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navigation drawer made from android studio : android.view.InflateException: Error inflating class fragment

I am a complete beginner in android studio with java and I have run across this error which seems to be very frequent here . I have seen solutions but nothing has helped so far . In my code I have created a navigation drawer using the already made one from android studio . When I try to run the app I get :
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.covidmobileapp/com.example.covidmobileapp.MainActivity}: android.view.InflateException: Binary XML file line #15 in com.example.covidmobileapp:layout/activity_main: Binary XML file line #20 in com.example.covidmobileapp:layout/content_main: Error inflating class fragment
Which seems to spot errors in 2 xml files I have : activity_main.xml and content_main.xml
Goind down the stack trace it seems that the error hits when the app view is created
at com.example.covidmobileapp.MainActivity.onCreate(MainActivity.java:55)
This is my code for the files above :
MainActivity.java
package com.example.covidmobileapp;
import android.os.Bundle;
import android.view.View;
import android.view.Menu;
import com.google.android.material.snackbar.Snackbar;
import com.google.android.material.navigation.NavigationView;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.appcompat.app.AppCompatActivity;
import com.example.covidmobileapp.databinding.ActivityMainBinding;
public class MainActivity extends AppCompatActivity {
private AppBarConfiguration mAppBarConfiguration;
private ActivityMainBinding binding;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
binding = ActivityMainBinding.inflate(getLayoutInflater());
setContentView(binding.getRoot());
setSupportActionBar(binding.appBarMain.toolbar);
binding.appBarMain.fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = binding.drawerLayout;
NavigationView navigationView = binding.navView;
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow , R.id.nav_homepage)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_main);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
setContentView(R.layout.activity_main);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_main);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
}
content_main.xml I have commented the line where the fragment error hits
<?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"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:showIn="#layout/app_bar_main">
<fragment
android:id="#+id/nav_host_fragment_content_main"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="#navigation/mobile_navigation" //this is where the fragment error hits
/>
</androidx.constraintlayout.widget.ConstraintLayout>
activity_main.xml I have also commented where the error is here
<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout 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/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
android:id="#+id/app_bar_main"
layout="#layout/app_bar_main"
android:layout_width="match_parent"
android:layout_height="match_parent" /> //this is where error for activity_main is
<com.google.android.material.navigation.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="#layout/nav_header_main"
app:menu="#menu/activity_main_drawer" />
</androidx.drawerlayout.widget.DrawerLayout>
I would appreciate your help as this is really frustrating . If more info is needed I will upload it .

I think you should declare:
NavigationView leftNavigationView;
in your main activity and get you nav view in on create method:
leftNavigationView = findViewById(R.id.nav_view);
setLeftNavigationView();
Then you havae to use setNavigationItemSelectedListener. You can create a method like this:
private void setLeftNavigationView() {
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this,
drawerLayout,
toolbar,
R.string.navigation_drawer_open,
R.string.navigation_drawer_close);
drawerLayout.addDrawerListener(toggle);
toggle.syncState();
leftNavigationView.setNavigationItemSelectedListener(item -> {
Fragment selectedFragment = null;
switch (item.getItemId()) {
case R.id.nav_yourFragment:
selectedFragment = new YourFragment();
drawerLayout.closeDrawer(GravityCompat.START);
break;
}
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.fragment_container, selectedFragment).addToBackStack("tag")
.commit();
return true;
});
and so on. R.id.nav_yourFragment is your item from your menu
Also you have to put a FrameLayout container in your xml file:
<FrameLayout
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
I hope this is useful for you

What code i need to input, and where, to switch to a different fragment once item is clicked?

