I have a java app for android using bottom navigation activity. The application worked well, but the state of the fragments was not saved during the transition. To solve this problem, I decided to make my own FragmentNavigator. Now when I use my fragment instead of the standard fragment in xml layout, I get the following error:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.wasd, PID: 13588
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mobileapp/com.example.mobileapp.AccountMainActivity}: android.view.InflateException: Binary XML file line #23: Binary XML file line #23: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: android.view.InflateException: Binary XML file line #23: Binary XML file line #23: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #23: Error inflating class fragment
Caused by: java.lang.RuntimeException: Exception inflating com.example.mobileapp:navigation/mobile_navigation line 12
at androidx.navigation.NavInflater.inflate(NavInflater.java:97)
at androidx.navigation.NavController.setGraph(NavController.java:557)
at androidx.navigation.NavController.setGraph(NavController.java:539)
at androidx.navigation.fragment.NavHostFragment.onCreate(NavHostFragment.java:248)
at androidx.fragment.app.Fragment.performCreate(Fragment.java:2981)
at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:474)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:257)
at androidx.fragment.app.FragmentLayoutInflaterFactory.onCreateView(FragmentLayoutInflaterFactory.java:142)
at androidx.fragment.app.FragmentController.onCreateView(FragmentController.java:135)
at androidx.fragment.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:295)
at androidx.fragment.app.FragmentActivity.onCreateView(FragmentActivity.java:274)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:780)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:863)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:824)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:706)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:195)
at com.example.mobileapp.AccountMainActivity.onCreate(AccountMainActivity.java:32)
at android.app.Activity.performCreate(Activity.java:6975)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: java.lang.IllegalStateException: Could not find Navigator with name "improved_fragment". You must call NavController.addNavigator() for each navigation type.
at androidx.navigation.NavigatorProvider.getNavigator(NavigatorProvider.java:98)
at androidx.navigation.NavInflater.inflate(NavInflater.java:107)
at androidx.navigation.NavInflater.inflate(NavInflater.java:141)
at androidx.navigation.NavInflater.inflate(NavInflater.java:88)
... 32 more
The main activity looks like this:
package com.example.mobileapp;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.fragment.NavHostFragment;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;
import com.example.mobileapp.databinding.AccountMainActivityBinding;
import com.example.mobileapp.ui.ImprovedFragmentNavigator;
import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.google.android.material.navigation.NavigationBarView;
public class AccountMainActivity extends AppCompatActivity {
private Handler mHandler = new Handler();
private AccountMainActivityBinding binding;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.account_main_activity);
BottomNavigationView navView = findViewById(R.id.nav_view);
AppBarConfiguration appBarConfiguration = new AppBarConfiguration.Builder(
R.id.navigation_user, R.id.navigation_orders, R.id.navigation_products, R.id.navigation_companies, R.id.navigation_map)
.build();
NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.nav_host_fragment_activity_main);
final NavController navController = navHostFragment.getNavController();
navController.getNavigatorProvider().addNavigator(new ImprovedFragmentNavigator(this, navHostFragment.getChildFragmentManager(), R.id.nav_host_fragment_activity_main));
navController.setGraph(R.navigation.mobile_navigation);
NavigationUI.setupWithNavController(navView, navController);
navView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
int id = item.getItemId();
if (item.isChecked()) return false;
switch (id)
{
case R.id.navigation_user :
navController.navigate(R.id.action_global_navigation_user);
break;
case R.id.navigation_orders :
navController.navigate(R.id.action_global_navigation_orders);
break;
case R.id.navigation_products :
navController.navigate(R.id.action_global_navigation_products);
break;
case R.id.navigation_companies :
navController.navigate(R.id.action_global_navigation_companies);
break;
case R.id.navigation_map :
navController.navigate(R.id.action_global_navigation_map);
break;
}
return true;
}
});
}
}
The main activity XML looks like this:
<?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:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".AccountMainActivity">
<fragment
