我有 2 个活动，其中有一个单独的
NavHostFragmentContainerView最初，我计划使用应用程序的所有片段，但现在，我决定在第一个版本中仅使用一个片段，然后稍后再处理其他片段，因为它的任务是一次处理所有片段
所以我想安全地删除底部导航视图和其他两个片段（第二个和第三个片段）。
我最初已经尝试通过删除这些片段并删除与其相关的任何代码来自己完成此操作，但它出现了很多错误，所以我决定将其带到这里，看看是否有人可以提供最安全的帮助这样我就可以删除它们，以便我的第一个片段 可以继续运行，没有任何问题。
它是一个天气应用程序，因此我在第一个片段上收到当前城市的更新。我应该每小时和每天收到第二个和第三个片段的更新，但我已经停止了我的计划，现在，我只想使用第一个片段。
主要代码如下：
活动\主页活动：
public class HomeActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
private DrawerLayout drawer;
// Last update time, click sound, search button, search panel.
TextView timeField;
MediaPlayer player;
ImageView Search;
EditText textfield;
// For scheduling background image change(using constraint layout, start counting from dubai, down to statue of liberty.
ConstraintLayout constraintLayout;
public static int count = 0;
int[] drawable = new int[]{R.drawable.nyc, R.drawable.lofoten_islands, R.drawable.parque, R.drawable.moraine_lake, R.drawable.eiffel_tower,
R.drawable.whitehaven_beach, R.drawable.london, R.drawable.cape_town, R.drawable.burj_al_arab,R.drawable.atuh_beach};
Timer _t;
private WeatherDataViewModel viewModel;
private AppBarConfiguration appBarConfiguration;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
// use home activity layout.
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Allow activity to make use of the toolbar
drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
// Hiding default Drawer fragment that has the BottomNavView
navigationView.getMenu().findItem(R.id.main_id).setVisible(false);
viewModel = new ViewModelProvider(this).get(WeatherDataViewModel.class);
// Trigger action to open & close navigation drawer
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar
, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
timeField = findViewById(R.id.textView9);
Search = findViewById(R.id.imageView4);
textfield = findViewById(R.id.textfield);
// find the id's of specific variables.
BottomNavigationView bottomNavigationView = findViewById(R.id.bottomNavigationView);
// host 3 fragments along with bottom navigation.
final NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.fragment);
assert navHostFragment != null;
final NavController navController = navHostFragment.getNavController();
// Make hourly & daily tab unusable
bottomNavigationView.setOnNavigationItemSelectedListener(item -> {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
}
return false;
});
toggle.setToolbarNavigationClickListener(v -> {
// Enable the functionality of opening the side drawer, when the burger icon is clicked
toggle.setDrawerIndicatorEnabled(true);
navController.navigate(R.id.main_id);
});
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
// remove up button from all these fragments
appBarConfiguration = new AppBarConfiguration.Builder(
R.id.main_id) // remove up button from all these fragments >> Keep up button in R.id.nav_setting, R.id.nav_slideshow
.setOpenableLayout(drawer)
.build();
NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
// navController.addOnDestinationChangedListener((controller, destination, arguments) -> navController.popBackStack(destination.getId(), false));
// navController.addOnDestinationChangedListener((controller, destination, arguments) -> {
// });
navController.addOnDestinationChangedListener((controller, destination, arguments) -> {
// Hide/show top search bar
if (destination.getId() == R.id.main_id) {
Search.setVisibility(View.VISIBLE);
textfield.setVisibility(View.VISIBLE);
} else {
Search.setVisibility(View.GONE);
textfield.setVisibility(View.GONE);
}
// Fragments that you want to show the back button
if (destination.getId() == R.id.about_id || destination.getId() == R.id.privacy_policy_id) {
// Disable the functionality of opening the side drawer, when the burger icon is clicked
toggle.setDrawerIndicatorEnabled(false);
}
});
// For scheduling background image change
constraintLayout = findViewById(R.id.layout);
constraintLayout.setBackgroundResource(R.drawable.nyc);
_t = new Timer();
_t.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
// run on ui thread
runOnUiThread(() -> {
if (count < drawable.length) {
constraintLayout.setBackgroundResource(drawable[count]);
count = (count + 1) % drawable.length;
}
});
}
}, 5000, 5000);
Search.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// make click sound when search button is clicked.
