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Return to a fragment already created

I'm working on an Android application that uses fragments.
The code is supposed to do the following:
I'm in the mainActivity;
In here there's a button that creates a fragment;
Turn on an on/off button;
I go back to the mainActivity;
I click on the button and go to the created fragment;
The on/off button is turned on;
I tried to implement this and it doesn't work. In step 5 I believe that it's creating a new fragment everytime, because the on/off button is always turned off.
Basically want I want is to go back to the same fragment that I created firstly.
This is the current code that I have:
MainActivity:
public void onStartSensors(View view) {
if(count > 0){
getSupportFragmentManager().popBackStack();
}
else{
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
transaction.add(R.id.container, new StartupFragment());
transaction.addToBackStack(null);
transaction.commit();
count++;
}
}
UPDATE:
In the link bellow, I got a representation of the present state of my application. When I enter the fragment for the second time, I want it to keep the accelerometer ON.
https://ibb.co/Sc7QZDt
I already tried the method popBackStack(), added a tag, name etc. and it doesn't work.
When I get out of the fragment the method getFragmentByTag() returns null.
This is the current state of the code:
public void onStartSensors(View view) {
FragmentManager fm = getSupportFragmentManager();
if(count > 0){
StartupFragment f1= (StartupFragment) fm.findFragmentByTag("A");
FragmentTransaction transaction=fm.beginTransaction();
if( f1 != null) {
transaction.attach(f1);
transaction.addToBackStack("sensors");
transaction.commit();
}
}
else{
StartupFragment f1=new StartupFragment();
FragmentTransaction transaction = fm.beginTransaction();
transaction.add(R.id.container, f1, "A");
transaction.addToBackStack("sensors");
transaction.commit();
count++;
}
}

It seems to me that you want to add a fragment to be displayed on top of the current activity that is able to be hidden and shown on demand. Looking at your code, every time you are 'showing' the fragment you are creating a new StartupFragment so the behaviour you are experiencing makes sense.
So I would instead recommend adding the fragment when the activity starts and then using FragmentTransaction.show(Fragment) and FragmentTransaction.hide(Fragment) to toggle it's visibility.

Handle onBackPressed in android in fragment

I want to handle onBackPressed in fragment
I use following code in my activity but this return 0
#Override
public void onBackPressed() {
int count = getFragmentManager().getBackStackEntryCount();
Toast.makeText(getBaseContext(), ""+count, Toast.LENGTH_SHORT).show();
if (count == 1) {
super.onBackPressed();
//additional code
} else {
getFragmentManager().popBackStack();
}
}

Just add .addToBackStack(null) in your Activity or Fragment . When you adding or replacing fragment. Like below
getSupportFragmentManager().beginTransaction().replace(R.id.parent_layout, new MyFragment()).addToBackStack(null).commit();
Note:- you don't have to do anything in your onBackPressed() method.

Just app this line when you want to replace any fragment and manage backsack on Fragment.
ClientHome per = new ClientHome();
Bundle bundle = new Bundle();
bundle.putString("usertype", "client");
per.setArguments(bundle);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.anim.slide_from_left, R.anim.slide_to_right);
fragmentTransaction.replace(R.id.content_frame, per, "tag");
fragmentTransaction.addToBackStack("tag");
fragmentTransaction.commit();

What is the best way to add fragment in the Tabs android

My application had a bottom navigation bar which has 5 tabs.
So according to these tabs, I have 5 fragments
When I click on the tab, the fragment changed according to that tab.
I can switch fragment by using the method beginTransaction().replace...
I dont want the fragment to be destroyed and recreated again each time I switch tabs, so my solution is sth like this
//I init 5 fragments
Fragment1 frag1 = new Fragment1();
Fragment2 frag2 = new Fragment2();
Fragment3 frag3 = new Fragment3();
Fragment4 frag4 = new Fragment4();
Fragment5 frag5 = new Fragment5();
//When I click on tab, for example tab1, I hide all fragments except tab1
//hide all fragments
getSupportFragmentManager()
.beginTransaction()
.hide(fragment1) //Fragment2, 3, 4, 5 as well
.commit();
//show fragment 1
getSupportFragmentManager()
.beginTransaction()
.show(fragment1)
.commit();
It works very well, but the problem is sometimes 2 fragments show at once time (I dont know why because I hide all fragments)
Any other way to achieve that? Switch fragment without destroying it and creating it again.

for adding fragment I make this code for my project, hope it will be help.
public static void replaceFragment(Fragment fragment, FragmentManager fragmentManager) {
String backStateName = fragment.getClass().getName();
String fragmentTag = backStateName;
Fragment currentFrag = fragmentManager.findFragmentById(R.id.frame_container);
Log.e("Current Fragment", "" + currentFrag);
// boolean fragmentPopped = fragmentManager.popBackStackImmediate(backStateName, 0);
int countFrag = fragmentManager.getBackStackEntryCount();
Log.e("Count", "" + countFrag);
if (currentFrag != null && currentFrag.getClass().getName().equalsIgnoreCase(fragment.getClass().getName())) {
return;
}
FragmentTransaction ft = fragmentManager.beginTransaction();
// if (!fragmentPopped) {
ft.replace(R.id.frame_container, fragment);
ft.addToBackStack(backStateName);
ft.commit();
// }
currentFrag = fragmentManager.findFragmentById(R.id.frame_container);
Log.e("Current Fragment", "" + currentFrag);
}
hope this will be help you, and use this method in entire project for replacing fragment.

Using ViewPager with FragmentPagerAdapter suits for you in this case.
Then use ViewPager#setOffsetPageLimit(5). This will help you show/hide your fragments without recreating it again.
Follow this tutorial
Let try it, then tell me if your problem is solved or not. ;)

you don't have to need to hide the fragment just replace the fragment like this method:
public void setFragment(Fragment fragmentWhichYouWantToShow) {
fm = getSupportFragmentManager();
ft = fm.beginTransaction();
ft.replace(R.id.container, fragmentWhichYouWantToShow);
ft.commit();
}

Try to make it in a singe transaction.
protected void showAsRootFragment(Fragment fragment, #NonNull String tag) {
FragmentManager supportFragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = supportFragmentManager.beginTransaction();
if (supportFragmentManager.getFragments() != null) {
for (Fragment attachedFragment : supportFragmentManager.getFragments()) {
if (attachedFragment != null && !tag.equals(attachedFragment.getTag())) {
transaction.hide(attachedFragment);
attachedFragment.setUserVisibleHint(false);
}
}
}
if (!fragment.isAdded()) {
transaction.add(R.id.frame_container, fragment, tag);
fragment.setUserVisibleHint(true);
} else {
transaction.show(fragment);
fragment.setUserVisibleHint(true);
}
transaction.commit();
}

MainActivity to Fragment and from that Fragment back to MainActivity

Solve by using getActivity()
I have this MainActivity.java and RepeatEntry.java
inside my MainActivity i have this code to have RepeatEntry ui
//i did hide two linear layout here with buttons and edittext inside it ,using the following method
hideTwoLinearLayout();
showCategoryContainerLayout();
Fragment fragment = new RepeatEntry();
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
//category_cont is a linear layout container for my fragment
ft.replace(R.id.category_cont, fragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.commit();
inside my RepeatEntry.java sample code
Button k = (Button) v.findViewById(R.id.button);
k.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Intent intent = new Intent(getActivity(),MainActivity.class);
// startActivity(intent);
// if i use popBackStack and also remove the code for intent , i cannot show what i hide
//note i have a method inside mainactivity to showTwoLinearLayout()
getFragmentManager().popBackStack();
}
});
Now my question is, do i have other option other than using intent to go back to MainActivity view
Note:Edited

You can add the transaction to backstack and then reverse with poping the backstack the code is here
Fragment fragment = new RepeatEntry();
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
//category_cont is a linear layout container for my fragment
ft.replace(R.id.category_cont, fragment).addToBackStack("tag");
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.commit();
And for going back to the activity view call this to pop backstack
FragmentManager fm = getFragmentManager();
fm.popBackStack();
Also you can use the tag to poping back the specific transaction with
fm.popBackStack("tag");

There is a method called onAttach in your fragment. You can write an interface and assign your fragment's activity like:
private MyFragmentListener mListener;
#Override public void onAttach(Activity activity) {
super.onAttach(activity);
mListener = ((MainActivity) activity);
}
public interface MyFragmentListener{
void onClicked(int value);
}
//Call your listener when button clicked or other events
... mListener.onClicked(position);
Or another solution is to use Otto or Eventbus to get rid unnecessary code

You can also go back in Fragment like
getActivity().getSupportFragmentManager().popBackStack();

any way i solve my problem just in case if anyone might see this.I came up with two solution which i think the first one is best for me.Thanks to Adnan Basar who give me idea.
First solution is so simple by just adding this code inside my onClick event
((MainActivity) getActivity()).showTwoLinearLayout();
((MainActivity) getActivity()).hideCategoryContainerLayout();
Second Solution I created Activity after extends Fragment{
Activity mainActivity;
And use override methods
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
mainActivity= activity;
}
#Override
public void onDestroy() {
super.onDestroy();
// this is where i call the method for showing the twolinearlayout again
((MainActivity) mainActivity).showTwoLinearLayout();
((MainActivity) mainActivity).hideCategoryContainerLayout();
}

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();