Develop Reference

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();`

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();
}
}

Add other fragment to backstack?

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

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().

Detecting the visible fragment in android

I want to implement the onbackpressed() in android and my code is as follows
public void backpressed(){
NDListeningFragment fragment1=(NDListeningFragment)getSupportFragmentManager().findFragmentByTag(ConnectedDevicesFragment.TAG);
if(fragment1!=null && fragment1.isVisible())
{
super.onBackPressed();
}
else
{
fragment1=(NDListeningFragment)SimpleFragmentFactory.createFragment(ConnectedDevicesFragment.TAG);
getSupportFragmentManager().beginTransaction().replace(R.id.content,fragment1).commit();
fragment1.setUserVisibleHint(true);
}
}
The above code checks if the visible fragment is ConnectedDevicesFragment. If yes then super() is called and if not then I create ConnectedDevicesFragment and replace it in the framelayout.
But I am not able to implement in this way. When I press back button it reloads the Connected DevicesFragment again and again.
can you help with some workaround.
Cheers!

You creates fragment1 object every time in the onBackPressed function it means it will not null and it is on invisible state. You need to add NDListeningFragment in backstack when you open NDListeningFragment first and check Is the fragment available in back stack. If yes then call super.onBackpressed.