player = MediaPlayer.create(HomeActivity.this, R.raw.click);
player.start();
getWeatherData(textfield.getText().toString().trim());
// make use of some fragment's data
Fragment currentFragment = navHostFragment.getChildFragmentManager().getFragments().get(0);
if (currentFragment instanceof FirstFragment) {
FirstFragment firstFragment = (FirstFragment) currentFragment;
firstFragment.getWeatherData(textfield.getText().toString().trim());
} else if (currentFragment instanceof SecondFragment) {
SecondFragment secondFragment = (SecondFragment) currentFragment;
secondFragment.getWeatherData(textfield.getText().toString().trim());
} else if (currentFragment instanceof ThirdFragment) {
ThirdFragment thirdFragment = (ThirdFragment) currentFragment;
thirdFragment.getWeatherData(textfield.getText().toString().trim());
}
}
private void getWeatherData(String name) {
ApiInterface apiInterface = ApiClient.getClient().create(ApiInterface.class);
Call<Example> call = apiInterface.getWeatherData(name);
call.enqueue(new Callback<Example>() {
@Override
public void onResponse(@NonNull Call<Example> call, @NonNull Response<Example> response) {
try {
assert response.body() != null;
timeField.setVisibility(View.VISIBLE);
timeField.setText("First Updated:" + " " + response.body().getDt());
} catch (Exception e) {
timeField.setVisibility(View.GONE);
timeField.setText("First Updated: Unknown");
Log.e("TAG", "No City found");
Toast.makeText(HomeActivity.this, "No City found", Toast.LENGTH_SHORT).show();
}
}
@Override
public void onFailure(@NotNull Call<Example> call, @NotNull Throwable t) {
t.printStackTrace();
}
});
}
});
}
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.about_id:
getSupportFragmentManager().beginTransaction().replace(R.id.fragment,
new About()).commit();
break;
case R.id.privacy_policy_id:
getSupportFragmentManager().beginTransaction().replace(R.id.fragment,
new Privacy_Policy()).commit();
break;
}
drawer.closeDrawer(GravityCompat.START);
return true;
}
@Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
// Open/close drawer animation
}
}
@Override
protected void onPause () {
super.onPause();
if (viewModel.getMediaPlayer() != null)
viewModel.getMediaPlayer().pause();
}
@Override
protected void onResume () {
super.onResume();
if (viewModel.getMediaPlayer() != null) {
viewModel.getMediaPlayer().start();
viewModel.getMediaPlayer().setLooping(true);
}
}
@Override
public boolean onSupportNavigateUp() {
final NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.fragment);
assert navHostFragment != null;
final NavController navController = navHostFragment.getNavController();
return NavigationUI.navigateUp(navController, appBarConfiguration)
|| super.onSupportNavigateUp(); // navigateUp tries to pop the backstack
}
}
Lightweatherforecast\HomeActivity：
public class HomeActivity extends AppCompatActivity {
private DrawerLayout drawer;
// Last update time, click sound, search button, search panel.
TextView timeField;
MediaPlayer player;
ImageView Search;
ConstraintLayout searchbar;
EditText textfield;
// For scheduling background image change(using constraint layout, start counting from dubai, down to statue of liberty.
ConstraintLayout constraintLayout;
public static int count = 0;
int[] drawable = new int[]{R.drawable.nyc, R.drawable.lofoten_islands, R.drawable.parque, R.drawable.moraine_lake, R.drawable.eiffel_tower,
R.drawable.whitehaven_beach, R.drawable.london, R.drawable.cape_town, R.drawable.burj_al_arab, R.drawable.atuh_beach};
Timer _t;
private WeatherDataViewModel viewModel;
private AppBarConfiguration appBarConfiguration;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
// use home activity layout.