on my activity_main_drawer i got many items but i don't know what code and where it goes to add for switching fragment
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
tools:showIn="navigation_view">
<group android:checkableBehavior="single">
<item
android:id="#+id/nav_contests"
android:icon="#drawable/ic_menu_camera"
android:title="#string/menu_home" />
<item
android:id="#+id/nav_rules"
android:icon="#drawable/irules"
android:title="#string/box_contest_rules" />
<item
android:id="#+id/nav_profile"
android:icon="#drawable/ic_baseline_face_24"
android:title="#string/profile_page" />
<item
android:id="#+id/nav_calendar"
android:icon="#drawable/icalendar"
android:title="#string/calendar_page" />
<item
android:id="#+id/nav_gallery"
android:icon="#drawable/igallery"
android:title="#string/gallery_page" />
<item
android:id="#+id/nav_stats"
android:icon="#drawable/istats"
android:title="#string/stats_page" />
<item
android:id="#+id/nav_rank"
android:icon="#drawable/irank"
android:title="#string/rank_page" />
<item
android:id="#+id/nav_shop"
android:icon="#drawable/ishop"
android:title="#string/shop_page" />
<item
android:id="#+id/nav_setting"
android:icon="#drawable/ic_baseline_settings_24"
android:title="#string/setting_page" />
</group>
</menu>
this is the java HomePage where i am struggling to understand where and what code to add
public class HomePage extends AppCompatActivity {
private AppBarConfiguration mAppBarConfiguration;
#SuppressLint("WrongViewCast")
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_page);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.home_page, menu);
return true;
}
#Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
}
and this is one of the fragment java as example.
public class GalleryFragment extends Fragment {
private GalleryViewModel galleryViewModel;
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
galleryViewModel =
ViewModelProviders.of(this).get(GalleryViewModel.class);
View root = inflater.inflate(R.layout.fragment_gallery, container, false);
final TextView textView = root.findViewById(R.id.text_gallery);
galleryViewModel.getText().observe(getViewLifecycleOwner(), new Observer<String>() {
#Override
public void onChanged(#Nullable String s) {
textView.setText(s);
}
});
return root;
}
}
it would be great as example to switch from HomePage to GalleryFragment and back

try-->
put this in your mainactivity:-
#Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_contests) {
//intent to next activity
} else if (id == R.id.nav_rules) {
//just an example
String message = "Text I want to share.";
Intent share = new Intent(Intent.ACTION_SEND);
share.setType("text/plain");
share.putExtra(Intent.EXTRA_TEXT, message);
startActivity(Intent.createChooser(share, "Title of the dialog the system will open"));
} else if (id == R.id.nav_profile) {
///your actions
}
} else if (id == R.id.nav_calendar) {
}
} else if (id == R.id.nav_gallery) {
}
} else if (id == R.id.nav_stats) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
Demo
main_activity:
package ijsolutions.appnav;
import android.os.Bundle;
import androidx.core.view.GravityCompat;
import androidx.appcompat.app.ActionBarDrawerToggle;
import android.view.MenuItem;
import com.google.android.material.navigation.NavigationView;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentTransaction;
import android.view.Menu;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
//add this line to display menu1 when the activity is loaded
displaySelectedScreen(R.id.nav_home);
}
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private void displaySelectedScreen(int itemId) {
//creating fragment object
Fragment fragment = null;
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
//initializing the fragment object which is selected
switch (itemId) {
case R.id.nav_home:
fragment = new Menu1();
//ft.addToBackStack(null);
break;
case R.id.nav_gallery:
fragment = new Menu2();
ft.addToBackStack(null);
break;
case R.id.nav_slideshow:
fragment = new Menu3();
ft.addToBackStack(null);
break;
}
//replacing the fragment
if (fragment != null) {
ft.replace(R.id.content_frame, fragment);
ft.commit();
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item) {
//calling the method displayselectedscreen and passing the id of selected menu
displaySelectedScreen(item.getItemId());
//make this method blank
return true;
}}
Menu1
public class Menu1 extends Fragment {
public Menu1() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_menu1, container, false);
}
}
xml of menu1
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Menu1"
android:background="#68a">
<!-- TODO: Update blank fragment layout -->
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="#string/Home"
android:layout_marginLeft="60dp"
android:textSize="50dp"
/>
so am not puting the rest menus as it is same
activitymain xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout
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/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="#layout/app_bar_main"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<com.google.android.material.navigation.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="#layout/nav_header_main"
app:menu="#menu/activity_main_drawer" />
</androidx.drawerlayout.widget.DrawerLayout>
activity_main_drawer
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
tools:showIn="navigation_view">
<group android:checkableBehavior="single">
<item
android:id="#+id/nav_home"
android:icon="#drawable/ic_menu_camera"
android:title="#string/menu_home" />
<item
android:id="#+id/nav_gallery"
android:icon="#drawable/ic_menu_gallery"
android:title="#string/menu_gallery" />
<item
android:id="#+id/nav_slideshow"
android:icon="#drawable/ic_menu_slideshow"
android:title="#string/menu_slideshow" />
<item
android:id="#+id/nav_tools"
android:icon="#drawable/ic_menu_manage"
android:title="#string/menu_tools" />
</group>
<item android:title="Communicate">
<menu>
<item
android:id="#+id/nav_share"
android:icon="#drawable/ic_menu_share"
android:title="#string/menu_share" />
<item
android:id="#+id/nav_send"
android:icon="#drawable/ic_menu_send"
android:title="#string/menu_send" />
</menu>
</item>
main.xml
<?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/action_settings"
android:orderInCategory="100"
android:title="#string/action_settings"
app:showAsAction="never" />
</menu>
content_main:
<?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"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context=".MainActivity"
tools:showIn="#layout/app_bar_main">
<FrameLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
app_bar_main
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
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">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</com.google.android.material.appbar.AppBarLayout>
<include layout="#layout/content_main" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Add in you activity. It works
#Override
public boolean onNavigationItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.nav_home) {
}else if (id == R.id.nav_logout) {
logOut(HomePage.this, "Logout due to nav. logout");
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}

