Summary of problems when coding

Git commit problems

1. Warning:(142, 62) Suspicious call to ‘HashMap.get’
2. android git commit Warning:(3, 1) Default File template
3. Not annotated parameter overrides @NonNull parameter

It's an annotation, but the correct name is NonNull:

protected void onSaveInstanceState(@NonNull Bundle outState)
(And also)

import android.support.annotation.NoNNull;

The purpose is to allow the compiler to warn when 
certain assumptions are being violated 
(such as a parameter of a method that should always have a value, 
as in this particular case, although there are others). 
From the Support Annotations documentation:

The @NonNull annotation can be used to indicate that a 
given parameter can not be null.

If a local variable is known to be null (for example 
because some earlier code checked whether it was null), 
and you pass that as a parameter to a method where that parameter 
is marked as @NonNull, the IDE will warn you that you have a potential crash.
They are tools for static analysis. Runtime behavior is not altered at all.

In this case, the particular warning is that the original method 
you're overriding (in Activity) has a @NonNull annotation 
on the outState parameter, but you did not include it 
in the overriding method. Just adding it should fix the issue, i.e.

@Override
protected void onSaveInstanceState(@NonNull Bundle outState) {
    super.onSaveInstanceState(outState);
}

4.BitmapDrawable() method deprecated

popupMessage.setBackgroundDrawable(null) will clear the background.

5.catch branch identical to ‘FileNotFoundException’ branch

You can collapse exception branches if they're identical, 
and with the multi-catch syntax, you'll wind up with one 
catch statement that does the same thing as your three:

RecyclerView Problem

1. When data changes, the view not change (Because Picasso cache)