具有不同主持人的相同片段

Question

I have an activity with 3 tabs: A, B & C. For every tab, I've created a fragment (-f) and presenter (-p). The problem is that all three fragments (Af, Bf, Cf) are the same, but presenters are not. So the question is how I can avoid code duplicity? I've tried to create a BaseFragment and extend it from Af, Bf, Cf, but if I'm in Af and something happens Cf (like UI update), then I receive java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setVisibility(int)' on a null object reference , because Cf at this is destroyed (am I right?) I don't want to create 3 same fragments with the same layouts.

Answer 1

I've done something similar and I've found using Views a lot simpler and less buggy. The android fragment managers can exhibit unpredictable behavior at times when executing various transactions. Here's a quick sample of how it can work:

YourActivity extends Activity {
      View a,b,c;

      @Override
      protected void onCreate(Bundle savedInstanceState) {
          a = getLayoutInflater().inflate(R.layout.YOUR_LAYOUT_ID, null);
          b = getLayoutInflater().inflate(R.layout.YOUR_LAYOUT_ID, null);
          c = getLayoutInflater().inflate(R.layout.YOUR_LAYOUT_ID, null);
      }
}

The activity is the presenter / controller for android, so I would go ahead and have the logic here instead of defining a presenter class for now. On each tab press you could then control which view to show. I don't see the code in which your are performing fragment transition so I cannot comment for sure if your fragment was destroyed.