I'm currently using a ViewGroup (SwipeyTab implementation) to switch between Fragments. However, some Fragment "pages" get replaced by other Fragments on the same Tab, so I initially tried:
FragmentTransaction ft = fragment.getFragmentManager().beginTransaction();
ft.remove(currentFragment);
ft.add(newFragment,"");
ft.commit();
That code would remove the current fragment but not add newFragment (from Logcat, it would get instantiated but not appear).
I ended up adding it in the FragmentPagerAdapter.getItem(int position) call based on current state (based on this: Replace Fragment inside a ViewPager). However, I'd like to be able to add each newly replaced fragment to be part of the back stack.
I tried adding to backstack before removing the fragment:
currentFragment.getFragmentManager().beginTransaction().addToBackStack(null).commit();
FragmentTransaction ft = fragment.getFragmentManager().beginTransaction();
ft.remove(currentFragment);
ft.commit();
and that didn't work - it added the last fragment to the backstack, so when I pressed back, it would just reload the current fragment.
Is there anyway I can add a fragment to the backstack that has been replaced in the "non traditional" way?
Related
I'm using multiple fragments inside an activity like this flow: Fragment A has a list on it's item click Fragment B opens and it also has a list opens Fragment C which has a list Open another Activity , The problem is when I go back from the other Activity I found Fragment A is opened, How I restore the last Fragment C when go back from the other activity?
here is the code of replacing Fragment inside my activity
protected void showFragment(Fragment fragment) {
String TAG = fragment.getClass().getSimpleName();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.container_home, fragment, TAG);
fragmentTransaction.addToBackStack(TAG);
fragmentTransaction.commit();
}
replace removes the existing fragment and adds a new fragment. This means when you press back button the fragment that got replaced will be created with its onCreateView being invoked. Whereas add retains the existing fragments and adds a new fragment that means existing fragment will be active.
Use add instead of replace
fragmentTransaction.add(R.id.container_home, fragment, TAG);
I had the same issue solved using the above code.
You can use
fragmentTransaction.addToBackStack(null);
instead of,
fragmentTransaction.addToBackStack(TAG);
Hope Your problem will solve.
Hardly can't get fragment from backstack, even start thinking of keeping in in singleton which is probably bad.
Saved to backstack like this and all time try to get it by tag or something gives me error.
Fragment fragment = UserProfileFragment.newInstance(null);
FragmentTransaction trans = getFragmentManager().beginTransaction();
trans.replace(FRAGMENT_PLACE_RESOURCES, fragment);
trans.addToBackStack("profile");
trans.commit();
It just return me null here so I can't use this fragment. No logs.
Fragment fragment2 = getFragmentManager().findFragmentByTag("profile");
getFragmentManager().findFragmentByTag("tag")
is only used when you have added a fragment with specific tag for e.g.
fragmentTransaction.add(R.id.order_container,mProfileFragment,"profile");
or
fragmentTransaction.replace(R.id.order_container,mProfileFragment,"sometag");
Then you will be able to find this fragment by the tag.
In your case you are adding a transaction to backstack so you will not be able to find that fragment by tag. You just adding a transaction to backstack thats it not a fragment. And also your fragment was removed from the activity and destroyed so you have to revert the transaction by popping backstack instead of finding that fragment by tag.
You have to call
getFragmentManager().popBackStack("profile");
to get that fragment back to the activity and make it visible on screen.
I have a problem with the backstack behaviour. That is what I am doing:
add(fragment1) + addToBackStack(null)
replace(fragment2) + addToBackStack(null)
What is happening:
Fragment 1 is added and in the backstack
Then the second fragment replaces the first one and it is added to the backstack.
Now I want to change my last backstacked fragment with a new transaction which put a new backstack fragment so:
[frag1, frag2] becomes [frag1, frag3]
but this transaction made by a popBackStack + replace is making the frag1 to load by calling its onCreateView and onActivityCreated. I know this is the expected behaviour since this is how backstack works, but I am trying to find a way to avoid this preload.
Edit
In this question I am using the concept of backstack fragment for the transaction to be more clear. Every transaction here is an add+remove (which is a replace).