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Allow activity to make use of the toolbar
drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// host 3 fragments along with bottom navigation.
final NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.fragment);
assert navHostFragment != null;
final NavController navController = navHostFragment.getNavController();
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
// remove up button from all these fragments
appBarConfiguration = new AppBarConfiguration.Builder(
R.id.main_id) // remove up button from all these fragments >> Keep up button in R.id.nav_setting, R.id.nav_slideshow
.setOpenableLayout(drawer)
.build();
// Hiding default Drawer fragment that has the BottomNavView
navigationView.getMenu().findItem(R.id.main_id).setVisible(false);
viewModel = new ViewModelProvider(this).get(WeatherDataViewModel.class);
// Trigger action to open & close navigation drawer
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar
, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
timeField = findViewById(R.id.textView9);
Search = findViewById(R.id.imageView4);
textfield = findViewById(R.id.textfield);
searchbar = findViewById(R.id.searchbar);
// find the id's of specific variables.
NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
toggle.setToolbarNavigationClickListener(v -> {
// Enable the functionality of opening the side drawer, when the burger icon is clicked
toggle.setDrawerIndicatorEnabled(true);
navController.navigate(R.id.main_id);
});
navController.addOnDestinationChangedListener((controller, destination, arguments) -> {
// Hide/show top search bar
if (destination.getId() == R.id.main_id) {
searchbar.setVisibility(View.VISIBLE);
toggle.setHomeAsUpIndicator(R.drawable.nav_back_arrow);
toggle.setDrawerIndicatorEnabled(true); // <<< Add this line of code to enable the burger icon
} else {
searchbar.setVisibility(View.GONE);
}
// Fragments that you want to show the back button
if (destination.getId() == R.id.about_id || destination.getId() == R.id.privacy_policy_id) {
// Disable the functionality of opening the side drawer, when the burger icon is clicked
toggle.setDrawerIndicatorEnabled(false);
}
});
// For scheduling background image change
constraintLayout = findViewById(R.id.layout);
constraintLayout.setBackgroundResource(R.drawable.nyc);
_t = new Timer();
_t.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
// run on ui thread
runOnUiThread(() -> {
if (count < drawable.length) {
constraintLayout.setBackgroundResource(drawable[count]);
count = (count + 1) % drawable.length;
}
});
}
}, 5000, 5000);
Search.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// make click sound when search button is clicked.
player = MediaPlayer.create(HomeActivity.this, R.raw.click);
player.start();
getWeatherData(textfield.getText().toString().trim());
// make use of some fragment's data
Fragment currentFragment = navHostFragment.getChildFragmentManager().getFragments().get(0);
if (currentFragment instanceof MainFragment) {
((MainFragment) currentFragment).getWeatherData(textfield.getText().toString().trim());
}
}
private void getWeatherData(String name) {
ApiInterface apiInterface = ApiClient.getClient().create(ApiInterface.class);
Call<Example> call = apiInterface.getWeatherData(name);
call.enqueue(new Callback<Example>() {
@Override
public void onResponse(@NonNull Call<Example> call, @NonNull Response<Example> response) {
try {
assert response.body() != null;
} catch (Exception e) {
Log.e("TAG", "No City found");
Toast.makeText(HomeActivity.this, "No City found", Toast.LENGTH_SHORT).show();
}
}
@Override
public void onFailure(@NotNull Call<Example> call, @NotNull Throwable t) {
t.printStackTrace();
}
});
}
});
}
@Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
// Open/close drawer animation
}
}
@Override
protected void onPause() {
