如何在 Android RecyclerView 中显示一组项目的上方日期/日期

Question

您好，我正在 JSONArray 中获取数据：

{ "chatArray": [
    {
        "msg_id": "193",
        "user_id": "15235",
        "first_name": "Vishal",
        "user_name": "vishal13",
        "message": "twilio",
        "chat_time": "2017-06-30 11:28:00"
    },
    {
        "msg_id": "192",
        "user_id": "15321",
        "first_name": "Rohit",
        "user_name": "rohit12",
        "message": "how are you?",
        "chat_time": "2017-06-30 11:28:00"
    }]}

我在RecyclerView 中显示完整的数据，现在我的要求是我想显示他们上面的日子的标题，比如whatsapp。

public ChatScreenAdapter(Activity con, List<EquityDetails> list, String senderImage, String receiverImage) {
    this.items = list;
    this.context = con;
    this.senderImage = senderImage;
    this.receiverImage = receiverImage;
    this.arraylist = new ArrayList<EquityDetails>();
    this.arraylist.addAll(items);
    if (con != null) {
        typeface_normal = Typeface.createFromAsset(con.getAssets(), "fonts/arial_regular.ttf");
        share = context.getSharedPreferences("quiz_sharePrefs", 0);
        login_checked = share.getBoolean("ConfirmLogin", false);
        if (login_checked) {
            user_id = share.getInt("user_id", 0);
        }
    }
}

public static int getTimeRemaining(long timeStamp) {
    Calendar sDate = toCalendar(timeStamp);
    Calendar eDate = toCalendar(System.currentTimeMillis());

    // Get the represented date in milliseconds
    long milis1 = sDate.getTimeInMillis();
    long milis2 = eDate.getTimeInMillis();

    // Calculate difference in milliseconds
    long diff = Math.abs(milis2 - milis1);

    return (int) (diff / (24 * 60 * 60 * 1000));
}

private static Calendar toCalendar(long timestamp) {
    Calendar calendar = Calendar.getInstance();
    calendar.setTimeInMillis(timestamp);
    calendar.set(Calendar.HOUR_OF_DAY, 0);
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    calendar.set(Calendar.MILLISECOND, 0);
    return calendar;
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.advisory_left_side_chat_screen, parent, false);
    return new MyViewHolder(itemView);
}

@Override
public void onBindViewHolder(final MyViewHolder holder, final int position) {
    final EquityDetails itemList = items.get(position);
    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
    Glide.with(context).load(Constants.Profile_images + "" + senderImage).asBitmap().centerCrop().placeholder(R.drawable.default_usr).into(new BitmapImageViewTarget(holder.userImageViewRight) {
        @Override
        protected void setResource(Bitmap resource) {
            RoundedBitmapDrawable circularBitmapDrawable =
                    RoundedBitmapDrawableFactory.create(context.getResources(), resource);
            circularBitmapDrawable.setCircular(true);
            holder.userImageViewRight.setImageDrawable(circularBitmapDrawable);
        }
    });
    Glide.with(context).load(receiverImage + "").asBitmap().centerCrop().placeholder(R.drawable.default_usr).into(new BitmapImageViewTarget(holder.userImageViewLeft) {
        @Override
        protected void setResource(Bitmap resource) {
            RoundedBitmapDrawable circularBitmapDrawable =
                    RoundedBitmapDrawableFactory.create(context.getResources(), resource);
            circularBitmapDrawable.setCircular(true);
            holder.userImageViewLeft.setImageDrawable(circularBitmapDrawable);
        }
    });
    if (Integer.parseInt(itemList.getId()) == user_id) {
        holder.leftSideLayout.setVisibility(View.GONE);
        holder.rightSideLayout.setVisibility(View.VISIBLE);
        holder.messageTextViewRight.setText(itemList.getReviews_message() + "");
        holder.nameTextViewRight.setText(itemList.getName());
        holder.timeTvRight.setText(parseDateToddMMyyyy(itemList.getCreated_time()));
    } else {
        holder.leftSideLayout.setVisibility(View.VISIBLE);
        holder.rightSideLayout.setVisibility(View.GONE);
        holder.messageTextViewLeft.setText(itemList.getReviews_message() + "");
        holder.nameTextViewLeft.setText(itemList.getName());
        holder.timeTvLeft.setText(parseDateToddMMyyyy(itemList.getCreated_time()));
    }
    long previousTs = 0;
   if (position > 1) {
        if (getTimeRemaining(parseDay(itemList.getCreated_time())) == 0)
            holder.dayTextView.setText("Today");
        else if (getTimeRemaining(parseDay(itemList.getCreated_time())) == 1)
            holder.dayTextView.setText("Yesterday");
        else
            holder.dayTextView.setText("convert the date and show");
    }

