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cannot use `BottomNavigationView` and `ViewPager` and `TabLayout` simultaneously

I did so much researches in the internet and the conclusion was that we cannot use BottomNavigationView and ViewPager and TabLayout simultaneously. but there are a lot of app such as Instagram that merged them.
my question is that how can they do that? do they use a special trick or not?

you can create bottomNavigationView in activity and attach fragment in it with this code when click a on item of it:
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction()
.replace(frameId, fragment, "fragTransaction");
transaction.commit();
and then create a fragment wiht a tabLayout and viewPager to control child fragment in it and you most using to control fragment in viewPagerAdapter
FragmentManager fragmentManager = getChildFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction()
.replace(frameId, fragment, "fragTransaction");
transaction.commit();

It is not difficult to use bottomNavigationView with ViewPager.
In your layout declare both of these controls.
Setup viewPageAdapter and add fragments to it, set adapter to viewPager.
Setup bottomNavigationView overriding onNavigationItemSelectedListener, which now will be setting current item of viewPagerAdapter.
Do you need more detailed code examples, or you are ready to rock?

Fragment with MapView is never removed from FragmentManager

I have a Fragment with MapView in it. I add Fragment to container with following code:
Fragment fragment = new MyLocationFragment()
String tag= fragment.getClass().getName();
FragmentTransaction transaction = fm.beginTransaction();
transaction.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left,
R.anim.slide_in_left, R.anim.slide_out_right);
transaction.replace(R.id.container, fragment, tag);
transaction.addToBackStack(null);
transaction.commit();
Now when user presses back, this Fragment is supposed to be removed from FragmentManager. But if execute this code :
Fragment fragment = getSupportFragmentManager().findFragmentByTag(MyLocationFragment.class.getName());
It never returns null, even if I replace other fragments in same container. What can I do to remove Fragment from FragmentManager? Am I doing something wrong here ?

When an activity is destroyed, its FragmentManagersaves out its list of fragments. When the activity is recreated, the new FragmentManager retrieves the list and recreates the listed fragments to make everything as it was before.
[Refer to book "Android Programming The Big Nerd Ranch Guide" P150]
So your should remove fragment from fragmentmanager.
Refer to this Q&A Remove old Fragment from fragment manager
Your question maybe duplicate with thisHow to get a Fragment to remove itself, i.e. its equivalent of finish()?

Replace a fragment or add fragment just once and then show/hide it. Efficient?

I am looking for a better approach here. What you suggest if i have 10+ fragments on a navigation drawer.
FragmentManager fragmentManager = getSupportFragmentManager ();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction ();
Using singleton pattern to get the instance of a fragment and add just once to fragmentTransaction if it's not added.
fragmentTransaction.add (R.id.testLayoutContent, fragment);
Or the another approach which initialize fragment each time and replace the fragment.
NOTE: Each fragments have customize components, live map etc.

Create/destroy or show/hide Fragments?

I have a situation in which I need to show/hide a fragment based on a dynamic variable. My question is should I create the fragment once, and then show/hide based on the variable. Or should I destroy/create it each time?
Create the fragment
Fragment alertFragment = new AlertFragment();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.add(android.R.id.content, alertFragment).commit();
After this should I call show/hide each time?
getSupportFragmentManager().beginTransaction()
.setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out)
.show(alertFragment) // or hide
.commit();
Seems like a lot of work to show/hide something each time. Is this the right way to do it?

I'd say that depends on weather it matters for your application if your Fragment is destroyed or not.
If it doesn't matter at all, simply replace the Fragment everytime by a new one. This is the simplest solution and does not require any logic.
Fragment f = new Fragment();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content, f).commit();

Android FragmentTransaction with fragment overlay

I have a actionbar tab setup with fragments for each of the pages. (extended default example from wizard).
I'm attempting to create a new fragment and make it the current fragment, with the other hidden
ConfigDetailSectionFragment configDetailSectionFragment = new ConfigDetailSectionFragment();
FragmentManager fragmentManager = getFragmentManager();
android.support.v4.app.FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(R.id.fragment_main_config, configDetailSectionFragment);
transaction.addToBackStack(null);
transaction.commit();
the code shows the new fragment but seems it is transparent and I can see the fragment below.
i'm probably forgetting to do something... what am i forgetting to do or am missing?

Adding an android:background="#FFFFFF" fixed the issue, per beworker. Thanks!