Change leaf from activit in fragment

You have chosen not the most successful approach to solving the problem.

The relationship between activism and fragments is complex, ambiguous and leads to a multitude of problems when misinterpreting the life cycle of both elements.

It is best (according to my experience) not to communicate with the fragment directly from the activation, but to use, for example, LocalBroadcastManager

Task:

Update the list of activations by assigning to it an adapter with the data that is in the activation. For this:

Decision:

1) In the onCreateView () fragment, we find the ListView and assign it to a fragment variable.

 ListView lV; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { //inflate root view View v; v = inflater.inflate(R.layout.YOURS_FRAGMENT_LAYOUT_WITH_LIST_VIEW, container, false); this.lV=v.findViewById(R.id.YOURS_LIST_VIEW_IN_FRAGMENTS_LAYOUT_ID); return v; } 

2) Create a method in the fragment that accepts data for the list, initializes the adapter and assigns it to the list:

 private void setAdapterForListView(String[] yoursStringArrayWithData) { ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.rowlayout, R.id.label, yoursStringArrayWithData); this.lv.setAdapter(adapter); } 

3) Describe how the fragment should respond to the LocalBroadcastManager messages:

 private BroadcastReceiver receiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { //наши данные из активити придут внутри Intent //значит надо их вытащить String[] yoursStringArrayWithDataFromIntent = intent.getStringArrayExtra("stringKeyToExtractData"); //вызываем наш метод, коий сделает адаптер с пришедшими данными //и присвоит его списку setAdapterForListView(yoursStringArrayWithDataFromIntent ) } }; 

4) The fragment should know that it can receive messages and respond to them. We write this line in the onCreate () of the fragment.

 LocalBroadcastManager.getInstance(this.act).registerReceiver(receiver, new IntentFilter("setAdapterToListView")); 

5) It is important to teach the fragment how to de-register a message and clear the memory. We write:

  @Override public void onDestroy() { //если reciver существует, то отменяем регистрацию и стираем его. if (receiver != null) { LocalBroadcastManager.getInstance(act).unregisterReceiver(receiver); receiver = null; } // Не забываем вызвать super метод в конце super.onDestroy(); } 

6) It remains only to activate the message with the data for the adapter, which will be received and processed by the fragment. We write in the right place to activate:

 //Наши данные для адаптера String[] data={"раз", "два", "три", "рубль", "расти"}; //Создаём интент, пихаем в него наши данные Intent intent=new Intent("setAdapterToListView"); Bundle b=new Bundle(); b.putStringArray("stringKeyToExtractData", data); intent.putExtras(b); //Посылаем сообщение с данными LocalBroadcastManager.getInstance(context).sendBroadcast(intent); 

Total:

1) At the right time (by clicking or by the arrival of data) from the activation we send a message with the data.

2) The fragment catches the message (determines that this message is to it by line, which is passed to the intent constructor.

3) Does everything you need. In this case, it pulls out the data, transfers it to the list.

Possible problems:

We must remember about the life cycle. There is no sense in sending a message with data from onCreate () activation, because there are no fragments yet, no markup in them, the application crashes.