AndroidDesignPattern | android源码设计模式 | Architecture library

I have problem with fragments in ViewPager. In my app I have 4 tabs implemented with FragmentStatePagerAdapter. Here is my SectionsPageAdapter.java

First of all, I've read dozens of SO questions and read excellent post by Alex Lockwood about the IllegalStateException problems connected with fragment transactions: https://www.androiddesignpatterns.com/2013/08/fragment-transaction-commit-state-loss.html - tl;dr I've done my homework

But what I didn't find anywhere is the IllegalStateException problem when the screen goes off and we are trying to commit fragment transaction - show DialogFragment in my case.

What is exactly happening in my app is reacting to other activity result and later on showing a DialogFragment. As suggested by many SO users, I'm not showing dialog from onActivityResult but from onPostResume (I've tried also with onResumeFragments) Simplified code looks like this

I'm using the BottomNavigationView from the Android Design Support Library on one of my Activities, alongside with Fragments for each navigation item.

Each time I select an item on the bar, I do a fragment transaction, like the snippet below (some parts of the code was removed for brevity):

I have an activity that loads multiple fragments depending on user action (button click) or event (FCM Data Message which triggers a LocalBroadcast).

I hit a snag recently when I put a Fragment Transaction inside a BroadcastReceiver, and as soon as the receiver gets triggered, instead of loading up the next fragment, I get the first (default) fragment which is loaded in the OnCreate of the activity, implying that the Activity has reset/restarted somehow.

Given the speed of this, the only error I managed to see before the logcat on Android Studio reset was this :

java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState

Digging around hasn't helped much, except for this article on Activity State Loss which I discovered. It is rather old (2013) but seems to make sense. However, there is no solution that I can think of, short of making my fragment a bit more complicated, and handing the next fragment's logic in this one itself.

Please find the bit of code where this happens below.

Actually i'm trying to make an app that take restaurant orders and i'm having some issues after adding child item to my order.

I have a recyclerView where i have different type's of food when i press on one of them i add it to recyclerView that work's something like a notebook, then i have an button that open an AlertDialog in which there is another recyclerView with variant's.

Example: i press on PIZZA from food recyclerView it's add it to the notebook after i press on variant's and i can add "WITH PEPERONI" or "LARGE" or both.

I have followed this guide ( here github project from the guide) for making the recyclerView with child item.

Now the issue is how can i add the child item to the last parent item?

like i'm adding parent item using this:

Following this article I modified my handler within the Activity class as follows:

Suppose I have a VectorDrawable that look like a top->down arrow:

So I've run into the infamous Can not perform this action after onSaveInstanceState problem and am having a tough time figuring out how to fix it.

Currently I can cause it by logging out of my application via the onNavigationItemSelected menu.

According to the documentation of Handler.postDelayed(Runnable r, long delayMillis):

Causes the Runnable r to be added to the message queue, to be run after the specified amount of time elapses. The runnable will be run on the thread to which this handler is attached.

On the other hand View.postDelayed(Runnable action, long delayMillis):

Causes the Runnable to be added to the message queue, to be run after the specified amount of time elapses. The runnable will be run on the user interface thread.

I want to know if there is a difference between the two while calling them from the main thread and in particular, if there is a difference when the activity is being destroyed?

I have read this article about how I might leak an Activity when I use an inner class Handler and I was wondering whether using View.postDelayed() would cause the same problem.

For example could foo() cause an issue or would the destruction of the activity solve the fact that the Runnable anonymous class is holding a reference to the activity?