android:id="@+id/nav_host_fragment_activity_main"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toTopOf="@id/nav_view"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0"
app:navGraph="@navigation/mobile_navigation" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/nav_view"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_below="@+id/nav_host_fragment_activity_main"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="@menu/bottom_nav_menu" />
</androidx.constraintlayout.widget.ConstraintLayout>
The navigation file looks like this:
<?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/mobile_navigation"
app:startDestination="@+id/navigation_user">
<improved_fragment
android:id="@+id/navigation_user"
android:name="com.example.mobileapp.ui.user.UserFragment"
android:label="@string/title_user"
tools:layout="@layout/fragment_user" />
<improved_fragment
android:id="@+id/navigation_orders"
android:name="com.example.mobileapp.ui.orders.OrdersFragment"
android:label="@string/title_orders"
tools:layout="@layout/fragment_orders" />
<improved_fragment
android:id="@+id/navigation_products"
android:name="com.example.mobileapp.ui.products.ProductsFragment"
android:label="@string/title_products"
tools:layout="@layout/fragment_products" />
<improved_fragment
android:id="@+id/navigation_companies"
android:name="com.example.mobileapp.ui.companies.CompaniesFragment"
android:label="@string/title_companies"
tools:layout="@layout/fragment_companies" />
<improved_fragment
android:id="@+id/navigation_map"
android:name="com.example.mobileapp.ui.map.MapFragment"
android:label="@string/title_map"
tools:layout="@layout/fragment_map" />
<action
android:id="@+id/action_global_navigation_user"
app:destination="@id/navigation_user"
app:launchSingleTop="true"
app:popUpTo="@id/navigation_user" />
<action
android:id="@+id/action_global_navigation_orders"
app:destination="@id/navigation_orders"
app:launchSingleTop="true"
app:popUpTo="@id/navigation_orders" />
<action
android:id="@+id/action_global_navigation_products"
app:destination="@id/navigation_products"
app:launchSingleTop="true"
app:popUpTo="@id/navigation_products" />
<action
android:id="@+id/action_global_navigation_companies"
app:destination="@id/navigation_companies"
app:launchSingleTop="true"
app:popUpTo="@id/navigation_companies" />
<action
android:id="@+id/action_global_navigation_map"
app:destination="@id/navigation_map"
app:launchSingleTop="true"
app:popUpTo="@id/navigation_map" />
</navigation>
And finally my fragment file looks like this:
package com.example.mobileapp.ui;
import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import androidx.annotation.CallSuper;
import androidx.annotation.IdRes;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import androidx.navigation.NavDestination;
import androidx.navigation.NavOptions;
import androidx.navigation.Navigator;
import androidx.navigation.NavigatorProvider;
import androidx.navigation.fragment.FragmentNavigator;
import com.example.mobileapp.R;
import java.util.ArrayDeque;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
@Navigator.Name("improved_fragment")
public class ImprovedFragmentNavigator extends Navigator<ImprovedFragmentNavigator.Destination>{
private static final String TAG = "ImprovedFragmentNavigator";
private static final String KEY_BACK_STACK_IDS = "androidx-nav-fragment:navigator:backStackIds";
private final Context mContext;
@SuppressWarnings("WeakerAccess") /* synthetic access */
final FragmentManager mFragmentManager;
private final int mContainerId;
@SuppressWarnings("WeakerAccess") /* synthetic access */
ArrayDeque<Integer> mBackStack = new ArrayDeque<>();
@SuppressWarnings("WeakerAccess") /* synthetic access */
boolean mIsPendingBackStackOperation = false;
public ImprovedFragmentNavigator(@NonNull Context context, @NonNull FragmentManager manager,
int containerId) {
mContext = context;
mFragmentManager = manager;
mContainerId = containerId;
}
@Override
public boolean popBackStack() {
if (mBackStack.isEmpty()) {
return false;
}
if (mFragmentManager.isStateSaved()) {
Log.i(TAG, "Ignoring popBackStack() call: FragmentManager has already"
+ " saved its state");
return false;
}
if (mFragmentManager.getBackStackEntryCount() > 0) {
mFragmentManager.popBackStack(
generateBackStackName(mBackStack.size(), mBackStack.peekLast()),
FragmentManager.POP_BACK_STACK_INCLUSIVE);
mIsPendingBackStackOperation = true;
} // else, we're on the first Fragment, so there's nothing to pop from FragmentManager
mBackStack.removeLast();
return true;
}
@NonNull
@Override
public ImprovedFragmentNavigator.Destination createDestination() {
return new ImprovedFragmentNavigator.Destination(this);
}
@Deprecated
@NonNull
public Fragment instantiateFragment(@NonNull Context context,
@NonNull FragmentManager fragmentManager,
@NonNull String className, @SuppressWarnings("unused") @Nullable Bundle args) {
return fragmentManager.getFragmentFactory().instantiate(
context.getClassLoader(), className);
}