How to make menu items clickable? [duplicate]

This question already has answers here:
Navigation Drawer closes on click
(1 answer)
Sliding navigation drawer not handling clicks on menu items android
(3 answers)
How to fix Android studio 3.5 navigation activity template onNavigationItemSelected not working
(5 answers)
Closed 3 years ago.
I am trying to set up a Navigation Activity in my application. The problem is that I cannot switch between the Menu fragments. It looks like the menu items are not clickable.
I tried to set up the Navigation Activity in the same way I have already set up a menu (Action Bar) before but it's just not working. Also with on Click Listener, the items don't react.
My question is now on how to make the onNavigationItemSelected() method work?
Sorry for the mass of code.
public class NavActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{
private AppBarConfiguration mAppBarConfiguration;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_nav);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow,
R.id.nav_tools, R.id.nav_share, R.id.nav_send)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
Toolbar myToolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(myToolbar);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.nav, menu);
return true;
}
#Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
#Override
public boolean onNavigationItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.nav_home: {
Toast.makeText(NavActivity.this, "Anmeldung Fehlgeschlagen", Toast.LENGTH_LONG).show();
return true;
}
case R.id.nav_gallery:
// User chose the "Favorite" action, mark the current item
// as a favorite...
return true;
}
return super.onOptionsItemSelected(item);
}
app_bar_nav.xml
<androidx.coordinatorlayout.widget.CoordinatorLayout 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=".NavActivity">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</com.google.android.material.appbar.AppBarLayout>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:clickable="true"
app:srcCompat="#android:drawable/ic_dialog_email" />
<include layout="#layout/content_nav" />
activity_nav_drawer.xml
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:App="http://schemas.android.com/apk/res-auto"
tools:showIn="navigation_view">
<group android:checkableBehavior="single">
<item
android:id="#+id/nav_home"
android:icon="#drawable/ic_menu_camera"
android:title="#string/menu_home"
android:clickable="true"/>
<item
android:id="#+id/nav_gallery"
android:icon="#drawable/ic_menu_gallery"
android:title="#string/menu_gallery"
android:clickable="true"/>
<item
android:id="#+id/nav_slideshow"
android:icon="#drawable/ic_menu_slideshow"
android:title="#string/menu_slideshow"
App:showAsAction="always"
android:clickable="true"/>
<item
android:id="#+id/nav_tools"
android:icon="#drawable/ic_menu_manage"
android:title="#string/menu_tools"
android:clickable="true"/>
</group>
<item android:title="Communicate">
<menu>
<item
android:id="#+id/nav_share"
android:icon="#drawable/ic_menu_share"
android:title="#string/menu_share"
android:clickable="true"/>
<item
android:id="#+id/nav_send"
android:icon="#drawable/ic_menu_send"
android:title="#string/menu_send"
android:clickable="true"/>
</menu>
</item>
mobile_navigation.xml
<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/nav_home">
<fragment
android:id="#+id/nav_home"
android:name="com.example.login.ui.home.HomeFragment"
android:label="#string/menu_home"
tools:layout="#layout/fragment_home"
android:clickable="true"/>
<fragment
android:id="#+id/nav_gallery"
android:name="com.example.login.ui.gallery.GalleryFragment"
android:label="#string/menu_gallery"
tools:layout="#layout/fragment_gallery" />
<fragment
android:id="#+id/nav_slideshow"
android:name="com.example.login.ui.slideshow.SlideshowFragment"
android:label="#string/menu_slideshow"
tools:layout="#layout/fragment_slideshow" />
<fragment
android:id="#+id/nav_tools"
android:name="com.example.login.ui.tools.ToolsFragment"
android:label="#string/menu_tools"
tools:layout="#layout/fragment_tools" />
<fragment
android:id="#+id/nav_share"
android:name="com.example.login.ui.share.ShareFragment"
android:label="#string/menu_share"
tools:layout="#layout/fragment_share" />
<fragment
android:id="#+id/nav_send"
android:name="com.example.login.ui.send.SendFragment"
android:label="#string/menu_send"
tools:layout="#layout/fragment_send" />
acitivty_nav.xml
<androidx.drawerlayout.widget.DrawerLayout 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/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<com.google.android.material.navigation.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="#layout/nav_header_nav"
app:menu="#menu/activity_nav_drawer" />
<include
layout="#layout/app_bar_nav"
android:layout_width="match_parent"
android:layout_height="match_parent" />

