使用Jetpack导航的BottomNavigation菜单无法导航 [英] BottomNavigation Menu with Jetpack Navigation does not navigate
问题描述
关于BottomNavigationBar，我遇到了一个奇怪的问题，尽管花了很多时间，我还是无法解决.当我以推荐"的方式(从许多教程中)使用它时，它只是无法导航.
I have a strange problem regarding a BottomNavigationBar which I could not solve altough having spent a huge amount of time into it. When I use it in the 'recommended' way (from many tutorials) it just does not navigate.
那么，推荐"方式是什么意思:我具有一个称为"MainActivity"的navHostFragment的单一性.这个主要活动有一个XML布局文件，我在其中放置了BottomNavigationBar.BottomNavigationBar还具有XML布局文件.现在，我有了一个名为"FR_Menu"的片段，其中包含一个Java文件和一个XML布局文件.我也有一个NavGraph.在片段"FR_Menu"的XML布局中，我不使用BottomNavigationBar，而在Java类中，我不实例化BottomNavigationBar，因为我已经在主Activity中完成了此操作.但是使用这种方法，导航不起作用.尽管在底部"FR_Menu"中正确显示了BottomNavigationBar，但单击Bottom却什么也没发生.
So what do I mean by 'recommended' way: I have a single acticity with a navHostFragment called 'MainActivity'. This main activity has a XML layout file in which I put the BottomNavigationBar. The BottomNavigationBar also has a XML layout file. Now I have a Fragment called 'FR_Menu' with a Java file and a XML layout file. I also have a NavGraph. In the XML layout of the Fragment 'FR_Menu' I do not use the BottomNavigationBar and in the Java class I do not instantiate the BottomNavigationBar as I have already done this in the main Activity. But using this approach the Navigation does not work. Altough the BottomNavigationBar is correctly displayd in the Fragment 'FR_Menu', when clicking on the Bottom just nothing happens.
现在来了奇怪的事情.当我使用发布的代码时，未将BottomNavigationBar放在主要活动的XML布局文件中，而是将其分别放在所有片段的每个XML布局文件中(在此示例中为片段FR_Menu)，而当我在每个片段的每个Java文件中实例化BottomNavigationBar(在此示例中为片段"FR_Menu")，然后导航就可以完美地工作了.因此，使用这种方法，我必须将BottomNavigationBar放入片段的每个XML布局文件中，并且还必须在Fragments的每个Java文件中实例化BottomNavigationBar.我知道通常不会使用Jetpack Navigation组件，而是应该只在MainActivity中实例化一次，因为BottomNavigationBar应该仅添加到MainActivity的XML布局文件中.
Now here come the strange thing. When I use the code as posted, but not put the BottomNavigationBar in the XML layout file of the main activity and instead put it separately in every XML-layout file of all Fragments (in this example the fragment 'FR_Menu') and when I also instantiate the BottomNavigationBar in every Java file of each Fragment (in this example the fragment 'FR_Menu'), then the Navigation works perfectly. So with this approach I have to put the BottomNavigationBar in every XML layout file of the fragments and also I have to instantiate the BottomNavigationBar in every Java file of the Fragments. I know that normally using the Jetpack Navigation components, this should not be the case and instead I should only have to instantiate once in the MainActivity as the BottomNavigationBar should only be added to the XML layout file of the MainActivity.
有人在尝试实施推荐"方法时有什么想法吗?名称都是正确的(在我显示的示例中可能有一个小错误，因为我不得不对其进行一些简化和调整)，因为使用第二种方法时(将BottomNavigationBar放在每个XML布局文件和每个Java文件中)的片段)，导航工作完美(我也尝试了多个项目和目的地).
Does anyone have an idea what goes wrong when I am trying to implement the 'recommended' approach? The names are all correct (maybe there is a small error in my shown example because I had to simplify and adjust it a little bit), because when using the second approach (putting the BottomNavigationBar in every XML-layout file and in every Java file of the fragments) the navigation works perfectly (I also tried it with multiple items and destinations).
我确实花了很多时间，我无法弄清楚我的错误.因此，我非常感谢您的每条评论，也非常感谢您的帮助.
I have really spent quite much time on that and I could not figure out what my mistake it. Because of this I would highly appreciate every comment and would be quite thankful for your help.
有人知道这种奇怪行为的原因是什么吗?
Does anyone have an idea what the reason for this strange behaviour might be?
