Question

我的日期时间当前存储为UNIX时间戳。我想在Recyclerview中将其显示为h：mm a。

在RecyclerView Adapter / Viewholder中，我应该在哪里将UNIX时间戳转换为正常时间（就最佳性能而言）？

我应该在getItemViewType(int position)的{{1}}还是RecyclerView.Adapter类的onBindViewHolder或bind函数中做到这一点？

编辑：我的代码

ViewHolder

这是正确的方法吗？我使用public class ChatListAdapter extends RecyclerView.Adapter { private final LayoutInflater mInflater; private List<Chat> mChats; private final String ownerMe = "OWNER_ME"; private static final int VIEW_TYPE_MESSAGE_ME = 1; private static final int VIEW_TYPE_MESSAGE_ME_CORNER = 2; private static final int VIEW_TYPE_MESSAGE_BF = 3; private static final int VIEW_TYPE_MESSAGE_BF_CORNER = 4; ChatListAdapter(Context context) {mInflater = LayoutInflater.from(context);} @Override public int getItemViewType(int position) { Chat chat = mChats.get(position); if(chat.getUser().equals(ownerMe)) { if(position == mChats.size()-1) { return VIEW_TYPE_MESSAGE_ME_CORNER; } if(chat.getUser().equals(mChats.get(position+1).getUser())) { return VIEW_TYPE_MESSAGE_ME; } else { return VIEW_TYPE_MESSAGE_ME_CORNER; } } else { if(position == mChats.size()-1) { return VIEW_TYPE_MESSAGE_BF_CORNER; } if(chat.getUser().equals(mChats.get(position+1).getUser())) { return VIEW_TYPE_MESSAGE_BF; } else { return VIEW_TYPE_MESSAGE_BF_CORNER; } } } @Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View view; if(viewType == VIEW_TYPE_MESSAGE_ME || viewType == VIEW_TYPE_MESSAGE_ME_CORNER) { view = mInflater.inflate(R.layout.recyclerview_item_right, parent, false); return new MeMessageHolder(view); } else if (viewType == VIEW_TYPE_MESSAGE_BF || viewType == VIEW_TYPE_MESSAGE_BF_CORNER) { view = mInflater.inflate(R.layout.recyclerview_item_left, parent, false); return new BfMessageHolder(view); } return null; } @Override public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) { if (mChats != null) { Chat current = mChats.get(position); long unixTime= current.getUnixTime(); Date time = new java.util.Date(unixTime*1000L); SimpleDateFormat sdf = new java.text.SimpleDateFormat("h:mm a"); String formattedTime = sdf.format(time); switch (holder.getItemViewType()) { case VIEW_TYPE_MESSAGE_ME: ((MeMessageHolder) holder).bind(current, formattedTime, false); break; case VIEW_TYPE_MESSAGE_ME_CORNER: ((MeMessageHolder) holder).bind(current, formattedTime, true); break; case VIEW_TYPE_MESSAGE_BF: ((BfMessageHolder) holder).bind(current, formattedTime, false); break; case VIEW_TYPE_MESSAGE_BF_CORNER: ((BfMessageHolder) holder).bind(current, formattedTime, true); break; } } } class MeMessageHolder extends RecyclerView.ViewHolder { private final TextView chatItemView; private final ImageView cornerRightIImageView; private final ConstraintLayout constraintLayout; private final TextView timeItemView; private MeMessageHolder(View itemView) { super(itemView); chatItemView = itemView.findViewById(R.id.textView); cornerRightIImageView = itemView.findViewById(R.id.corner_view_right); constraintLayout = itemView.findViewById(R.id.chat_bubble_id); timeItemView = itemView.findViewById(R.id.text_message_time); } void bind(Chat chat, String formattedTime, boolean isCorner) { chatItemView.setText(chat.getMessage()); timeItemView.setText(formattedTime); if(isCorner) { constraintLayout.setBackgroundResource(R.drawable.chat_bubble_v2); } else { cornerRightIImageView.setVisibility(View.INVISIBLE); } } } class BfMessageHolder extends RecyclerView.ViewHolder { private final TextView chatItemView; private final ImageView cornerLeftImageView; private final ConstraintLayout constraintLayout; private final TextView timeItemView; private BfMessageHolder(View itemView) { super(itemView); chatItemView = itemView.findViewById(R.id.textView); cornerLeftImageView = itemView.findViewById(R.id.corner_view_left); constraintLayout = itemView.findViewById(R.id.chat_bubble_id); timeItemView = itemView.findViewById(R.id.text_message_time); } void bind(Chat chat, String formattedTime, boolean isCorner) { chatItemView.setText(chat.getMessage()); timeItemView.setText(formattedTime); if(isCorner) { constraintLayout.setBackgroundResource(R.drawable.chat_bubble_v3); } else { cornerLeftImageView.setVisibility(View.INVISIBLE); } } } void setChats(List<Chat> chats) { mChats = chats; notifyDataSetChanged(); } @Override public int getItemCount() { if(mChats!=null) return mChats.size(); else return 0; } }方法