super.onPause();
if (viewModel.getMediaPlayer() != null)
viewModel.getMediaPlayer().pause();
}
@Override
protected void onResume() {
super.onResume();
if (viewModel.getMediaPlayer() != null) {
viewModel.getMediaPlayer().start();
viewModel.getMediaPlayer().setLooping(true);
}
}
@Override
public boolean onSupportNavigateUp() {
final NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.fragment);
assert navHostFragment != null;
final NavController navController = navHostFragment.getNavController();
// return NavigationUI.navigateUp(navController,drawer);
return NavigationUI.navigateUp(navController, appBarConfiguration)
|| super.onSupportNavigateUp(); // navigateUp tries to pop the backstack
}
}
MainFragment（Navhost 片段）：
public class MainFragment extends Fragment {
private NavHostFragment navHostFragment;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
//
BottomNavigationView bottomNavigationView = rootView.findViewById(R.id.bottomNavigationView);
navHostFragment = (NavHostFragment) getChildFragmentManager().findFragmentById(R.id.nav_host_fragment_content_bottom_nav_view);
if (navHostFragment != null) {
NavController navController = navHostFragment.getNavController();
NavigationUI.setupWithNavController(bottomNavigationView, navController);
}
requireActivity().getOnBackPressedDispatcher().addCallback(getViewLifecycleOwner(), new OnBackPressedCallback(true) {
@Override
public void handleOnBackPressed() {
// Exit the app when back is pressed
requireActivity().finish();
}
});
return rootView;
}
public void getWeatherData(String name) {
Fragment currentFragment = navHostFragment.getChildFragmentManager().getFragments().get(0);
if (currentFragment instanceof FirstFragment) {
FirstFragment firstFragment = (FirstFragment) currentFragment;
firstFragment.getWeatherData(name);
} else if (currentFragment instanceof SecondFragment) {
SecondFragment secondFragment = (SecondFragment) currentFragment;
secondFragment.getWeatherData(name);
} else if (currentFragment instanceof ThirdFragment) {
ThirdFragment thirdFragment = (ThirdFragment) currentFragment;
thirdFragment.getWeatherData(name);
}
}
}
其他包括：
*FirstFragment
*SecondFragment
*ThirdFragment with their respective layouts
*Navigation and menu layouts.
我暂时不会发布它们，如果需要的话，为了降低复杂性，请不要发布 犹豫不决要问。
因此，当前的导航总结如下：
HomeActivity
MainFragment
BottomNavigationView navGraph
FirstFragment
SecondFragment
ThirdFragment
Other fragments...
你需要：
BottomNavigationViewFirstFragmentSecondFragmentThirdFragment由于
MainFragmentBottomNavigationViewFirstFragmentHomeActivity
FirstFragment
Other fragments...
要做到这一点：
1。在 HomeActivity 的主导航图中：
MainFragmentFirstFragmentFirstFragmentBottomNavigationViewFirstFragmentMainFragmentHomeActivityFirstFragment2。在
HomeActivityMainFragmentif (currentFragment instanceof MainFragment) {
((MainFragment) currentFragment).getWeatherData(textfield.getText().toString().trim());
}
所以，将会是：
if (currentFragment instanceof FirstFragment) {
((FirstFragment) currentFragment).getWeatherData(textfield.getText().toString().trim());
}
这是共享代码中出现的内容；但您可以将每一次出现的
MainFragmentFirstFragment现在，您可以安全地删除
MainFragmentBottomNavigationView您尝试使用底部导航吗？
android:visibility="gone"
我以前也做过同样的事情。
navController.addOnDestinationChangedListener { _, destination, _ ->
if(destination.id == R.id.first_fragment) {
// your intro fragment will hide your bottomNavigationView
bottomNavigationView.visibility = View.GONE
} else if (destination.id == R.id.second_fragment){
// your second fragment will show your bottomNavigationView
bottomNavigationView.visibility = View.VISIBLE
}
}
您可以根据相关目的地隐藏和显示。
您应该在 MainActivity 中编写此代码。
navController.addOnDestinationChangedListener { _, destination, _ ->
when (destination.id) {
R.id.navigation_order_active,
R.id.navigation_order_open,
R.id.navigation_main_more -> binding.navView.isVisible = true
else -> binding.navView.isVisible = true
}
}