"MainActivity"的Java代码:
Java code of the 'MainActivity':
package com.example.td.bapp;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.NavigationUI;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.example.td.bapp.databinding.ActivityMainBinding;
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
binding = ActivityMainBinding.inflate(inflater, container, false);
NavController navController = Navigation.findNavController(this, R.id.navHostfragment);
NavigationUI.setupWithNavController(binding.bottomNavigation,navController );
setContentView(binding.getRoot());
return binding.getRoot();
}
}
"MainActivity"的XML布局文件:
XML layout file of the 'MainActivity':
<?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"
tools:context=".MainActivity"
tools:ignore="ExtraText">
<fragment
android:id="@+id/navHostfragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toTopOf="@+id/bottom_navigation"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/nav_graph" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/bottom_navigation"
app:labelVisibilityMode="labeled"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/colorGreen"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="@menu/bottom_navigation"
app:itemIconTint="@color/colorPrimaryDark"
app:itemTextColor="@color/colorAccent"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
BottomNavigationBar的XML布局文件:
XML-layout file of BottomNavigationBar:
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<item
android:id="@+id/FR_LanguageSelection"
android:icon = "@drawable/ic_add_circle_full"
android:title = "Language" />
</menu>
片段"FR_Menu"的Java文件
Java file of the Fragment 'FR_Menu'
package com.example.td.bapp;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.NavigationUI;
import com.example.td.bapp.databinding.ActivityMainBinding;
import com.example.td.bapp.databinding.FragmentMenuBinding;
public class FR_Menu extends Fragment implements View.OnClickListener {
// TODO: Rename and change types of parameters
public FR_Menu() {
}
public static FR_Menu newInstance(String param1, String param2) {
FR_Menu fragment = new FR_Menu();
Bundle args = new Bundle();
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
private FragmentMenuBinding binding;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// return inflater.inflate(R.layout.fragment_menu, container, false);
binding = FragmentMenuBinding.inflate(inflater, container, false);
/*
// IMPORTANT REMARK: When I use the following code in the second option this in the second option,
with the BottomNavigationBar in the XML document, the navigation works well
NavController navController = Navigation.findNavController(getActivity(), R.id.navHostfragment);
NavigationUI.setupWithNavController(binding.bottomNavigation,navController );
*/
return binding.getRoot();
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
binding.imageButton_A.setOnClickListener(this);
binding.imageButton_B.setOnClickListener(this);
}
public void onDestroyView() {
super.onDestroyView();
binding = null;
}
@Override
public void onClick(View view) {
if(view.getId() == R.id.imageButton_A) {
String argument = DataBaseEntries.A;
FR_MenuDirections.ActionFRMenuToFRGenericD action =
FR_MenuDirections.actionFRMenuToFRGenericD(argument);
Navigation.findNavController(view).navigate(action);
}
if(view.getId() == R.id.imageButton_B) {
String argument = DataBaseEntries.B;
FR_MenuDirections.ActionFRMenuToFRGenericD action =
FR_MenuDirections.actionFRMenuToFRGenericD(argument);
Navigation.findNavController(view).navigate(action);
}
}
}
这是片段"FR_Menu"的XML布局文件
Here is the XML layout file of the fragment 'FR_Menu'
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar_mainActivity"
android:layout_width="match_parent"
android:layout_height="135dp"
android:background="#435cb53f"
android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
app:titleTextColor="@android:color/holo_green_light">
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:gravity="center"
android:layout_gravity="center"
android:textColor="@android:color/white"
android:textSize="24sp"
android:text="Menu" />
</androidx.appcompat.widget.Toolbar>
<ScrollView
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="10dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/toolbar_mainActivity">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
tools:context=".MainActivity"
tools:ignore="ExtraText">
<ImageButton
android:id="@+id/imageButton_A"
android:layout_width="0dp"
android:layout_height="128dp"
android:background="#00000000"
android:scaleType="fitCenter"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@id/imageButton_B"
app:layout_constraintHorizontal_chainStyle="spread"
app:layout_constraintHorizontal_weight="1"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/menu_A" />
<ImageButton
android:id="@+id/imageButton_B"
android:layout_width="0dp"
android:layout_height="128dp"
android:layout_marginTop="12dp"
android:background="#00000000"
android:scaleType="fitCenter"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_weight="1"
app:layout_constraintStart_toEndOf="@id/imageButton_A"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/menu_B" />
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
NavGraph的XML代码
XML code of the NavGraph
<?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/nav_graph"
app:startDestination="@id/FR_LanguageSelection">
<fragment
android:id="@+id/FR_Menu"
android:name="com.example.td.bapp.FR_Menu"
android:label="FR_Menu"
tools:layout="@layout/fragment_menu" >
<action
android:id="@+id/action_FR_Menu_to_FR_LanguageSelection"
app:destination="@id/FR_LanguageSelection" />
</fragment>
<fragment
android:id="@+id/FR_LanguageSelection"
android:name="com.example.td.bapp.FR_LanguageSelection"
android:label="FR_LanguageSelection" >
<action
android:id="@+id/action_FR_LanguageSelection_to_FR_Menu"
app:destination="@id/FR_Menu" />
</fragment>
</navigation>
推荐答案
onCreateView 是Fragment的方法，不是 Activity 上的方法，因此您的方法在您的框架从未调用 MainActivity .
onCreateView is a method of a Fragment, not a method on Activity, so your method in your MainActivity isn't ever called by the framework.
实际上，根据查看绑定文档.
因此，您的 MainActivity 应该看起来像这样:
Therefore your MainActivity should instead look like:
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Inflate, and then call setContentView() on the returned view root
binding = ActivityMainBinding.inflate(getLayoutInflater());
setContentView(binding.getRoot());
NavController navController = Navigation.findNavController(this,
R.id.navHostfragment);
NavigationUI.setupWithNavController(binding.bottomNavigation, navController);
}
}
这篇关于使用Jetpack导航的BottomNavigation菜单无法导航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！