格式化了日期

Answer 1

这取决于您是要在recyclerview的不同项目上显示不同的日期，还是要在recyclerview的所有项目上显示相同的日期。如果要对所有项目显示相同的日期，最好在适配器之外进行，然后将解析的日期传递给recyclerview适配器。或者，如果要在每个项目上显示不同的日期，则应在onBindViewHolder中执行此操作，因为它可以访问项目位置。

请记住，getItemViewType用于从可用视图类型中获取视图类型。如果要放大多个视图，则使用此方法。考虑一个chatapp，其中view1将在左侧显示消息，而view2将在右侧显示消息；都在同一个回收站视图中。

onBindViewHolder方法仅执行通用绑定任务。绑定what：膨胀视图的项目和数据。

Answer 2

似乎是业务逻辑。因此，例如，我建议您在Model中将UNIX时间戳转换。

class Chat {

   private Long unixTime;

   // another code

   public Long getUnixTime() {
      return unixTime;
   }

   public String convertedUnixTimeToString(String format) {
      // Also need to add some format validation     
      if(format == null) {
         // do some action, like trowing exception, or setting default value in format
      } 

      Date time = new java.util.Date(unixTime*1000L);
      SimpleDateFormat sdf = new java.text.SimpleDateFormat(format);

      return sdf.format(time);
   }

}

我建议您使用JodaTime进行日期和时间格式化。非常有用的东西。

然后，只需修改您的代码


public class ChatListAdapter extends RecyclerView.Adapter {


    private final LayoutInflater mInflater;
    private List<Chat> mChats;
    private final String ownerMe = "OWNER_ME";
    private static final int VIEW_TYPE_MESSAGE_ME = 1;
    private static final int VIEW_TYPE_MESSAGE_ME_CORNER = 2;
    private static final int VIEW_TYPE_MESSAGE_BF = 3;
    private static final int VIEW_TYPE_MESSAGE_BF_CORNER = 4;

    ChatListAdapter(Context context) {mInflater = LayoutInflater.from(context);}

    @Override
    public int getItemViewType(int position) {
        Chat chat = mChats.get(position);

        if(chat.getUser().equals(ownerMe)) {
            if(position == mChats.size()-1) {
                return VIEW_TYPE_MESSAGE_ME_CORNER;
            }
            if(chat.getUser().equals(mChats.get(position+1).getUser())) {
                return VIEW_TYPE_MESSAGE_ME;
            } else {
                return VIEW_TYPE_MESSAGE_ME_CORNER;
            }
        } else {
            if(position == mChats.size()-1) {
                return VIEW_TYPE_MESSAGE_BF_CORNER;
            }
            if(chat.getUser().equals(mChats.get(position+1).getUser())) {
                return VIEW_TYPE_MESSAGE_BF;
            } else {
                return VIEW_TYPE_MESSAGE_BF_CORNER;
            }
        }
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view;

        if(viewType == VIEW_TYPE_MESSAGE_ME || viewType == VIEW_TYPE_MESSAGE_ME_CORNER) {
            view = mInflater.inflate(R.layout.recyclerview_item_right, parent, false);
            return new MeMessageHolder(view);
        } else if (viewType == VIEW_TYPE_MESSAGE_BF || viewType == VIEW_TYPE_MESSAGE_BF_CORNER) {
            view = mInflater.inflate(R.layout.recyclerview_item_left, parent, false);
            return new BfMessageHolder(view);
        }
        return null;