}

public long parseDay(String time) {
    // Make a Calendar whose DATE part is some time yesterday.
    Calendar cal = Calendar.getInstance();
    cal.roll(Calendar.DATE, -1);

    String inputPattern = "yyyy-MM-dd HH:mm:ss";
    String outputPattern = "dd MM";
    SimpleDateFormat inputFormat = new SimpleDateFormat(inputPattern);
    Date date = null;
    String str = null;
    Date d = null;

    try {
        date = inputFormat.parse(time);
        if (date.before(cal.getTime())) {
            //  myDate must be yesterday or earlier
            SimpleDateFormat outputFormat = new SimpleDateFormat(outputPattern);
            str = outputFormat.format(date);
            d = outputFormat.parse(str);
        } else {
            //  myDate must be today or later
            SimpleDateFormat outputFormat = new SimpleDateFormat(outputPattern);
            str = outputFormat.format(date);
            d = outputFormat.parse(str);
        }

    } catch (ParseException e) {
        e.printStackTrace();
    }

    return d.getTime();
}

public String parseDateToddMMyyyy(String time) {
    // Make a Calendar whose DATE part is some time yesterday.
    Calendar cal = Calendar.getInstance();
    cal.roll(Calendar.DATE, -1);

    String inputPattern = "yyyy-MM-dd HH:mm:ss";
    String outputPattern = "dd MMM";
    SimpleDateFormat inputFormat = new SimpleDateFormat(inputPattern);
    Date date = null;
    String str = null;

    try {
        date = inputFormat.parse(time);
       /* if (date.before(cal.getTime())) {
            //  myDate must be yesterday or earlier
            SimpleDateFormat outputFormat = new SimpleDateFormat(outputPattern);
            str = outputFormat.format(date);
        } else {*/
        //  myDate must be today or later
        outputPattern = "hh:mm aa";
        SimpleDateFormat outputFormat = new SimpleDateFormat(outputPattern);
        str = outputFormat.format(date);
        //}
    } catch (ParseException e) {
        e.printStackTrace();
    }

    return str.toUpperCase();
}

@Override
public int getItemCount() {
    return items.size();
}

public class MyViewHolder extends RecyclerView.ViewHolder {
    private RelativeLayout leftSideLayout;
    private RelativeLayout topLayoutLeft;
    private ImageView userImageViewLeft;
    private TextView nameTextViewLeft;
    private TextView staticTextViewLeft;
    private TextView messageTextViewLeft;
    private TextView timeTvLeft;
    private RelativeLayout rightSideLayout;
    private RelativeLayout topLayoutRight;
    private ImageView userImageViewRight;
    private TextView nameTextViewRight;
    private TextView staticTextViewRight;
    private TextView messageTextViewRight;
    private TextView timeTvRight;
    private TextView dayTextView;

    public MyViewHolder(View view) {
        super(view);
        leftSideLayout = (RelativeLayout) view.findViewById(R.id.left_side_layout);
        topLayoutLeft = (RelativeLayout) view.findViewById(R.id.top_layout_left);
        userImageViewLeft = (ImageView) view.findViewById(R.id.user_image_view_left);
        nameTextViewLeft = (TextView) view.findViewById(R.id.name_textView_left);
        staticTextViewLeft = (TextView) view.findViewById(R.id.static_textView_left);
        messageTextViewLeft = (TextView) view.findViewById(R.id.message_textView_left);
        timeTvLeft = (TextView) view.findViewById(R.id.time_tv_left);
        rightSideLayout = (RelativeLayout) view.findViewById(R.id.right_side_layout);
        topLayoutRight = (RelativeLayout) view.findViewById(R.id.top_layout_right);
        userImageViewRight = (ImageView) view.findViewById(R.id.user_image_view_right);
        nameTextViewRight = (TextView) view.findViewById(R.id.name_textView_right);
        staticTextViewRight = (TextView) view.findViewById(R.id.static_textView_right);
        messageTextViewRight = (TextView) view.findViewById(R.id.message_textView_right);
        timeTvRight = (TextView) view.findViewById(R.id.time_tv_right);
        dayTextView = (TextView) view.findViewById(R.id.day_textView);
        nameTextViewLeft.setTypeface(typeface_normal);
        nameTextViewRight.setTypeface(typeface_normal);
        messageTextViewLeft.setTypeface(typeface_normal);
        messageTextViewRight.setTypeface(typeface_normal);
        timeTvLeft.setTypeface(typeface_normal);
        timeTvRight.setTypeface(typeface_normal);
        dayTextView.setTypeface(typeface_normal);
        dayTextView.setVisibility(View.GONE);
    }
}

