I am experiencing an issue where the previous fragment on my stack displays when transitioning to another fragment on low end devices.
Lets say I have three fragments on my stack; A, B and C. From fragment C I am starting fragment A, but I am seeing fragment B before fragment A loads. Is there any way to prevent this, other than using a transition which seems to do the trick.
I guess I am hoping there is some attribute that might be useful in this scenario. Here is how I am making my fragment transitions.
private void fragReplaceContentFragment(Fragment fragment, boolean withBackStack) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(contentFragmentContainer.getId(), fragment, String.valueOf(fragment.hashCode()));
if (withBackStack) {
transaction.addToBackStack(null);
}
transaction.commitAllowingStateLoss();
}
Try to replace transaction.commitAllowingStateLoss(); by transaction.commit(); and give a feedback here.
Related
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)
I've been working with fragments for a while now, but I regularly encounter a problem that just annoys me. Fragments remain drawn over each other some times. Now, I managed to isolate one use case for this, and it goes like this:
Add Fragment A (also use addToBackStack with a name "backstack_state")
Replace Fragment A with Fragment B (use addToBackStack)
Replace Fragment B with Fragment C WITHOUT using addToBackStack
at a given point use popBackStack("backstack_state", 0) and here comes the issue:
The backstack is popped until Fragment A but Fragment C is overlaid with Fragment A, both are visible at the same time. Is this normal behavior or is it me who makes a mistake?
Here's a remark also: all the fragments have transparent background.
Thanks!
This happens because the top fragment (in this case Fragment C) is not removed. You have to remove it first inside a fragment transaction. Try this:
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Fragment topFragment = fragmentManager.findFragmentById(R.id.fragment_container);
if (topFragment != null) {
fragmentTransaction.remove(topFragment);
}
fragmentTransaction.commit();
fragmentManager.popBackStack("backstack_state", 0);
I have following issue with Android compatibility package fragments.
There is following hierarchy of fragments:
A(login) -> B(dashboard) -> C(details)
Login fragment is added with function:
private void addFragment(Fragment f) {
FragmentTransaction ft = mFragmentManager.beginTransaction();
ft.replace(R.id.main_content, f);
ft.commit();
}
After successfull login dashboard is added same way, without adding transaction to backstack. C fragment is added like:
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.main_content, f, id);
ft.addToBackStack(null);
ft.commit();
So basically on detail screen I have logout button, which should bring me to login A and remove all fragments from backstack. According to android developer docs:
Whereas, if you do call addToBackStack() when removing a fragment, then the fragment is stopped and will be resumed if the user navigates back.
But it is not the issue in my case. When logout is pressed in C fragment:
getFragmentManager.popBackStackImmediate();
FragmentTransaction ft = mFragmentManager.beginTransaction();
ft.replace(R.id.main_content, new LoginFragment());
ft.commit();
onActivityCreated(), onStart() of B fragment are also called (instead of onResume written in docs), making my code crash because in this fragment Im starting some thread operation, and after adding login fragment I got IllegalStateException that fragment B is not attached to an activity (when thread operation is over it updates fragment UI) Do anyone knows how replace really works and how overcome this problem?
I guess you should call
addToBackStack for each fragment you add giving a different name to them.
Reading your code seems to me you don't do it.
So I have enabled the setting to destroy actvities when you navigate away from an activity
Settings=>Developer Options=>Don't Keep activites
This should basically replicate an activity or fragment getting garbaged collected and then I have to restore the data via the bundle savedinstancestate.
So I understand how that works. But it seems when I navigate from fragment 1 to fragment 2 and then put the application in the background and then in the foreground(destroying the activity)
Both fragment 1 and fragment 2 show at the same time. In which only fragment 2 should be showing.
I do not know if this is something standard that I have to manage hiding and showing fragments onsavedinstance. Or if something in my code is breaking things. Below is how I push fragments which I hope is helpful:
public void pushFragmentWithAnimation(FragmentManager fm, int parentId, Fragment currentFrag, Fragment newFrag, int animEntry, int animExit) {
hideSoftKeyboard(currentFrag.getActivity());
FragmentTransaction ft = fm.beginTransaction();
// See: http://developer.android.com/reference/android/app/FragmentTransaction.html#setCustomAnimations(int, int, int, int)
ft.setCustomAnimations(animEntry, animExit, animEntry, animExit);
ft.add(parentId, newFrag, String.format("Entry%d", fm.getBackStackEntryCount())).hide(currentFrag).show(newFrag);
ft.addToBackStack(null);
ft.commit();
}
Fragment 1 is still in the backstack because when I press back I only see fragment 1. Let me know if you know why this is happening.
The lifecycle of XML added Fragments and programmatically added Fragments differ enough to make mixing them a bad idea, as explained in detail here.
The easiest way around this is to make all fragments programmatically added by replacing your XML inflated Fragment with a FrameLayout of the same ID, then in your onCreate add
FragmentManager fragMgr = getSupportFragmentManager();
if (null == fragMgr.findFragmentByTag(FRAG_TAG))
{
fragMgr.beginTransaction().
add(R.id.fragment, new Fragment1(), FRAG_TAG).commit();
}
Where FRAG_TAG is any unique string. This ensures that Fragment1 is only created if it is not already in the layout.
I am not entirely sure why this solution works. I assume its related to if the activity gets killed that it does not keep track of which fragment is currently shown and shows all of the fragments. So basically I needed to replace:
ft.add(parentId, newFrag, String.format("Entry%d", fm.getBackStackEntryCount())).hide(currentFrag).show(newFrag);
with
ft.replace(parentId, newFrag, tag);
Then when I create the initial fragment in the main activity. I only would do that when
if(savedInstanceState==null){
My updated code is below: https://github.com/CorradoDev/FragmentTest/tree/2c53f9f42e835da768f61b0233f3ab5b3adf2448
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.