biquillo
biquillo

Reputation: 6539

Clear back stack using fragments

I ported my Android app to honeycomb and I did a big refactor in order to use fragments. In my previous version, when I pressed the Home button I used to do a ACTIVITY_CLEAR_TOP in order to reset the back stack.

Now my app is just a single Activity with multiple fragments, so when I press the Home button I just replace one of the fragments inside it. How can I clear my back stack without having to use startActivity with the ACTIVITY_CLEAR_TOP flag?

Upvotes: 280

Views: 296442

Answers (16)

ΓDΛ
ΓDΛ

Reputation: 11060

Kotlin extension

fun AppCompatActivity.clearAllFragments() {
    supportFragmentManager.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE)
}

Upvotes: 1

Marius Kohmann
Marius Kohmann

Reputation: 721

For the kotlin people around here:

repeat(supportFragmentManager.backStackEntryCount) {
    supportFragmentManager.popBackStack()
}

Upvotes: 8

PJL
PJL

Reputation: 18794

I posted something similar here

From Joachim's answer, from Dianne Hackborn:

http://groups.google.com/group/android-developers/browse_thread/thread/d2a5c203dad6ec42

I ended up just using:

FragmentManager fm = getActivity().getSupportFragmentManager();
for(int i = 0; i < fm.getBackStackEntryCount(); ++i) {    
    fm.popBackStack();
}

But could equally have used something like:

((AppCompatActivity)getContext()).getSupportFragmentManager().popBackStack(String name, FragmentManager.POP_BACK_STACK_INCLUSIVE)

Which will pop all states up to the named one. You can then just replace the fragment with what you want

Upvotes: 471

Alok Singh
Alok Singh

Reputation: 660

It is working for me,try this one:

public void clearFragmentBackStack() {
        FragmentManager fm = getSupportFragmentManager();
        for (int i = 0; i < fm.getBackStackEntryCount() - 1; i++) {
            fm.popBackStack();
        }
    }

Upvotes: 4

Chenxi
Chenxi

Reputation: 171

Hi~I found a solution which is much better,from: https://gist.github.com/ikew0ng/8297033

    /**
 * Remove all entries from the backStack of this fragmentManager.
 *
 * @param fragmentManager the fragmentManager to clear.
 */
private void clearBackStack(FragmentManager fragmentManager) {
    if (fragmentManager.getBackStackEntryCount() > 0) {
        FragmentManager.BackStackEntry entry = fragmentManager.getBackStackEntryAt(0);
        fragmentManager.popBackStack(entry.getId(), FragmentManager.POP_BACK_STACK_INCLUSIVE);
    }
}

Upvotes: 14

Morten Holmgaard
Morten Holmgaard

Reputation: 7806

To make an answer for @Warpzit's comment and make it easier for others to find.

Use:

fragmentManager.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);

Upvotes: 200

user3509903
user3509903

Reputation: 65

private boolean removeFragFromBackStack() {
    try {
        FragmentManager manager = getSupportFragmentManager();
        List<Fragment> fragsList = manager.getFragments();
        if (fragsList.size() == 0) {
            return true;
        }
        manager.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
        return true;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return false;
}

Upvotes: 1

Wajid
Wajid

Reputation: 2341

    private void clearBackStack(){
        SupportFragmentManaer fm = getSupportFragmentManager();
        fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
    }

Call to this method would be very neat.

  1. No Loop required.
  2. If you are using animation in fragments, it will not show too many animations. But using loop will.

Upvotes: 1

Arhat Baid
Arhat Baid

Reputation: 1023

Just use this method and pass Context & Fragment tag upto which we need to remove the backstake fragments.

Usage

clearFragmentByTag(context, FragmentName.class.getName());



public static void clearFragmentByTag(Context context, String tag) {
    try {
        FragmentManager fm = ((AppCompatActivity) context).getSupportFragmentManager();

        for (int i = fm.getBackStackEntryCount() - 1; i >= 0; i--) {
            String backEntry = fm.getBackStackEntryAt(i).getName();
            if (backEntry.equals(tag)) {
                break;
            } else {
                 fm.popBackStack();
            }
        }
    } catch (Exception e) {
        System.out.print("!====Popbackstack error : " + e);
        e.printStackTrace();
    }
}

Upvotes: 4

trans
trans

Reputation: 1441

Reading the documentation and studying what the fragment id is, it appears to simply be the stack index, so this works:

fragmentManager.popBackStackImmediate(0, FragmentManager.POP_BACK_STACK_INCLUSIVE);

Zero (0) is the the bottom of the stack, so popping up to it inclusive clears the stack.

