如何解决由于XML文件而导致类片段膨胀错误
我有一个应用程序，我想使用一个活动的多片段方法。因此，为此，我实现了一个主要的活动类，该类应充当片段的容器。在这里，您可以看到它的XML布局文件（称为activity_main2）：
<?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">
<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"
/>
<fragment
android:id="@+id/fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:defaultNavHost="true"
app:navGraph="@navigation/nav_graph"
tools:layout_editor_absoluteX="1dp"
tools:layout_editor_absoluteY="1dp"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
在这里您会看到它的Java文件：
package com.example.td.barapp;
import android.content.Intent;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import com.example.td.barapp.databinding.ActivityMain2Binding;
import com.example.td.barapp.databinding.ActivityMainBinding;
public class MainActivity extends AppCompatActivity {
private ActivityMain2Binding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
binding=ActivityMain2Binding.inflate(getLayoutInflater());
setContentView(binding.getRoot());
}
}
不幸的是，当我启动该应用程序时，该应用程序未启动，并且在logcat中，我收到以下错误消息堆栈：
2020-08-26 17:07:47.202 16384-16384/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.td.barapp,PID: 16384
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.td.barapp/com.example.td.barapp.MainActivity}: android.view.InflateException: Binary XML file line #25 in com.example.td.barapp:layout/activity_main2: Binary XML file line #25 in com.example.td.barapp:layout/activity_main2: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: android.view.InflateException: Binary XML file line #25 in com.example.td.barapp:layout/activity_main2: Binary XML file line #25 in com.example.td.barapp:layout/activity_main2: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #25 in com.example.td.barapp:layout/activity_main2: Error inflating class fragment
Caused by: androidx.fragment.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.td.barapp.Menu_Fragment: could not find Fragment constructor
at androidx.fragment.app.Fragment.instantiate(Fragment.java:563)
at androidx.fragment.app.FragmentContainer.instantiate(FragmentContainer.java:57)
at androidx.fragment.app.FragmentManager$3.instantiate(FragmentManager.java:390)
at androidx.navigation.fragment.FragmentNavigator.instantiateFragment(FragmentNavigator.java:132)
因此，我在上面发布的activity_main2的XML布局文件据说有问题。我花了很多时间才弄清楚问题到底出在哪里。你能帮我吗？我真的很感谢您的评论，因为我不知道如何进行。感谢您的帮助。
更新：以下是Dev（请参阅下文）要求我发布的其他文件： 这是menu_fragment的Java文件：
package com.example.td.barapp;
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.NavDirections;
import androidx.navigation.Navigation;
import com.example.td.barapp.databinding.FragmentMenuBinding;
/**
* A simple {@link Fragment} subclass.
* Use the {@link Menu_Fragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class Menu_Fragment extends Fragment implements View.OnClickListener {
// 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;
private Menu_Fragment() {
// 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 Menu_Fragment.
*/
// TODO: Rename and change types and number of parameters
public static Menu_Fragment newInstance(String param1,String param2) {
Menu_Fragment fragment = new Menu_Fragment();
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);
}
}
private FragmentMenuBinding binding;
@Override
public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
binding = FragmentMenuBinding.inflate(inflater,container,false);
return binding.getRoot();
}
@Override
public void onViewCreated(@NonNull View view,@Nullable Bundle savedInstanceState) {
super.onViewCreated(view,savedInstanceState);
binding.imageButtonCocktailsEn.setOnClickListener(this);
binding.imageButtonCocktailsAlcfreeEn.setOnClickListener(this);
binding.imageButtonLongdrinksEn.setOnClickListener(this);
binding.imageButtonWhiskyEn.setOnClickListener(this);
binding.imageButtonLiquorEn.setOnClickListener(this);
binding.imageButtonBeerEn.setOnClickListener(this);
binding.imageButtonSoftdrinksEn.setOnClickListener(this);
binding.imageButtonHotDrinksEn.setOnClickListener(this);
}
public void onDestroyView() {
super.onDestroyView();
binding = null;
}
@Override
public void onClick(View view) {
if(view.getId() == R.id.imageButton_Softdrinks_en) {
int amount = 1;
Menu_FragmentDirections.ActionMenuFragmentToSoftdrinks action = Menu_FragmentDirections
.actionMenuFragmentToSoftdrinks(amount);
Navigation.findNavController(view).navigate(action);
}
}
}
这里是菜单片段的XML布局文件：
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".Menu_Fragment">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar_mainActivity"