I have updated my answer please check I have added listener
public class NavActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{
private AppBarConfiguration mAppBarConfiguration;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_nav);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow,
R.id.nav_tools, R.id.nav_share, R.id.nav_send)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
Toolbar myToolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(myToolbar);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.nav, menu);
return true;
}
#Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
#Override
public boolean onNavigationItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.nav_home: {
Toast.makeText(NavActivity.this, "Anmeldung Fehlgeschlagen", Toast.LENGTH_LONG).show();
return true;
}
case R.id.nav_gallery:
// User chose the "Favorite" action, mark the current item
// as a favorite...
return true;
}
return super.onOptionsItemSelected(item);
}

Can't find TextView from MainActivity [duplicate]

This question already has answers here:
NavigationView get/find header layout
(9 answers)
Closed 5 years ago.
I have a DrawerLayout in my android app that has a NavigationView which is using a nav_header_main2 layout. Inside the nav_header_main2 layout file there is an ImageView and 2 TextViews, in my MainActivity I am trying to grab those TextView items so I can dynamically fill in the content with the username and email address, however I am always getting a null reference whenever I try to access them.
Here is the main layout file...
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
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/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="#layout/app_bar_main2"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<android.support.design.widget.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="#layout/nav_header_main2"
app:menu="#menu/activity_main2_drawer"/>
</android.support.v4.widget.DrawerLayout>
As you can see, the NavigationView is using "nav_header_main2", here is that file...
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="#dimen/nav_header_height"
android:background="#drawable/side_nav_bar"
android:gravity="bottom"
android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:theme="#style/ThemeOverlay.AppCompat.Dark">
<de.hdodenhof.circleimageview.CircleImageView
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/menu_user_photo"
android:layout_width="64dp"
android:layout_height="64dp"
android:layout_gravity="center_horizontal"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:src="#drawable/ic_person_white"
app:border_color="#color/colorTransparent"
android:layout_marginStart="10dp"
android:layout_marginLeft="10dp"
android:layout_marginTop="3dp"
android:layout_marginBottom="0dp"
app:border_width="1dp"/>
<!--<ImageView-->
<!--android:id="#+id/imageView"-->
<!--android:layout_width="wrap_content"-->
<!--android:layout_height="wrap_content"-->
<!--android:paddingTop="#dimen/nav_header_vertical_spacing"-->
<!--app:srcCompat="#android:drawable/sym_def_app_icon"/>-->
<TextView
android:id="#+id/menu_username"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingTop="#dimen/nav_header_vertical_spacing"
android:layout_gravity="center_horizontal"
android:gravity="center_horizontal"
android:text="Android Studio"
android:textAppearance="#style/TextAppearance.AppCompat.Body1"/>
<TextView
android:id="#+id/textView"
android:gravity="center_horizontal"
android:layout_gravity="center_horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="android.studio#android.com"/>
</LinearLayout>
Then in my MainActivity, I have tried multiple ways of accessing the "menu_username" item but all of them return a null reference. Here is my main class right now...
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
public static final String EXTRA_MESSAGE = "text.notreal.justatest.MESSAGE";
public static final int TAG_KEY = 0;
public static final int TAG_VALUE = 0;
public List<Post> posts = new ArrayList<>();
public FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this,
drawer,
toolbar,
R.string.navigation_drawer_open,
R.string.navigation_drawer_close
);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
//THIS IS WHAT IS FAILING
//I HAVE ALSO TRIED JUST USING findViewById(R.id.menu_username); NULL STILL
TextView menuUserName = (TextView) navigationView.findViewById(R.id.menu_username);
if(menuUserName == null) {
Log.d("MAIN ACTIVITY", "Somehow the menu_username doesn't exist");
}
if(findViewById(R.id.frameLayout) != null) {
if(savedInstanceState != null) {
return;
}
AllPostsFragment fragment = new AllPostsFragment();
fragment.setArguments(getIntent().getExtras());
getSupportFragmentManager().beginTransaction().add(R.id.frameLayout, fragment).commit();
}
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case android.R.id.home:
this.finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_camera) {
// Handle the camera action
} else if (id == R.id.nav_gallery) {
} else if (id == R.id.nav_slideshow) {
} else if (id == R.id.nav_manage) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
As you can see I am trying to grab it using the NavigationView object, which doesn't work, but I have also tried just using
TextView menuUsername = (TextView) findViewById(R.id.menu_username);
which also returns a null reference. How can I get the username and email fields in my main activity so I can dynamically fill in the content? Thank you