CAVEAT: Although the above works in my program, I hesitate a bit because the FragmentManager documentation never actually states that the id is the stack index. It makes sense that it would be, and all my debug logs bare out that it is, but perhaps in some special circumstance it would not? Can any one confirm this one way or the other? If it is, then the above is the best solution. If not, this is the alternative:

while(fragmentManager.getBackStackEntryCount() > 0) { fragmentManager.popBackStackImmediate(); }

Upvotes: 4

georgehardcore
georgehardcore

Reputation: 1055

Clear backstack without loops

String name = getSupportFragmentManager().getBackStackEntryAt(0).getName();
getSupportFragmentManager().popBackStack(name, FragmentManager.POP_BACK_STACK_INCLUSIVE);

Where name is the addToBackStack() parameter

getSupportFragmentManager().beginTransaction().
                .replace(R.id.container, fragments.get(titleCode))
                .addToBackStack(name)

Upvotes: 28

Nicks
Nicks

Reputation: 16317

I just wanted to add :--

Popping out from backstack using following

fragmentManager.popBackStack()

is just about removing the fragments from the transaction, no way it is going to remove the fragment from the screen. So ideally, it may not be visible to you but there may be two or three fragments stacked over each other, and on back key press the UI may look cluttered,stacked.

Just taking a simple example:-

Suppose you have a fragmentA which loads Fragmnet B using fragmentmanager.replace() and then we do addToBackStack, to save this transaction. So the flow is :--

STEP 1 -> FragmentA->FragmentB (we moved to FragmentB, but Fragment A is in background, not visible).

Now You do some work in fragmentB and press the Save button—which after saving should go back to fragmentA.

STEP 2-> On save of FragmentB, we go back to FragmentA.

STEP 3 ->So common mistake would be... in Fragment B,we will do fragment Manager.replace() fragmentB with fragmentA.

But what actually is happenening, we are loading Fragment A again, replacing FragmentB . So now there are two FragmentA (one from STEP-1, and one from this STEP-3).

Two instances of FragmentsA are stacked over each other, which may not be visible , but it is there.

So even if we do clear the backstack by above methods, the transaction is cleared but not the actual fragments. So ideally in such a particular case, on press of save button you simply need to go back to fragmentA by simply doing fm.popBackStack() or fm.popBackImmediate().

So correct Step3-> fm.popBackStack() go back to fragmentA, which is already in memory.

Upvotes: 11

Md Mohsin
Md Mohsin

Reputation: 1568

Works for me and easy way without using loop:

 FragmentManager fragmentManager = getSupportFragmentManager();
 //this will clear the back stack and displays no animation on the screen
 fragmentManager.popBackStackImmediate(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);

Upvotes: 23

dbm
dbm

Reputation: 10485

With all due respect to all involved parties; I'm very surprised to see how many of you could clear the entire fragment back stack with a simple

fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);

According to Android documentation (regarding the name argument - the "null" in the claimed working proposals).

If null, only the top state is popped

Now, I do realize that I'm lacking knowledge of your particular implementations (like how many entries you have in the back stack at the given point in time), but I would bet all my money on the accepted answer when expecting a well defined behaviour over a wider range of devices and vendors:

(for reference, something along with this)

FragmentManager fm = getFragmentManager(); // or 'getSupportFragmentManager();'
int count = fm.getBackStackEntryCount();
for(int i = 0; i < count; ++i) {    
    fm.popBackStack();
}

Upvotes: 48

Pedro Andrade
Pedro Andrade

Reputation: 4634

I got this working this way:

public void showHome() {
    getHandler().post(new Runnable() {
        @Override
        public void run() {
            final FragmentManager fm = getSupportFragmentManager();
            while (fm.getBackStackEntryCount() > 0) {
                fm.popBackStackImmediate();
            }
        }
    });
}

Upvotes: 1

Sukru A.
Sukru A.

Reputation: 483

Accepted answer was not enough for me. I had to use :

FragmentManager fm = getSupportFragmentManager();
int count = fm.getBackStackEntryCount();
for(int i = 0; i < count; ++i) {
    fm.popBackStackImmediate();
}

Upvotes: 18

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