[Android] Anomalia durante la modifica manuale del savedInstanceState di un ViewPager

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Salve a tutti, ho aperto una discussione su stackoverflow ma non ho ricevuto risposta.

Incollo qui la mia domanda che ho fatto lì.

Se ci sono problemi con il fatto che il seguente testo è in inglese vi prego di farmelo sapere, lo traduco senza alcun problema!

I have a ViewPager (instantiated with FragmentStatePagerAdapter) with some Fragment attached to it.

In a specific usecase I need to reset instanceBean and UI for most of the fragments in the pager.

After some googling I have tried some solutions like this but the side effects were not easy manageable. Other solution like this doesn't match my needs.

So I decided to go straight with the manual reset of the UI and instanceBean obj like in the code below:

The code

Single fragment reset

	public void initFragment() {
		notaBean = new NoteFragmentTO();
		
		fromSpinnerListener = false;
	}
	
	public void resetFragment() {
		initFragment();
		NoteFragment.retainInstanceState = false;
	}

This is done with the following code from the parent Activity:

Fragment reset from parent

        private void resetAfterSaving() {
		mIndicator.setCurrentItem(POSITION_F*****);
		f*****Info.resetFragment();
		
		mIndicator.setCurrentItem(POSITION_NOTE);
		noteInfo.resetFragment();
		
		mIndicator.setCurrentItem(POSITION_M*****);
		m*****Info.resetFragment();
		
		mIndicator.setCurrentItem(POSITION_V*****);
		v*****.resetFragment();
	}

AfterViews method:

        @AfterViews
    	public void afterView() {
    		if (mSavedInstanceState != null) {
    			restoreState(mSavedInstanceState);
    		}
    
    		NoteFragment.retainInstanceState = true;
    		
    		// Inits the adapters
    		noteAdapter = new NoteArrayAdapter(this, noteDefaultList);
    
    		sp_viol_nota_default.setAdapter(noteAdapter);
    		//sp_viol_nota_default.seton
    		
    		et_viol_nota.setOnFocusChangeListener(new OnFocusChangeListener() {
    
    			@Override
    			public void onFocusChange(View v, boolean hasFocus) {
    				if (!hasFocus) {
    					String readText = et_viol_nota.getText().toString().trim();
    					
    					notaBean.setNota(readText == "" ? null : readText);
    				}
    			}
    		});
    	}

OnSavedInstanceState

    @Override
    public void onSaveInstanceState(Bundle outState) {
    	super.onSaveInstanceState(outState);
    	
    	outState.putParcelableArrayList(KEY_NOTE_D_LIST, (ArrayList<VlzAnagraficaNoteagente>) noteDefaultList);
    	outState.putInt(KEY_NOTE_D_POSITION, !NoteFragment.retainInstanceState ? 0 : notePosition);
    
    	notaBean.setNota(!NoteFragment.retainInstanceState ? "" : et_viol_nota.getText().toString().trim());
    	outState.putParcelable(NoteFragmentTO.INTENT_KEY, notaBean);
    }

----------

Why do I set every page before resetting them?

Because like explained here:

When pages are not visible to the user, their entire fragment may be destroyed, only keeping the saved state of that fragment.

and because until I don't select the relative fragment the @AfterViews method (that is everything processed right after OnCreateView of the fragment) is not executed.
This throws NullPointerException for a thousand of reason (Usually in the @AfterViews method You launch RestoreState method, initializes adapter, do UI stuff).

Setting the relative page before the reset let @AfterViews method be processed.


----------


Before checking what would happened when rotating the device, all the fragment I need are correcly reset.

When rotating the device, the error comes out:

The views (mainly EditText) go back to their previous state BEFORE my reset.


What happens?

When switching between the page, at a certain point the page will be destroyed and OnSavedInstanceState is called everytime for each page.

I have already handled the OnSavedInstanceState (like above) that when the boolean is false saves the state like if it had just been created.

I found that until within AfterView method the EditText has its text set to blank (like I want) but going on with the debug the EditText goes back to its previous state, so at the end it will show the last text it had.

Question

How can I keep the manually set (in OnSavedInstanceState) EditText text after destroying/recreating a fragment?