Android-TabLayout和ViewPager>片段> OnListFragmentInteractionListener

Question

I'm new to Android and I started building a "Navigation Drawer Activity" project. I added a TabLayout and ViewPager to my activity_main.xml and now I can swipe between different lists. When I click an item in a list, it calls onListFragmentInteraction in my MainActivity.java. I tried the code below to dynamically add a Detail fragment when a user clicks an item in the list, but I get this error. My MainActivity class does "implement CustomerFragment.OnListFragmentInteractionListener"

First , is my attempt at showing a detail fragment inside a ViewPager correct? Would the code I am attempting below add a fragment in the current tab?

Secondly , does anyone know why I am getting this error?

Thanks so much!

Error:

java.lang.RuntimeException: com.myproject.android.MainActivity@186e12d must implement OnFragmentInteractionListener

MainActivity:

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener, TabLayout.OnTabSelectedListener, CustomerFragment.OnListFragmentInteractionListener, GoogleApiClient.OnConnectionFailedListener {

    private GoogleApiClient mGoogleApiClient;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    private Pager adapter;

    public void onListFragmentInteraction(Customer customer){

            FragmentManager fm = getSupportFragmentManager();
            CustomerDetailFragment fragment = CustomerDetailFragment.newInstance(customer);
            fm.beginTransaction().add(R.id.pager, fragment).commit();
    }

    @Override
    public void onTabSelected(TabLayout.Tab tab) {
        viewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(TabLayout.Tab tab) { }

    @Override
    public void onTabReselected(TabLayout.Tab tab) { }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        tabLayout = (TabLayout) findViewById(R.id.tabLayout);
        tabLayout.addTab(tabLayout.newTab().setText("Home"));
        tabLayout.addTab(tabLayout.newTab().setText("Customers"));
        tabLayout.addTab(tabLayout.newTab().setText("Jobs"));
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        viewPager = (ViewPager) findViewById(R.id.pager);
        adapter = new Pager(getSupportFragmentManager(), tabLayout.getTabCount());
        viewPager.setAdapter(adapter);
        tabLayout.addOnTabSelectedListener(this);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        FirebaseMessaging.getInstance().subscribeToTopic("global");
        String token = FirebaseInstanceId.getInstance().getToken();

        // Check Google Play Services
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .enableAutoManage(this, this)
                .addApi(Drive.API)
                .addScope(Drive.SCOPE_FILE)
                .build();

        // test
        Date d = new Date();
        DbHandler dbHandler = new DbHandler(this, null, null, 1);
        Customer customer = new Customer(1, 1, 1, 1, "Test", "Test", "Test", false, d, 1, d, 1);
        dbHandler.addCustomer(customer);
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_camera) {
            startActivity(new Intent(this, LoginActivity.class));
        } else if (id == R.id.nav_gallery) {
            startActivity(new Intent(this, SyncActivity.class));
        } else if (id == R.id.nav_slideshow) {

        } else if (id == R.id.nav_manage) {

        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_send) {

        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {

    }
}

Customer List Fragment:

public class CustomerFragment extends Fragment {

    private OnListFragmentInteractionListener mListener;

    public CustomerFragment() {
    }

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

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_customer_list, container, false);

        SearchView sv = (SearchView) view.findViewById(R.id.searchview);
        RecyclerView rv = (RecyclerView) view.findViewById(R.id.recyclerview);

        // Adapter
        rv.setLayoutManager(new LinearLayoutManager(view.getContext()));
        final CustomerAdapter adapter = new CustomerAdapter(getCustomers(), mListener);
        rv.setAdapter(adapter);

        // Search
        sv.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }
            @Override
            public boolean onQueryTextChange(String query) {
                //adapter.getFilter().filter(query);
                return false;
            }
        });

        return view;
    }

    private ArrayList<Customer> getCustomers() {
        DbHandler dbHandler = new DbHandler(this.getActivity(), null, null, 1);
        ArrayList<Customer> customers = dbHandler.getCustomers();
        return customers;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnListFragmentInteractionListener) {
            mListener = (OnListFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString() + " must implement OnListFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnListFragmentInteractionListener {
        void onListFragmentInteraction(Customer customer);
    }
}

Customer Adapter:

public class CustomerAdapter extends RecyclerView.Adapter<CustomerAdapter.ViewHolder> {

    private final List<Customer> mValues;
    private final OnListFragmentInteractionListener mListener;

    public CustomerAdapter(List<Customer> items, OnListFragmentInteractionListener listener) {
        mValues = items;
        mListener = listener;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.fragment_customer, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, int position) {
        Customer customer = mValues.get(position);
        holder.mItem = customer;
        holder.mIdView.setText(String.valueOf(customer.getId()));
        holder.mContentView.setText(customer.getCompanyName());
        holder.mView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            if (null != mListener) {
                mListener.onListFragmentInteraction(holder.mItem);
            }
            }
        });
    }

    @Override
    public int getItemCount() {
        return mValues.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public final View mView;
        public final TextView mIdView;
        public final TextView mContentView;
        public Customer mItem;

        public ViewHolder(View view) {
            super(view);
            mView = view;
            mIdView = (TextView) view.findViewById(R.id.id);
            mContentView = (TextView) view.findViewById(R.id.content);
        }

        @Override
        public String toString() {
            return super.toString() + " '" + mContentView.getText() + "'";
        }
    }
}

UPDATE: It looks like I needed to add both onListFragmentInteraction AND onFragmentInteraction. The first is for the CustomerListFragment and the 2nd is for the CustomerDetailFragment.

And to get the CustomerDetailFragment working with the tabs, I followed this and got it working: https://medium.com/@nilan/separate-back-navigation-for-a-tabbed-view-pager-in-android-459859f607e4#.lrjeexdcp

@Override
public void onListFragmentInteraction(Customer customer){
        FragmentManager fm = getSupportFragmentManager();
        CustomerDetailFragment fragment = CustomerDetailFragment.newInstance(customer);
        fm.beginTransaction().add(R.id.pager, fragment).commit();
}

@Override
public void onFragmentInteraction(Uri uri) {

}

Answer 1

You need to put

public void onListFragmentInteraction(Customer customer){
    FragmentManager fm = getSupportFragmentManager();
    CustomerDetailFragment fragment = CustomerDetailFragment.newInstance(customer);
    fm.beginTransaction().add(R.id.pager, fragment).commit();
}

Inside your MainActivity class instead of outside of it.

If that's not actually how your code is, edit your answer to break up the blocks to accurately represent how your code is built and include your interfance inside the fragment for the listener. You also may need the @Override tag above the onListFragmentInteraction implementation

Edit

As I mentioned above you need to put the @Override tag above the onListFragmentInteraction implementation, look at every other listener implementation you already have.