java – clicking on the Listview closes the application when trying to access the list item's markup

Question:

I have a problem with clicking in a Listview after scrolling. That is, if I click on the content that was originally visible, then everything is OK. But if I click while scrolling through the list (that is, I click on a position that was not visible), then the program crashes with the following text in the logs:

java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference

Who faced?

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {  
         @Override 
         public void onItemClick(AdapterView<?> parent, View itemClicked, int position, long id) { 
              TextView tp = (TextView)listView.getChildAt(position).findViewById(R.id.userid);
              Log.v("mes",tp.getText().toString()); 
         }
});

Answer:

Your mistake is that you are trying to get a View from a ListView . So it is not necessary.
The View you need, i.e. the list item markup – already passed as the second argument to the onItemClick(AdapterView<?> parent, View itemClicked, int position, long id) method. Do this:

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {  
         @Override 
         public void onItemClick(AdapterView<?> parent, View itemClicked, int position, long id) { 
              TextView tp = (TextView)itemClicked.findViewById(R.id.userid);
              Log.v("mes",tp.getText().toString()); 
         }
});

Even better – hang the listener inside the adapter. Better yet – rewrite under RecyclerView