但是这里dayTextView 显示在每个项目的上方，而不是根据日期。我只想在相应消息的顶部显示每个日期一次。

Answer 1

主活动

public class MainActivity extends AppCompatActivity {

    private ChatAdapter chatAdapter;
    private RecyclerView recyclerView;
    private Context context;
    private int loggedInUserID;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        bindRecyclerView();
        // TODO get logged in user id and initialize into 'loggedInUserID'
    }

    @Override
    protected void onResume() {
        super.onResume();
        getData();
    }

    private void getData() {
        /**
         *Your server call to get data and parse json to your appropriate model
         * after parsing json to model simply call the
         */
        List<ChatModel> chatModelList = ParseData.chatParser(jsonArray);
        groupDataIntoHashMap(chatModelList);
    }

    private void bindRecyclerView() {
        chatAdapter = new ChatAdapter(null);
        chatAdapter.setUser(loggedInUserID);
        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(context);
        recyclerView.setLayoutManager(mLayoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(chatAdapter);
    }


    private void groupDataIntoHashMap(List<ChatModel> chatModelList) {
        LinkedHashMap<String, Set<ChatModel>> groupedHashMap = new LinkedHashMap<>();
        Set<ChatModel> list = null;
        for (ChatModel chatModel : chatModelList) {
            //Log.d(TAG, travelActivityDTO.toString());
            String hashMapKey = DateParser.convertDateToString(chatModel.getChatTime());
            //Log.d(TAG, "start date: " + DateParser.convertDateToString(travelActivityDTO.getStartDate()));
            if (groupedHashMap.containsKey(hashMapKey)) {
                // The key is already in the HashMap; add the pojo object
                // against the existing key.
                groupedHashMap.get(hashMapKey).add(chatModel);
            } else {
                // The key is not there in the HashMap; create a new key-value pair
                list = new LinkedHashSet<>();
                list.add(chatModel);
                groupedHashMap.put(hashMapKey, list);
            }
        }
        //Generate list from map
        generateListFromMap(groupedHashMap);

    }


    private List<ListObject> generateListFromMap(LinkedHashMap<String, Set<ChatModel>> groupedHashMap) {
        // We linearly add every item into the consolidatedList.
        List<ListObject> consolidatedList = new ArrayList<>();
        for (String date : groupedHashMap.keySet()) {
            DateObject dateItem = new DateObject();
            dateItem.setDate(date);
            consolidatedList.add(dateItem);
            for (ChatModel chatModel : groupedHashMap.get(date)) {
                ChatModelObject generalItem = new ChatModelObject();
                generalItem.setChatModel(chatModel);
                consolidatedList.add(generalItem);
            }
        }

        chatAdapter.setDataChange(consolidatedList);

        return consolidatedList;
    }

}

ChatModel.java

public class ChatModel implements Serializable {
        private String messageId;
        private int userId;
        private String firstName;
        private String userName;
        private String message;
        private Date chatTime;

        //TODO generate getter and setter

    }

ListObject.java（判断消息的类型）

public abstract class ListObject {
        public static final int TYPE_DATE = 0;
        public static final int TYPE_GENERAL_RIGHT = 1;
        public static final int TYPE_GENERAL_LEFT = 2;

        abstract public int getType(int userId);
    }

日期对象.java

public class DateObject extends ListObject {
        private String date;

        public String getDate() {
            return date;
        }

        public void setDate(String date) {
            this.date = date;
        }

        @Override
        public int getType(int userId) {
            return TYPE_DATE;
        }
    }

ChatModelObject.java

 public class ChatModelObject extends ListObject {

        private ChatModel chatModel;

        public ChatModel getChatModel() {
            return chatModel;
        }

        public void setChatModel(ChatModel chatModel) {
            this.chatModel = chatModel;
        }

