Android

Question

我正在动态添加城市名称作为菜单项，所有这些都指向 Home Fragment。但是，当我 select 一个城市名称，然后是任何其他菜单选项时，两个片段重叠，如下图所示。

Fragments overlapping

Navigation Drawer

主要活动

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    drawer = findViewById(R.id.drawer_layout);
    navigationView = findViewById(R.id.nav_view);
    menuItem = navigationView.getMenu().findItem(R.id.locations);
    addCityToMenu("London");
    addCityToMenu("New York");
    addCityToMenu("Milan");
    addCityToMenu("Paris");
    addCityToMenu("Monaco");


    // Passing each menu ID as a set of Ids because each
    // menu should be considered as top level destinations.
    mAppBarConfiguration = new AppBarConfiguration.Builder(
            R.id.nav_home, R.id.nav_locations, R.id.nav_settings)
            .setOpenableLayout(drawer)
            .build();
    NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
    NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
    NavigationUI.setupWithNavController(navigationView, navController);
}
private void addCityToMenu(String city) {
    menuItem.getSubMenu().add(Menu.NONE, R.id.nav_home, 1, city)
            .setOnMenuItemClickListener(item -> loadCity(city));
}

public boolean loadCity(String city) {
    Toast.makeText(getApplicationContext(), city, Toast.LENGTH_SHORT).show();
    Bundle bundle = new Bundle();
    bundle.putString("cityName", city);
    HomeFragment fragment = new HomeFragment();
    fragment.setArguments(bundle);
    getSupportFragmentManager().beginTransaction()
            .replace(R.id.nav_host_fragment, fragment)
            .commit();
    drawer.closeDrawers();
    return true;
}

fragment_home

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#121010"
    tools:context=".ui.home.HomeFragment">

    <TextView
        android:id="@+id/text_home"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:textAlignment="center"
        android:textColor="#FFFFFF"
        android:textSize="20sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

HomeFragment.java

public class HomeFragment extends Fragment {

    private HomeViewModel homeViewModel;

    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {
        homeViewModel =
                new ViewModelProvider(this).get(HomeViewModel.class);
        View root = inflater.inflate(R.layout.fragment_home, container, false);
        if(getArguments()!=null) {
            homeViewModel.setText(getArguments().getString("cityName"));
        }
        final TextView textView = root.findViewById(R.id.text_home);
        homeViewModel.getText().observe(getViewLifecycleOwner(), new Observer<String>() {
            @Override
            public void onChanged(@Nullable String s) {
                textView.setText(s);
            }
        });
        return root;
    }
}

所有代码都可以在 https://github.com/vishnu-android/DynamicNavigationDrawer

Answer 1

正如您提到的，您遇到了片段重叠问题。我有一个解决方案。

XML部分

1)删除mobile_navigation.xml

2) 您需要将 app:navGraph="@navigation/mobile_navigation" 替换为您的默认片段名称 tools:layout="@layout/fragment_home" 位于 content_main.xml 文件中。

之前:

<fragment
    android:id="@+id/nav_host_fragment"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:defaultNavHost="true"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:navGraph="@navigation/mobile_navigation" />

之后：

<fragment
    android:id="@+id/nav_host_fragment"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:defaultNavHost="true"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    tools:layout="@layout/fragment_home" />

MainActivity.java

1) 删除默认导航代码

  mAppBarConfiguration = new AppBarConfiguration.Builder(
            R.id.nav_home, R.id.nav_locations, R.id.nav_settings)
            .setOpenableLayout(drawer)
            .build();
    NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
    NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
    NavigationUI.setupWithNavController(navigationView, navController);

2) 添加自定义抽屉菜单

// set custom toggle menu to open and close drawer
    ActionBarDrawerToggle drawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar,
            R.string.navigation_drawer_open,
            R.string.navigation_drawer_close);
    //set menu icon
    drawerToggle.setHomeAsUpIndicator(R.drawable.ic_baseline_menu_24);
    drawerToggle.setDrawerIndicatorEnabled(false);
    drawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            drawer.openDrawer(GravityCompat.START);
        }
    });

3) 将默认片段设置为主页片段

//set default fragment which will open first
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,
                new HomeFragment()).commit();
    }

4) 设置 NavigationItemSelectedListener

 //set navigation menu item click event
    navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()) {
                case R.id.nav_home:
                    getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,
                            new HomeFragment()).commit();
                    drawer.closeDrawers();
                    break;
                case R.id.nav_gallery:
                    getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,
                            new GalleryFragment()).commit();
                    drawer.closeDrawers();
                    break;
                case R.id.nav_slideshow:
                    getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,
                            new SlideshowFragment()).commit();
                    drawer.closeDrawers();
                    break;
                default:
                    break;
            }
            return true;
        }
    });

样本： https://github.com/Vatsal-Dholakiya/navigation_drawer

Android - 导航抽屉 - 与动态菜单项重叠的片段

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android-fragments

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