@Nullable
@Override
public NavDestination navigate(@NonNull Destination destination, @Nullable Bundle args,
@Nullable NavOptions navOptions, @Nullable Navigator.Extras navigatorExtras) {
if (mFragmentManager.isStateSaved()) {
Log.i(TAG, "Ignoring navigate() call: FragmentManager has already"
+ " saved its state");
return null;
}
String className = destination.getClassName();
if (className.charAt(0) == '.') {
className = mContext.getPackageName() + className;
}
final FragmentTransaction ft = mFragmentManager.beginTransaction();
int enterAnim = navOptions != null ? navOptions.getEnterAnim() : -1;
int exitAnim = navOptions != null ? navOptions.getExitAnim() : -1;
int popEnterAnim = navOptions != null ? navOptions.getPopEnterAnim() : -1;
int popExitAnim = navOptions != null ? navOptions.getPopExitAnim() : -1;
if (enterAnim != -1 || exitAnim != -1 || popEnterAnim != -1 || popExitAnim != -1) {
enterAnim = enterAnim != -1 ? enterAnim : 0;
exitAnim = exitAnim != -1 ? exitAnim : 0;
popEnterAnim = popEnterAnim != -1 ? popEnterAnim : 0;
popExitAnim = popExitAnim != -1 ? popExitAnim : 0;
ft.setCustomAnimations(enterAnim, exitAnim, popEnterAnim, popExitAnim);
}
String tag = Integer.toString(destination.getId());
Fragment primaryNavigationFragment = mFragmentManager.getPrimaryNavigationFragment();
if(primaryNavigationFragment != null)
ft.hide(primaryNavigationFragment);
Fragment destinationFragment = mFragmentManager.findFragmentByTag(tag);
if(destinationFragment == null) {
destinationFragment = instantiateFragment(mContext, mFragmentManager, className, args);
destinationFragment.setArguments(args);
ft.add(mContainerId, destinationFragment , tag);
}
else
ft.show(destinationFragment);
ft.setPrimaryNavigationFragment(destinationFragment);
final @IdRes int destId = destination.getId();
final boolean initialNavigation = mBackStack.isEmpty();
// TODO Build first class singleTop behavior for fragments
final boolean isSingleTopReplacement = navOptions != null && !initialNavigation
&& navOptions.shouldLaunchSingleTop()
&& mBackStack.peekLast() == destId;
boolean isAdded;
if (initialNavigation) {
isAdded = true;
} else if (isSingleTopReplacement) {
// Single Top means we only want one instance on the back stack
if (mBackStack.size() > 1) {
// If the Fragment to be replaced is on the FragmentManager's
// back stack, a simple replace() isn't enough so we
// remove it from the back stack and put our replacement
// on the back stack in its place
mFragmentManager.popBackStackImmediate(
generateBackStackName(mBackStack.size(), mBackStack.peekLast()), 0);
mIsPendingBackStackOperation = false;
}
isAdded = false;
} else {
ft.addToBackStack(generateBackStackName(mBackStack.size() + 1, destId));
mIsPendingBackStackOperation = true;
isAdded = true;
}
if (navigatorExtras instanceof FragmentNavigator.Extras) {
FragmentNavigator.Extras extras = (FragmentNavigator.Extras) navigatorExtras;
for (Map.Entry<View, String> sharedElement : extras.getSharedElements().entrySet()) {
ft.addSharedElement(sharedElement.getKey(), sharedElement.getValue());
}
}
ft.setReorderingAllowed(true);
ft.commit();
// The commit succeeded, update our view of the world
if (isAdded) {
mBackStack.add(destId);
return destination;
} else {
return null;
}
}
@Override
@Nullable
public Bundle onSaveState() {
Bundle b = new Bundle();
int[] backStack = new int[mBackStack.size()];
int index = 0;
for (Integer id : mBackStack) {
backStack[index++] = id;
}
b.putIntArray(KEY_BACK_STACK_IDS, backStack);
return b;
}
@Override
public void onRestoreState(@Nullable Bundle savedState) {
if (savedState != null) {
int[] backStack = savedState.getIntArray(KEY_BACK_STACK_IDS);
if (backStack != null) {
mBackStack.clear();
for (int destId : backStack) {
mBackStack.add(destId);
}
}
}
}
@NonNull
private String generateBackStackName(int backStackIndex, int destId) {
return backStackIndex + "-" + destId;
}
private int getDestId(@Nullable String backStackName) {
String[] split = backStackName != null ? backStackName.split("-") : new String[0];
if (split.length != 2) {
throw new IllegalStateException("Invalid back stack entry on the "
+ "NavHostFragment's back stack - use getChildFragmentManager() "
+ "if you need to do custom FragmentTransactions from within "
+ "Fragments created via your navigation graph.");
}
try {
// Just make sure the backStackIndex is correctly formatted
Integer.parseInt(split[0]);
return Integer.parseInt(split[1]);
} catch (NumberFormatException e) {
throw new IllegalStateException("Invalid back stack entry on the "
+ "NavHostFragment's back stack - use getChildFragmentManager() "
+ "if you need to do custom FragmentTransactions from within "
+ "Fragments created via your navigation graph.");
}
}
@SuppressWarnings("WeakerAccess") /* synthetic access */
boolean isBackStackEqual() {
int fragmentBackStackCount = mFragmentManager.getBackStackEntryCount();
// Initial fragment won't be on the FragmentManager's back stack so +1 its count.
