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Why a fragment from the backstack gets triggered when adding a new fragment

Something strange is happening..!
So I have an activity with TextView in the center of the toolbar acting as toolbar title, once the activity gets launched, I commit the MainFragment or let's name it Fragment (A).
Inside Fragment (A), I replace it with Fragment (B) when a button
gets clicked.
Inside Fragment (B), I replace it with Fragment (C)
when a button gets clicked.
so in each fragment I access the activity's toolbar text view and change it accordingly using this:
TextView title = getActivity().findViewById(R.id.titleText);
title.setText("Some title");
And it works fine in Fragments (A) & (B), but in (C) it shows the title of Fragment (A)??
I even printed a log inside the onCreateView of each fragment and this is what showed up..!
the last two logs showed at the same time..!?
I/MY_TEST: onCreateView: of Fragment (A)
I/MY_TEST: onCreateView: of Fragment (B)
I/MY_TEST: onCreateView: of Fragment (C)
I/MY_TEST: onCreateView: of Fragment (A)
Update
Here's the full click listener
orderDetailsButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
AppCompatActivity activity = (AppCompatActivity) getActivity();
Fragment fragment = new Teacher_Bar_Fragment();
Bundle bundle = new Bundle();
bundle.putInt("index", 1); // I use this to show or hide views
fragment.setArguments(bundle);
FragmentTransaction ft = activity.getSupportFragmentManager().beginTransaction();
ft.replace(R.id.fragment_container, fragment);
ft.addToBackStack(null);
ft.commit();
}
});

ListView of a Fragment (of a ViewPager inside a Fragment) that implements LoaderCallbacks<Cursor> is empty when I return back to it

The ListView inside of a Fragment that contains a ViewPager is empty when I return back to it. This ViewPager is inside of a Fragment because I'm using a Navigation Drawer Layout. I'll try to explain it in more details now:
I am using a Navigation Drawer layout and, consequently, using Fragments. In the main activity, in onCreate, I set the current Fragment with these lines of code:
#Override
protected void onCreate(Bundle savedInstanceState) {
/* More code */
currentFragment = new MainFragment();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.layout_for_fragments, currentFragment).commit();
}
The MainFragment class contains a ViewPager that is initialized with these lines of code in the onCreateView():
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
/* More code */
ViewPager viewPager = (ViewPager) rootView.findViewById(R.id.main_view_pager);
viewPager.setAdapter(new SimpleFragmentPagerAdapter(getActivity(), getActivity().getSupportFragmentManager()));
/* Code for Tablayout */
return rootView;
}
One of the Fragments of the SimpleFragmentPagerAdapter class is this one that implements LoaderManager.LoaderCallbacks
public class ExpensesFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {
private ExpenseCursorAdapter mExpenseCursorAdapter;
private static final int EXPENSE_LOADER = 1;
public ExpensesFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_expenses, container, false);
ListView expensesListView = (ListView) rootView.findViewById(R.id.expenses_list_view);
mExpenseCursorAdapter = new ExpenseCursorAdapter(getContext(), null);
expensesListView.setAdapter(mExpenseCursorAdapter);
getLoaderManager().initLoader(EXPENSE_LOADER, null, this);
return rootView;
}
#Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
return new CursorLoader(/* arguments */);
}
#Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
mExpenseCursorAdapter.swapCursor(data);
}
#Override
public void onLoaderReset(Loader<Cursor> loader) {
mExpenseCursorAdapter.swapCursor(null);
}
}
On the first run, everything works fine. However, if I click on the navigation drawer menu, which I'm implementing this way, the ListView becomes empty:
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
int id = item.getItemId();
if (id == R.id.nav_main) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().remove(currentFragment).commit();
currentFragment = new MainFragment();
fragmentManager.beginTransaction().replace(R.id.layout_for_fragments, currentFragment).commit();
} else if (id == R.id.nav_blank) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().remove(currentFragment).commit();
currentFragment = new BlankFragment();
fragmentManager.beginTransaction().replace(R.id.layout_for_fragments, currentFragment).commit();
}
drawer.closeDrawer(GravityCompat.START);
return true;
}
The problem also exists when I rotate the device. There is a difference though. When I use the Navigation Drawer menu, none of the methods of the LoaderManager.LoaderCallbacks are called, but when I rotate the device, onLoadFinished is called.
Anyway, the problem persists. Any ideias how to solve it?
Thanks in advance.

I have found the solution!
Basically, I made two mistakes.
The first one is about the rotation of the device.
When the device is rotated, the Activity is destroyed and onCreate is called again. In this case, I should't call new MainFragment(). So, I check if the savedInstanceState is null before I call it, like this:
if (savedInstanceState == null) {
currentFragment = new MainFragment();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().
replace(R.id.layout_for_fragments, currentFragment).commit();
}
The second one is about a fragment within a fragment. In this case, I can't simply call getSupportFragmentManager(). I should call getChildFragmentManager() instead and that's it!

