Add other fragment to backstack? - android

My app use 5 fragment, like this:
[1]through[onClick on actionBar defined in activity]->[2]->[3]->[4]->[5]
Each fragment is added to the back stack so I can go back while pressing the back button. However, I would like to return to the first fragment when pressing the back button on the 5th fragment, like this:
[1]<-[2]<-[3]<-[4] [1]<-[5]
I tried to make it this way:
fragmentTransaction.addToBackStack("firstfragmenttag");
When adding the 5th fragment on the 4th one, but when I press the back button it still send me back to the 4th instead of the 1st! Is it a simple way do do that programmatically? Thanks in advance.

In your case, you just need to add first fragment in stack.
No need to add others to stack
This could be achieved in following way:
Fragment F1 = new <Fragment Name>();
fragmenttransaction.add(R.id.content,F1).commit();
And for others like F2,F3,F4 & F5
you could use
Fragment F2 = new <Fragment Name>();
fragmenttransaction.replace(R.id.content,F2).addToBackstack(null).commit();
And then you need to override OnBackpressed [inside Activity] like below:
#Override
public void onBackPressed() {
if(getSupportFragmentManager().getBackStackEntryCount() >0) {
getSupportFragmentManager().popBackStack();
}
else{
super.onBackPressed();
}
}
Hope it helps!

you can actually get the backstack count in onBackPressed and check count , if it is 5 then perform popfrombackstack 4 times to get back to 1 fragment

Related

How to determine if fragment at top of other fragment is removed

I have fragment A and adding fragment B in same container (not replacing). I am adding this transaction on backstack also. Now, when device back is pressed, fragment B will be removed and fragment A will become visible. I want to do something when fragment A becomes visible. I searched lot but could not find anything helpful.
Note - I don't want to add backstackchangelistner and call onResume on that fragment.
You can override onHiddenChanged(boolean hidden) in a Fragment.
This will be called when its shown/hidden.
I use the same approach in my app, where i add a fragment and hide the old one, and then use the onHiddenChanged callback when the user presses Back, and the old fragment is shown again.
As you have 2 entries in Back stack, you can check back stack count on
Back Pressed method.
FragmentManager mFragmentManager = getSupportFragmentManager();
int count= mFragmentManager.getBackStackEntryCount();
if(count==1){
// do your work
}
you can try
#Override
public void setMenuVisibility(boolean menuVisible) {
super.setMenuVisibility(menuVisible);
}
or
`fragment.isVisible();`

Saving Fragment State on Back Button Select

I'm so very confused and have been reading on this topic for a while.
I have a MainActivity that has multiple possible contents (switched between via navigation drawer), which I've set via multiple fragments (lets call them Fragment1, Fragment2 and Fragment3).
That works fine.
One of my fragments, Fragment3, is a View that can segue to a new activity, View2.
View2 has a back button. When I press on the View2 back button I want to see Fragment3 on my MainActivity, not Fragment1, which is what I currently get. This is because OnCreate, by default, loads Fragment1.
What is the best way to do this?
Thanks so much in advance! (vent: iOS makes this so much easier).
The official documentation for Fragments states that you should make sure to call addToBackStack() before commiting your fragment transaction on your first activity holding the 3 fragments.
In order to go back to the last used fragment from the second activity , you should override the onBackPressed() method in this activity :
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
The documentation is very complete on the subject : Read it here
Update:
I just added this to the back button code:
finish();
return true;
I had to do it within onOptionsItemSelected(MenuItem item)... for some reason onBackPressed is not fired.

