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why viewPage keeps previous viewpage content after clicking back button

I have a problem when I click back button while using ViewPage. When I enter to ViewPage after going out and coming back, it shows me the content of previous ViewPage, not new ones.
I'm entering to ViewPage from a RecyclerView and I want to change ViewPage content by clicking on items of RecyclerView.
So my problem is that why ViewPage is not reset to new content?

before committing the fragment do this! it won't remember the last open fragment and please read about BackStack management in fragments here
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
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();

If by saying ViewPage you mean 'ViewPager'. Then you must be displaying the content using a fragment. So when you open the ViewPager screen 'Replace' the fragment with new content.
Use this syntax:
getSupportFragmentManager().beginTransaction()
.replace(R.id.container, new Frag_four()).commit();
Or this one
getFragmentManager().beginTransaction()
.replace(R.id.container, new Frag_four()).commit();
You are facing this issue because may be you are not removing previous content from the container. So just give it a try.
EDIT:
In your fragment displaying activity place the following code in 'OnDestory' method.
getFragmentManager().beginTransaction().remove(getFragmentManager().findFragmentById(R.id.your_container)).commit();
This will empty the container. So next time it will load the new fragment.

How to recreate fragment without adding its previous state

i want to recreate or refreash a fragment without adding previuos state.I searched many thing but not find any appropriate method.please give me some suggestion.......

Your best bet is FragmentTransaction.replace().
E.g.:
// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
However, remember that you can only add a single instance of a Fragment class once. Trying to add the same instance again will result in a Fragment already added exception. To resolve this, either get a new instance of the Fragment class you need to add using MyFragmentClass.instantiate() or new MyFragmentClass().

back stack and statically added fragment

I have a fragment added statically from XML I want to replace this fragment by another fragment, I did that by adding this code:
CFragment singleStationFragment = new CFragment();
android.support.v4.app.FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
transaction.replace(R.id.layoutlist, singleStationFragment);
transaction.addToBackStack(null);
transaction.commit();
the problem is that when I press the back button the first fragment is not shown because it was not added through a transaction and the manager doesn't know about it, is there a way I could add the first fragment (ALREADY ADDED FROM XML), to my backstack or I could just show it when I click back instead of exiting the app ? Thanks !

As far as I'm aware you will have to add your first fragment to the activity in code rather than in the layout file. Do this with the add method of FragmentTransaction
transaction.add(R.id.FragmentContainer, fragment);

Is it OK to addToBackStack and replace in a fragment transaction?

Any thoughts on the following code? In my testing I've found the replaced fragment isn't destroyed and the instance is still around when popping the back stack. Just looking to verify that this is a valid way to use fragment transactions.
getSupportFragmentManager().beginTransaction().addToBackStack(null).replace(frame, fragmentB).commit();
My reason for using replace is that it causes the replaced fragment to run it's exit animation.

You can refer to the android designer guide for fragment transaction:
http://developer.android.com/guide/components/fragments.html
Specificly the snippet below:
// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
So yes, what you are doing is the correct approach in replacing fragments.

Fragment best practice - Android

I am struggling with the structure of the fragment, Thing is... In Activity there is two fragments. One contains a list. Call this FragmentA. The other contains detail. Call this FragmentB.
With every list item in FragmentA there is a different view for FragmentB, so what is the preferred way to handle this kind of scenario?
Thank You

Without seeing the complexity of the app in question, I would suggest that each different view for FragmentB be represented in its own fragment.
The use the Fragment Transaction method to replace the placeholder (let's call this R.id.fragment_container) where FragmentB is with the appropriate fragment depending on your selection in FragmentA. Something like this:
// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();