RecycleView adapters refactoring

[mikolevy]

In all RecyclerViewAdapter classes we have some common, not needed code. We should refactor it to remove this code.

1. Initialization
   It's always done in three steps:

• Create an adapter with the constructor (planListAdapter = new PlanRecyclerViewAdapter(planItemClickListener);)
• set adapter in recycle view (recyclerView.setAdapter(planListAdapter);)
• set adapter items via setter method (planListAdapter.setPlanItems(planTemplateRepository.getAll());)

We can pass data in constructor to avoid initialization with empty ArrayList and extra setter call:

planListAdapter = new PlanRecyclerViewAdapter(planTemplateRepository.getAll(), planItemClickListener);
recyclerView.setAdapter(planListAdapter);

2. onBindViewHolder
   Currently, we do checking against null or empty values list: (planItemList != null && !planItemList.isEmpty())

Actually we don't need those checks, cause:

• value list should never be null (it's inited in the constructor with a list of values from the repo, or updated later via setter with the same kind of data). Setting null value should be considered as programming error and should cause app crash instead of undefined behavior.
• If the list is empty there is nothing to display so Android won't call this method
  We can just remove those checks

3. getItemCount
   Currently, we do checking against null or empty values list: return planItemList != null && planItemList.size() != 0 ? planItemList.size() : 0;

• List won't be null (as described in 2) )
• We don't need special treatment for the situation when list.size() == 0 cause return list.size() already resolves it (return list.size() != 0 ? list.size() : 0; is identical to return list.size();
  We can refactor it to simply return list.size();