        @Override
        public int getType(int userId) {
            if (this.chatModel.getUserId() == userId) {
                return TYPE_GENERAL_RIGHT;
            } else
                return TYPE_GENERAL_LEFT;
        }
    }

DateParse.java 解析日期以对聊天进行分组

 public class DateParser {
        private static DateFormat dateFormat1 = new SimpleDateFormat("dd/MM/yyyy");

        public static String convertDateToString(Date date) {
            String strDate = "";
            strDate = dateFormat1.format(date);
            return strDate;
        }
    }

ChatAdapter.java

 public class ChatAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

        private List<ListObject> listObjects;
        private int loggedInUserId;

        public ChatAdapter(List<ListObject> listObjects) {
            this.listObjects = listObjects;
        }

        public void setUser(int userId) {
            this.loggedInUserId = userId;
        }

        public void setDataChange(List<ListObject> asList) {
            this.listObjects = asList;
            //now, tell the adapter about the update
            notifyDataSetChanged();
        }

        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            RecyclerView.ViewHolder viewHolder = null;
            LayoutInflater inflater = LayoutInflater.from(parent.getContext());
            switch (viewType) {
                case ListObject.TYPE_GENERAL_RIGHT:
                    View currentUserView = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_chat_list_row_right, parent, false);
                    viewHolder = new ChatRightViewHolder(currentUserView); // view holder for normal items
                    break;
                case ListObject.TYPE_GENERAL_LEFT:
                    View otherUserView = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_chat_list_row_left, parent, false);
                    viewHolder = new ChatLeftViewHolder(otherUserView); // view holder for normal items
                    break;
                case ListObject.TYPE_DATE:
                    View v2 = inflater.inflate(R.layout.date_row, parent, false);
                    viewHolder = new DateViewHolder(v2);
                    break;
            }

            return viewHolder;

        }

        @Override
        public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
            switch (viewHolder.getItemViewType()) {
                case ListObject.TYPE_GENERAL_RIGHT:
                    ChatModelObject generalItem = (ChatModelObject) listObjects.get(position);
                    ChatRightViewHolder chatViewHolder = (ChatRightViewHolder) viewHolder;
                    chatViewHolder.bind(generalItem.getChatModel());
                    break;
                case ListObject.TYPE_GENERAL_LEFT:
                    ChatModelObject generalItemLeft = (ChatModelObject) listObjects.get(position);
                    ChatLeftViewHolder chatLeftViewHolder = (ChatLeftViewHolder) viewHolder;
                    chatLeftViewHolder.bind(generalItemLeft.getChatModel());
                    break;
                case ListObject.TYPE_DATE:
                    DateObject dateItem = (DateObject) listObjects.get(position);
                    DateViewHolder dateViewHolder = (DateViewHolder) viewHolder;
                    dateViewHolder.bind(dateItem.getDate());
                    break;
            }
        }

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

        @Override
        public int getItemViewType(int position) {
            return listObjects.get(position).getType(loggedInUserId);
        }

        public ListObject getItem(int position) {
            return listObjects.get(position);
        }
    }

当前用户消息的ChatRightViewHolder.java

public class ChatRightViewHolder extends RecyclerView.ViewHolder {
        private final String TAG = ChatRightViewHolder.class.getSimpleName();

        public ChatRightViewHolder(View itemView) {
            super(itemView);
            //TODO initialize your xml views
        }

        public void bind(final ChatModel chatModel) {
            //TODO set data to xml view via textivew.setText();
        }
    }

ChatLeftViewHolder.java 用于显示其他用户消息。

public class ChatLeftViewHolder extends RecyclerView.ViewHolder {
        private final String TAG = ChatRightViewHolder.class.getSimpleName();

        public ChatLeftViewHolder(View itemView) {
            super(itemView);
            //TODO initialize your xml views
        }

        public void bind(final ChatModel chatModel) {
            //TODO set data to xml view via textivew.setText();
        }
    }

DateViewHolder.java 显示日期

public class DateViewHolder extends RecyclerView.ViewHolder {
        public DateViewHolder(View itemView) {
            super(itemView);
            //TODO initialize your xml views
        }

        public void bind(final String date) {
            //TODO set data to xml view via textivew.setText();
        }
    }