The code for replace I am using is:
public int replaceFragment(BaseFragment newFragment, boolean addToBackStack, boolean animated, PopStackMode popMode) {
if (popMode != null) {
getSupportFragmentManager().popBackStack(newFragment.getFragmentTag(), popMode == PopStackMode.POP_INCLUSIVE ? FragmentManager
.POP_BACK_STACK_INCLUSIVE : 0);
}
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
if (animated) {
ft.setCustomAnimations(R.anim.slide_in_left, 0, R.anim.slide_out_right, 0);
}
ft.replace(R.id.fragment_container, newFragment, newFragment.getFragmentTag());
if (addToBackStack) {
ft.addToBackStack(newFragment.getFragmentTag());
}
return ft.commit();
}
You can see I am creating a navigation history based on the fragment backstack, as it was kind of a browser. When a "page" is added there is a fragment and a backstack transaction. In this context, I trying to:
Remove the current fragment.
Remove the transaction from the backstack.
Add a new fragment without poping and loading the previous backstack fragment.
I hope it is more clear.
Edit 2
I have filled a request feature for a flag that supports this behavior. Find it here.
First, you should understand that the backstack doesn't save fragments, but it saves transactions instead. When you call popBackStack what it actually does is revert the previous transaction. More on this here.
I think that you can do this:
Name your transactions by providing a unique name to your addToBackStack instead of null. i.e. addToBackStack("frag1").
Don't call popBackStack + replace, but instead just call replace.
Then, in your activity, override your onBackPressed and if the current fragment being displayed is Frag3 (you can check this using findFragmentByTag if you provided a tag in the replace method) you can call getSupportFragmentManager().popBackStackImmediate("frag1", FragmentManager.POP_BACK_STACK_INCLUSIVE); (otherwise call the super.onBackPressed)
Working with fragments I've always used replace() for my transactions, but I wish I didn't have to save instance states anymore to restore a fragment's view and prevent reloading when coming back to that fragment. So, I've decided to work with add(). The thing is when I add another fragment, the previous fragment view remains in the background and that's fine (that's the behavior I expected), but the problem is I can actually interact with the views in the background. Example:
Fragment A has a Button
Fragment B has a TextView
When I add Fragment A and later add Fragment B, I'm able to click on Fragment A's Button, even staying on Fragment B's view.
I'm using:
FragmentTransaction fragmentTransaction =
getSupportFragmentManager().beginTransaction().
add(getRootViewContainer(),fragment,fragment.getClass().getSimpleName());
if (shouldGoBack)
fragmentTransaction.addToBackStack(fragment.getClass().getSimpleName());
where getRootViewContainer() returns the id of the FrameLayout I'm using as my activity main container.
Now, is it really the default behavior of add()?
If so, is there a proper way to avoid this or one just has to use replace()?
What you can do here is just hide previous fragment at the time of transaction of current fragment.
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
Fragment newFragment= new MyFragment ();
ft.hide(CurrentFragment.this);
ft.show(newFragment);
ft.commit();
It worked for me just try it.
FragmentTransaction.hide(fragmentBehind); //works for me!
example :
//I have it globally available
FragmentTransaction trans = MainActivity.getManager().beginTransaction();
//not globally
FragmentTransaction trans = getFragmentManager().beginTransaction();
MapFragment newFragment = new newFragment();
trans.add(R.id.fragmentContainer, newFragment, tag);
trans.hide(this);
trans.addToBackStack(tag);
trans.commit();
Yes, this is a default behaviour of add().
If you really don't want to user replace(), you can try to disable views which are inside "old" fragment.
I use a holder activity with FrameLayout.
There I put a fragment with a listview. It works fine.
ft = getSupportFragmentManager().beginTransaction();
ft.add(R.id.fragments, feedFragment);
ft.commit();
Then I add another fragment.
android.support.v4.app.Fragment targetFragment = new MainPhotoFragment();
ft = getSupportFragmentManager().beginTransaction();
ft.add(R.id.fragments, targetFragment);
ft.addToBackStack(null);
ft.commit();
Here I use add() instead of replace() to return to previous position of the listview when hitting back key. It works fine.
But it is possible to navigate to the third fragment from the second fragment.
android.support.v4.app.Fragment targetFragment = new FullPhotoFragment();
ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.fragments, targetFragment);
ft.addToBackStack(null);
ft.commit();
Here I use replace to force the 2nd fragment to reload when hitting back key.
Sometimes back key from the third fragment works fine, it displays the second fragment that is reloading on appearing.
But sometimes (as I can see it happens first time when I try this steps) hitting back key from the third fragment leads me to the first fragment, closing the second fragment against my expectations. And the first fragment is reloading.
How to prevent this strange behavious?
add() method will add Fragments to Container and any other fragments added to the Container will be queued back of the first fragment. They will be not visible until and unless first fragment made Invisible. I hope this is the problem you are facing. It would be good if you use replace() for the first-->second fragment navigation also.