Fragment Back Navigation Exiting to Home Screen - Android

I have one fragment in an activity, I can launch the fragment using FragmentManager and FragmentTransaction, but when I try to navigate back to the Activity via the back button, the app exits.
Here is my fragment creation & transaction in the Activity class:
DetailFragment df = new DetailFragment();
try {
df.initFragment(jsonObject);
} catch (Exception e) {
e.printStackTrace();
}
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, df);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
I also override onBackPressed()
#Override
public void onBackPressed() {
super.onBackPressed();
}
With the above setup, one press of the back button exits to the home screen.
I also tried to modify onBackPressed() to do:
#Override
public void onBackPressed(){
FragmentManager fm = getFragmentManager();
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
} else {
super.onBackPressed();
}
}
On this second version of onBackPressed(), it takes 2 back presses to go back to the home screen. Keep in mind I am trying to return to the original Activity.
Any suggestions?
P.S. I can add my fragment code if needed

Your second version of onBackPressed() requires 2 back presses to go back to the home screen. So it seems like fm.popBackStack() is getting called. Try replacing it with popBackStackImmediate().
Edit:
When you are creating the fragment, try using the following instead of .replace:
fragmentTransaction.add(R.id.fragment_container, df);
If that still doesn't work, try:
#Override
public void onBackPressed(){
FragmentManager fm = getFragmentManager();
if (df.isVisible) {
fm.beginTransaction().remove(df).commit();
} else {
super.onBackPressed();
}
}
(although this is less desirable as you are hard-coding what to remove).

The navigation was working, but in my Fragment's onCreateView I used setContentView() to the fragment view which painted the fragment view to the main activity, so it appeared that the back button would exit out if it was pressed twice, but it was actually returning to the main activity as it should, it just repainted the main activity so it wasnt possible to tell.
Thanks for the help #RogueBaneling !!
original code:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View fragmentView = inflater.inflate(R.layout.fragment_detail, container, false);
fragmentView.setClickable(true);
getActivity().setContentView(R.layout.fragment_detail);
final TextView movieTitleText = (TextView) getActivity().findViewById(R.id.movie_title_text);
movieTitleText.setText(title);
// editing textView code...
return fragmentView;
}
into:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View fragmentView = inflater.inflate(R.layout.fragment_detail, container, false);
fragmentView.setClickable(true);
final TextView movieTitleText = (TextView) fragmentView.findViewById(R.id.movie_title_text);
movieTitleText.setText(title);
// editing textView code...
return fragmentView;
}

Removing a fragment not working

I want to remove a fragment and show a toast when I click a textView. My code shows the toast, but doesn't remove the fragment.
My method:
public void hide(View view) {
My_frag myFrag= new My_frag();
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.remove(myFrag);
transaction.commit();
Toast.makeText(getApplicationContext(), "Hello", Toast.LENGTH_LONG)
.show();
}
My_frag class:
public class My_frag extends android.support.v4.app.Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.my_frag_layout, container, false);
}
}

At some point you must create and add the Fragment correct? You are re-creating the fragment in your hide(...) method so you are trying to remove something that has never been added. Sure you may have added an instance, but not the instance you are trying to remove.
Instead, create a global variable Fragment fragToRemove in your Activity. When you create the fragment (that is where ever you do transaction.add(fragToRemove = new My_Frag);) you will hold an instance. then change your transaction.remove(myFrag) to transaction.remove(fragToRemove) and it should work just fine.

Take the instance of Fragment Transaction other than that was taken while adding fragment to activity and call remove method on that and pass the same instance of Fragment which was used at the time.
Example:
public class MainActivity extends AppCompatActivity {
FragmentTransaction fragmentTransaction;
BlankFragment blankFragment;
Button b;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
b = (Button) findViewById(R.id.activity_button);
fragmentTransaction = getSupportFragmentManager().beginTransaction();
blankFragment=new BlankFragment(); //Fragment instance
fragmentTransaction.add(R.id.main_layout,blankFragment).commit();
b.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.remove(blankFragment).commit(); //created different
}
});
}
In the same way you can do in fragments also and can also remove fragment X on the click of component of fragment X.

Replacing a fragment with another fragment inside activity group

I have a fragment inside a group activity and I want to replace it with another fragment:
FragmentTransaction ft = getActivity().getFragmentManager().beginTransaction();
SectionDescriptionFragment bdf = new SectionDescriptionFragment();
ft.replace(R.id.book_description_fragment, bdf);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.addToBackStack(null);
ft.commit();
It works fine when it is done as a seperate project without using activity group, every thing works fine in log cat as control goes inside getview(), but no view is visible, not even any exception arises, I want the book detail fragment to be replaced by section detail fragment.
Xml of book detail fragment has id book_description_fragment and xml for section description fragment has id section_description_fragment.
The above code is in onClick method of an item, I want that when user taps on an item in horizontal scroll view, then the fragment changes.