Remove multiple fragments in back stack

Suppose we have three fragments hosted in an activity on our back stack
A->B->C
When I click on back press on fragment C I also want to immediately remove B from the back stack.Note that in some cases I might want to go back to B but for the most part I want to clear out C and B together to get to A.How can I achieve this should I call popBackStack() twice or should I have some kind of delegate mechanism to notify B that C has been closed and we don't expect to show B so please clean up.
In fragment A do this..
getSupportFragmentManager().beginTransaction()
.add(R.id.containerMain, new FragmentA()).addToBackStack("BACKSTACK_FRAGMENT_A")
.commit();
and do not use addToBackStack(..)
in this case you'll always return to Fragment A when you press back from other Fragments.
and when are going to specify back press to specific fragment
Add Fragments To BackStack. Before commit() the transaction, use addToBackStack() method i.e
addToBackStack("Some String").commit();
and in onBackPressed()
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
} else {
this.finish();
}
}

how to maintain the fragment depend upon back button?

I've got a navigation drawer. In that navigation drawer I've got five fragments. When I select a fragment, it shows up. When I press the back button, it goes to the previous fragment. However, I need the back button to send you back to the first fragment. How do I do this?
Overwrite the onBackPressed() method in your Activity:
#Override
public void onBackPressed(){
FragmentTransactionn ft = getFragmentManager().beginTransaction();
ft.replace([your fragment container], yourfirstFragment, TAG_FRAGMENTFIRST);
ft.commit();
}
Apparently you already figured out how to show fragments. I'd suggest using the same code you use in your navigation drawer in the public void onBackPressed() to draw up the first fragment again. To make users able to exit the app, check if the first fragment is already visible. If so, call super.onBackPressed() or finish().

Recreate Fragments on BackKey Pressed

Im trying to Solve a problem where when a user press back key, the fragment should be recreated rather than loading from back stack. I have a single Main activity with a frame layout and i replace the fragments within the single frame dynamically. the code below works when the user go from fragment within fragment. but when the user select from navigation drawer, the replaced fragment is going on to the top of backstack which is causing problems.
Right now the code i wrote in BackKey Pressed Event
public override void OnBackPressed()
{
Android.Support.V4.App.FragmentManager.IBackStackEntry entry =
SupportFragmentManager.GetBackStackEntryAt(SupportFragmentManager.BackStackEntryCount - 1);
string str = entry.Name;
if (SupportFragmentManager.BackStackEntryCount == 0)
{
this.Finish();
}
else
{
Fragment fr = (Fragment)MagicallyCreateInstance(str);
SupportFragmentManager.BeginTransaction().Replace(Resource.Id.content_frame, fr).Commit();
SupportFragmentManager.PopBackStack();
}
base.OnBackPressed();
}
i also have a replace fragment method which i use to replace fragments. but in this process the back key is getting disabled by default somehow (Not sure how) but whenever there is existing fragment in the backstack, the old UI is getting loaded. Can i refresh the layout here?
public void ReplaceFragment(Fragment fragment, FragmentManager fragmentManager)
{
string backStateName = fragment.Class.SimpleName;
bool fragmentPopped = fragmentManager.PopBackStackImmediate(backStateName, 0);
if (!fragmentPopped && fragmentManager.FindFragmentByTag(backStateName) == null)
{
fragmentManager.BeginTransaction()
.Replace(Resource.Id.content_frame, fragment).SetTransitionStyle(FragmentTransaction.TransitFragmentFade)
.AddToBackStack(backStateName)
.Commit();
}
}
Can anyone please help me solve this any one of the above?
I hope I'm understanding your problem correctly. But it sounds like you want to make sure that when the user selects a destination from your main navigation you want to make sure the back stack is cleared or reset.
Ex:
Stack looks like this:
A->B->C
User selects D from main navigation, stack should look like:
D
NOT
A->B->C->D
If this is the case, you should clear the back stack before navigating to any top-level destinations. This can be done like so:
FragmentManager.PopBackStack(null, FragmentManager.PopBackStackInclusive);
The documentation for this method is not great, but it will pop everything off the back stack. A discussion can be found here: https://groups.google.com/d/msg/android-developers/0qXCA9rW7EI/M9riRM0kl9QJ

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