在底部导航视图上多次点击时应用程序崩溃 [英] App crashes when tapping multiple times on Bottom Navigation Views
问题描述
我的应用有一个包含 3 个片段的 Activity.这些片段可以通过点击底部导航视图来导航.它工作得很好，只是当我尝试分别点击底部导航视图时，它在运行时崩溃并出现以下错误:
My app has an activity that hosts 3 fragments. These fragments can be navigated by tapping on the bottom navigation views. It works quite fine only that when I tried tapping on the bottom navigation views severally, it crashed with the following error at runtime:
java.lang.IllegalArgumentException: saveBackStack("48c3d9bf-beff-4ec0-8a1b-fb91b56a2765") must be self contained and not reference fragments from non-saved FragmentTransactions. Found reference to fragment SecondFragment{57f9be2} (dd3744e7-8aa3-4c45-b6bc-312a9d46afb4 id=0x7f0a00b0) in BackStackEntry{ba06b73 48c3d9bf-beff-4ec0-8a1b-fb91b56a2765} that were previously added to the FragmentManager through a separate FragmentTransaction.
at androidx.fragment.app.FragmentManager.saveBackStackState(FragmentManager.java:2052)
at androidx.fragment.app.FragmentManager$SaveBackStackState.generateOps(FragmentManager.java:3172)
at androidx.fragment.app.FragmentManager.generateOpsForPendingActions(FragmentManager.java:1953)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1643)
at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:480)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6819)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:497)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:912)
我已经检查了整个站点和其他几个站点以寻找问题的解决方案，但没有找到.所以我想如果有人可以帮忙.
I've checked throughout this site and several other sites for a solution to the issue but found none. So i would like if anyone could help out.
这是我当前活动的代码:
Here's my current activity's code:
public class HomeActivity extends AppCompatActivity {
private DrawerLayout drawer;
// Last update time, click sound, search button, search panel.
TextView time_field;
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.dubai, R.drawable.central_bank_of_nigeria, R.drawable.eiffel_tower, R.drawable.hong_kong, R.drawable.statue_of_liberty};
Timer _t;
private WeatherDataViewModel viewModel;
@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);
viewModel = new ViewModelProvider(this).get(WeatherDataViewModel.class);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar
, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
time_field = 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();
NavigationUI.setupWithNavController(bottomNavigationView, navController);
// For scheduling background image change
constraintLayout = findViewById(R.id.layout);
constraintLayout.setBackgroundResource(R.drawable.dubai);
_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;
time_field.setVisibility(View.VISIBLE);
time_field.setText("First Updated:" + " " + response.body().getDt());
} catch (Exception e) {
time_field.setVisibility(View.GONE);
time_field.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();
}
});
}
});
}
}
编辑
第二个片段:
public class SecondFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
public SecondFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment SecondFragment.
*/
// TODO: Rename and change types and number of parameters
public static SecondFragment newInstance(String param1, String param2) {
SecondFragment fragment = new SecondFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_second, container, false);
}
public void getWeatherData(String trim) {
}
}
导航图:
<?xml version="1.0" encoding="utf-8"?>
<navigation 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:id="@+id/my_nav"
app:startDestination="@id/firstFragment">
<fragment
android:id="@+id/firstFragment"
android:name="com.wiz.lightweatherforecast.FirstFragment"
android:label="fragment_first"
tools:layout="@layout/fragment_first" />
<fragment
android:id="@+id/secondFragment"
android:name="com.wiz.lightweatherforecast.SecondFragment"
android:label="fragment_second"
tools:layout="@layout/fragment_second" />
<fragment
android:id="@+id/thirdFragment"
android:name="com.com.wiz.lightweatherforecast.ThirdFragment"
android:label="fragment_third"
tools:layout="@layout/fragment_third" />
</navigation>
我通过单击底部导航视图(用红色勾号表示)浏览片段:https://i.stack.imgur.com/ScFW6.jpg 使用这种依赖；实现 "androidx.navigation:navigation-fragment:2.4.0-alpha01"
I navigate through fragments by clicking on the bottomnavviews(illustrated with red ticks): https://i.stack.imgur.com/ScFW6.jpg making use of this dependency; implementation "androidx.navigation:navigation-fragment:2.4.0-alpha01"
推荐答案
java.lang.IllegalArgumentException:saveBackStack 必须是自包含的，不能引用来自未保存的 FragmentTransactions 的片段.在之前通过单独的 FragmentTransaction 添加到 FragmentManager 的 BackStackEntry 中找到对片段 SecondFragment 的引用.
试图理解:
当您尝试从
底部导航视图;它说这个特定的片段(SecondFragment) 已经存在于 Back Stack 中，并带有一个旧的/单独的FragmentTransaction;所以把它重新添加到后堆栈是错误的.>>相反，它应该被重用.
When you try to navigate to the
SecondFragmentfrom theBottomNavigationView; it says that this particular fragment (SecondFragment) already exists in the Back Stack with an old / separateFragmentTransaction; so it's wrong to re-add it to the back stack. >> Instead it should be reused.
这意味着，而不是做:fm.beginTransaction().hide(currentFragment).show(newFragment).commit()
相反:fm.beginTransaction().add(R.id.frag_container, newFragment, tag).commit()
当反复点击 BottomNavView 时，由于某种原因它到达未保存的 fragmentTransaction(未提交)；和在那之后，当您尝试导航到另一个片段时，它会说"你不应该从当前未提交的片段中引用新的片段交易".
When repeatedly tapping on the BottomNavView, for some reason it
reaches to a non-saved fragmentTransaction (non-committed); and
just after that when you try to navigate to another fragment, it says
"You should not reference a new fragment from the current uncommitted
transaction".
现在尝试在项目(重新选择)时解决此问题，通过在BottonNavView中重新选择项目时通过设置弹出返回堆栈>OnItemReselectedListener:
Now try to resolve this when item is (re-selected), by poping the back stack when an item is re-selected in the BottonNavView by setting OnItemReselectedListener:
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();
NavigationUI.setupWithNavController(bottomNavigationView, navController);
bottomNavigationView.setOnItemReselectedListener((BottomNavigationView.OnNavigationItemReselectedListener)
item -> navController.popBackStack(item.getItemId(), false)
);
这篇关于在底部导航视图上多次点击时应用程序崩溃的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