You won't find it that way. The proper way is first to find your NavigationView, then get its HeaderView using getHeaderView() and then search your widgets in that HeaverView:
NavigationView nv = findViewById(R.id.nav_view);
TextView menuUsername = nv.getHeaderView(0).findViewById(R.id.menu_username);
or more compact way
TextView menuUsername = findViewById(R.id.nav_view)
.getHeaderView(0).findViewById(R.id.menu_username);

In my Fragment is the Layout of Mainactivity also shown

I'm working the first time with Fragments, so sorry if I did smt very stupid :D
I have a Navigation Drawer Activity. When I click in it on the first item i want to open a Fragment. When I open it, there is not only the Layout of the Fragment shown, but also the layout of my MainActivity, it looks very strange.
[1]: https://i.stack.imgur.com/iqTAq.png MainActivity
[2]: https://i.stack.imgur.com/kULQY.png Navigation Drawer
[3]: https://i.stack.imgur.com/T2vDJ.png First Fragment
How can I solve the problem?
Here is my code if you need it:
MainActivity(Navigation Drawer Templated, I wrote only in the onNavigationItemSelected, so that it goes to the fragment when I click on the first item:
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
}
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_camera) {
setTitle("First Fragment");
first first = new first();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.fragment, first).commit();
} else if (id == R.id.nav_gallery) {
} else if (id == R.id.nav_slideshow) {
} else if (id == R.id.nav_manage) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
content_main (It should belong to MainActivity)
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout 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"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context="com.gsr.fragmenttest.MainActivity"
tools:showIn="#layout/app_bar_main">
<FrameLayout
android:id="#+id/fragment"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="This is the Mainactivity, no fragemnt"/>
</FrameLayout>
</RelativeLayout>
First Fragment Activity
public class first extends Fragment {
Button btn;
TextView textView;
public first() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_first, container, false);
btn=(Button)v.findViewById(R.id.button);
textView=(TextView)v.findViewById(R.id.textView);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
textView.setText("Nice, it works !!");
}
});
// Inflate the layout for this fragment
return v;
}
}
And at least the fragment layout file
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.gsr.fragmenttest.first">
<!-- TODO: Update blank fragment layout -->
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/textView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="Hello Fragment"
android:textSize="50dp"/>
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"/>
</RelativeLayout>
</FrameLayout>
I hope someone can help me :)

Add a background to your fragment layout, it should solve your problem.
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white" //Your background color
tools:context="com.gsr.fragmenttest.first">
<!-- TODO: Update blank fragment layout -->
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
...

I think the problem is in your activity layout
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<FrameLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</FrameLayout>
</android.support.v4.widget.DrawerLayout>
try to change your main activity layout like above. Hope it will solve your problem.

1) implements first.OnOnFragmentInteractionListener
2) in onNavigationItemSelected method put this code
if (id == R.id.nav_camera) {
setTitle("First Fragment");
first first = new first();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.fragment, new first()).commit();
3)In first fragment use this line
import android.app.Fragment;