    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (mChats != null) {
            Chat current = mChats.get(position);

            switch (holder.getItemViewType()) {
                case VIEW_TYPE_MESSAGE_ME:
                    ((MeMessageHolder) holder).bind(current, false);
                    break;
                case VIEW_TYPE_MESSAGE_ME_CORNER:
                    ((MeMessageHolder) holder).bind(current, true);
                    break;
                case VIEW_TYPE_MESSAGE_BF:
                    ((BfMessageHolder) holder).bind(current, false);
                    break;
                case VIEW_TYPE_MESSAGE_BF_CORNER:
                    ((BfMessageHolder) holder).bind(current, true);
                    break;
            }
        }
    }

    class MeMessageHolder extends RecyclerView.ViewHolder {
        private final TextView chatItemView;
        private final ImageView cornerRightIImageView;
        private final ConstraintLayout constraintLayout;
        private final TextView timeItemView;


        private MeMessageHolder(View itemView) {
            super(itemView);
            chatItemView = itemView.findViewById(R.id.textView);
            cornerRightIImageView = itemView.findViewById(R.id.corner_view_right);
            constraintLayout = itemView.findViewById(R.id.chat_bubble_id);
            timeItemView = itemView.findViewById(R.id.text_message_time);

        }

        void bind(Chat chat, boolean isCorner) {
            chatItemView.setText(chat.getMessage());
            timeItemView.setText(chat.convertedUnixTimeToString("h:mm a"));
            if(isCorner) {
                constraintLayout.setBackgroundResource(R.drawable.chat_bubble_v2);
            } else {
                cornerRightIImageView.setVisibility(View.INVISIBLE);
            }
        }
    }

    class BfMessageHolder extends RecyclerView.ViewHolder {
        private final TextView chatItemView;
        private final ImageView cornerLeftImageView;
        private final ConstraintLayout constraintLayout;
        private final TextView timeItemView;

        private BfMessageHolder(View itemView) {
            super(itemView);
            chatItemView = itemView.findViewById(R.id.textView);
            cornerLeftImageView = itemView.findViewById(R.id.corner_view_left);
            constraintLayout = itemView.findViewById(R.id.chat_bubble_id);
            timeItemView = itemView.findViewById(R.id.text_message_time);
        }

        void bind(Chat chat, boolean isCorner) {
            chatItemView.setText(chat.getMessage());
            timeItemView.setText(chat.convertedUnixTimeToString("h:mm a"));
            if(isCorner) {
                constraintLayout.setBackgroundResource(R.drawable.chat_bubble_v3);
            } else {
                cornerLeftImageView.setVisibility(View.INVISIBLE);
            }
        }
    }

    void setChats(List<Chat> chats) {
        mChats = chats;
        notifyDataSetChanged();
    }

    @Override
    public int getItemCount() {
        if(mChats!=null)
            return mChats.size();
        else return 0;
    }
}

Answer 3

您需要通过将时间戳乘以1000来将其转换为毫秒：

java.util.Date dateTime=new java.util.Date((long)timeStamp*1000);

然后首先需要将UNIX时间戳转换为日期时间格式

final long unixTime = 1372339860;
final String formattedDtm = Instant.ofEpochSecond(unixTime)
        .atZone(ZoneId.of("GMT-4"))
        .format(formatter);

System.out.println(formattedDtm);   // => '2013-06-27 09:31:00'

然后您要将此数据存储到RecyclerView的字段值那么您可以从这种时间格式（例如h:mm

）对其进行格式化

Answer 4

您应该使用onBindViewHolder方法更新UI更改。您可以在bind中调用ViewHolder的{{1}}方法。

示例：

onBindViewHolder

Answer 5

只需将SimpleDateFormat与yyyy-MM-dd模式一起使用。

在SimpleDateFormat.format(millis)的{{1}}方法中应用onBindViewHolder

Recyclerview Adapter（Android）中的数据处理位置

5 个答案: