切换TabLayout标签返回ChatFragment时RecyclerView条目翻倍求解决方案

根本原因 #

你当前的ChatFragment中，存储列表数据的list是类成员变量，Fragment实例在切换页面时不会被销毁，只会销毁视图层。每次切回ChatFragment触发onCreateView回调时，都会调用getChatList()方法向同一个list中追加数据，不会清空旧数据，同时重复绑定新Adapter，最终导致条目数量累加翻倍。

可行解决方案 #

• 方案1：加载数据前先清空原有列表
  在getChatList()方法最开头加入列表清空逻辑，避免重复累加数据：

  private void getChatList() {
      // 先清空原有数据，防止累加
      list.clear();
      list.add(new ChatListModel("11","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
      list.add(new ChatListModel("12","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
      list.add(new ChatListModel("13","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
      list.add(new ChatListModel("14","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
      list.add(new ChatListModel("15","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
      // 第一次初始化后不需要重复创建Adapter
      if(rv.getAdapter() == null) {
          rv.setAdapter(new ChatListAdapter(list,getContext()));
      } else {
          rv.getAdapter().notifyDataSetChanged();
      }
  }
  

• 方案2：优化Adapter复用逻辑（推荐）
  将Adapter设置为Fragment的成员变量，全局只初始化一次，后续数据变更仅刷新列表，避免重复创建Adapter带来的性能损耗：

  public class ChatsFragment extends Fragment {
      public ChatsFragment() {}
      private List<ChatListModel> list = new ArrayList<>();
      private RecyclerView rv;
      // 新增Adapter成员变量
      private ChatListAdapter adapter;
  
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
                               Bundle savedInstanceState) {
          View v =  inflater.inflate(R.layout.fragment_chats, container, false);
          rv = v.findViewById(R.id.recycler_view);
          rv.setLayoutManager(new LinearLayoutManager(getContext()));
          // 全局只初始化一次Adapter
          if(adapter == null) {
              adapter = new ChatListAdapter(list, getContext());
              rv.setAdapter(adapter);
          }
          getChatList();
          return v;
      }
  
      private void getChatList() {
          list.clear();
          // 此处添加模拟数据逻辑不变
          list.add(new ChatListModel("11","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
          list.add(new ChatListModel("12","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
          list.add(new ChatListModel("13","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
          list.add(new ChatListModel("14","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
          list.add(new ChatListModel("15","Devesh","good bye","15/10/2020","https://i.pinimg.com/550x/7d/1a/3f/7d1a3f77eee9f34782c6f88e97a6c888.jpg"));
          // 数据更新后通知Adapter刷新即可
          adapter.notifyDataSetChanged();
      }
  }
  

• 方案3：可选适配ViewPager场景
  如果你是通过ViewPager/ViewPager2加载Fragment，可以设置页面缓存数量，避免Fragment视图重复销毁重建，减少不必要的onCreateView回调：

  // ViewPager2 示例，参数根据你的总页面数调整，保证ChatFragment在缓存范围内
  viewPager2.setOffscreenPageLimit(2);
  

内容的提问来源于stack exchange，提问作者Devesh Parmar