Question

我正在使用带有（碎片）的androidx导航抽屉，HomeFragment由RecyclerView组成以显示图像。我正在尝试调用getMenu()方法，该方法会更新MainActivity中的图像，但不起作用

我尝试使用此MainActivity，但不起作用

HomeFragment fragment=new HomeFragment();
fragment.getMenu();

=========================== HomeFragment ================== =============

  public class HomeFragment extends Fragment {
     public View onCreateView(@NonNull LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_home, container, false);

    recycler_menu = (RecyclerView)view.findViewById(R.id.recycler_menu);
    recycler_menu.setLayoutManager(new GridLayoutManager(context,2));
    recycler_menu.setHasFixedSize(true);
    mService = Common.getAPI();

    getMenu();
    return view;

}

public void getMenu() {
    compositeDisposable.add(mService.getMenu()
    .observeOn(AndroidSchedulers.mainThread())
    .subscribeOn(Schedulers.io())
    .subscribe(new Consumer<List<Category>>() {
        @Override
        public void accept(List<Category> categories) throws Exception {
            displayMenuList(categories);
        }
    }));
}

private void displayMenuList(List<Category> categories) {
    MenuAdapter adapter = new MenuAdapter(context,categories);
    recycler_menu.setAdapter(adapter);
    }


}

============================ MainActivity =================== =============

    public class MainActivity extends AppCompatActivity {

    private AppBarConfiguration mAppBarConfiguration;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    DrawerLayout drawer = findViewById(R.id.drawer_layout);
    NavigationView navigationView = findViewById(R.id.nav_view);
    // Passing each menu_action_bar ID as a set of Ids because each
    // menu_action_bar should be considered as top level destinations.
    mAppBarConfiguration = new AppBarConfiguration.Builder(
            R.id.nav_home, R.id.nav_send)
            .setDrawerLayout(drawer)
            .build();
    NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
    NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
    NavigationUI.setupWithNavController(navigationView, navController);

   }


  @Override
public void onResume() {
    super.onResume();

    HomeFragment fragment=new HomeFragment();
     fragment.getMenu();
    }
 }

Answer 1

不能，因为该方法无效，并且结果通过另一种方法返回，并且位于您的片段中。

您应该创建一个接口以将数据从片段传递到活动。

HomeFragment：

public class HomeFragment extends Fragment {
    private OnAcceptListener listener;

    //...

    public void getMenu() {
        compositeDisposable.add(mService.getMenu()
                .observeOn(AndroidSchedulers.mainThread())
                .subscribeOn(Schedulers.io())
                .subscribe(new Consumer<List<Category>>() {
                    @Override
                    public void accept(List<Category> categories) throws Exception {
                        listener.onAccept(categories);
                    }
                }));
    }

    public void setOnAcceptListener(OnAcceptListener listener) {
        this.listener = listener;
    }

    public interface OnAcceptListener{
        void onAccept(List<Category> categories);
    }
}

活动：

public class MainActivity extends AppCompatActivity implements HomeFragment.OnAcceptListener {

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

        HomeFragment homeFragment = new HomeFragment();
        homeFragment.setOnAcceptListener(this);
    }

    @Override
    public void onAccept(List<Category> categories) {
        //update here
    }
}

从活动中访问片段方法中的方法

1 个答案: