Develop Reference

Android Back to previous fragment by popBackStack

I have 3 fragments: Home, A and B. Home and A are in mobile navigation menu.
User goes from A to B and then press back button. The issue that if I use getFragmentManager().popBackStack(); onCreateView of fragment A is calling and I have duplicating of content.
But if I use getActivity().onBackPressed(); it goes to Home fragment instead of A.
How to display fragment A by clicking back button without refreshing the view?
Here is how I make transaction from A to B
CertificateItemFragment certificateItemFragment = new CertificateItemFragment(item);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.nav_host_fragment, certificateItemFragment).addToBackStack(null);
fragmentTransaction.commit();

You need to know some premise before using FragmentManager.
in Activity there is FragmentManager and we should call it with getSupportFragmentManager(), getFragmentManager() is deprecated.
in Fragment there are multiple FragmentManagers called ParentFragmentManager and ChildFragmentManager, the final FragmentManager which is deprecated too. And ParentFragmentManager will be same as Activity's FragmentManager
getActivity().onBackPressed() will pull out fragment if any stack exists in Activity's FragmentManager
fragmentManager.popBackStack() will pull out fragment if any stack exists in Activity's or Fragment's FragmentManager rely on who calls
Base on above points
(1) If You want to hold fragments in Activity, you should call getSupportFragmentManager() in Activity, and call getParentManager() in Fragment, then onBackPressed() will pull out the fragment you last add to stack.
(2) If you want to hold fragments in a Fragment and Separated from Activity, you should call getChildFragmentManager() in Fragment, then activity.onBackPressed() will pull out the fragment which in Activity's fragment stack and ignore other fragments in Fragment's fragment stack.
For question will be same as case (1), and if you dont want re-create fragment, you should use add() instead of replace()
in Fragment A
CertificateItemFragment certificateItemFragment = new CertificateItemFragment(item);
FragmentManager fragmentManager = getParentFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.nav_host_fragment, certificateItemFragment).addToBackStack(CertificateItemFragment.TAG);
fragmentTransaction.commit();
now onBackPressed() will backstack from CertificateItemFragment to Pre-Fragment

In normal case navigation item list menu open fragment which are replace to each other but when we move inside of any item as like in your case move from fragment A to B,
In this case normally we use another activity on which create fragment.
If you do't want to use activity then, you just need to add fragment.
try below code that may help you
CertificateItemFragment certificateItemFragment = new CertificateItemFragment(item);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.nav_host_fragment, certificateItemFragment).addToBackStack(CertificateItemFragment.TAG);
fragmentTransaction.commit();

How to change the current fragment view with other fragment

How to change the whole view of a fragment with other fragment !!
Or how to close the current fragment with another fragment, please explain with layout also
Thanks in advance...

You can either add or replace fragments in your activity. Create a FrameLayout in activity's layout xml file.
Then do this in your activity to replace fragment. You can use same code each time you want to replace one fragment with other.
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.container,YOUR_FRAGMENT_NAME,YOUR_FRAGMENT_STRING_TAG);
transaction.addToBackStack(null);
transaction.commit();
If you want to add fragment instead of replace then do this:
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.container,YOUR_FRAGMENT_NAME,YOUR_FRAGMENT_STRING_TAG);
transaction.addToBackStack(null);
transaction.commit();
When you want to replace added frogment with anu other fragment then you have to remove previous fragment first (or you can hide previous fragment; depends on your requirement). See following code:
Fragment fragment = getSupportFragmentManager().findFragmentByTag(YOUR_FRAGMENT_STRING_TAG);
if(fragment != null)
getSupportFragmentManager().beginTransaction().remove(fragment).commit();
See following related questions on SO:
Difference between add(), replace(), and addToBackStack()
Basic difference between add() and replace() method of Fragment
Difference between add() & replace() with Fragment's lifecycle
Or see my answer to a similar question:
How to start Fragment from an Activity

getSupportFragmentManager().beginTransaction().replace(R.id.fragmentlayout,new fragment()).commit()
This will help you replace your existing fragment in view with id FragmentLayout with a new fragment().
ThankYou i hope this was helpful.

First you take one Framelayout in Your Activity where you add fragment.
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.framelayout,fragment_1);
transaction.addToBackStack(null);
transaction.commit();
When you replace first fragment with second one you write, just change fragment_1 to fragment_2
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.framelayout,fragment_2);
transaction.addToBackStack(null);
transaction.commit();

how to add two fragments in one activity

Android: I have a list Fragment on an activity.based on the choice, another fragment will be shown on the same activity
but the other fragment should be replaced and i don't know how to do that when the list fragment is fixed !

From google guide for replacing fragments : http://developer.android.com/training/basics/fragments/fragment-ui.html
// Create fragment and give it an argument specifying the article it should show
ArticleFragment newFragment = new ArticleFragment();
Bundle args = new Bundle();
args.putInt(ArticleFragment.ARG_POSITION, position);
newFragment.setArguments(args);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack so the user can navigate back
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();

There's a guide on Fragments in the developers portal. Take a look at the "programmatically add" part (and at the whole guide actually). In short: you need a ViewGroup that is used as a container for the fragments and a FragmentTransaction that is used to add/replace fragment in this container.
Something like (taken from the guide):
FragmentManager fragmentManager = getFragmentManager()
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
ExampleFragment fragment = new ExampleFragment();
fragmentTransaction.add(R.id.fragment_container, fragment);//fragment_container is the ID of the ViewGroup container in your layout
fragmentTransaction.commit();
in your activity.
EDIT:
Long story short - don't put a fixed fragment in your activity's layout. Instead place a container, dynamically add your first fragment in the container and replace it with another fragment when you need to do so (by using FragmentTransaction's replace).

Reset/reload fragment container

How can I reset or reload a fragment container, to make it empty.
I have a master detail view and I want to reset the detail container to empty on a menu item click.This works in some cases and does not in some.
NullFragment fragment = new NullFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
fragmentTransaction.replace(R.id.item_detail_container,
fragment);
int count = fragmentManager.getBackStackEntryCount();
fragmentManager.popBackStackImmediate(count, 0);
fragmentTransaction.commit();

Usually you simply remove the fragment from it.
For example do something like
getFragmentManager().beginTransaction().remove(getFragmentManager().findFragmentById(R.id.your_container)).commit();
this will remove the fragment from the your_container holding it.
This gets the fragment currently present in your_container
getFragmentManager().findFragmentById(R.id.your_container)
and this remove the fragment
getFragmentManager().beginTransaction().remove(fragment).commit();
EDIT
Also sometimes it is useful to ensure all transactions are performed and finished, this can be done by using
getFragmentManager().executePendingTransactions();

Remove fragments from detail view

I wanted to remove fragments(stack of fragments) from a master-detail's Detail view. If i click on a list item in the master view, it opens up a fragment, if i edit the list view's item another fragment is used.
What i want to do is, remove all the fragments from the detail view changing it to a blank container, as it is when the app starts up.
Currently i am replacing the container with a blank fragment, but it does not work in few detail view cases.
NullFragment fragment = new NullFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
fragmentTransaction.replace(R.id.item_detail_container,
fragment);
fragmentManager.popBackStackImmediate();
fragmentTransaction.commit();

You can use FragmentManager.getBackStackEntryCount() to get number of fragments in backstack and use FragmentManager.popBackStack() to pop the top fragment in stack one-by-one.