the drawer
                        // setTitle(TITLES[position]);

                    mDrawerLayout.closeDrawers();
                    return true;
                }
                return false;
            }

            @Override
            public void onTouchEvent(RecyclerView rv, MotionEvent e) {

            }
        });

This is how I'm handling the MainActivity portion. I use the getter method to get the fragment and then attempt to set it using the usual process.

Here's where the error lies: I'm getting null when I use the getter in MainActivity to get the Fragment. Now, when analyzed, I assume it's because onClick (from DrawerAdapter.ViewHolder) is not called first, or at all.

Let's troubleshoot!

1 Answer

Kevin Haube
Kevin Haube
12,265 Points

Solution:

mDrawerRecyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
            @Override
            public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
                View child = rv.findChildViewUnder(e.getX(),e.getY());

                if(child!=null && mGestureDetector.onTouchEvent(e)){

                    int position = mDrawerRecyclerView.getChildAdapterPosition(child);
                    Fragment fragment = null;

                    switch (position) {
                        case 0:
                            fragment = new CrumbsFragment();
                            Log.d("KMH", "Working case 0");
                            break;
                        case 1:
                            fragment = new CrumbsFragment();
                            Log.d("KMH", "Working case 1");
                            break;
                        case 2:
                            fragment = new CrumbsFragment();
                            Log.d("KMH", "Working case 2");
                            break;
                        default:
                            fragment = new CrumbsFragment();
                            Log.d("KMH", "Working default case");
                            break;
                    }

                        // Insert the fragment by replacing any existing fragment
                        FragmentManager fragmentManager = getFragmentManager();
                        fragmentManager.beginTransaction()
                                .replace(R.id.container, fragment)
                                .commit();

                        // Highlight the selected item, update the title, and close the drawer
                        setTitle(TITLES[position]);

                    mDrawerLayout.closeDrawers();
                    return true;
                }
                return false;
            }

            @Override
            public void onTouchEvent(RecyclerView rv, MotionEvent e) {

            }
        });

The solution is to get the child view of the RecyclerView, then use it as a param and call .getChildAdapterPosition(child); on your RecyclerView. :)