How to Handle backPress with Fragment

Question

i have Fragment Activity With contatin navigation drawer.after clicking navigation drawer item it open a Fragment 1, fragment 2, Fragment 3.and then after button click event in Fragment 1 open new Fragment 4.

i want handle back key press event how can i do this on Fragment 4?after clicking back key in Fragment 4 i want to go back Fragment 1.

enter image description here

if you don't do any thing this must be happened, witch fragment opened after backPress ? — Shayan Pourvatan, Dec 31 '14 at 06:30
http://stackoverflow.com/questions/7992216/android-fragment-handle-back-button-press — duggu, Dec 31 '14 at 06:33
no after backpress it open a my home layout which is `Fragment 2` it is set as main fragment in navigation drawer — hash, Dec 31 '14 at 06:36
please post some code, because i think if you don't change any thing pre fragment must be opened — Shayan Pourvatan, Dec 31 '14 at 06:40

score 20 · Accepted Answer · edited Dec 31 '14 at 09:11

20

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(); 
    }
}

edited Dec 31 '14 at 09:11

hash

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answered Dec 31 '14 at 06:36

sandeepmaaram

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you mean like this `getFragmentManager() .beginTransaction() .replace(R.id.content_frame, Entry_Account.newInstance(), Entry_Account.TAG).addToBackStack() .commit();` inside my `Fragment 1` but it says `The method addToBackStack(String) in the type FragmentTransaction is not applicable for the arguments ()` – hash Dec 31 '14 at 06:39
5

In Activity onBackPressed() method if(fm.getBackStackEntryCount()>0){pop the fragment} else{super.onBackPressed();} – sandeepmaaram Dec 31 '14 at 06:46
what do you mean in `{pop the fragment}` – hash Dec 31 '14 at 06:48
remove fragment from stack like fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE); – sandeepmaaram Dec 31 '14 at 06:50
1

This is the correct answer. Adding fragment transactions to the backstack will reverse the transaction on back pressed. – DeeV Dec 31 '14 at 06:55
Fragments don't get added to the backstack. The transaction does. Everything you do in a transaction (add, replace, remove, hide, etc.) will be reversed all at once if you push it on the stack and then pressed "back". – DeeV Dec 31 '14 at 06:56
@Sameera Is it working for you? Yeah agree with above comment – sandeepmaaram Dec 31 '14 at 06:57
i add this on your code's `{pop the fragment}` section `getSupportFragmentManager().popBackStack();` – hash Dec 31 '14 at 06:58
`@Override public void onBackPressed() { if (getSupportFragmentManager().getBackStackEntryCount() > 0) { getSupportFragmentManager().popBackStack(); } else { this.finish(); } }` – hash Dec 31 '14 at 06:59
1

`addToBackStack("Some string") .commit();` – hash Dec 31 '14 at 09:07
1

I think else { super.onBackPressed(); } would provide a more graceful fallback than assuming Activity.finish(). Also, it's strange you need to implement this logic when using android.app.FragmentManager, but _not_ android.support.v4.app.FragmentManager. I received default back stack handling when using the support library version. – Damien Diehl Jul 01 '15 at 15:12
@damien5314 Oh my god this^ I just spent close to 2 hours trying to figure out what the hell had happened to my back stack and I had swapped from support fragments to normal ones recently. God dammit! – Daniel Wilson Nov 04 '15 at 14:51

score 5 · Answer 2 · answered Dec 31 '14 at 06:51

5

Your code for adding fragment to backstack should be like:

getFragmentManager() .beginTransaction() .replace(R.id.content_frame, Entry_Account.newInstance(), Entry_Account.TAG).addToBackStack("Some string") .commit();

Then On Activity's onBackPressed method,use this snippet:

@Override
public void onBackPressed () {
if(getFramentManager().getBackStackEntryCount()>0){
      // popback statck.
}
 else{
     // finish your activity.
 }
}

answered Dec 31 '14 at 06:51

Bhawna Raheja

524
6
9

`@Override public void onBackPressed() { if (getSupportFragmentManager().getBackStackEntryCount() > 0) { getSupportFragmentManager().popBackStack(); } else { this.finish(); } }` – hash Dec 31 '14 at 07:04

Sanket Kachhela · Answer 3 · 2014-12-31T06:54:20.337

4

Override onBackPress() method and check that your fragement manager has backStack entry>0 if it has greater than 0 than do popback stack otherwise finish your activity..

if(getFramentManager().getBackStackEntryCount()>0){
      // popback statck.
}
 else{
     // finish your activity.
 }

don't forget to add your fragement to BackStack to maintain fragment hierarchy..

fragTransacion.addToBackStack(TAG);

edited Dec 31 '14 at 06:54

answered Dec 31 '14 at 06:40

Sanket Kachhela

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how can i add fragement to BackStack to maintain fragment hierarchy? – hash Dec 31 '14 at 06:49

How to Handle backPress with Fragment

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