Fragments that are hard coded in XML, cannot be replaced. If you need to replace a fragment with another, you should have added them dynamically, first of all.
Note: R.id.fragment_container is a layout or container of your choice in the activity you are bringing the fragment to.
// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack if needed
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();

Please see this Question
You can only replace a "dynamically added fragment".
So, if you want to add a dynamic fragment, see this example.

I've made a gist with THE perfect method to manage fragment replacement and lifecycle.
It only replace the current fragment by a new one, if it's not the same and if it's not in backstack (in this case it will pop it).
It contain several option as if you want the fragment to be saved in backstack.
=> See Gist here
Using this and a single Activity, you may want to add this to your activity:
#Override
public void onBackPressed() {
int fragments = getSupportFragmentManager().getBackStackEntryCount();
if (fragments == 1) {
finish();
return;
}
super.onBackPressed();
}

Use the below code in android.support.v4
FragmentTransaction ft1 = getFragmentManager().beginTransaction();
WebViewFragment w1 = new WebViewFragment();
w1.init(linkData.getLink());
ft1.addToBackStack(linkData.getName());
ft1.replace(R.id.listFragment, w1);
ft1.commit();

Use ViewPager. It's work for me.
final ViewPager viewPager = (ViewPager) getActivity().findViewById(R.id.vp_pager);
button = (Button)result.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
viewPager.setCurrentItem(1);
}
});

hope you are doing well.when I started work with Android Fragments then I was also having the same problem then I read about
1- How to switch fragment with other.
2- How to add fragment if Fragment container does not have any fragment.
then after some R&D, I created a function which helps me in many Projects till now and I am still using this simple function.
public void switchFragment(BaseFragment baseFragment) {
try {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.setCustomAnimations(android.R.anim.slide_in_left, android.R.anim.slide_out_right);
if (getSupportFragmentManager().findFragmentById(R.id.home_frame) == null) {
ft.add(R.id.home_frame, baseFragment);
} else {
ft.replace(R.id.home_frame, baseFragment);
}
ft.addToBackStack(null);
ft.commit();
} catch (Exception e) {
e.printStackTrace();
}
}
enjoy your code time :)

you can use simple code its work for transaction
Fragment newFragment = new MainCategoryFragment();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame_NavButtom, newFragment);
ft.commit();

You Can Use This code
((AppCompatActivity) getActivity()).getSupportFragmentManager().beginTransaction().replace(R.id.YourFrameLayout, new YourFragment()).commit();
or You Can This Use Code
YourFragment fragments=(YourFragment) getSupportFragmentManager().findFragmentById(R.id.FrameLayout);
if (fragments==null) {
getSupportFragmentManager().beginTransaction().replace(R.id.FrameLayout, new Fragment_News()).commit();
}

I change fragment dynamically in single line code
It is work in any SDK version and androidx
I use navigation as BottomNavigationView
BottomNavigationView btn_nav;
FragmentFirst fragmentFirst;
FragmentSecond fragmentSecond;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search);
fragmentFirst = new FragmentFirst();
fragmentSecond = new FragmentSecond ();
changeFragment(fragmentFirst); // at first time load the fragmentFirst
btn_nav = findViewById(R.id.bottomNav);
btn_nav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem menuItem) {
switch(menuItem.getItemId()){
case R.id.menu_first_frag:
changeFragment(fragmentFirst); // change fragmentFirst
break;
case R.id.menu_second_frag:
changeFragment(fragmentSecond); // change fragmentSecond
break;
default:
Toast.makeText(SearchActivity.this, "Click on wrong bottom SORRY!", Toast.LENGTH_SHORT).show();
}
return true;
}
});
}
public void changeFragment(Fragment fragment) {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_layout_changer, fragment).commit();
}

In kotlin you can do:
// instantiate the new fragment
val fragment: Fragment = ExampleFragment()
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.book_description_fragment, fragment)
transaction.addToBackStack("transaction_name")
// Commit the transaction
transaction.commit()

This will work if you're trying to change the fragment from another fragment.
Objects.requireNonNull(getActivity()).getSupportFragmentManager()
.beginTransaction()
.replace(R.id.home_fragment_container,new NewFragment())
NOTE As stated in the above answers, You need to have dynamic fragments.

You can use fragment-ktx
// If you are in fragmet
childFragmentManager.beginTransaction()
// or if you are in activiry
supportFragmentManager.beginTransaction()
// Create and commit a new transaction
supportFragmentManager.commit {
setReorderingAllowed(true)
// Replace whatever is in the fragment_container view with this fragment
replace<ExampleFragment>(R.id.fragment_container)
}

To replace a fragment with another one do this, Note that R.id.fragment comes from the id that you give to the first tag of the fragment in the XML.
barAudioPlaying.setOnClickListener(view -> {
getActivity().getSupportFragmentManager()
.beginTransaction()
.replace(R.id.fragment,new HomeFragment())
.commit();