android:layout_width="432dp"
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/textView_ToolBar_CocktailSelectionActivity"
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="Drinks" />
</androidx.appcompat.widget.Toolbar>
<ScrollView
android:layout_width="0dp"
android:layout_height="0dp"
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_Cocktails_en"
android:layout_width="0dp"
android:layout_height="128dp"
android:layout_marginTop="12dp"
android:background="#00000000"
android:scaleType="fitCenter"
app:layout_constraintEnd_toStartOf="@id/imageButton_Cocktails_alcfree_en"
app:layout_constraintHorizontal_chainStyle="spread"
app:layout_constraintHorizontal_weight="1"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/menu_cocktails" />
<ImageButton
android:id="@+id/imageButton_Cocktails_alcfree_en"
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_Cocktails_en"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/menu_cocktails_acoholfree" />
<ImageButton
android:id="@+id/imageButton_Longdrinks_en"
android:layout_width="0dp"
android:layout_height="128dp"
android:layout_marginTop="12dp"
android:background="#00000000"
android:scaleType="fitCenter"
app:layout_constraintEnd_toStartOf="@id/imageButton_Whisky_en"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/imageButton_Cocktails_en"
app:layout_constraintVertical_chainStyle="packed"
app:srcCompat="@drawable/menu_longdrinks" />
<ImageButton
android:id="@+id/imageButton_Whisky_en"
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_constraintStart_toEndOf="@id/imageButton_Longdrinks_en"
app:layout_constraintTop_toBottomOf="@id/imageButton_Cocktails_en"
app:srcCompat="@drawable/menu_whisky" />
<ImageButton
android:id="@+id/imageButton_Liquor_en"
android:layout_width="0dp"
android:layout_height="128dp"
android:layout_marginTop="12dp"
android:background="#00000000"
android:scaleType="fitCenter"
app:layout_constraintEnd_toStartOf="@id/imageButton_Beer_en"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/imageButton_Longdrinks_en"
app:layout_constraintVertical_chainStyle="packed"
app:srcCompat="@drawable/menu_liquor" />
<ImageButton
android:id="@+id/imageButton_Beer_en"
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_constraintStart_toEndOf="@id/imageButton_Liquor_en"
app:layout_constraintTop_toBottomOf="@id/imageButton_Longdrinks_en"
app:srcCompat="@drawable/menu_beer" />
<ImageButton
android:id="@+id/imageButton_Softdrinks_en"
android:layout_width="0dp"
android:layout_height="128dp"
android:layout_marginTop="12dp"
android:background="#00000000"
android:scaleType="fitCenter"
app:layout_constraintEnd_toStartOf="@id/imageButton_HotDrinks_en"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/imageButton_Liquor_en"
app:layout_constraintVertical_chainStyle="packed"
app:srcCompat="@drawable/menu_softdrinks" />
<ImageButton
android:id="@+id/imageButton_HotDrinks_en"
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_constraintStart_toEndOf="@id/imageButton_Softdrinks_en"
app:layout_constraintTop_toBottomOf="@id/imageButton_Liquor_en"
app:srcCompat="@drawable/menu_hot_drinks" />
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>
<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>
</FrameLayout>
解决方法
首先，将activity_main2.xml文件中的<fragment标记更改为FrameLayout，因为在片段之间进行切换必须使用FrameLayout。然后在MainActivity Java类中使用以下代码：
public class MainActivity extends AppCompatActivity {
//This will be used to switch between Fragments
private static FragmentManager fragmentManager;
private BottomNavigationView bottomNavView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
//Initialize the FragmentManager
fragmentManager = getSupportFragmentManager();
//Initialize the BottomNavigationView and add listener to it
bottomNavView = findViewById(R.id.bottom_navigation);
bottomNavView.setOnNavigationItemSelectedListener(bottomNavListener);
}
private BottomNavigationView.OnNavigationItemSelectedListener bottomNavListener =
new BottomNavigationView.OnNavigationItemSelectedListener(){
@Override
public boolean OnNavigationItemSelected(@NonNull MenuItem item){
Fragment selectedFragment = null;
switch(item.getItemId()){
case R.id.{first fragment}:
selectedFragment = new {first fragment}();
break;
case R.id.{second fragment}:
selectedFragment = new {second fragment}();
break;
.
.
.
{Make a case for each of your fragments}
}
fragmentManager.beginTransaction().replace(R.id.{id of your FrameLayout},selectedFragment).commit();
}
};
}
现在应该可以使用。
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