if (mBackStack.size() != fragmentBackStackCount + 1) {
return false;
}
// From top to bottom verify destination ids match in both back stacks/
Iterator<Integer> backStackIterator = mBackStack.descendingIterator();
int fragmentBackStackIndex = fragmentBackStackCount - 1;
while (backStackIterator.hasNext() && fragmentBackStackIndex >= 0) {
int destId = backStackIterator.next();
try {
int fragmentDestId = getDestId(mFragmentManager
.getBackStackEntryAt(fragmentBackStackIndex--)
.getName());
if (destId != fragmentDestId) {
return false;
}
} catch (NumberFormatException e) {
throw new IllegalStateException("Invalid back stack entry on the "
+ "NavHostFragment's back stack - use getChildFragmentManager() "
+ "if you need to do custom FragmentTransactions from within "
+ "Fragments created via your navigation graph.");
}
}
return true;
}
@NavDestination.ClassType(Fragment.class)
public static class Destination extends NavDestination {
private String mClassName;
public Destination(@NonNull NavigatorProvider navigatorProvider) {
this(navigatorProvider.getNavigator(ImprovedFragmentNavigator.class));
}
public Destination(@NonNull Navigator<? extends ImprovedFragmentNavigator.Destination> fragmentNavigator) {
super(fragmentNavigator);
}
@CallSuper
@Override
public void onInflate(@NonNull Context context, @NonNull AttributeSet attrs) {
super.onInflate(context, attrs);
TypedArray a = context.getResources().obtainAttributes(attrs,
R.styleable.FragmentNavigator);
String className = a.getString(R.styleable.FragmentNavigator_android_name);
if (className != null) {
setClassName(className);
}
a.recycle();
}
@NonNull
public final ImprovedFragmentNavigator.Destination setClassName(@NonNull String className) {
mClassName = className;
return this;
}
@NonNull
public final String getClassName() {
if (mClassName == null) {
throw new IllegalStateException("Fragment class was not set");
}
return mClassName;
}
@NonNull
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append(super.toString());
sb.append(" class=");
if (mClassName == null) {
sb.append("null");
} else {
sb.append(mClassName);
}
return sb.toString();
}
}
public static final class Extras implements Navigator.Extras {
private final LinkedHashMap<View, String> mSharedElements = new LinkedHashMap<>();
Extras(Map<View, String> sharedElements) {
mSharedElements.putAll(sharedElements);
}
@NonNull
public Map<View, String> getSharedElements() {
return Collections.unmodifiableMap(mSharedElements);
}
public static final class Builder {
private final LinkedHashMap<View, String> mSharedElements = new LinkedHashMap<>();
@NonNull
public ImprovedFragmentNavigator.Extras.Builder addSharedElements(@NonNull Map<View, String> sharedElements) {
for (Map.Entry<View, String> sharedElement : sharedElements.entrySet()) {
View view = sharedElement.getKey();
String name = sharedElement.getValue();
if (view != null && name != null) {
addSharedElement(view, name);
}
}
return this;
}
@NonNull
public ImprovedFragmentNavigator.Extras.Builder addSharedElement(@NonNull View sharedElement, @NonNull String name) {
mSharedElements.put(sharedElement, name);
return this;
}
@NonNull
public ImprovedFragmentNavigator.Extras build() {
return new ImprovedFragmentNavigator.Extras(mSharedElements);
}
}
}
}
As per the documentation:
Caution: When manually calling setGraph(), note the following:
- Don't use the app:navGraph element when adding the NavHostFragment in XML.
- Don't call NavHostFragment.create(@NavigationRes int).
- Don't use any other APIs that rely solely on the R.navigation ID to inflate and set your graph.
So just remove your app:navGraph attribute from your XML file to only set your graph via setGraph after your addition of your custom Navigator.